What size hole saw do I use?

I need to cut a panel to mount one 3.125" and one 2.25" What size hole
saws do I use? Do I use smaller sizes, say 2.125" for 2.25" and 3" for
3.125"? Thanks.

In article .com,
" wrote:

I need to cut a panel to mount one 3.125" and one 2.25" What size hole
saws do I use? Do I use smaller sizes, say 2.125" for 2.25" and 3" for
3.125"? Thanks.


I use a fly cutter sized to each hole size and then finish off the holes
with a "slapper wheel" sanding wheel. I have tried the hole punches and
hole saws, but prefer the fly cutter, in a drill press set to the lowest
speed. That way, I have the best control over the hole-making process.

--
Remove _'s from email address to talk to me.

Hey,
Your best bet is to use one of the adjustable hole cutters, I have never
seen a hole saw that actually cut the diameter that was written on the side.
I guess the wobble factor , etc. If you use a 2 1/4" hole saw you may well
end up with a 2 1/2 " hole depending on thickness of material.

Patrick
student SPL
aircraft structural mech


wrote in message
oups.com...
I need to cut a panel to mount one 3.125" and one 2.25" What size hole
saws do I use? Do I use smaller sizes, say 2.125" for 2.25" and 3" for
3.125"? Thanks.

Earlier, wrote:

I need to cut a panel to mount one 3.125" and one 2.25" What size hole
saws do I use? Do I use smaller sizes, say 2.125" for 2.25" and 3" for
3.125"? Thanks.

YMMV, but I've had good luck making 3-1/8" instrument holes with a
3-1/8" hole saw, likewise with the 2-1/4" saw. The hard part is finding
them in those sizes; you might have to order-in from www.mcmaster.com
or some such. The holes did tend to come out .020" or so oversize, but
the instruments I was mounting tended to be on the large size anyways.
If it's for something important, try it on scrap aluminum of the
correct thickness first.

These days I use a single-point suicide cutter as others mention.

Thanks, and best regards to all

Bob K.
http://www.hpaircraft.com

"Bob Kuykendall" wrote
These days I use a single-point suicide cutter as others mention.

Thanks, and best regards to all

I haven't seen anyone mention the importance of being safe, with a fly
cutter.

If you have never used one, on something like a panel, clamp it down to the
drill press table, like you never have clamped anything before. Then double
the clamps.
--
Jim in NC

wrote in message
oups.com...
I need to cut a panel to mount one 3.125" and one 2.25" What size hole
saws do I use? Do I use smaller sizes, say 2.125" for 2.25" and 3" for
3.125"? Thanks.


I have done this several ways. Hole saws - messy, fly cutters - dangerous
if not clamped VERY well and still messy, and milling machines - neat but
hard to get access.

The best way is to get the whole panel laser cut and then anodized black
after test fitting the instruments. Not all instruments are exactly 2.250
or 3.125 so specify the holes a few thou oversize. I did it this way for my
new glider panel. The results were very neat and not expensive at all.

If you really want to cut the metal yourself, make a tool/fixture out of
high density composite particle board - I think it's called MDX or something
like that. Forstner bits cut very neat 2.250 and 3.125 holes in the MDX
tooling. Mount the panel blank to the tool and rout the panel with tungsten
router bits with ball bearing guides. Cut undersize instrument holes in the
panel with a hole saw or fly cutter and finish with the router. Make or buy
a drill guide for the instrument screw holes.

BTW, I've never had countersunk instrument screw holes all come out
perfectly. At least a couple were slightly out of alignment putting stress
on the instrument cases. The last time around I used black button head
Allen screws in oversize holes which look as nice as the countersunk variety
and allowed for some misalignment.

Bill Daniels

Do a neat job - after all, you are going to be looking at the thing for a
long time.

Bill Daniels

Using a laser cutter changes the temper of the aluminum along the edges
of the cut. Perhaps not a big deal in a instrument panel, if it isn't
structural, but it is on a wing rib or other structural part.

A waterjet cutter can do the same thing, but you don't have to worry
about the temper. It will leave a slight burr, but nothing that can't be
dealed with simply.

John

I prefer not to anodize anything on the airplane. Anodizing forms a VERY
hard insulating film that you have to spot-face down to the aluminum to make
an electrical connection. I prefer to powder coat, which is nearly as tough
under operating conditions but not nearly as difficult to get an electrical
connection.

Jim


The best way is to get the whole panel laser cut and then anodized black
after test fitting the instruments.

The best way is to get the whole panel laser cut and then anodized black


Most laser machines don't like aluminum. It's too shinny, and can reflect
back into the lens. Look into water jet instead.

On Mon, 11 Jul 2005 08:55:14 -0700, "RST Engineering"
wrote:

I prefer not to anodize anything on the airplane. Anodizing forms a VERY
hard insulating film that you have to spot-face down to the aluminum to make
an electrical connection. I prefer to powder coat, which is nearly as tough
under operating conditions but not nearly as difficult to get an electrical
connection.

Jim

Another point against anodizing is that it increases the notch
sensitivity of already notch sensitive aluminum. This is far more
significant with hard anodizing than with decorative, but that
aluminum oxide will crack then concentrate the stress in the crack.

Powder coat has its problems too, and they are aluminum grade, product
and process dependent. All the processes I know actually "melt" a
powder on the surface. The temperatures of some powder processes are
above safe operating (change of properties) temperatures of some heat
treated aluminum alloys. I use "some" because I don't know details.

The best way is to get the whole panel laser cut and then anodized black
after test fitting the instruments.

George