What size hole saw do I use?

On Mon, 11 Jul 2005 02:11:41 GMT, Orval Fairbairn
wrote:

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.

Your drill press must run much slower than mine:-)) Even at the
slowest speed mine is far too fast for a fly-cutter of larger hole
saws. I prefer to use the fly-cutter chucked up in a good quality
floor mill.

A fly-cutter, at least in my experience will give the best finish to
the holes of just about any method including knock-out punches which
tend to roll the edges slightly. It's also easier to get all the
holes right where you want them which can sometimes be difficult with
the larger knockout punches. OTOH it takes a bit more skill to
sharpen the bit and to set up a fly cutter, but you can get a hole
that only requires breaking the edges to finish them up.

Hole saws tend to give a rather ragged edge and want to creep although
that can be minimized. A really sharp hole saw will do a pretty good
job but you have to be careful about it grabbing.

As for the size of a hole saw to use I go with one just as close to
the proper size I can get, while still staying under sized. I then
finish out the hole using a sanding drum. The larger ones take less
skill (and work) to keep the hole edges circular.

No matter which method is used, clamping the piece down with the
proper clamps and wood blocks (to protect the metal) is very important
from both the finished result and safety.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

On Mon, 11 Jul 2005 08:34:50 -0500, John T
wrote:

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.

A plasma torch properly set up can cut a hole in thin metal without
scorching the adjacent paint, but it takes a good set up and lots of
practice. They are fast. this would not be my choice for a first
timer.

I've cut sheets of white painted "barn metal" with a smaller self
contained unit. After being used to a torch (not on barn metal), it
took a bit of practice to get used to the speed (moving fast enough)
to do a good job. If the paint started to feather, or discolor along
the edge of the cut I knew I was moving too slow.

On a panel you'd want to build a fixture to move the tip in a circle,
or use a wood template. Wood works just fine as the plasma will, or
should be at least a quarter to half inch away from it.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

John

"LCT Paintball" wrote in message
news:7ExAe.145539$x96.83501@attbi_s72...
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.


My panel was .125" 6061 and I got it laser cut for $70 including material.
I never use the panel for an electrical ground, running ground wires to each
electrical device instead so decorative black anodize worked out
beautifully.

Bill Daniels

Morgans wrote:
"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.

Excellent point. Sounds like I am not the only one who learned the hard way.

Dan, U.S. Air Force, retired

On Sun, 10 Jul 2005 22:42:32 -0400, "Morgans"
wrote:


"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.

I would suggest that the safety issue of clamping applies equally to
using hole saws as well as fly cutters. I once had a half inch drill
bit hang up in a 4" X 12" piece of soft Aluminum 1/4" thick. When I
looked around after getting that sucker stopped all you could see were
eyeballs peaking over the tops of the work benches out in the shop. At
the first "clang" every one dove for cover. Man, but it was quiet in
there! Nobody wanted to look as they were afraid of what they were
going to see.

I never knew a good 1/2" drill bit could spring that far without
bending or breaking.

Of course the fly cutter has the added danger of getting caught on
clothing or tender body parts.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

When I get to my panel, which isn't going to be soon, I'll probably do
it on the mill. But for those who don't have access to a machine shop, I
wonder why you're talking about hole saws and fly cutters. Don't the
Greenlee type punches work pretty well? You only need a small pilot hole
and a couple of wrenches.

On Thu, 14 Jul 2005 08:23:48 -0700, Smitty
wrote:



When I get to my panel, which isn't going to be soon, I'll probably do
it on the mill. But for those who don't have access to a machine shop, I
wonder why you're talking about hole saws and fly cutters. Don't the
Greenlee type punches work pretty well? You only need a small pilot hole
and a couple of wrenches.

They cut a pretty good hole with cleaner edges than the hole saw and
are physically easier to use than a fly-cutter and safer than both,
but they do have some short comings.

Good hole saws can do a reasonably good job if the piece is firmly
clamped, the drill press, or mill is running very slow, and you use a
good cutting lubricant. Apply a very light pressure when starting the
cut although the saw will probably still grab. You should be able to
cut a nice round hole with out the saw wandering. The edges of the
hole will be a tad rough though.

With a fly-cutter, firm clamping is equally important. In addition
the bit needs to be properly shaped and sharpened as well as set at
the proper angle.

BTW, The quality of the hole with either the hole saw or fly cutter
depends highly on how well the piece is clamped in addition to the
safety issue.

The punches have to be in good shape other wise the edges of the hole
(usually by the points) can roll in and they oft times have a small
lip on the inside. This *usually* isn't much of a problem, however
the pilot hole needs to be a slip fit for the bolt and it needs to be
round if you expect close tolerances in positioning. That brings me
to the next one which is the larger punches. They require a pilot
hole punched with a smaller punch which needs to be a good fit to the
larger bolt. This can either give the user a chance to even out any
misplacement with the first hole, or accidentally add the
displacements to the point of where they are noticeably out-of-line.
I'd probably use a lot of Aluminum sigh and I've punched a *lot* of
holes using both the mechanical and hydraulic operated ones.

One final point. This type of punch is *EXPENSIVE*. Good quality
ones large enough for instruments will run well over a $100 and you
need a smaller one for the pilot. Over all it'd probably take about 5
different punches to do a panel with the punches ranging from about
$65 to $150 if they are real Greenlee punches. (Now if you know some
one with a set that's in good shape... G)

I was going to purchase a set and came away with a real case of
"sticker shock". I'm still keeping my eyes open for a used set in
good condition though.

Having said all of that, like any of the methods, skill plays a part
from the user and I've seen some very nice panels cut using all three
methods and I've seen some of the rejects too. :-))

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Most community colleges have a voc ed program where sheetmetal is one of the
classes offered. Most of them have Greenlee punches up through 5". Your
"class project" could certainly be an instrument panel AND most of them have
CNC machines available also.

Your tax dollars at work; you might as well take advantage of it.

Jim



One final point. This type of punch is *EXPENSIVE*. Good quality
ones large enough for instruments will run well over a $100 and you
need a smaller one for the pilot. Over all it'd probably take about 5
different punches to do a panel with the punches ranging from about
$65 to $150 if they are real Greenlee punches. (Now if you know some
one with a set that's in good shape... G)

I was going to purchase a set and came away with a real case of
"sticker shock". I'm still keeping my eyes open for a used set in
good condition though.

Having said all of that, like any of the methods, skill plays a part
from the user and I've seen some very nice panels cut using all three
methods and I've seen some of the rejects too. :-))

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Roger wrote:
On Thu, 14 Jul 2005 08:23:48 -0700, Smitty
wrote:


snip

The punches have to be in good shape other wise the edges of the hole
(usually by the points) can roll in and they oft times have a small
lip on the inside. This *usually* isn't much of a problem, however
the pilot hole needs to be a slip fit for the bolt and it needs to be
round if you expect close tolerances in positioning. That brings me
to the next one which is the larger punches. They require a pilot
hole punched with a smaller punch which needs to be a good fit to the
larger bolt. This can either give the user a chance to even out any
misplacement with the first hole, or accidentally add the
displacements to the point of where they are noticeably out-of-line.
I'd probably use a lot of Aluminum sigh and I've punched a *lot* of
holes using both the mechanical and hydraulic operated ones.

One final point. This type of punch is *EXPENSIVE*. Good quality
ones large enough for instruments will run well over a $100 and you
need a smaller one for the pilot. Over all it'd probably take about 5
different punches to do a panel with the punches ranging from about
$65 to $150 if they are real Greenlee punches. (Now if you know some
one with a set that's in good shape... G)

I was going to purchase a set and came away with a real case of
"sticker shock". I'm still keeping my eyes open for a used set in
good condition though.

I have bought several Greenlee hole punches from e-bay relatively
cheaply. My 3 1/8" cost me $100 plus shipping. Two things must be taken
into consideration: first most are used and need to be sharpened and
second conduit punches run 3/8" larger than the given size, e.g. a 2"
conduit punch is 2 3/8" actual. Sharpening is easy with either a medium
grit wheel (you use the side of the wheel) or a good, flat medium grit
whet stone. Punches listed as radio chassis punches are acual size.

Dan, U.S. Air Force, retired

In article ,
Smitty wrote:

When I get to my panel, which isn't going to be soon, I'll probably do
it on the mill. But for those who don't have access to a machine shop, I
wonder why you're talking about hole saws and fly cutters. Don't the
Greenlee type punches work pretty well? You only need a small pilot hole
and a couple of wrenches.

I much prefer the fly cutter, as the Greenlee punches take a lot of
torque and may leave the panel warped in places.

If you turn the fly cutter slow enough and use a good aluminum cutting
fluid, it works well and safely.

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