I need a small slot in my sundial bases. Usually I pre-drill the hole
(either 3/16" or 1/4") and then extend by 0.075" (1/4" hole) or 0.50" (3/16"
hole) the material is 3/8" key stock, galvanized, made in USA. The mill is a
generic X2, the mill bits are Chinese box set.

I have been using the side of the mill doing the full thickness all at once.
The slots have been coming out skewed which was visually obvious even at
these short distances. The wise was checked and is fine (0.001" over 4"
parallel).

Today I decided to experiment. First I did this:

http://www.flickr.com/photos/2768312...n/photostream/

then I progressed to this:

http://www.flickr.com/photos/2768312...n/photostream/

and this:

http://www.flickr.com/photos/2768312...n/photostream/

with the final event documented he

http://www.flickr.com/photos/2768312...n/photostream/


I interpret this that doing the full thickness slot is a bad thing,
presumably the mill is conventionally milling one side of the slot and climb
milling the other with resulting sideways movement. I have not seen this
documented elsewhere so my question is: Do those with the Big Beasts see the
same thing? Is this a reflection on poor rigidity of my mini or is this a
universally bad procedure to do the full thickness at once?

The other question is the mill bit: I think I milled less than 10 slots with
this particular one. Am I unreasonable expecting it to last longer? Was it
my technique or the provenance of the bit? Are there manufacturers I should
look to preferentially for replacement?

Thanks,

--
Michael Koblic
Campbell River, BC

I think your problem is that you are not locking the table in the X
direction when you are moving in the Y direction.

Dan

I interpret this that doing the full thickness slot is a bad thing,
presumably the mill is conventionally milling one side of the slot and
climb
milling the other with resulting sideways movement. I have not seen this
documented elsewhere so my question is: Do those with the Big Beasts see
the
same thing? Is this a reflection on poor rigidity of my mini or is this a
universally bad procedure to do the full thickness at once?

The other question is the mill bit: I think I milled less than 10 slots
with
this particular one. Am I unreasonable expecting it to last longer? Was it
my technique or the provenance of the bit? Are there manufacturers I
should
look to preferentially for replacement?

Thanks,

--

Given the result, obviously something is moving.

Since that particular set-up is not giving you the results you want, I would
try this.

Center drill and then drill undersize holes at each end of the slot.

Swap to a full size end mill to then size each end of the slot.

Next swap to an under size mill and go between the holes at each end taking
passes until you get to full depth.

Now work the edges of the slot to bring it to full width.

By sneaking up on your desired dimension the flex in the cutter or the
machine will cause you a lot less mischief and your cutters will last
longer.

--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.

"Michael Koblic" wrote in message
...

snip


I interpret this that doing the full thickness slot is a bad thing,
presumably the mill is conventionally milling one side of the slot and
climb milling the other with resulting sideways movement. I have not seen
this documented elsewhere so my question is: Do those with the Big Beasts
see the same thing? Is this a reflection on poor rigidity of my mini or is
this a universally bad procedure to do the full thickness at once?

The other question is the mill bit: I think I milled less than 10 slots
with this particular one. Am I unreasonable expecting it to last longer?
Was it my technique or the provenance of the bit? Are there manufacturers
I should look to preferentially for replacement?

Thanks,

--
Michael Koblic
Campbell River, BC

short answer "no"
longer answer - as someone else posted, you need to lock your table in the
direction you are not expecting it to move.

I have no problem cutting a 1 inch wide by 1 inch deep slot with a 1 inch
end mill on my Abene - it's a bit bigger than your mini, but I don't know
that I 'd call it a "beast"

On Sun, 4 Oct 2009 19:01:03 -0700, "Michael Koblic"
wrote:

I need a small slot in my sundial bases. Usually I pre-drill the hole
(either 3/16" or 1/4") and then extend by 0.075" (1/4" hole) or 0.50" (3/16"
hole) the material is 3/8" key stock, galvanized, made in USA. The mill is a
generic X2, the mill bits are Chinese box set.

I have been using the side of the mill doing the full thickness all at once.
The slots have been coming out skewed which was visually obvious even at
these short distances. The wise was checked and is fine (0.001" over 4"
parallel).

Today I decided to experiment. First I did this:

http://www.flickr.com/photos/2768312...n/photostream/

then I progressed to this:

http://www.flickr.com/photos/2768312...n/photostream/

and this:

http://www.flickr.com/photos/2768312...n/photostream/

with the final event documented he

http://www.flickr.com/photos/2768312...n/photostream/


My eyes!! My Eyes!!!

Sigh..you are doing every ..and I mean EVERY newbie error in milling Ive
ever seen.

Ill wait and see what the others have to say..maybe Ill not have to
write you a chapter on milling.

That cutter btw..should have gone another 50 or 100 of those slots at
the very very least. Minimum



I interpret this that doing the full thickness slot is a bad thing,
presumably the mill is conventionally milling one side of the slot and climb
milling the other with resulting sideways movement. I have not seen this
documented elsewhere so my question is: Do those with the Big Beasts see the
same thing? Is this a reflection on poor rigidity of my mini or is this a
universally bad procedure to do the full thickness at once?

The other question is the mill bit: I think I milled less than 10 slots with
this particular one. Am I unreasonable expecting it to last longer? Was it
my technique or the provenance of the bit? Are there manufacturers I should
look to preferentially for replacement?

Thanks,

Political Correctness is a doctrine fostered by a delusional,
illogical liberal minority, and rabidly promoted by an
unscrupulous mainstream media, which holds forth the
proposition that it is entirely possible to pick up a turd by the clean end.

On 2009-10-05, Michael Koblic wrote:
I need a small slot in my sundial bases. Usually I pre-drill the hole
(either 3/16" or 1/4") and then extend by 0.075" (1/4" hole) or 0.50" (3/16"
hole) the material is 3/8" key stock, galvanized, made in USA. The mill is a
generic X2, the mill bits are Chinese box set.

I have been using the side of the mill doing the full thickness all at once.
The slots have been coming out skewed which was visually obvious even at
these short distances. The wise was checked and is fine (0.001" over 4"
parallel).

[ ... ]

I interpret this that doing the full thickness slot is a bad thing,

Yes -- and doing it with a four-flute end mill is another bad
thing.

presumably the mill is conventionally milling one side of the slot and climb
milling the other with resulting sideways movement.

While you are cutting, the leading flute in the direction of
travel (which is doing most of the work) deflects the end mill to the
side opposite of its travel, allowing the next flute back to cut out the
one side of the slot. This causes the kind of thing you see -- with the
amount you see depending on the rigidity of the entire setup and the
length of exposed end-mill. (A longer mill has more flex than a shorter
one.

I have not seen this
documented elsewhere so my question is: Do those with the Big Beasts see the
same thing? Is this a reflection on poor rigidity of my mini or is this a
universally bad procedure to do the full thickness at once?

Bad to do more than about half the diameter of the end mill in
thickness at a pass.

Even worse to use 4-flute end mills. What you want to use is
two-flute ones (often called "slot drills" in the UK I believe because
they are so much beter for slotting).

The other question is the mill bit: I think I milled less than 10 slots with
this particular one. Am I unreasonable expecting it to last longer? Was it
my technique or the provenance of the bit? Are there manufacturers I should
look to preferentially for replacement?

What coolant? What RPM? What feed per tooth? And the
galvanized key stock is probably a rather gummy steel. Go for 12L14 (as
for turning) to find out how much better things can be.

But yes -- the Chinese origin of the end mill suggests that it
could be very poor quality steel.

Buy some *two*-flute end cutting mills by a maker such as
Cleveland, check the RPM against the diameter (calculate the SFM
(Surface Feet per Minute) and compare it to the tables in books like
_Machinery's Handbook_ (pretty much any old edition will do for this).
look up the feed per tooth (for a two-flute end mill here), and working
with the RPM calculate how many inches per minute you want to feed. You
don't want to go faster, but you don't want to go too much slower,
either.

Note that some Chinese boxed sets have both two-flute and
four-flute in each size, and some of them can be pretty good. It
depends on where you get them, among other things. I have a set which I
got from MSC, and they are useful for a lot of things, but for serious
work I use Cleveland or other US-made mills bought for the task.

Good Luck,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

wrote in message
...
I think your problem is that you are not locking the table in the X
direction when you are moving in the Y direction.


No, that is not it. I locked the stationary axis every time (I tried this
milling along both x and y).
I should also add that when I pulled the mill out of the end of the first
(banana shaped) slot it would not go down the same hole again and returned
to its original position along the (in this case) x-axis. It is apparent in
the second pic.

--
Michael Koblic
Campbell River, BC

"Bill Noble" wrote in message
...

short answer "no"
longer answer - as someone else posted, you need to lock your table in the
direction you are not expecting it to move.

I have no problem cutting a 1 inch wide by 1 inch deep slot with a 1 inch
end mill on my Abene - it's a bit bigger than your mini, but I don't know
that I 'd call it a "beast"

Interesting. Makes me wonder if it is the property of *this particular*
mill. As I said, I have not heard anyone mention this phenomenon before and
I did a ton of looking and reading before I cut anything.

--
Michael Koblic
Campbell River, BC

On Sun, 4 Oct 2009 20:47:34 -0700, "Bill Noble"
wrote:


"Michael Koblic" wrote in message
...

snip


I interpret this that doing the full thickness slot is a bad thing,
presumably the mill is conventionally milling one side of the slot and
climb milling the other with resulting sideways movement. I have not seen
this documented elsewhere so my question is: Do those with the Big Beasts
see the same thing? Is this a reflection on poor rigidity of my mini or is
this a universally bad procedure to do the full thickness at once?

The other question is the mill bit: I think I milled less than 10 slots
with this particular one. Am I unreasonable expecting it to last longer?
Was it my technique or the provenance of the bit? Are there manufacturers
I should look to preferentially for replacement?

Thanks,

--
Michael Koblic
Campbell River, BC

short answer "no"
longer answer - as someone else posted, you need to lock your table in the
direction you are not expecting it to move.

I have no problem cutting a 1 inch wide by 1 inch deep slot with a 1 inch
end mill on my Abene - it's a bit bigger than your mini, but I don't know
that I 'd call it a "beast"


While its not as tall as a Bridgeport..its far far more rigid than
one..and head and hands more rigid than an import minimill.

Crom but I love my Abene!!!!


Gunner

Political Correctness is a doctrine fostered by a delusional,
illogical liberal minority, and rabidly promoted by an
unscrupulous mainstream media, which holds forth the
proposition that it is entirely possible to pick up a turd by the clean end.

I have no idea what a "generic x2" milling machine is, but
these two comments suggest to me that you must be feeding 'way too fast
for the stiffness of the setup/machine.

Is the machine bolted down? If not, do it.

Pete Stanaitis
------------------

Michael Koblic wrote:
---- I have never got as high as 1100
(nominal) as the machine starts shaking.


----- IMHO they should also include operator's nerves.

On Mon, 05 Oct 2009 11:33:19 -0500, spaco wrote:

I have no idea what a "generic x2" milling machine is, but these two
comments suggest to me that you must be feeding 'way too fast for the
stiffness of the setup/machine.

Sieg X2, also known as mini-mill. See
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=44991
or http://www.mini-lathe.com/Mini_mill/Versions/versions.htm

Is the machine bolted down? If not, do it.
....
Michael Koblic wrote:
---- I have never got as high as 1100
(nominal) as the machine starts shaking.

----- IMHO they should also include operator's nerves.



--
jiw

Cutting tools on steel .

Tool needs to be small tooth , so force is low . .

Then speed it up .. Carbide does higher speed than M2 HSS .

You are using big cutters , use 1/4" carbide , 4 flute .



You can reduce the force by using a tiny

cutter , some thing that pulls out a chip ,

with little HorsePower .

Luddite liberal designed Mills need torque breakover clutches .

1) clutch ( cause operators are never perfect)

2) very low pressure of cutter against workpiece . This means
speeding
up and less tooth ., small diameter ..
carbide allows higher speeds , clutch protects tool , if operator
hand feeds ..

3) Obviously 4 flutes are better than 2 ! Cause cutter must enter
cut at perfect speed , so 2 flutes take twice as long to cut , nobody
has
that patience .







Image a cheap 18vdc 550 RPM VAR-speed cordless drill , with
breakover clutch ,, tiny 4 flute , 3/16" carbide cutter , in DIY
mill .

Clever ...

"Bill Noble" wrote in message
...

just so you don't get put off by my comment, the Abene mill is pictured
under hobbies/tools on my web page wbnoble.com - it has a 6 HP spindle
motor and a 2 hp ways motor, which places it in the "bit bigger"
category - 'real' mills in production seem to have about 10X that power
nowadays, but this is enough for me to break the tool of my choice every
time I make a stupid mistake.


That is only 18x more powerful than mine...Bet you cannot throw yours across
the room in a fit of rage!

"spaco" wrote in message
...
I have no idea what a "generic x2" milling machine is, but
these two comments suggest to me that you must be feeding 'way too fast
for the stiffness of the setup/machine.

It is a thought but I doubt that. Usually I feed slowly so that neither the
machine nor myself are shaking.

Is the machine bolted down? If not, do it.

It is.

"heytwo" wrote in message
...


Cutting tools on steel .

Tool needs to be small tooth , so force is low . .

Then speed it up .. Carbide does higher speed than M2 HSS .

You are using big cutters , use 1/4" carbide , 4 flute .



You can reduce the force by using a tiny

cutter , some thing that pulls out a chip ,

with little HorsePower .

Luddite liberal designed Mills need torque breakover clutches .

You are standing right there watching, and listening, and feeling, and
smelling the cut as it progresses. If these four senses fail you then I
have my doubts that you will have the brains to stop turning the crank when
the cutter stops.




1) clutch ( cause operators are never perfect)

2) very low pressure of cutter against workpiece . This means
speeding
up and less tooth ., small diameter ..
carbide allows higher speeds , clutch protects tool , if operator
hand feeds ..

3) Obviously 4 flutes are better than 2 ! Cause cutter must enter
cut at perfect speed , so 2 flutes take twice as long to cut , nobody
has
that patience .



While carbide will allow you to speed up the cutter to improve cycle time
they are a lot pricer and the small slots he is making in key stock can be
milled with HSS just fine. I doubt someone making sundials is woried about
making a few more parts per hour.


--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.

On Oct 5, 12:01*pm, "Michael Koblic" wrote:
I need a small slot in my sundial bases. Usually I pre-drill the hole
(either 3/16" or 1/4") and then extend by 0.075" (1/4" hole) or 0.50" (3/16"
hole) the material is 3/8" key stock, galvanized, made in USA. The mill is a
generic X2, the mill bits are Chinese box set.


Ah, nostalgia........................

I posted a similar query (almost identical, really)ages ago and DON
Nichols kind response was that I was trying to do several years of
shop in 20 minutes (or something to that effect) and he was right.
Thanks DON. Went and enrolled at a apprentice level course , still
there, still finding creative ways of stuffing things up...

My mill is an X2 - and does the same as yours - what I have found is:-
vibration is the killer - it will do God knows what if its not
rigidly, VERY rigidly bolted down. And even then, its really only good
for plastic/aluminium, its design limitations are that its a cheap
Chinese mill. If its vibrating, or the bench its on is vibrating,
then its too much.
You will break cutters through vibration - think about it, the thing
is being bounced around like blazes, no wonder their wearing out fast.
Your expecting a bit too much from it - I would suggest cutting
multiple small slots, creeping up on the final size. Speed? - almost
irrelevant here as the thing doesnt have a tachometer, or a power feed
- you have to go by ear, and you will develop this in time. What sort
of vise are you using? - if its one of the ones that can swivel on its
base, take off the base and mount it directly on the table. It helps.
Are you using the proper sized holder for the bit, not just the Jacobs
chuck you use for drilling?. Have you set up the mill properly (or at
least tried to) - out of the box, their pretty shocking, play in the
gibs, out of plump, lotsa backlash. The belt drive conversion helps
too - makes them a lot smoother, you have probably broken a tooth in
the gearbox by now (stick it in low range, manually turn the spindle -
it should be smooth ALL the way round, if there's a "click at one
spot, then a (plastic) gear is broken. Google X2, there's HEAPS of
information/mods for the things....

AND - finally - yes, if you have a decent industrial machine, (and you
have 3-phase power and a BIG workshop) as mentioned, then these
problems dont exist - any machine that takes a forklift or trained
riggers to move it is going to be more rigid, with more power, and
built to tighter tolerances so things like you describe are ho-hum,
run of the mill sort of thing. But, when you do make a mistake, 5hp
will throw something a lot further and with greater terminal velocity
than the X2... when and if you can, upgrade to the X3, its
significantly better, or take the industrial machine route if you so
desire and can get it past SWMBO.....

Good luck - it will drive you absolutely NUTS, the learning curve is
near vertical to start with, but after a while things start to get
better/easier ...which means you start trying to do more complex
things, so its a lifelong process.

Andrew VK3BFA.

On Tue, 6 Oct 2009 00:10:46 -0700, "Roger Shoaf"
wrote:


"heytwo" wrote in message
...


Cutting tools on steel .

Tool needs to be small tooth , so force is low . .

Then speed it up .. Carbide does higher speed than M2 HSS .

You are using big cutters , use 1/4" carbide , 4 flute .



You can reduce the force by using a tiny

cutter , some thing that pulls out a chip ,

with little HorsePower .

Luddite liberal designed Mills need torque breakover clutches .

You are standing right there watching, and listening, and feeling, and
smelling the cut as it progresses. If these four senses fail you then I
have my doubts that you will have the brains to stop turning the crank when
the cutter stops.




1) clutch ( cause operators are never perfect)

2) very low pressure of cutter against workpiece . This means
speeding
up and less tooth ., small diameter ..
carbide allows higher speeds , clutch protects tool , if operator
hand feeds ..

3) Obviously 4 flutes are better than 2 ! Cause cutter must enter
cut at perfect speed , so 2 flutes take twice as long to cut , nobody
has
that patience .



While carbide will allow you to speed up the cutter to improve cycle time
they are a lot pricer and the small slots he is making in key stock can be
milled with HSS just fine. I doubt someone making sundials is woried about
making a few more parts per hour.


and carbide has the bending/loading ability of a piece of glass rod.
You cant feel the cut and you can/will snap a small carbide cutter in a
heart beat when turning a crank.

Carbide is great for a nice rigid PROGRAMABLE CNC milling machine. You
can really kick ass with it.

On a manual..with a small carbide cutter...CLINKDINKBANG!! is what you
are likely to get far far too often unless you have a lot of
experience. Even I bust far far too many small carbide cutters.

As for 4 flutes pulling more chips out and cutting faster with a bigger
chip load.......blink blink...I see we have a paper expert on line with
us today.......



Gunner

Political Correctness is a doctrine fostered by a delusional,
illogical liberal minority, and rabidly promoted by an
unscrupulous mainstream media, which holds forth the
proposition that it is entirely possible to pick up a turd by the clean end.

It would seem to me that if the cutting path errors aren't caused by
unintended table movement, then the wandering path is likely to be caused by
flexing of the endmill.

It's not easy to see the length of the endmill, or just the cutting section
of it, from the photo.

Another significant problem that happens when a small endmill is used to cut
the full width of a slot, is chip evacuation, or lack of it.

With cut chips present in the cutting area, the endmill is frequently
jamming as it's rotating, causing the endmill to try to cut fresh material,
plus the thickness of the chip(s) passing by the flute on the opposite side
of the endmill.
Chip interference can be heard as clicking or crunching sounds as the
endmill is cutting.
Some erratic table movement can probably be detected by placing a finger at
the point where the table dovetails meet.

The two conditions will lead to a wandering cutting path. The limited
rigidity of the minimill may also be a contributing factor.

Using a cutting tool lubricant in a squirt bottle, to constantly flush the
chips out of the cut should improve the results, but the sides of the slot
probably still won't be perfectly straight.
The spiral of the flutes will help carry chips away, but only to a limited
degree (less at lower RPMs). Using a medium viscosity cutting lubricant will
help the chips flow outward from the cut.

The other recommendation of drilling the ends of the slot location with a
rigid drill, followed by material removal with a smaller diameter endmill
would likely be the best procedure, especially with a light duty machine.

Flooding a cutting tool lubricant to flush chips away can obviously be
fairly messy, so coming up with a method to recover and contain the lube
might be worthwhile.
A small endmill isn't going to be slinging much lube, but the flooding
action should be constrained to the table area.

It might be possible to retrofit a gutter system around the edge of the
table, or the workpiece clamping methods might need to be reconsidered, to
allow the small parts to be cut with them sitting in a shallow pan on the
table.

The type of dispenser bottle I prefer for cutting lube is the wash bottle
with 90 degree spout shown near the bottom of this page (but in a 6oz
version)

http://www.zeph.com/dispensing-bottl...-dispenser.htm

or

http://www.2spi.com/catalog/plasticware/plast4.shtml

These types of squeeze bottles doesn't need to be inverted, and the tip
allows very good visibility of the work area.

--
WB
..........
metalworking projects
www.kwagmire.com/metal_proj.html


"Michael Koblic" wrote in message
...
I need a small slot in my sundial bases. Usually I pre-drill the hole
(either 3/16" or 1/4") and then extend by 0.075" (1/4" hole) or 0.50"
(3/16" hole) the material is 3/8" key stock, galvanized, made in USA. The
mill is a generic X2, the mill bits are Chinese box set.

I have been using the side of the mill doing the full thickness all at
once. The slots have been coming out skewed which was visually obvious
even at these short distances. The wise was checked and is fine (0.001"
over 4" parallel).

Today I decided to experiment. First I did this:

http://www.flickr.com/photos/2768312...n/photostream/

then I progressed to this:

http://www.flickr.com/photos/2768312...n/photostream/

and this:

http://www.flickr.com/photos/2768312...n/photostream/

with the final event documented he

http://www.flickr.com/photos/2768312...n/photostream/


I interpret this that doing the full thickness slot is a bad thing,
presumably the mill is conventionally milling one side of the slot and
climb milling the other with resulting sideways movement. I have not seen
this documented elsewhere so my question is: Do those with the Big Beasts
see the same thing? Is this a reflection on poor rigidity of my mini or is
this a universally bad procedure to do the full thickness at once?

The other question is the mill bit: I think I milled less than 10 slots
with this particular one. Am I unreasonable expecting it to last longer?
Was it my technique or the provenance of the bit? Are there manufacturers
I should look to preferentially for replacement?

Thanks,

--
Michael Koblic
Campbell River, BC

On Oct 5, 10:16*pm, "Michael Koblic" wrote:

The simple answer is to rough out the slot with a smaller end mill and
then finish each side separately.

jsw

On Tue, 6 Oct 2009 03:05:53 -0700 (PDT), Andrew VK3BFA
wrote:

On Oct 5, 12:01*pm, "Michael Koblic" wrote:
I need a small slot in my sundial bases. Usually I pre-drill the hole
(either 3/16" or 1/4") and then extend by 0.075" (1/4" hole) or 0.50" (3/16"
hole) the material is 3/8" key stock, galvanized, made in USA. The mill is a
generic X2, the mill bits are Chinese box set.


Ah, nostalgia........................

I posted a similar query (almost identical, really)ages ago and DON
Nichols kind response was that I was trying to do several years of
shop in 20 minutes (or something to that effect) and he was right.
Thanks DON. Went and enrolled at a apprentice level course , still
there, still finding creative ways of stuffing things up...

My mill is an X2 - and does the same as yours - what I have found is:-
vibration is the killer - it will do God knows what if its not
rigidly, VERY rigidly bolted down. And even then, its really only good
for plastic/aluminium, its design limitations are that its a cheap
Chinese mill. If its vibrating, or the bench its on is vibrating,
then its too much.
You will break cutters through vibration - think about it, the thing
is being bounced around like blazes, no wonder their wearing out fast.
Your expecting a bit too much from it - I would suggest cutting
multiple small slots, creeping up on the final size. Speed? - almost
irrelevant here as the thing doesnt have a tachometer, or a power feed
- you have to go by ear, and you will develop this in time. What sort
of vise are you using? - if its one of the ones that can swivel on its
base, take off the base and mount it directly on the table. It helps.
Are you using the proper sized holder for the bit, not just the Jacobs
chuck you use for drilling?. Have you set up the mill properly (or at
least tried to) - out of the box, their pretty shocking, play in the
gibs, out of plump, lotsa backlash. The belt drive conversion helps
too - makes them a lot smoother, you have probably broken a tooth in
the gearbox by now (stick it in low range, manually turn the spindle -
it should be smooth ALL the way round, if there's a "click at one
spot, then a (plastic) gear is broken. Google X2, there's HEAPS of
information/mods for the things....

AND - finally - yes, if you have a decent industrial machine, (and you
have 3-phase power and a BIG workshop) as mentioned, then these
problems dont exist - any machine that takes a forklift or trained
riggers to move it is going to be more rigid, with more power, and
built to tighter tolerances so things like you describe are ho-hum,
run of the mill sort of thing. But, when you do make a mistake, 5hp
will throw something a lot further and with greater terminal velocity
than the X2... when and if you can, upgrade to the X3, its
significantly better, or take the industrial machine route if you so
desire and can get it past SWMBO.....

Good luck - it will drive you absolutely NUTS, the learning curve is
near vertical to start with, but after a while things start to get
better/easier ...which means you start trying to do more complex
things, so its a lifelong process.

Andrew VK3BFA.


Very very well said! Kudos!!



Political Correctness is a doctrine fostered by a delusional,
illogical liberal minority, and rabidly promoted by an
unscrupulous mainstream media, which holds forth the
proposition that it is entirely possible to pick up a turd by the clean end.

"Wild_Bill" wrote in
news
snip
Another significant problem that happens when a small endmill is used
to cut the full width of a slot, is chip evacuation, or lack of it.

With cut chips present in the cutting area, the endmill is frequently
jamming as it's rotating, causing the endmill to try to cut fresh
material, plus the thickness of the chip(s) passing by the flute on
the opposite side of the endmill.
Chip interference can be heard as clicking or crunching sounds as the
endmill is cutting.
Some erratic table movement can probably be detected by placing a
finger at the point where the table dovetails meet.

The two conditions will lead to a wandering cutting path. The limited
rigidity of the minimill may also be a contributing factor.

If you can get away without coolant, you can keep the chips out of the
slot with a vacuum cleaner. I had to mill some ~ 5/8" diameter holes in
some aluminum extrusions, where the hole intersected several cutouts. I
had a good stiff end mill, but a not absolutely rigid Clausing 8520 mill.
Chips would constantly get caught between the end mill flutes and the
interrupted cuts, and cause momentary jams & lots of vibration. You
could hear & feel the machine jumping around. I set up my shop vac with
a nozzle to keep the chips clear, and it worked MUCH better.

Doug White

On 2009-10-05, Michael Koblic wrote:

"DoN. Nichols" wrote in message
...

I interpret this that doing the full thickness slot is a bad thing,

Yes -- and doing it with a four-flute end mill is another bad
thing.

Hm. when I started I was told "two flutes good, four flutes better (for
steel)"

That depends. If you are using just one side to face the edge
of a workpiece, then four flutes doubles the number of "teeth", so the
feed per tooth can be doubled for a given RPM and workpiece
material/cutter material combination.

presumably the mill is conventionally milling one side of the slot and
climb
milling the other with resulting sideways movement.

While you are cutting, the leading flute in the direction of
travel (which is doing most of the work) deflects the end mill to the
side opposite of its travel, allowing the next flute back to cut out the
one side of the slot. This causes the kind of thing you see -- with the
amount you see depending on the rigidity of the entire setup and the
length of exposed end-mill. (A longer mill has more flex than a shorter
one.

I have not seen this
documented elsewhere so my question is: Do those with the Big Beasts see
the
same thing? Is this a reflection on poor rigidity of my mini or is this a
universally bad procedure to do the full thickness at once?

Bad to do more than about half the diameter of the end mill in
thickness at a pass.

It may be even less than that. I have not shown all I have done but when I
did 0.100" passes there was a definite tendency for the slot to wander.

O.K. And as someone else mentioned, are you locking the axis
which you don't want to move? Vibration can cause the handwheel to
rotate, especially if it is not a balanced handwheel (extra mass on the
side opposite the crank handle, so it will balance in any position).

Even worse to use 4-flute end mills. What you want to use is
two-flute ones (often called "slot drills" in the UK I believe because
they are so much better for slotting).

The other question is the mill bit: I think I milled less than 10 slots
with
this particular one. Am I unreasonable expecting it to last longer? Was
it
my technique or the provenance of the bit? Are there manufacturers I
should
look to preferentially for replacement?

What coolant?

Jus Rapid Tap.

Hmm ... I would use something like Rigid's high sulfur threading
oil in preference to that for that particular task.

And an alternative possibility is simply a jet of compressed air
directed right at the cut to blow chips clear so they can't build up on
the cutter and bind it in the cut.

What RPM?

I could BS and say 550 rpm but the truth is somewhere between "vroom-vroom"
and low pitched "brrr". The regulator is supposed to go from zero to 1100
rpm but I strongly suspect it is not linear. How it holds rpm under load is
anyone's guess.

O.K. With a 1/4" end mill, your top speed puts you at 71.99
SFM, which is probably not bad with a mild steel and a *good* HSS milling
cutter.

What feed per tooth?

That is even harder to quantify.

Yes -- when your RPM is an unknown, yes, you don't know what you
have even if you know your IPM (inches per minute) based on how fast you
are cranking the leadscrew. (Of course, in the machines where it really
matters, the spindle is geared to the table feed, so it is truly a feed
per tooth, even if the spindle loads down a bit -- so does the feed.)
And in CNC, it is computer determined.

I follow the Machinery's book advice (see
below).

And the
galvanized key stock is probably a rather gummy steel. Go for 12L14 (as
for turning) to find out how much better things can be.

But yes -- the Chinese origin of the end mill suggests that it
could be very poor quality steel.

Buy some *two*-flute end cutting mills by a maker such as
Cleveland, check the RPM against the diameter (calculate the SFM
(Surface Feet per Minute) and compare it to the tables in books like
_Machinery's Handbook_ (pretty much any old edition will do for this).
look up the feed per tooth (for a two-flute end mill here), and working
with the RPM calculate how many inches per minute you want to feed. You
don't want to go faster, but you don't want to go too much slower,
either.

There seems to be a lot of room for interpretation vis-a-vis the steel
hardness.

And with key stock, it is more the gummyness of the steel, not
the hardness. I believe that key stock is low enough carbon so you
can't harden it.

But yes -- if you had hardened steel, the speeds have to be
reduced.

I usually take it that I should be OK with 60-90 SFM. At the high
end the rpm for 1/4" mill are appx. 1500. I have never got as high as 1100
(nominal) as the machine starts shaking.

And the shaking could cause the other axis to feed if it is not
locked. Does your machine have locks for each axis?

As for rough milling the feed should be "all that the machine, work, fixture
and tool will withstand". IMHO they should also include operator's nerves.

:-) Read the posting by Teenut (archived somewhere that someone will
surely point out) discussing how a real machinist sets the feed on a
machine in production. (The basic idea is to start cranking until you
feel uncomfortable about the machine's behavior, back off a little, and
then bring the power feed up until you feel it catch up with your
cranking. :-)

Note that some Chinese boxed sets have both two-flute and
four-flute in each size, and some of them can be pretty good. It
depends on where you get them, among other things. I have a set which I
got from MSC, and they are useful for a lot of things, but for serious
work I use Cleveland or other US-made mills bought for the task.

Right, two flutes it is!

For slot milling, at least. For a lot of other things, four
flutes is a better choice. Slots are a special case.

Good Luck,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

"DoN. Nichols" wrote in message
...

snip

O.K. And as someone else mentioned, are you locking the axis
which you don't want to move? Vibration can cause the handwheel to
rotate, especially if it is not a balanced handwheel (extra mass on the
side opposite the crank handle, so it will balance in any position).

Yes. The one that I forgot most frequently was 'z', but few disasters cured
me of that .

snip

As for rough milling the feed should be "all that the machine, work,
fixture
and tool will withstand". IMHO they should also include operator's
nerves.

:-) Read the posting by Teenut (archived somewhere that someone will
surely point out) discussing how a real machinist sets the feed on a
machine in production. (The basic idea is to start cranking until you
feel uncomfortable about the machine's behavior, back off a little, and
then bring the power feed up until you feel it catch up with your
cranking. :-)

Great minds think alike...

snip

Right, two flutes it is!

For slot milling, at least. For a lot of other things, four
flutes is a better choice. Slots are a special case.

I shall have both. They should be on their way as we speak. A unexpected
benefit of the whole episode was that while studying catalogs for the mills
I found a digital indicator on sale for Cdn $40. I could not resist it. My
Taig will thank me. I got them to throw it in the bag with the mills.

--
Michael Koblic
Campbell River, BC

"Doug White" wrote in message
...

If you can get away without coolant, you can keep the chips out of the
slot with a vacuum cleaner. I had to mill some ~ 5/8" diameter holes in
some aluminum extrusions, where the hole intersected several cutouts. I
had a good stiff end mill, but a not absolutely rigid Clausing 8520 mill.
Chips would constantly get caught between the end mill flutes and the
interrupted cuts, and cause momentary jams & lots of vibration. You
could hear & feel the machine jumping around. I set up my shop vac with
a nozzle to keep the chips clear, and it worked MUCH better.

I found that coolant/lubricant and ease of chip removal are mutually
exclusive. I find it hard to get the chips out with a shopvac *after* I
finshed milling. The best I find is what someone else suggested and that is
blasting the chips out by compressed air. They of course end up in other
undesirable places.

Having said that I find it difficult to believe that chip removal is the
*main* cause of the phenomenon described in a 0.050" slot.

--
Michael Koblic
Campbell River, BC

Andrew VK3BFA wrote:
Ah, nostalgia........................

I posted a similar query (almost identical, really)ages ago and DON
Nichols kind response was that I was trying to do several years of
shop in 20 minutes (or something to that effect) and he was right.
Thanks DON. Went and enrolled at a apprentice level course , still
there, still finding creative ways of stuffing things up...

My mill is an X2 - and does the same as yours - what I have found is:-
vibration is the killer - it will do God knows what if its not
rigidly, VERY rigidly bolted down. And even then, its really only good
for plastic/aluminium, its design limitations are that its a cheap
Chinese mill. If its vibrating, or the bench its on is vibrating,
then its too much.
You will break cutters through vibration - think about it, the thing
is being bounced around like blazes, no wonder their wearing out fast.
Your expecting a bit too much from it - I would suggest cutting
multiple small slots, creeping up on the final size.

I think I pretty much demonstrated that. I was surprised that the effect is
apparent in slots as short as 0.050".

Speed? - almost
irrelevant here as the thing doesnt have a tachometer, or a power feed
- you have to go by ear, and you will develop this in time. What sort
of vise are you using? - if its one of the ones that can swivel on its
base, take off the base and mount it directly on the table. It helps.

I tried that, but for some reason the mounting holes on the top part of the
viseare just enough off so the vise cannot be mounted parallel.

Are you using the proper sized holder for the bit, not just the Jacobs
chuck you use for drilling?.

E-type collet.

Have you set up the mill properly (or at
least tried to) - out of the box, their pretty shocking, play in the
gibs, out of plump, lotsa backlash.

Yes.

The belt drive conversion helps
too - makes them a lot smoother, you have probably broken a tooth in
the gearbox by now (stick it in low range, manually turn the spindle -
it should be smooth ALL the way round, if there's a "click at one
spot, then a (plastic) gear is broken. Google X2, there's HEAPS of
information/mods for the things....

So far no evidence of that. Belt conversion is the next thing if there is
any doubt about the state of the gears.

AND - finally - yes, if you have a decent industrial machine, (and you
have 3-phase power and a BIG workshop) as mentioned, then these
problems dont exist - any machine that takes a forklift or trained
riggers to move it is going to be more rigid, with more power, and
built to tighter tolerances so things like you describe are ho-hum,
run of the mill sort of thing. But, when you do make a mistake, 5hp
will throw something a lot further and with greater terminal velocity
than the X2... when and if you can, upgrade to the X3, its
significantly better, or take the industrial machine route if you so
desire and can get it past SWMBO....

Or I can take up knitting...


--
Michael Koblic
Campbell River, BC

Wild_Bill wrote:
It would seem to me that if the cutting path errors aren't caused by
unintended table movement, then the wandering path is likely to be
caused by flexing of the endmill.

If I had to place my money it would be the column, given the spring-back
phenomenon I described elsewhere.

It's not easy to see the length of the endmill, or just the cutting
section of it, from the photo.

5/8"

Another significant problem that happens when a small endmill is used
to cut the full width of a slot, is chip evacuation, or lack of it.

I woudld have thought the contribution of this would be small over a 0.075"
but perhaps not altogether negligible.

snip


Using a cutting tool lubricant in a squirt bottle, to constantly
flush the chips out of the cut should improve the results, but the
sides of the slot probably still won't be perfectly straight.
The spiral of the flutes will help carry chips away, but only to a
limited degree (less at lower RPMs). Using a medium viscosity cutting
lubricant will help the chips flow outward from the cut.

I tried both RapidTap and squirting a water /oil mixture. I did not see much
difference except for the mess with the squirting.

The other recommendation of drilling the ends of the slot location
with a rigid drill, followed by material removal with a smaller
diameter endmill would likely be the best procedure, especially with
a light duty machine.

Drilling 1/4" holes 0.075" apart is well beyond my skill level.

Flooding a cutting tool lubricant to flush chips away can obviously be
fairly messy, so coming up with a method to recover and contain the
lube might be worthwhile.
A small endmill isn't going to be slinging much lube, but the flooding
action should be constrained to the table area.

The squirt bottle does enough slinging...

It might be possible to retrofit a gutter system around the edge of
the table, or the workpiece clamping methods might need to be
reconsidered, to allow the small parts to be cut with them sitting in
a shallow pan on the table.

Or I could just cut the slot in small passes as it seems to work :-)


--
Michael Koblic
Campbell River, BC

"Michael Koblic" wrote in message
...



Drilling 1/4" holes 0.075" apart is well beyond my skill level.


Did you mean .075" apart or .750 inches apart?

If you wanted the slot .250 X .325 then what you do is to center drill and
drill an under size hole, swap to the end mill (2 flute or 4 will work fine
and enlarge the hole to size.

Next unlock your table, turn your crank .010", Loch the gib and plunge.
Repeat toll you get to the end and then use a smaller diameter end mill to
cut off the little tits between the plunges.

This should yield a perfect slot even with a shaky machine.


--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.

"Roger Shoaf" wrote in message
...

"Michael Koblic" wrote in message
...



Drilling 1/4" holes 0.075" apart is well beyond my skill level.


Did you mean .075" apart or .750 inches apart?

If you wanted the slot .250 X .325 then what you do is to center drill and
drill an under size hole, swap to the end mill (2 flute or 4 will work
fine
and enlarge the hole to size.

Next unlock your table, turn your crank .010", Loch the gib and plunge.
Repeat toll you get to the end and then use a smaller diameter end mill to
cut off the little tits between the plunges.

This should yield a perfect slot even with a shaky machine.

Worth trying.
Do you feel that there is an incremental benefit in this method rather than
just making 8 passes of 0.075" from the initial hole increasing the depth by
0.050" each time?

--
Michael Koblic
Campbell River, BC

"Michael Koblic" wrote in message
...
Drilling 1/4" holes 0.075" apart is well beyond my skill level.


Did you mean .075" apart or .750 inches apart?

If you wanted the slot .250 X .325 then what you do is to center drill
and
drill an under size hole, swap to the end mill (2 flute or 4 will work
fine
and enlarge the hole to size.

Next unlock your table, turn your crank .010", Loch the gib and plunge.
Repeat toll you get to the end and then use a smaller diameter end mill
to
cut off the little tits between the plunges.

This should yield a perfect slot even with a shaky machine.

Worth trying.
Do you feel that there is an incremental benefit in this method rather
than
just making 8 passes of 0.075" from the initial hole increasing the depth
by
0.050" each time?


Since you don't have a very rigid set-up, you have to avoid doing the things
that promote flex. To start off with a center drill spots the beginning of
the hole as close as possible.

When you drill the hole under size, it removes the bulk of the material yet
still permits a bit of wandering to occur.

When you then switch to the end mill to size the end of the slot, you are
not removing very much material and even on a non rigid machine you get very
little walking if the end mill, so your hole will be as true as you can get.


Now when you offset one axis by only .010", that should allow enough
rigidity to keep the cutter from walking on you.

When you then switch to an undersize mill to clear the tits, the tendency of
the cutter to walk will be deflected into the waste area of the slot, and as
material is removed the spring in the cutter relaxes and straightens out the
slot wall.

By milling shallow passes you are going left to right and then back so you
are getting two slightly different feed paths and increasing the amount of
walk and flex that will widen the slot on you.

The question is if on your machine the end result is acceptable to you, is
one of practical application.

You can try it both ways and see what the limits of you machine are. I have
done some pretty close work on some really tired old machines and have got
**** poor results on great machines and it seems that the key to getting the
good result consistently is to work within the limitations of what you have
got to work with at the time you are doing the work.

When you think about all the forces Murphy has to botch up a project, you
are always well advised to limit the degree of mischief he can cause.


--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the solvent.

On Oct 7, 7:04*pm, "Michael Koblic" wrote:
"Roger Shoaf" wrote in message

...







"Michael Koblic" wrote in message
...

Drilling 1/4" holes 0.075" apart is well beyond my skill level.

Did you mean .075" apart or .750 inches apart?

If you wanted the slot .250 X .325 then what you do is to center drill and
drill an under size hole, swap to the end mill (2 flute or 4 will work
fine
and enlarge the hole to size.

Next unlock your table, turn your crank .010", Loch the gib and plunge.
Repeat toll you get to the end and then use a smaller diameter end mill to
cut off the little tits between the plunges.

This should yield a perfect slot even with a shaky machine.

Worth trying.
Do you feel that there is an incremental benefit in this method rather than
just making 8 passes of 0.075" from the initial hole increasing the depth by
0.050" each time?

--
Michael Koblic
Campbell River, BC-

Both work, to me the quill feed with clip-on depth stop is faster and
easier than cranking the table, and only the end dulls so I can
resharpen the endmill without reducing its diameter. I usually advance
0.1" per plunge for a 1/4" endmill and 0.2" for 1/2", or less if the
end mill deflects too much. Generally the slot cleans up with one
final full-depth pass, unless it's a bearing surface like a dovetail,
then I experiment to find a feed rate and cut depth that give a good
finish before cutting to the final size.

For reference, last week I milled DB9 connector slots in thin plastic
boxes with a 1/4" carbide end mill on a Bridgeport and saw sideways
deflection on the first pass.

jsw

On Oct 7, 12:19*pm, "Michael Koblic" wrote:
Andrew VK3BFA wrote:
Ah, nostalgia........................


Or I can take up knitting...

--
Michael Koblic
Campbell River, BC

Yes, you could take up knitting - no doubt there are knitting groups
you could argue with too. You have been given good advice, try some of
it out. You have an X2, and a lot of really good work is done on them
by people who work within the limitations of the machine.
For what your doing, it would be quicker and easier (for you) if you
drilled it out as much as possible and then used a file - a technique
used before milling machines were invented.
If you can, enroll in a trade course - that way, you will have enough
knowledge to know if its your own limitations or the machines.....

Andrew VK3BFA.

"Jim Wilkins" wrote in message
...
On Oct 7, 7:04 pm, "Michael Koblic" wrote:
"Roger Shoaf" wrote in message

...







"Michael Koblic" wrote in message
...

Drilling 1/4" holes 0.075" apart is well beyond my skill level.

Did you mean .075" apart or .750 inches apart?

If you wanted the slot .250 X .325 then what you do is to center drill
and
drill an under size hole, swap to the end mill (2 flute or 4 will work
fine
and enlarge the hole to size.

Next unlock your table, turn your crank .010", Loch the gib and plunge.
Repeat toll you get to the end and then use a smaller diameter end mill
to
cut off the little tits between the plunges.

This should yield a perfect slot even with a shaky machine.

Worth trying.
Do you feel that there is an incremental benefit in this method rather
than
just making 8 passes of 0.075" from the initial hole increasing the depth
by
0.050" each time?

--
Michael Koblic
Campbell River, BC-

Both work, to me the quill feed with clip-on depth stop is faster and
easier than cranking the table, and only the end dulls so I can
resharpen the endmill without reducing its diameter. I usually advance
0.1" per plunge for a 1/4" endmill and 0.2" for 1/2", or less if the
end mill deflects too much. Generally the slot cleans up with one
final full-depth pass, unless it's a bearing surface like a dovetail,
then I experiment to find a feed rate and cut depth that give a good
finish before cutting to the final size.

For reference, last week I milled DB9 connector slots in thin plastic
boxes with a 1/4" carbide end mill on a Bridgeport and saw sideways
deflection on the first pass.

jsw

I would be a dial indicator on the quill and check the movement. Maybe
loose bearings.

"Roger Shoaf" wrote in message
...

Do you feel that there is an incremental benefit in this method rather
than
just making 8 passes of 0.075" from the initial hole increasing the depth
by
0.050" each time?


Since you don't have a very rigid set-up, you have to avoid doing the
things
that promote flex. To start off with a center drill spots the beginning
of
the hole as close as possible.

When you drill the hole under size, it removes the bulk of the material
yet
still permits a bit of wandering to occur.

OK, so far the procedure is identical to mine with the exception that I did
not drill the hole undersize. Something I really should have thought about.
As it happens it did not matter in this application.

When you then switch to the end mill to size the end of the slot, you are
not removing very much material and even on a non rigid machine you get
very
little walking if the end mill, so your hole will be as true as you can
get.


Now when you offset one axis by only .010", that should allow enough
rigidity to keep the cutter from walking on you.

When you then switch to an undersize mill to clear the tits, the tendency
of
the cutter to walk will be deflected into the waste area of the slot, and
as
material is removed the spring in the cutter relaxes and straightens out
the
slot wall.

Let me see if I uderstand what you are saying: The plunge is less likely to
walk if you remove only 0.010" of one end of the slot even if you go the
whole thickness (3/8" in this case).

The process of tit removal is something I am a little concerned about (it
may be a routine procedure for you but bear with me here): The idea is that
the tits are removed completely and *only* the tits are removed. I can see
in my hands two possible outcomes: One, the tits are removed incompletely
and the inside of the slot is wavy, and two, the tits are removed with
excess material making the slot wider than specified. In my case the latter
probably would not be such a disaster if limited to a few thou but for the
argument's sake how do you ensure that the latter does not happen? I assume
you line yourself up on the widest diameter of the initial hole at right
angles in the direction of the slot - but that cannot be easy! I do not see
an edge finder being much help.

By milling shallow passes you are going left to right and then back so you
are getting two slightly different feed paths and increasing the amount of
walk and flex that will widen the slot on you.

The question is if on your machine the end result is acceptable to you, is
one of practical application.

True - my tolerancies are quite - tolerant. However, the reason I am beating
this topic to death is to know the right way the next time when the job is
not so forgiving.

You can try it both ways and see what the limits of you machine are. I
have
done some pretty close work on some really tired old machines and have got
**** poor results on great machines and it seems that the key to getting
the
good result consistently is to work within the limitations of what you
have
got to work with at the time you are doing the work.

True. At this point it is sometimes difficult to tell which are the
limitations of the machinery and which of the operator. What I got so far is
a mixture of both.


--
Michael Koblic
Campbell River, BC

Jim Wilkins wrote:

Do you feel that there is an incremental benefit in this method
rather than just making 8 passes of 0.075" from the initial hole
increasing the depth by
0.050" each time?
-

Both work, to me the quill feed with clip-on depth stop is faster and
easier than cranking the table, and only the end dulls so I can
resharpen the endmill without reducing its diameter. I usually advance
0.1" per plunge for a 1/4" endmill and 0.2" for 1/2", or less if the
end mill deflects too much. Generally the slot cleans up with one
final full-depth pass, unless it's a bearing surface like a dovetail,
then I experiment to find a feed rate and cut depth that give a good
finish before cutting to the final size.

That's 0.1" not 0.01" like Roger suggested? 'Cos my slots are only 0.075" at
the most.

Just so I understand your method:
1) Drill undersize
2) Plunge full size full thickness.
3) Move (in my case) 0.075" + plunge again.
4) Run the mill back to the original position to clean up the "tits".
5) Presumably run the mill back again over the same path to allow for the
differences in the type of milling on either side of the slot.

That has a nice ring of simplicity to it suited to my caveman style even
though Roger mentioned a possible issue with 4) and 5) making the slot too
wide.

For reference, last week I milled DB9 connector slots in thin plastic
boxes with a 1/4" carbide end mill on a Bridgeport and saw sideways
deflection on the first pass.

You mean the mill deflected or the boxes?

--
Michael Koblic
Campbell River, BC

"Michael Koblic" wrote in message
...

"Roger Shoaf" wrote in message
...

Let me see if I uderstand what you are saying: The plunge is less likely
to
walk if you remove only 0.010" of one end of the slot even if you go the
whole thickness (3/8" in this case).

Sure you will get less walk. The surface incontact with the work is only
the small portion of the end face of the tool. Your X any Y gibs are locked
and your quill gib is snugged, so you have very little room for wiggle.
The feed is linear to your hand and you can feel if you start to over do it
easier than when you are turning a crank.

Also bu unly taking .010" at a time you will be able to plunge fairly
quickly and you only have to do it 7 or 8 times.

If the mill does flex sideways, you will end up with only a small deviation
twords the bottom of the slot and it will only be a couple of thou wide and
deep. This gives you a straight wall of at least 80%.




The process of tit removal is something I am a little concerned about (it
may be a routine procedure for you but bear with me here): The idea is
that
the tits are removed completely and *only* the tits are removed. I can see
in my hands two possible outcomes: One, the tits are removed incompletely
and the inside of the slot is wavy, and two, the tits are removed with
excess material making the slot wider than specified. In my case the
latter
probably would not be such a disaster if limited to a few thou but for the
argument's sake how do you ensure that the latter does not happen?

Ok let me see if I can explain. You have done all of your plunges, and you
now swap your 1/4" end mill for a 3/16" end mill. Since the diameter of the
new end mill is smaller, You would start from the right side of the slot and
plunge it to depth or raise the table to bring the mill to depth. Your
cutter should be then centered in the slot and you move the table about .025
away from you and the cutter should then be .007 from the kiss point.

You now lock the gib, and loosten the side travel gib, and re-snug it so it
allows you to turn the crank, but with some resistance. Now feed the work
into the cutter. You are going to get a little flex in the end mill but you
are taking a small bite and all of the flex is going to be away from your
final desired dimention so you still have room to make a clean up cut. When
you get near the end of your pass, you are going to run out of metal to cut
as you enter the quarter inch hole. Now you can take a clean up pass back
doing climb milling or extract the cutter and restart from the right side of
the slot but this timetake about a .003 bite. The bottom of the slot will
be narrower than the top but the end mill will be trying to remove less
material so the flex-away will be a lot less and the side wall should be
really close to square.

Now reset to make your final clean up cut, perhaps upping the speed a notch
this time you will be climb milling and you should clean up really close to
what you want to be at.

Now you do the same thing on the other side of the slot.



I assume
you line yourself up on the widest diameter of the initial hole at right
angles in the direction of the slot - but that cannot be easy! I do not
see
an edge finder being much help.

Your dial is set and locked from when you did the plunge cuts, so you should
be able to just adjust the crank to accomidate the smaller cutter.

When you get ready to cut the back side of the slot, you need to be
cognisant of the backlash in the feed screw so when you make your first pass
onthe back side you can sneak up on the firast pass and you will be able to
keep the slot width from going too wide.


By milling shallow passes you are going left to right and then back so
you
are getting two slightly different feed paths and increasing the amount
of
walk and flex that will widen the slot on you.

The question is if on your machine the end result is acceptable to you,
is
one of practical application.

True - my tolerancies are quite - tolerant. However, the reason I am
beating
this topic to death is to know the right way the next time when the job is
not so forgiving.

Practice on some scrap to hone the technique, and pretty soon it will become
second nature.

I learned this technique from a very fussy german mold maker when my task
was to cut the pockets in mold bases 6 inches thick. He started by having
me cut to within .005" of the desired size and then he did the final sizing
until I had the tecnique down pat, then he let me finish them up to final
size.

You can try it both ways and see what the limits of you machine are. I
have
done some pretty close work on some really tired old machines and have
got
**** poor results on great machines and it seems that the key to getting
the
good result consistently is to work within the limitations of what you
have
got to work with at the time you are doing the work.

True. At this point it is sometimes difficult to tell which are the
limitations of the machinery and which of the operator. What I got so far
is
a mixture of both.


Practice, and observe the results, and be willing to learn from your
mistakes. Soon the techniques will become second nature, you will get over
confident has some part you have many hours into and your mistakes will
become fewer and farther in-between.

Also when you by the next machine that has less slop you will really be
appreciative of all of your futzing time. I remember the firs project I
made on a Hardenge lathe Wow!!!


--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.

On Fri, 9 Oct 2009 00:51:39 -0700, "Roger Shoaf"
wrote:


"Michael Koblic" wrote in message
...

"Roger Shoaf" wrote in message
...

Let me see if I uderstand what you are saying: The plunge is less likely
to
walk if you remove only 0.010" of one end of the slot even if you go the
whole thickness (3/8" in this case).

Sure you will get less walk. The surface incontact with the work is only
the small portion of the end face of the tool. Your X any Y gibs are locked
and your quill gib is snugged, so you have very little room for wiggle.
The feed is linear to your hand and you can feel if you start to over do it
easier than when you are turning a crank.

Also bu unly taking .010" at a time you will be able to plunge fairly
quickly and you only have to do it 7 or 8 times.

If the mill does flex sideways, you will end up with only a small deviation
twords the bottom of the slot and it will only be a couple of thou wide and
deep. This gives you a straight wall of at least 80%.




The process of tit removal is something I am a little concerned about (it
may be a routine procedure for you but bear with me here): The idea is
that
the tits are removed completely and *only* the tits are removed. I can see
in my hands two possible outcomes: One, the tits are removed incompletely
and the inside of the slot is wavy, and two, the tits are removed with
excess material making the slot wider than specified. In my case the
latter
probably would not be such a disaster if limited to a few thou but for the
argument's sake how do you ensure that the latter does not happen?

Ok let me see if I can explain. You have done all of your plunges, and you
now swap your 1/4" end mill for a 3/16" end mill. Since the diameter of the
new end mill is smaller, You would start from the right side of the slot and
plunge it to depth or raise the table to bring the mill to depth. Your
cutter should be then centered in the slot and you move the table about .025
away from you and the cutter should then be .007 from the kiss point.

You now lock the gib, and loosten the side travel gib, and re-snug it so it
allows you to turn the crank, but with some resistance. Now feed the work
into the cutter. You are going to get a little flex in the end mill but you
are taking a small bite and all of the flex is going to be away from your
final desired dimention so you still have room to make a clean up cut. When
you get near the end of your pass, you are going to run out of metal to cut
as you enter the quarter inch hole. Now you can take a clean up pass back
doing climb milling or extract the cutter and restart from the right side of
the slot but this timetake about a .003 bite. The bottom of the slot will
be narrower than the top but the end mill will be trying to remove less
material so the flex-away will be a lot less and the side wall should be
really close to square.

Now reset to make your final clean up cut, perhaps upping the speed a notch
this time you will be climb milling and you should clean up really close to
what you want to be at.

Now you do the same thing on the other side of the slot.



I assume
you line yourself up on the widest diameter of the initial hole at right
angles in the direction of the slot - but that cannot be easy! I do not
see
an edge finder being much help.

Your dial is set and locked from when you did the plunge cuts, so you should
be able to just adjust the crank to accomidate the smaller cutter.

When you get ready to cut the back side of the slot, you need to be
cognisant of the backlash in the feed screw so when you make your first pass
onthe back side you can sneak up on the firast pass and you will be able to
keep the slot width from going too wide.


By milling shallow passes you are going left to right and then back so
you
are getting two slightly different feed paths and increasing the amount
of
walk and flex that will widen the slot on you.

The question is if on your machine the end result is acceptable to you,
is
one of practical application.

True - my tolerancies are quite - tolerant. However, the reason I am
beating
this topic to death is to know the right way the next time when the job is
not so forgiving.

Practice on some scrap to hone the technique, and pretty soon it will become
second nature.

I learned this technique from a very fussy german mold maker when my task
was to cut the pockets in mold bases 6 inches thick. He started by having
me cut to within .005" of the desired size and then he did the final sizing
until I had the tecnique down pat, then he let me finish them up to final
size.

You can try it both ways and see what the limits of you machine are. I
have
done some pretty close work on some really tired old machines and have
got
**** poor results on great machines and it seems that the key to getting
the
good result consistently is to work within the limitations of what you
have
got to work with at the time you are doing the work.

True. At this point it is sometimes difficult to tell which are the
limitations of the machinery and which of the operator. What I got so far
is
a mixture of both.


Practice, and observe the results, and be willing to learn from your
mistakes. Soon the techniques will become second nature, you will get over
confident has some part you have many hours into and your mistakes will
become fewer and farther in-between.

Also when you by the next machine that has less slop you will really be
appreciative of all of your futzing time. I remember the firs project I
made on a Hardenge lathe Wow!!!

Something else too....if one has a long endmill..it will deflect far
more than will a short one, unless one finds its sweetspot in rpm and
feed rate. Which on a light duty mill...may be damned hard to do.

Use as short an endmill as you possibly can, and use as little quill as
you possibly can..dont extend the quill any farther than you absolutely
need to. A local guy called me up today because of a very similar
problem and it turned out he was using long endmills rather than stubby
ones. I loaned him a couple, he went home and called me later that they
had worked like a charm. (mine were sharp too..shrug)


Gunner

GUNNER'S PRAYER:
"God grant me the serenity to accept the people
that don't need to get shot, the courage to shoot
the people that need shooting and the wisdom to know the difference.
And if need be, the skill to get it done before I have to reload."


0

On Oct 8, 8:41*pm, "Michael Koblic" wrote:
Jim Wilkins wrote:
Do you feel that there is an incremental benefit in this method
rather than just making 8 passes of 0.075" from the initial hole
increasing the depth by
0.050" each time?
-

Both work, to me the quill feed with clip-on depth stop is faster and
easier than cranking the table, and only the end dulls so I can
resharpen the endmill without reducing its diameter. I usually advance
0.1" per plunge for a 1/4" endmill and 0.2" for 1/2", or less if the
end mill deflects too much. Generally the slot cleans up with one
final full-depth pass, unless it's a bearing surface like a dovetail,
then I experiment to find a feed rate and cut depth that give a good
finish before cutting to the final size.

That's 0.1" not 0.01" like Roger suggested? 'Cos my slots are only 0.075" at
the most.

Just so I understand your method:
1) Drill undersize
2) Plunge full size full thickness.
3) Move (in my case) 0.075" + plunge again.
4) Run the mill back to the original position to clean up the "tits".
5) Presumably run the mill back again over the same path to allow for the
differences in the type of milling on either side of the slot.

That has a nice ring of simplicity to it suited to my caveman style even
though Roger mentioned a possible issue with 4) and 5) making the slot too
wide.

For reference, last week I milled DB9 connector slots in thin plastic
boxes with a 1/4" carbide end mill on a Bridgeport and saw sideways
deflection on the first pass.

You mean the mill deflected or the boxes?

--
Michael Koblic
Campbell River, BC

Probably the boxes, possibly play in the quill which was most of the
way down to give safe clearance to rapidly swap the boxes without
shutting off power. Otherwise it simply shows that the problem doesn't
go away on larger machines. I know my ~50 year old Clausing has play
in the quill which increases as it lowers, meaning I have to clamp the
quill and raise the table to bore a hole to final size.

0.1" and 0.2" are convenient to move without reading the dial and
about the maximum the endmill will cut freely, since the center
doesn't cut as well.

jsw

On Oct 6, 9:19*pm, Gunner Asch wrote:
On Tue, 6 Oct 2009 03:05:53 -0700 (PDT), Andrew VK3BFA



wrote:
On Oct 5, 12:01*pm, "Michael Koblic" wrote:
I need a small slot in my sundial bases. Usually I pre-drill the hole
(either 3/16" or 1/4") and then extend by 0.075" (1/4" hole) or 0.50" (3/16"
hole) the material is 3/8" key stock, galvanized, made in USA. The mill is a
generic X2, the mill bits are Chinese box set.

Ah, nostalgia........................

I posted *a similar query (almost identical, really)ages ago *and DON
Nichols kind response was that I was trying to do several years of
shop in 20 minutes (or something to that effect) and he was right.
Thanks DON. Went and enrolled at a apprentice level course , still
there, still finding creative ways of stuffing things up...

My mill is an X2 - and does the same as yours - what I have found is:-
vibration is the killer - it will do God knows what if its not
rigidly, VERY rigidly bolted down. And even then, its really only good
for plastic/aluminium, its design limitations are that its a cheap
Chinese mill. *If its vibrating, or the bench its on is vibrating,
then its too much.
You will break cutters through vibration - think about it, the thing
is being bounced around like blazes, no wonder their wearing out fast.
Your expecting a bit too much from it - I would suggest cutting
multiple small slots, creeping up on the final size. Speed? - almost
irrelevant here as the thing doesnt have a tachometer, or a power feed
- you have to go by ear, and you will develop this in time. What sort
of vise are you using? - if its one of the ones that can swivel on its
base, take off the base and mount it directly on the table. It helps.
Are you using the proper sized holder for the bit, not just the Jacobs
chuck you use for drilling?. Have you set up the mill properly (or at
least tried to) - out of the box, their pretty shocking, play in the
gibs, out of plump, lotsa backlash. The belt drive conversion helps
too - makes them a lot smoother, you have probably broken a tooth in
the gearbox by now (stick it in low range, manually turn the spindle -
it should be smooth ALL the way *round, if there's a "click at one
spot, then a (plastic) gear is broken. Google X2, there's HEAPS of
information/mods for the things....

AND - finally - yes, if you have a decent industrial machine, (and you
have 3-phase power and a BIG workshop) as mentioned, then these
problems dont exist - any machine that takes a forklift or trained
riggers to move it is going to be more rigid, with more power, and
built to tighter tolerances so things like you describe are ho-hum,
run of the mill sort of thing. But, when you do make a mistake, 5hp
will throw something a lot further and with greater terminal velocity
than the X2... when and if you can, upgrade to the X3, its
significantly better, or take the industrial machine route if you so
desire and can get it past SWMBO.....

Good luck - it will drive you absolutely NUTS, the learning curve is
near vertical to start with, but after a while things start to get
better/easier ...which means you start trying to do more complex
things, so its a lifelong process.

Andrew VK3BFA.

Very very well said! *Kudos!!

Political Correctness is a doctrine fostered by a delusional,
illogical liberal minority, and rabidly promoted by an
unscrupulous mainstream media, which holds forth the
proposition that it is entirely possible to pick up a turd by the clean end.

Faaaaarrrrkkk! - Gunner, you still have the capacity to blow me away
sometimes - thank you - a lot of what I have learnt is from this
group, even the political Neanderthals.......
Andrew VK3BFA.

On Oct 9, 5:04*am, Gunner Asch wrote:
....
Gunner

GUNNER'S PRAYER:
"God grant me the serenity to accept the people
that don't need to get shot, the courage to shoot
the people that need shooting and the wisdom to know the difference.
And if need be, the skill to get it done before I have to reload."

0-
.......................

1) You cannot legislate the poor into prosperity by legislating
the wealthy out of prosperity.

2) What one person receives without working for, another person
must work for, without receiving.

3) The government cannot give to anybody anything that the govern-
ment does not first take from somebody else.

4) When half of the people get the idea that they do not have to
work because the other half is going to take care of them, and
when the other half gets the idea that it does no good to work
because somebody else is going to get what they work for, that
my dear friend, is the beginning of the end of any nation.

5) You cannot multiply wealth by dividing it.

- Adrian Rogers, 1931

Jim Wilkins wrote:

For reference, last week I milled DB9 connector slots in thin plastic
boxes with a 1/4" carbide end mill on a Bridgeport and saw sideways
deflection on the first pass.


That would be a 'DE9' cutout, even though a lot of people use the
wrong name. The second letter is the shell size.


--
The movie 'Deliverance' isn't a documentary!