Finally I need to make something to good precision, which is to make a
mounting plate for a US Digital encoder. The spec says shaft
misalignment should be under 0.01", which means that the individual
mounting holes need to be even more precisely placed, so as the
cumulative error will stay within spec.

Anyway, step number 1 is to cut a 4x1/4"x12" aluminum flat into three
pieces. I would like to do this on a Bridgeport and to use a thin
endmill, so as to keep as much material as possible. Should I use
carbide or HSS and what speed would you recommend for, say, a 1/8"
endmill?

Second question, I will need to tap #4-40 holes in same aluminum. How
risky is this as far as tap is concerned and should I use lubrication?

i

Ignoramus13320 fired this volley in
:

Second question, I will need to tap #4-40 holes in same aluminum. How
risky is this as far as tap is concerned and should I use lubrication?

In revers order, Iggy: Yes, you should lubricate the tap, and in a hole
that deep (which is deep for 4-40) you should not try to power through in
one pass, but back it out and clear chips several times.

On the first part: it's no risk whatsoever to the tap, so long as you
don't torque it to the breaking point G.

Whatever you do, don't try to freehand tap those. Even if you don't use
power, use the mill with a center chucked in it to keep that tap straight
over the hole the entire time (if you're using a tap wrench), or just
chuck up the tap and use your hand to turn the spindle. Off-line tapping
breaks more taps than the character of the metal being tapped.

LLoyd

Ignoramus13320 wrote:

Finally I need to make something to good precision, which is to make a
mounting plate for a US Digital encoder. The spec says shaft
misalignment should be under 0.01", which means that the individual
mounting holes need to be even more precisely placed, so as the
cumulative error will stay within spec.

Anyway, step number 1 is to cut a 4x1/4"x12" aluminum flat into three
pieces. I would like to do this on a Bridgeport and to use a thin
endmill, so as to keep as much material as possible. Should I use
carbide or HSS and what speed would you recommend for, say, a 1/8"
endmill?

Second question, I will need to tap #4-40 holes in same aluminum. How
risky is this as far as tap is concerned and should I use lubrication?

i

Slicing up plate with a small endmill is a lousy way to go. Better to
cut with a bandsaw or even hacksaw and then finish mill the edge with a
decent sized end mill (.5"+).

Tapping small holes is very risky. Do the complete process for each hole
without moving the mill X/Y. Load up your chuck in the spindle, put a
small center drill in the chuck, lock the X and Y and spot the hole.
Change the center drill out for the appropriate tap drill and drill the
hole, using a squirt or two of Kroil (or other suitable lube) as you
peck drill. Change out the drill bit for a spring loaded tap center
(ENCO, MSC, etc.) with a point that will rest in the center hole at the
back of your tap handle. Load the tap in the tap handle, rest the tip of
the tap in the hole and bring the spindle with the spring center down to
rest in the back of the tap handle, compressing through most of the
spring travel. Apply a few more squirts if Kroil and begin tapping, 1/2
turn in, 1/4 turn back, gradually progressing. If the hole is deep,
periodically back the tap most of the way out and blast if clean with
air, relube with Kroil and continue. Doing all of this in one sequence
with the X and Y locked ensures you remain on center and avoid side
strain that would break the tap. When one hole is complete, unlock the X
and Y, locate the next hole position and start the process over.

The spec says shaft
misalignment should be under 0.01", which means that the individual
mounting holes need to be even more precisely placed, so as the
cumulative error will stay within spec.

Second question, I will need to tap #4-40 holes in same aluminum. How
risky is this as far as tap is concerned and should I use lubrication?

Not certain which US Digital encoders you are using but here are some
being installed directly to tiny motors (no plate). One way to achieve
accuracy with this encoder type is to use the centering tool with
double sided tape on the plastic plate then use the plate as a drill
template.

Hand tapping machine (Enco) and Tap Ease "crayon" was used for
tapping. Also, flat instead of pan head screws were used only for
neatness. The supplied pan heads work just fine. Pictures here;

http://www.pbase.com/eldata/motor_mod&page=1


On Jun 18, 3:40*pm, Ignoramus13320 ignoramus13...@NOSPAM.
13320.invalid wrote:

"Ignoramus13320" wrote in message
...
Finally I need to make something to good precision, which is to make a
mounting plate for a US Digital encoder. The spec says shaft
misalignment should be under 0.01", which means that the individual
mounting holes need to be even more precisely placed, so as the
cumulative error will stay within spec.

Anyway, step number 1 is to cut a 4x1/4"x12" aluminum flat into three
pieces. I would like to do this on a Bridgeport and to use a thin
endmill, so as to keep as much material as possible. Should I use
carbide or HSS and what speed would you recommend for, say, a 1/8"
endmill?

Second question, I will need to tap #4-40 holes in same aluminum. How
risky is this as far as tap is concerned and should I use lubrication?

i

OK, the task is to cut a 12 inch long chunk of aluminum into three pieces
that need to be square and as large as possible. (not quite what you said
but this is what I think you mean.

The problem with using an end mill to make a really thin cut is that the
smaller the end mill the easier it is to overload the cutter and have it
flex.

What I would do is to use a skill saw or a band saw or a jig saw to make the
cuts and then square them up with the mill. If the saw kerf of the skill
saw is 1/8 you will loose 1/4 to 3/8 over all. that means you end up with
square plates 3 7/8 finished size. If that is not good enough then go buy
some more aluminum.

The skill saw technique will be to attach the plate to a chunk of wood that
has a stop affixed to it. Now to this you clamp a saw guide that you can
hold the guide of the skill saw against and keep everything as square as you
can. make one cut from each side after marking lines to delineate the outer
limits of what you are willing to go.

Now once you have the three blanks you can then square them up and size them
on the mill.

If you don't have a skill saw (or a table saw) the band saw or the jig saw
can be used if you mark the lines with a caliper and then carefully cut
between them.

The 4-40 tap will work fine just drill carefully (center drill, then tap
drill) and then use aluma-tap and go easy.

When you size and square the plates, be sure to tram the head of the mill
and then indicate the vise. Doing that will get you as close to dead nuts
as you are going to get.

Good luck.

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

Ignoramus13320 wrote:

Finally I need to make something to good precision, which is to make a
mounting plate for a US Digital encoder. The spec says shaft
misalignment should be under 0.01", which means that the individual
mounting holes need to be even more precisely placed, so as the
cumulative error will stay within spec.

Anyway, step number 1 is to cut a 4x1/4"x12" aluminum flat into three
pieces. I would like to do this on a Bridgeport and to use a thin
endmill, so as to keep as much material as possible. Should I use
carbide or HSS and what speed would you recommend for, say, a 1/8"
endmill?

Second question, I will need to tap #4-40 holes in same aluminum. How
risky is this as far as tap is concerned and should I use lubrication?

i

Sounds like you don't have a bandsaw. A tablesaw or chop saw (depending on cut direction)
is perfectly capable of cutting aluminum. Hack saws work too, this is aluminum.

The other day my uncle called me to tell me he stopped over and borrowed my chop saw to
put up some crow molding. I asked him how it cut, he indicated it cut fine, that is when
I told him I've been using the blade on it to cut 80/20 and other aluminum extrusions for
years. Wear ear and eye protection.

The tapping has been addressed by others.

Wes

A tablesaw can rip Alu, depending on thickness, as if it was wood;

http://www.pbase.com/eldata/image/46673198

On Jun 18, 4:45*pm, Wes wrote:

On 2010-06-18, Ignoramus13320 wrote:
Finally I need to make something to good precision, which is to make a
mounting plate for a US Digital encoder. The spec says shaft
misalignment should be under 0.01", which means that the individual
mounting holes need to be even more precisely placed, so as the
cumulative error will stay within spec.

Is it possible to mount it in such a way that you can adjust the
location? 0.010" is not that tight a spec anyway. If it were 0.001"
that would be a bit more trouble.

Anyway, step number 1 is to cut a 4x1/4"x12" aluminum flat into three
pieces. I would like to do this on a Bridgeport

Don't you have a bandsaw? You could use a bandsaw to make it
just a little oversized, and then the mill to clean up the finish on the
edges.

and to use a thin
endmill, so as to keep as much material as possible. Should I use
carbide or HSS and what speed would you recommend for, say, a 1/8"
endmill?

No need for carbide, and it is a lot more brittle.

You probably want to add only a 1/16" depth of cut for each pass
(half the diameter of the end mill). It should be a two-flute one so it
is center cutting, and so cutting forces are less likely to deflect the
sides of the mill into the sides of the cut. (The greatest deflection
force on a 2-flute end mill is when a flute is passing across the
direction of travel -- and with a two-flute, the other will be behind
the mill where the already cut space is.) If you get deep enough, you
will have part of the flute twist around to the sides.

The Brits call a two-flute center cutting end mill a "slot
drill" because it is so good for this task.

You'll want to have compressed air blowing chips away from the
groove so they don't keep getting re-cut. (Or a shop vac nozzle right
beside the cutting location.)

Perhaps use something like WD-40 as a cutting lube if you can't
clear the chips as you go.

Second question, I will need to tap #4-40 holes in same aluminum. How
risky is this as far as tap is concerned and should I use lubrication?

Depends on the tap -- and the grade of the aluminum. If it is
something like 6061-T6 it should tap and mill nicely. If it is a plain
mild aluminum it will gum up both the end mill and the tap with likely
disaster to both.

For mild aluminum, you probably want a thread forming tap
(displaces metal instead of cutting it out) and a different size tap
hole than with a cutting tap. (_Machinery's Handbook_ has a table which
gives the right size for that.)

For the 6061-T6, use WD-40 as a threading lubricant or the
TapMatic marked explicitly for Aluminum (absolutely *not* the original
formula -- if you can find it -- which attacks the aluminum).

And Ideally, you want to use a "gun" tap (spiral point tap) in a
tapping head in the drill press or the mill for tapping through holes.
That is designed to chase the chips ahead of the tap, so you don't have
to keep backing up the tap to break the chips. Regular (plug) taps are
more of a problem -- especially in soft aluminum. If you don't have the
tapping head, a hand wrench and a guide to keep the tap perpendicular to
the surface of the workpiece.

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 ---

On Fri, 18 Jun 2010 14:40:33 -0500, Ignoramus13320
wrote:

Finally I need to make something to good precision, which is to make a
mounting plate for a US Digital encoder. The spec says shaft
misalignment should be under 0.01", which means that the individual
mounting holes need to be even more precisely placed, so as the
cumulative error will stay within spec.

Anyway, step number 1 is to cut a 4x1/4"x12" aluminum flat into three
pieces. I would like to do this on a Bridgeport and to use a thin
endmill, so as to keep as much material as possible. Should I use
carbide or HSS and what speed would you recommend for, say, a 1/8"
endmill?

Second question, I will need to tap #4-40 holes in same aluminum. How
risky is this as far as tap is concerned and should I use lubrication?

i

Look at
http://www.use-enco.com/CGI/INPDFF?P...MITEM=319-6567

tap guide, 325-5179. The pin is spring-loaded and reversable, the
other end is pointed. It says for #10 thru 1" taps but I've used mine
with taps down to 00-80. I use it both at the mill and at the lathe.
I about never tap a hole without it.

For lube on ally, try Goo-Gone. I'm not kidding!

On 2010-06-19, Don Foreman wrote:
On Fri, 18 Jun 2010 14:40:33 -0500, Ignoramus13320
wrote:

Second question, I will need to tap #4-40 holes in same aluminum. How
risky is this as far as tap is concerned and should I use lubrication?

[ ... ]

Look at
http://www.use-enco.com/CGI/INPDFF?P...MITEM=319-6567

tap guide, 325-5179. The pin is spring-loaded and reversable, the
other end is pointed.

I've got one -- and was just using it downstairs in the shop
within about the past hour. It was on the lathe with the bed turret in
place, so I swapped it into the drill chuck on one station which had
just drilled the hole to be tapped.

It says for #10 thru 1" taps but I've used mine
with taps down to 00-80. I use it both at the mill and at the lathe.
I about never tap a hole without it.

It is very nice as long as you have not shifted the workpiece
with respect to the spindle since drilling the tap hole.

But for multiple threaded holes on the drill press I am more
likely to use a TapMatic tapping head with gun taps. It (the larger of
my two) was a lifesaver when I had to drill and tap 24 holes for 1/4-20
in 1/4" thick steel plate. I also had to be creative in supporting the
fairly long (24") workpiece when drilling and tapping the holes near the
ends.

For lube on ally, try Goo-Gone. I'm not kidding!

Interesting. I'll have to try that.

Enjoy,
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 ---

On 19 Jun 2010 04:27:48 GMT, "DoN. Nichols"
wrote:

On 2010-06-19, Don Foreman wrote:
On Fri, 18 Jun 2010 14:40:33 -0500, Ignoramus13320
wrote:

Second question, I will need to tap #4-40 holes in same aluminum. How
risky is this as far as tap is concerned and should I use lubrication?

[ ... ]

Look at
http://www.use-enco.com/CGI/INPDFF?P...MITEM=319-6567

tap guide, 325-5179. The pin is spring-loaded and reversable, the
other end is pointed.

I've got one -- and was just using it downstairs in the shop
within about the past hour. It was on the lathe with the bed turret in
place, so I swapped it into the drill chuck on one station which had
just drilled the hole to be tapped.

It says for #10 thru 1" taps but I've used mine
with taps down to 00-80. I use it both at the mill and at the lathe.
I about never tap a hole without it.

It is very nice as long as you have not shifted the workpiece
with respect to the spindle since drilling the tap hole.

I never do it in a drillpress, always in the BP. The DRO makes it
easy to return to a hole for tapping if it isn't tapped immediately
after drilling. If the holes are close together it's quicker to drill
them all, then go back and tap them all. If they're further apart
it's quicker to change from drill to tap at each location.

But for multiple threaded holes on the drill press I am more
likely to use a TapMatic tapping head with gun taps. It (the larger of
my two) was a lifesaver when I had to drill and tap 24 holes for 1/4-20
in 1/4" thick steel plate. I also had to be creative in supporting the
fairly long (24") workpiece when drilling and tapping the holes near the
ends.

I once watched a machinist tapping hundreds of holes in what I think
was a prototype Mark 46 torpedo. He did it with a pneumatic hand
drill. Zoop zoop, slick as snot. I suspected that he'd done this
before.

A pneumatic drill isn't nearly as likely to snap a tap as an electric
drill. If the tap gets in trouble the pneumatic drill will stall,
saving both the tap and the job. It still takes a steady hand, though.
I've done it with #10 and 1/4" but I wouldn't try it with 6-32 or
smaller.

"Don Foreman" wrote in message
...

A pneumatic drill isn't nearly as likely to snap a tap as an electric
drill. If the tap gets in trouble the pneumatic drill will stall,
saving both the tap and the job. It still takes a steady hand, though.
I've done it with #10 and 1/4" but I wouldn't try it with 6-32 or
smaller.

An ordinary battery operated drill works fine in most cases, especially ones
with a clutch.

The 6-32 tap tends to break just looking at the thing, but that is not due
to it being a #6 screw, it is due to the ultra-course pitch. 6-40 works
much better.

--

Roger Shoaf

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

I once watched a machinist tapping hundreds of holes in what I think
was a prototype Mark 46 torpedo. He did it with a pneumatic hand
drill. Zoop zoop, slick as snot. I suspected that he'd done this
before.

A pneumatic drill isn't nearly as likely to snap a tap as an electric
drill. If the tap gets in trouble the pneumatic drill will stall,
saving both the tap and the job. It still takes a steady hand, though.
I've done it with #10 and 1/4" but I wouldn't try it with 6-32 or
smaller.

A speed wrench makes a GREAT quick tapping tool. I pressed a tap holder with
the handle removed into a 3/8 drive socket, 12mm IIRC. Put this on the speed
wench with your tap installed and go to town!

If I'm drilling on the manual mill, I use the same tool you suggested.
Course, i prefer the cnc mill. Iggy's job would only take a couple minutes
if he had his CNC mill running.

Karl

Is it possible to mount it in such a way that you can adjust the
location? 0.010" is not that tight a spec anyway. If it were 0.001"
that would be a bit more trouble.

He needs to purchase a centering tool (CT) or make one. IIRC, they do
not come with the units. It's just a tapered bushing matching shaft
size (internal diameter) and encoder mounting plate opening (tapered
external diameter) that centers the device around the shaft so you can
drill the holes within reason.

Hole locations do not have to be as precise as the OP is implying. You
use the CT again to center the encoder ***precisely*** while
tightening the screws. Installing a US Digital encoder accurately is
really a piece of cake. In fact, dual shaft PM motors from CNC
suppliers these days typically come with holes either drilled directly
in the motor or on a plate attached to the motor, meeting Agilent/USD
mounting specs.


On Jun 18, 10:35*pm, "DoN. Nichols" wrote:

On Jun 18, 3:40*pm, Ignoramus13320 ignoramus13...@NOSPAM.
13320.invalid wrote:
Finally I need to make something to good precision, which is to make a
mounting plate for a US Digital encoder. The spec says shaft
misalignment should be under 0.01", which means that the individual
mounting holes need to be even more precisely placed, so as the
cumulative error will stay within spec.

Anyway, step number 1 is to cut a 4x1/4"x12" aluminum flat into three
pieces. I would like to do this on a Bridgeport and to use a thin
endmill, so as to keep as much material as possible. Should I use
carbide or HSS and what speed would you recommend for, say, a 1/8"
endmill?

Second question, I will need to tap #4-40 holes in same aluminum. How
risky is this as far as tap is concerned and should I use lubrication?

i

1/8" HSS at the highest speed your Bridgeport is comfortable with
should be fine. The last one I used was loud enough at 2000 RPM that I
could no longer hear the end mill cut. I run 1/8" HSS at 3200 RPM on
the Clausing. That's a skosh high but not excessive even for steel.

One advantage of milling vs bandsawing is that you don't have to
square up the rhomboidal center piece afterwards.

If the ends are square I think I would set a vise stop to put the cut
line just past the end of the jaws and then make four passes, both
sides of both ends, so you only have to mill 1/8" deep. If they aren't
square a rod work stop clamped in a tee slot and touching the work at
its center should get you close enough to clean and square them up
easily.

Since my mill doesn't have a DRO or enough quill travel to accommodate
the fancy gizmos I start a tap straight in the drilled hole by guiding
the tap shank with the untightened drill chuck jaws and turning the
tap with one of these:
https://www.hardwareworld.com/files/pi/mD/U/TVE3.jpg
clamped onto the flutes.

Once it's started straight I back off the quill and switch to another
tap in a more convenient holder.

My well-used Clausing mill has a smooth and sensitive enough feel to
use it as a manual tapper
http://www.phase2plus.com/pics/265-110.jpg
but I wouldn't try that on a Bridgeport, and usually on the Clausing
only to start the tap.

You don't need to tap #4-40 the full 1/4" depth. If you drill part way
through from the back at one size smaller than the OD of the tap
threads you can hand-tap the holes by using the larger hole as a
starting guide. The very shallow cut is enough to force the tap to run
straight but not enough to break it. A hole slightly larger than the
tap saves time but doesn't force alignment quite as well. Use a stub
drill bit bottomed in the chuck so you can swap it with a jobbers
length tap size drill without losing your depth stop position.

Some people like this method:
http://www.finelinehair.com/home/tai...iage_mod_2.jpg
The next time I tram the head of my mill really square and maybe
surface-grind the vise base I might make one. It could be bored on a
lathe too, if you have the small boring bars.

Which one of those I use varies with diameter and material. Sometimes
I even power-tap.

jsw

On Jun 19, 6:53*pm, Joseph Gwinn wrote:
...
Jokisch is actually the best but can be difficult to find.
http://www.intercononline.com/jokisch/tapping.htm

Do they sell in small quantities, directly or by distributors?

Joe Gwinn

I have a pretty good selection of tapping fluids but aluminum is so
easy with good taps that I just use kerosine from a needle bottle.

jsw

In article ,
Jim Wilkins wrote:

On Jun 19, 6:53*pm, Joseph Gwinn wrote:
...
Jokisch is actually the best but can be difficult to find.
http://www.intercononline.com/jokisch/tapping.htm

Do they sell in small quantities, directly or by distributors?

Joe Gwinn

I have a pretty good selection of tapping fluids but aluminum is so
easy with good taps that I just use kerosine from a needle bottle.

I find that denatured alcohol works pretty well for aluminum, and evaporates far
faster than kerosene.

But I was thinking of fluids for working steel.

Joe Gwinn

A little update.

Unfortunately, the 1/4" alimunum plate was not thick enough.

I would have to go with a 3/8" plate. To simplify my life, I will
spend a few extra $$ and will buy a brass plate 4x12x3/8". It is $40
more, but I think that it will actually save me money, due to less
chances of things going badly.

i

I find that denatured alcohol works pretty well for aluminum, and evaporates far
faster than kerosene.

Educate me.....Why would fast evaporation be a desirable property for
a cutting/tapping fluid especially since heat is involved? I would
think just the opposite.


On Jun 20, 10:21*am, Joseph Gwinn wrote:

On Jun 20, 1:10*pm, " wrote:
I find that denatured alcohol works pretty well for aluminum, and evaporates far
faster than kerosene.

Educate me.....Why would fast evaporation be a desirable property for
a cutting/tapping fluid especially since heat is involved? I would
think just the opposite.

In electronics 91% isopropyl alcohol is about the only solvent we can
use now, so we use it everywhere. It's somewhat better than nothing
and doesn't mess up your drawing too badly. The evaporation rate is
reasonable for a cutting fluid.

jsw

In article ,
" wrote:

On Jun 20, 10:21*am, Joseph Gwinn wrote:

I find that denatured alcohol works pretty well for aluminum, and
evaporates far
faster than kerosene.

Educate me.....Why would fast evaporation be a desirable property for
a cutting/tapping fluid especially since heat is involved? I would
think just the opposite.

We are not talking of shipyard sized work pieces here.

It's easy to provide enough alcohol to flood the drilling zone despite the heat
of drilling. Then a puff of compressed air cleans everything away. Except the
burr.

Joe Gwinn

On Sun, 20 Jun 2010 10:30:48 -0500, Ignoramus32553
wrote:

A little update.

Unfortunately, the 1/4" alimunum plate was not thick enough.

I would have to go with a 3/8" plate. To simplify my life, I will
spend a few extra $$ and will buy a brass plate 4x12x3/8". It is $40
more, but I think that it will actually save me money, due to less
chances of things going badly.

i

Why not cut it out of steel?????

Gunner

One could not be a successful Leftwinger without realizing that,
in contrast to the popular conception supported by newspapers
and mothers of Leftwingers, a goodly number of Leftwingers are
not only narrow-minded and dull, but also just stupid.
Gunner Asch