Hi,

I have recently purchased a vertical milling machine to cut slots in
front panels of enclosures for our prototypes.

The main 2 jobs are cutting small (10mm x 15mm) slots in 2mm aluminum
flat plate (plate is 65 x 30mm).
And cutting slots in the end of 1.5mm ABS plastic enclosures.

My main issues are.

1. What is a good way to hold down the jobs. (I have a set of T-Bolts
and threaded rods etc but not sure how to hold the jobs securely in
place without marking them).
2. What sort of jig or template could I use to repeat jobs (small runs
up to 30)

Finally any good web sites for info on milling operation and/or jig
making would be very helpful.


Thanks in advance


--

Kind Regards

David Huisman
General Manager
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ORBIT COMMUNICATIONS Pty Ltd - Wireless Solutions that Work
(Telemetry, Control, Monitoring, Security, HVAC ...)
A.C.N. 107 441 869


Website : http://www.orbitcoms.com
PO Box 4474 Lakehaven
NSW 2263, AUSTRALIA
Phone: 61-2-4393-3627
Fax : 61-2-4393-3685
Mobile: 61-413-715-986

David,

I have recently purchased a vertical milling machine to cut slots in
front panels of enclosures for our prototypes.

The main 2 jobs are cutting small (10mm x 15mm) slots in 2mm aluminum
flat plate (plate is 65 x 30mm).
And cutting slots in the end of 1.5mm ABS plastic enclosures.

My main issues are.

1. What is a good way to hold down the jobs. (I have a set of T-Bolts
and threaded rods etc but not sure how to hold the jobs securely in
place without marking them).

I will leave that to others. I suspect recommendations will include
putting something between the work and a stap clamp, but there could
easily be a better way.


2. What sort of jig or template could I use to repeat jobs (small runs
up to 30)

I have been using qcad to create and print heavily (purists would say
"over") dimensioned drawings. If you read through some of the recent
replies (particularly Harold's) to me in the past few months, you will
pick up a lot. A short version is that you can set your dials to 0-0 at
the top left of your work and then count your way to any coordinates you
need; it's even easier if you have a DRO. Back to the drawings,
dimension everything of interest from the top left, and it becomes a
very useful map. I doubt you will need a jig.

If that sounds like too much trouble, you could make a mask and spray
paint through it to mark the work, and mill out the stuff that got hit.

Especially with the Al, you can stack several pieces and mill them all
at one time. They probably should be bolted or pinned together; again I
will defer to those with more experience.

Good luck!

Bill

I have been holding down single pieces of thin flat stock with double
sided sticky tape.
I put it on the flat part of the mill vice.

For cutting many at once, you might make clamp bars with holes that
pinch a stack of sheets with nuts and bolts.

Look at two fluted cutters running very fast and making a loud squeaking
noise when cutting Aluminum.

--
Accidental creation should not be taught as a fact.
Intelligent creation should not be banned from teachings as
unconstitutional.

....
1. What is a good way to hold down the jobs. (I have a set of T-Bolts and
threaded rods etc but not sure how to hold the jobs securely in place
without marking them).
2. What sort of jig or template could I use to repeat jobs (small runs up
to 30)

A vacuum plate would be just great for this. You have a straight edge on the
top and one side to locate parts. The plate area has a bunch of small holes
that connect to a vacuum pump. You make a sacrifical part that covers the
entire plate and has holes to pass vacuum where your production part is.
You wouldn't believe how high a hold force you can get this way and no
marking, super quick to go to next part, located exactly. Make your own,
buy on Ebay, or buy new.

Karl

David wrote in news:WHNof.26205$V7.21554@news-
server.bigpond.net.au:

Hi,

I have recently purchased a vertical milling machine to cut slots in
front panels of enclosures for our prototypes.

The main 2 jobs are cutting small (10mm x 15mm) slots in 2mm aluminum
flat plate (plate is 65 x 30mm).
And cutting slots in the end of 1.5mm ABS plastic enclosures.

My main issues are.

1. What is a good way to hold down the jobs. (I have a set of T-Bolts
and threaded rods etc but not sure how to hold the jobs securely in
place without marking them).
2. What sort of jig or template could I use to repeat jobs (small runs
up to 30)

Finally any good web sites for info on milling operation and/or jig
making would be very helpful.


Thanks in advance



A vise and parallels for the aluminum should work fine. If you are going
to power tap, add a hold-down clamp on top. Clamp a vertical bar, or some
other straight piece of metal to the table at one end of the vise to use
as a solid stop. Use the shortest parallel and stack the parts as deep
as the vise jaws allow, so you can make several at one time, one set-up.
You didn't mention the size of the abs enclosure, but a vise would
probably work for that also.

For a manual machine and repeatable work, a DRO (digital read out) is a
must.

If you set the vise at one end of the table, you can fixture the abs
housings at the other. Then using the DRO, you set one zero reference
for the vise fixture, and another for the housings.

--
Anthony

You can't 'idiot proof' anything....every time you try, they just make
better idiots.

Remove sp to reply via email

Anthony,

A vise and parallels for the aluminum should work fine. If you are going
to power tap, add a hold-down clamp on top. Clamp a vertical bar, or some
other straight piece of metal to the table at one end of the vise to use
as a solid stop. Use the shortest parallel and stack the parts as deep
as the vise jaws allow, so you can make several at one time, one set-up.
You didn't mention the size of the abs enclosure, but a vise would
probably work for that also.

For the metal, how do you control buckling? Any tricks to holding them
well enough w/o squeezing so hard that they distort? I see just such
task for myself early next year, and am open to any/all advice.


For a manual machine and repeatable work, a DRO (digital read out) is a
must.

Despite many years as a beginner, I am basically just starting out.
With that said, I am becoming convinced that Harold is correct. A DRO
is a convenience, but not necessary if one understands how to manage
backlash. In fact, he is obviously correct, because people did
repeatable work long before DROs existed. You might argue that modern
or small machines are not as accurate as the early monsters??

This from a guy who had 0.01 inch errors on two of four parts in a run
One of the slips was (I strongly suspect) due to inadequate stops
(soon to be corrected). The other has no explanation short of operator
error; I suspect I read the wrong number from the drawing. Whatever
happened, I blew it. I care only for practice, +/- 0.05 inch would be
more than adequate for the parts in question.

Mistakes aside, by measuring +/- 0.1 inch and reading the dials in a
backlash-friendly way, I get where I want to go often enough to suggest
that with a little practice, a DRO will not be necessary. I am also
discovering that once a slot or window is partially cut, or
(extrapolating because I didn't know to do this the last time) a hole is
drilled, all one needs is the dial reading; an error in the number of
revolutions will be visible with some care and bringing the endmill/bit
close to the work.


If you set the vise at one end of the table, you can fixture the abs
housings at the other. Then using the DRO, you set one zero reference
for the vise fixture, and another for the housings.

Just don't turn your back on the power feed, or better yet just reset
the relevant stop if the abs is below the vise =:0 No, I haven't made
the implied mistake, yet

Bill

"David" wrote in message
...
Hi,

I have recently purchased a vertical milling machine to cut slots in
front panels of enclosures for our prototypes.

---snip---

I'd mount a good vice then make a T bed to support and locate the plate,
with a top to clamp the piece and also serve as a jig. The trunk of the T
would be clamped in the vice, the top of the T bolted to the bottom plate to
secure firmly while cutting. You'd probably make two jigs due to the length
of the piece, or flip it if a mirror image.

Bill Schwab wrote:


For the metal, how do you control buckling? Any tricks to holding them
well enough w/o squeezing so hard that they distort? I see just such
task for myself early next year, and am open to any/all advice.


2 mm aluminum in the size you are working with should not be buckling
unless you are cutting away a lot of metal in the interior.

When that is a problem, you use a sacrificial fixture, or "scab plate".
This is some suitable piece of scrap that can be held in the vise (or
bolted to the table if large) and the part is bolted to it. In some
cases, the panel needs holes in in, so you drill the holes and then
bolt through the panel's holes into threaded holes in the fixture.
This clamps the interior, making it stiffer.

The fixture can have clamps or bolts placed at good locations to
hold and align the part.

Jon

Jon,

For the metal, how do you control buckling? Any tricks to holding
them well enough w/o squeezing so hard that they distort? I see just
such task for myself early next year, and am open to any/all advice.


2 mm aluminum in the size you are working with should not be buckling
unless you are cutting away a lot of metal in the interior.

I think you are confusing me with the OP. I noted that the plates are
fairly small in that case; mine will be larger, and yes, they will be
fairly well splattered with slots.


When that is a problem, you use a sacrificial fixture, or "scab plate".
This is some suitable piece of scrap that can be held in the vise (or
bolted to the table if large) and the part is bolted to it. In some
cases, the panel needs holes in in, so you drill the holes and then
bolt through the panel's holes into threaded holes in the fixture.
This clamps the interior, making it stiffer.

That would work. The only other concern I have is how to get the holes
in the right places so they line up in all of the plates. Thinking out
loud a little, perhaps only the relative spacing would be critical, so I
could clamp them to the fixture (using holes and clamps as you suggest),
put a couple of holes at known locations in each, and the bolt the whole
stack and clean up the edges. Getting the edges in relation to the
original holes might be a problem, but if the first holes are in waste,
it would not matter, or it might simply not matter.

Am I making any sense? Is there a better sequence?

Thanks,

Bill

On Sat, 17 Dec 2005 05:51:50 GMT, David
wrote:

Hi,

I have recently purchased a vertical milling machine to cut slots in
front panels of enclosures for our prototypes.

The main 2 jobs are cutting small (10mm x 15mm) slots in 2mm aluminum
flat plate (plate is 65 x 30mm).
And cutting slots in the end of 1.5mm ABS plastic enclosures.


Any chance of posting a drawing of the part? DXF, IGS or DWG formats
would fine It is easier to offer suggestions if there is a clear
picture to work from.

Post to the Dropbox at www.metalworking.com If you have not used it
before the directions are simple and easy to follow.

Errol Groff
Errol Groff

Instructor, Manufacturing Technology
H.H. Ellis Technical High School
613 Upper Maple Street
Danielson, CT 06239

New England Model Engineering Society
www.neme-s.org

Bill Schwab wrote in
nk.net:

Anthony,


For the metal, how do you control buckling? Any tricks to holding
them well enough w/o squeezing so hard that they distort? I see just
such task for myself early next year, and am open to any/all advice.


If you stack these pieces 1-1/2" - 1-3/4" deep in the vice (whatever your
end mill will take and keep on the flutes), there will be very little to
no bucking, as it acts more like a 1-1/2" thick piece of solid material.
You may get a little bucking on the top piece, if you do a hold-down
clamp from the table should be all it takes.


Despite many years as a beginner, I am basically just starting out.
With that said, I am becoming convinced that Harold is correct. A DRO
is a convenience, but not necessary if one understands how to manage
backlash. In fact, he is obviously correct, because people did
repeatable work long before DROs existed. You might argue that modern
or small machines are not as accurate as the early monsters??

While a DRO isn't absolutely required, it is a handy addition. If you are
setting this up as a small production type situation, adding solid stops,
two stations, and a zero point for each is nice.


This from a guy who had 0.01 inch errors on two of four parts in a run
One of the slips was (I strongly suspect) due to inadequate stops
(soon to be corrected). The other has no explanation short of
operator error; I suspect I read the wrong number from the drawing.
Whatever happened, I blew it. I care only for practice, +/- 0.05 inch
would be more than adequate for the parts in question.

Should be no problem then, however, one should strive for accuracy
whenever possible.





--
Anthony

You can't 'idiot proof' anything....every time you try, they just make
better idiots.

Remove sp to reply via email

Anthony,

If you stack these pieces 1-1/2" - 1-3/4" deep in the vice (whatever your
end mill will take and keep on the flutes), there will be very little to
no bucking, as it acts more like a 1-1/2" thick piece of solid material.
You may get a little bucking on the top piece, if you do a hold-down
clamp from the table should be all it takes.

Am I correct in thinking that the pieces need to have fairly consistent
width for the clamping to work? If so, then would you put them in the
vise on end to square them first?

For my related job, I will be starting by rough cutting sheets.



This from a guy who had 0.01 inch errors on two of four parts in a run
One of the slips was (I strongly suspect) due to inadequate stops
(soon to be corrected). The other has no explanation short of
operator error; I suspect I read the wrong number from the drawing.
Whatever happened, I blew it. I care only for practice, +/- 0.05 inch
would be more than adequate for the parts in question.


Should be no problem then, however, one should strive for accuracy
whenever possible.

Very true, and I was quite pleased with two of the four, and even the
"rejects" were better than most work I did in the past. I can't bring
myself to scrap them; metal ain't cheap and time is priceless.

I mentioned it in fairness given the side I took on DROs ~:0

Bill

Bill Schwab wrote:
Jon,

For the metal, how do you control buckling? Any tricks to holding
them well enough w/o squeezing so hard that they distort? I see just
such task for myself early next year, and am open to any/all advice.


2 mm aluminum in the size you are working with should not be buckling
unless you are cutting away a lot of metal in the interior.


I think you are confusing me with the OP.
(I was replying to the thread, not necessarily to a particular person.)

I noted that the plates are
fairly small in that case; mine will be larger, and yes, they will be
fairly well splattered with slots.


When that is a problem, you use a sacrificial fixture, or "scab plate".
This is some suitable piece of scrap that can be held in the vise (or
bolted to the table if large) and the part is bolted to it. In some
cases, the panel needs holes in in, so you drill the holes and then
bolt through the panel's holes into threaded holes in the fixture.
This clamps the interior, making it stiffer.


That would work. The only other concern I have is how to get the holes
in the right places so they line up in all of the plates. Thinking out
loud a little, perhaps only the relative spacing would be critical, so I
could clamp them to the fixture (using holes and clamps as you suggest),
put a couple of holes at known locations in each, and the bolt the whole
stack and clean up the edges. Getting the edges in relation to the
original holes might be a problem, but if the first holes are in waste,
it would not matter, or it might simply not matter.

Here's a procedure I used for making some parts that had a round
exterior. I cut squares out of sheet stock, and clamped them to the
fixture. I had holes in a recessed part of the fixture, beyond the
part OD. Clamps held the blanks on the fixture. I then center-drilled
and then drilled through all the holes. Under these holes were
tapped holes in the fixture. After drilling the holes, I then
blew out the chips with compressed air, and inserted clamping bolts
into three of the holes. I then could remove the clamps around the
OD, and mill the entire OD without any interference.

This is much easier with CNC, but can be done with a manual machine, too.

Jon

Bill Schwab wrote:
Anthony,

If you stack these pieces 1-1/2" - 1-3/4" deep in the vice (whatever
your end mill will take and keep on the flutes), there will be very
little to no bucking, as it acts more like a 1-1/2" thick piece of
solid material. You may get a little bucking on the top piece, if you
do a hold-down clamp from the table should be all it takes.


Am I correct in thinking that the pieces need to have fairly consistent
width for the clamping to work? If so, then would you put them in the
vise on end to square them first?

Yes. Even when I gang-machine the plates together, and then put them
flat between the jaws, some will try to slip. You can put a sheet of
paper between the jaws and the plates. Sometimes, I put a piece of soft
wood between the plates and the movable jaw. (The fixed jaw is the
reference jaw, so you don't want anything crushable there.)

I used to have badly worn leadscrews on my manual Bridgeport, and
couldn't figure out why two parts wouldn't align well. When I got
an optical measuring system (forerunner to DROs) I found out that
the screws were unevenly worn, and therefore quite inaccurate from
point to point, even if you stayed to one side of the backlash.
There was an error of almost .050" over 9". Once I had accurate
measurement of machine position, I no longer had to file out bolt
holes to get two parts to bolt together.

Jon

Jon,

Yes. Even when I gang-machine the plates together, and then put them
flat between the jaws, some will try to slip. You can put a sheet of
paper between the jaws and the plates. Sometimes, I put a piece of soft
wood between the plates and the movable jaw. (The fixed jaw is the
reference jaw, so you don't want anything crushable there.)

Understood.


I used to have badly worn leadscrews on my manual Bridgeport, and
couldn't figure out why two parts wouldn't align well. When I got
an optical measuring system (forerunner to DROs) I found out that
the screws were unevenly worn, and therefore quite inaccurate from
point to point, even if you stayed to one side of the backlash.
There was an error of almost .050" over 9".

Ouch! Is there a way to replace the leadscrews?


Once I had accurate
measurement of machine position, I no longer had to file out bolt
holes to get two parts to bolt together.

That would defeat the purpose of having a precision machine tool.

Thanks!

Bill

Bill Schwab wrote in
news
Anthony,

If you stack these pieces 1-1/2" - 1-3/4" deep in the vice (whatever
your end mill will take and keep on the flutes), there will be very
little to no bucking, as it acts more like a 1-1/2" thick piece of
solid material. You may get a little bucking on the top piece, if you
do a hold-down clamp from the table should be all it takes.

Am I correct in thinking that the pieces need to have fairly
consistent width for the clamping to work? If so, then would you put
them in the vise on end to square them first?

For my related job, I will be starting by rough cutting sheets.

Yes, the width needs to be exactly the same, so I most definately would
square up the material first if you are cutting it from sheet.
Put a bunch of pieces in the vice on edges, take a clean-up pass to get
them all one height, then turn them over and finish to size.


--
Anthony

You can't 'idiot proof' anything....every time you try, they just make
better idiots.

Remove sp to reply via email

Anthony,

Yes, the width needs to be exactly the same, so I most definately would
square up the material first if you are cutting it from sheet.
Put a bunch of pieces in the vice on edges, take a clean-up pass to get
them all one height, then turn them over and finish to size.

Got it - thanks!!

Bill

Yes, the width needs to be exactly the same, so I most definately would
square up the material first if you are cutting it from sheet.
Put a bunch of pieces in the vice on edges, take a clean-up pass to get
them all one height, then turn them over and finish to size.


--
Anthony


If the parts are large enough, I like to clamp them together with C clamps.
Square all the sides before removing the clamps.

Bill Schwab wrote:

Ouch! Is there a way to replace the leadscrews?


Why, yes, of course! First, I got a Bridgeport optical readout, and
then converted the machine to CNC with high precision ground leadscrews
that I was lucky enough to come across.
Once I had accurate

measurement of machine position, I no longer had to file out bolt
holes to get two parts to bolt together.


That would defeat the purpose of having a precision machine tool.
Right, when it WASN'T precise, I had to file the holes to fit.
I don't have to do that wretched stuff anymore.

Jon