I need to make a total of 44 rectangular holes in some reasonably thin
aluminum. 22 of them have to be .56" x .52"; 22 have to be .81" x .52"

I had assumed I would be able to go down to harbor freight and buy a
rectangular chassis punch; no, the cheap generic punches are all round,
and the only rectangular punches I've seen are special-order for
hundreds of dollars.

So... any good ideas (or sources of cheap rectangular punches!), or
should I plan on a day or so with my nibbler and a corner punch?
--
As we enjoy great advantages from the inventions of others, we should
be glad of an opportunity to serve others by any invention of ours;
and this we should do freely and generously. (Benjamin Franklin)

Joe Pfeiffer wrote:

I need to make a total of 44 rectangular holes in some reasonably thin
aluminum. 22 of them have to be .56" x .52"; 22 have to be .81" x .52"

I had assumed I would be able to go down to harbor freight and buy a
rectangular chassis punch; no, the cheap generic punches are all round,
and the only rectangular punches I've seen are special-order for
hundreds of dollars.

So... any good ideas (or sources of cheap rectangular punches!), or
should I plan on a day or so with my nibbler and a corner punch?
--
As we enjoy great advantages from the inventions of others, we should
be glad of an opportunity to serve others by any invention of ours;
and this we should do freely and generously. (Benjamin Franklin)

Since your holes don't look like a standard size, and are too small for
a typical pull stud punch set, you're in custom punch territory anyway.

Depending on the tolerances needed you might consider plasma cutting
with a template or CNC. CNC milling or routing would be another option.

A .5" square punch in a press might work ok if you can make several
punches to get the full shape.

On 9/4/2010 4:23 PM, Joe Pfeiffer wrote:
I need to make a total of 44 rectangular holes in some reasonably thin
aluminum. 22 of them have to be .56" x .52"; 22 have to be .81" x .52"

I had assumed I would be able to go down to harbor freight and buy a
rectangular chassis punch; no, the cheap generic punches are all round,
and the only rectangular punches I've seen are special-order for
hundreds of dollars.

So... any good ideas (or sources of cheap rectangular punches!), or
should I plan on a day or so with my nibbler and a corner punch?
You don't say how far from the edge or what size panel and if the
aluminum is flat, but it wouldn't take too long to cut them out with a
jeweler's saw with a swiveling blade holder if access allowed.

On Sep 4, 4:23*pm, Joe Pfeiffer wrote:
I need to make a total of 44 rectangular holes in some reasonably thin
aluminum. *22 of them have to be .56" x .52"; 22 have to be .81" x .52"


How thick is the aluminum? And how far are the holes from the edge?
Can the aluminum be put an a mill or drill press? Can the panels be
stacked so you can do 22 at a time? From your thoughts about a punch
from Harbor Freight, I suspect the panels can not be put on a mill or
stacked.


Dan

Joe Pfeiffer wrote in message
...
I need to make a total of 44 rectangular holes in some reasonably thin
aluminum. 22 of them have to be .56" x .52"; 22 have to be .81" x .52"

I had assumed I would be able to go down to harbor freight and buy a
rectangular chassis punch; no, the cheap generic punches are all round,
and the only rectangular punches I've seen are special-order for
hundreds of dollars.

So... any good ideas (or sources of cheap rectangular punches!), or
should I plan on a day or so with my nibbler and a corner punch?
--
As we enjoy great advantages from the inventions of others, we should
be glad of an opportunity to serve others by any invention of ours;
and this we should do freely and generously. (Benjamin Franklin)


I have a collection of old carpenter's chisels for this purpose. Grind a
decent cutting edge to them and grind back 2 of them width-wise for
dimensions of each rectancle. Then "chisel" through after marking , with a
backing of roof lead sheet over steel plate.

Joe Pfeiffer wrote:

I need to make a total of 44 rectangular holes in some reasonably thin
aluminum. 22 of them have to be .56" x .52"; 22 have to be .81" x .52"

I had assumed I would be able to go down to harbor freight and buy a
rectangular chassis punch; no, the cheap generic punches are all round,
and the only rectangular punches I've seen are special-order for
hundreds of dollars.

So... any good ideas (or sources of cheap rectangular punches!), or
should I plan on a day or so with my nibbler and a corner punch?

Aluminum, Thin. Hmm. Wood chisel, hardwood or aluminum backer, BFH (big ? hammer). Mark
the lines, line up the chisel, hit with whacker beater, repeat.

Wes

Actually following up to several different responses at once:

It's 22 of the smaller rectangles in one panel, 22 of the larger ones in
a second panel. Some will be too far away for a jeweler's saw. I don't
have good access to a plasma cutter (else the plasma cutter would almost
certainly be the right answer) or mill.

The wood chisel idea is certainly worth a try.
--
As we enjoy great advantages from the inventions of others, we should
be glad of an opportunity to serve others by any invention of ours;
and this we should do freely and generously. (Benjamin Franklin)

On Sep 4, 5:38*pm, Joe Pfeiffer wrote:
...
The wood chisel idea is certainly worth a try.

You could punch a half inch round hole and then shear the edges square
into the corners with the chisel on top and a steel bar clamped under
the cut line as the lower shear blade. Tilt the chisel sideways so it
shears the metal like tin snips

That's how I cut the slits for the louvers here
http://picasaweb.google.com/KB1DAL/P...37862376318882

I had just made this bending brake from scrap:
http://picasaweb.google.com/KB1DAL/H...95632358276434
Later, with a better clamping cam:
http://picasaweb.google.com/KB1DAL/H...33137678036386

I clamped the sheet in the brake with the folding leaf removed and
sheared along the edge of the lower frame. It's mild steel channel and
was scarred a little but that doesn't affect bending. I aligned the
hold-down bar with the edge of the frame and used it to line up the
cut. Perhaps you could grind the edge of an old lawnmower blade square
for the lower blade.

jsw

On Sat, 04 Sep 2010 15:38:04 -0600, Joe Pfeiffer wrote:
following up to several different responses at once:

It's 22 of the smaller rectangles in one panel, 22 of the larger ones in
a second panel. Some will be too far away for a jeweler's saw. I don't
have good access to a plasma cutter (else the plasma cutter would almost
certainly be the right answer) or mill.

The wood chisel idea is certainly worth a try.

If the chisel approach doesn't work out, consider using a scroll
saw. Typically they have a 16" - 22" throat and use 5" blades,
with or without pins. I've used the same blades (without pins,
30 to 40 tpi, 0.014 thick, 0.30 wide, 5" long) on both a little
Hitachi scroll saw and an 'Aven PS-21 Delux' jeweler's saw.

--
jiw

On 9/4/2010 6:54 PM, James Waldby wrote:
On Sat, 04 Sep 2010 15:38:04 -0600, Joe Pfeiffer wrote:
following up to several different responses at once:

It's 22 of the smaller rectangles in one panel, 22 of the larger ones in
a second panel. Some will be too far away for a jeweler's saw. I don't
have good access to a plasma cutter (else the plasma cutter would almost
certainly be the right answer) or mill.

The wood chisel idea is certainly worth a try.

If the chisel approach doesn't work out, consider using a scroll
saw. Typically they have a 16" - 22" throat and use 5" blades,
with or without pins. I've used the same blades (without pins,
30 to 40 tpi, 0.014 thick, 0.30 wide, 5" long) on both a little
Hitachi scroll saw and an 'Aven PS-21 Delux' jeweler's saw.

Not seeing the original post and not finding it on Google Groups so
don't know what the question was, but that said, if there is a need to
make rectangular holes in thin aluminum of the kind typically used for
instrument panels or the like, one possibility is a nibbler--you can get
a hand nibbler for 7 bucks from Harbor Fright, or if you're got 18 CFM
at 90 PSI an air nibbler for 30. Takes a little practice to get a clean
hole but the cheap handheld nibblers work surprisingly well.

On Sep 4, 5:38*pm, Joe Pfeiffer wrote:
Actually following up to several different responses at once:

It's 22 of the smaller rectangles in one panel, 22 of the larger ones in
a second panel. *Some will be too far away for a jeweler's saw. *I don't
have good access to a plasma cutter (else the plasma cutter would almost
certainly be the right answer) or mill.

The wood chisel idea is certainly worth a try.

If the panels are only about .030 thick, a box knife might work well.

Dan

On Sep 4, 1:23*pm, Joe Pfeiffer wrote:
I need to make a total of 44 rectangular holes in some reasonably thin
aluminum. *22 of them have to be .56" x .52"; 22 have to be .81" x .52"

Two solutions that haven't been mentioned: punch a round hole, then
use a coarse file to open it up (this can be rather fast in thin
aluminum).
A bit of chalk on the file might be helpful.

Also, electrical discharge machining can sink a graphite electrode of
any shape (square or rectangular is easy) into metal. In mass
production, that might be good (or you can make square dies this
way, then punch it mechanically).

On 2010-09-04, Mouse wrote:
On 9/4/2010 4:23 PM, Joe Pfeiffer wrote:
I need to make a total of 44 rectangular holes in some reasonably thin
aluminum. 22 of them have to be .56" x .52"; 22 have to be .81" x .52"

I had assumed I would be able to go down to harbor freight and buy a
rectangular chassis punch; no, the cheap generic punches are all round,
and the only rectangular punches I've seen are special-order for
hundreds of dollars.

The only rectangular ones which used to be available were the
ones for the socket for the Potter & Brumfield 4PDT plug-in relays.

So... any good ideas (or sources of cheap rectangular punches!), or
should I plan on a day or so with my nibbler and a corner punch?
You don't say how far from the edge or what size panel and if the
aluminum is flat, but it wouldn't take too long to cut them out with a
jeweler's saw with a swiveling blade holder if access allowed.

Or -- if you have a die filer, drill out near the border of the
holes. then smooth to scribed lines on the die filer.

Good Luck,
DoN.

--
Remove oil spill source from e-mail
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 ---

"J. Clarke" writes:

On 9/4/2010 6:54 PM, James Waldby wrote:
On Sat, 04 Sep 2010 15:38:04 -0600, Joe Pfeiffer wrote:
following up to several different responses at once:

It's 22 of the smaller rectangles in one panel, 22 of the larger ones in
a second panel. Some will be too far away for a jeweler's saw. I don't
have good access to a plasma cutter (else the plasma cutter would almost
certainly be the right answer) or mill.

The wood chisel idea is certainly worth a try.

If the chisel approach doesn't work out, consider using a scroll
saw. Typically they have a 16" - 22" throat and use 5" blades,
with or without pins. I've used the same blades (without pins,
30 to 40 tpi, 0.014 thick, 0.30 wide, 5" long) on both a little
Hitachi scroll saw and an 'Aven PS-21 Delux' jeweler's saw.

Not seeing the original post and not finding it on Google Groups so
don't know what the question was, but that said, if there is a need to
make rectangular holes in thin aluminum of the kind typically used for
instrument panels or the like, one possibility is a nibbler--you can
get a hand nibbler for 7 bucks from Harbor Fright, or if you're got 18
CFM at 90 PSI an air nibbler for 30. Takes a little practice to get a
clean hole but the cheap handheld nibblers work surprisingly well.

I need to check to see if I can nibble as small as needed here -- the
smaller holes I need is roughly half an inch on a side...
--
As we enjoy great advantages from the inventions of others, we should
be glad of an opportunity to serve others by any invention of ours;
and this we should do freely and generously. (Benjamin Franklin)

On Sep 4, 9:25*pm, whit3rd wrote:
...

Two solutions that haven't been mentioned: punch a round hole, then
use a coarse file to open it up (this can be rather fast in thin
aluminum).
...

I skipped that because one mistake can ruin the panel.

I added some afterthought holes to the 3/16" thick control panel of a
welded robot chassis by hand, since it was too big and obstructed by
then for a machine tool. After four holes my hands were tired and less
accurate; I wouldn't want to do 44.

If you take this route clamp the panel between boards to keep it
steady and quieter. I use a coarse half round rasp to square up the
hole if I can't saw it, then a "hand" file with a safe edge to cut to
the scribed outline.

If you have trouble controlling the rasp, the thin edges are easy to
grind 'safe'.

jsw

Joe Pfeiffer wrote:

"J. Clarke" writes:

On 9/4/2010 6:54 PM, James Waldby wrote:
On Sat, 04 Sep 2010 15:38:04 -0600, Joe Pfeiffer wrote:
following up to several different responses at once:

It's 22 of the smaller rectangles in one panel, 22 of the larger ones in
a second panel. Some will be too far away for a jeweler's saw. I don't
have good access to a plasma cutter (else the plasma cutter would almost
certainly be the right answer) or mill.

The wood chisel idea is certainly worth a try.

If the chisel approach doesn't work out, consider using a scroll
saw. Typically they have a 16" - 22" throat and use 5" blades,
with or without pins. I've used the same blades (without pins,
30 to 40 tpi, 0.014 thick, 0.30 wide, 5" long) on both a little
Hitachi scroll saw and an 'Aven PS-21 Delux' jeweler's saw.

Not seeing the original post and not finding it on Google Groups so
don't know what the question was, but that said, if there is a need to
make rectangular holes in thin aluminum of the kind typically used for
instrument panels or the like, one possibility is a nibbler--you can
get a hand nibbler for 7 bucks from Harbor Fright, or if you're got 18
CFM at 90 PSI an air nibbler for 30. Takes a little practice to get a
clean hole but the cheap handheld nibblers work surprisingly well.

I need to check to see if I can nibble as small as needed here -- the
smaller holes I need is roughly half an inch on a side...

The nibblers I've see are about 1/8"-3/16" square so they should work
fine.

Joe Pfeiffer wrote:

I need to make a total of 44 rectangular holes in some reasonably thin
aluminum. 22 of them have to be .56" x .52"; 22 have to be .81" x .52"

I had assumed I would be able to go down to harbor freight and buy a
rectangular chassis punch; no, the cheap generic punches are all round,
and the only rectangular punches I've seen are special-order for
hundreds of dollars.

So... any good ideas (or sources of cheap rectangular punches!), or
should I plan on a day or so with my nibbler and a corner punch?


Nibbler.


--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

On 2010-09-05, Michael A. Terrell wrote:

Joe Pfeiffer wrote:

I need to make a total of 44 rectangular holes in some reasonably thin
aluminum. 22 of them have to be .56" x .52"; 22 have to be .81" x .52"

I had assumed I would be able to go down to harbor freight and buy a
rectangular chassis punch; no, the cheap generic punches are all round,
and the only rectangular punches I've seen are special-order for
hundreds of dollars.

So... any good ideas (or sources of cheap rectangular punches!), or
should I plan on a day or so with my nibbler and a corner punch?


Nibbler.

For the Adel Nibbler, to start it in the smallest hole, drill a
hole which matches the diagonal of the square shank (punch), partially
unscrew the stop screw at the other end, swing the lever arm out to
allow withdrawing the punch, thread the small end of the punch through
the hole and re-assemble the Nibbler to punch your way out to the
outlines.

If you are even more space constrained -- drill a hole to clear
the across-the-flats dimension of the punch, and file corners to allow
it to be started.

If you want to cut slightly thicker aluminum than it is set up
for, you can file a flat on the proper side of the stop screw -- at the
expense of sore hand muscles sooner in the project. :-) (You didn't
mention what *you* considered "reasonably thin" to be -- and opinions
differ. :-)

If you are using an air-powered round Nibbler beware that the
punchings are nasty crescents with sharp points on each end of the
crescent.

And set up guides to follow so you don't wander outside the
intended hole -- far to easy to do with the air nibblers.

Enjoy,
DoN.

--
Remove oil spill source from e-mail
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:

On 2010-09-05, Michael A. Terrell wrote:

Joe Pfeiffer wrote:

I need to make a total of 44 rectangular holes in some reasonably thin
aluminum. 22 of them have to be .56" x .52"; 22 have to be .81" x .52"

I had assumed I would be able to go down to harbor freight and buy a
rectangular chassis punch; no, the cheap generic punches are all round,
and the only rectangular punches I've seen are special-order for
hundreds of dollars.

So... any good ideas (or sources of cheap rectangular punches!), or
should I plan on a day or so with my nibbler and a corner punch?


Nibbler.

For the Adel Nibbler, to start it in the smallest hole, drill a
hole which matches the diagonal of the square shank (punch), partially
unscrew the stop screw at the other end, swing the lever arm out to
allow withdrawing the punch, thread the small end of the punch through
the hole and re-assemble the Nibbler to punch your way out to the
outlines.

If you are even more space constrained -- drill a hole to clear
the across-the-flats dimension of the punch, and file corners to allow
it to be started.

If you want to cut slightly thicker aluminum than it is set up
for, you can file a flat on the proper side of the stop screw -- at the
expense of sore hand muscles sooner in the project. :-) (You didn't
mention what *you* considered "reasonably thin" to be -- and opinions
differ. :-)

If you are using an air-powered round Nibbler beware that the
punchings are nasty crescents with sharp points on each end of the
crescent.

And set up guides to follow so you don't wander outside the
intended hole -- far to easy to do with the air nibblers.


I've worn out quite a few bits and two Adel handles over the last 40
years. I currently have a cheapo hand nibbler I bought when no one had a
new Adel in stock The design is different and has more leverage which
is good for my Carpal Tunnel. I recently bought an air nibbler, but
haven't tried it yet.


--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

On Sep 4, 2:23*pm, Joe Pfeiffer wrote:
I need to make a total of 44 rectangular holes in some reasonably thin
aluminum. *22 of them have to be .56" x .52"; 22 have to be .81" x .52"

I had assumed I would be able to go down to harbor freight and buy a
rectangular chassis punch; no, the cheap generic punches are all round,
and the only rectangular punches I've seen are special-order for
hundreds of dollars.

So... *any good ideas (or sources of cheap rectangular punches!), or
should I plan on a day or so with my nibbler and a corner punch?
--
As we enjoy great advantages from the inventions of others, we should
be glad of an opportunity to serve others by any invention of ours;
and this we should do freely and generously. (Benjamin Franklin)

Drill round, nibble and file to mark. HF DOES carry a pneumatic file,
cheap at the half-off price. Where they nail you is with the file
sets. It does work, I've used it on several projects where the amount
of filing would be tedious. I have a square Greenlee punch, runs 1/2"
square, though, and worth a lot more than the $5 I paid from the odd-
tool closeout bin. Have never seen another except on paper and special
order at that.

Could also use a micro-die grinder with an appropriate burr to square
the hole a lot faster. Would leave less to file to square the corners
out. I've used a carbide burr on steel panels for expanding a knockout
for an off-center conduit, worked well, watch out for hot flying
chips. Another old dodge is to drill the corners with a really small
drill, then chew to that point with whatever and quit.

Stan