Cutting holes for gages...

[PeteVS]

How do you people cut holes for gages in sheet metal? They're kind of odd sizes (2-1/16") and Greenlee punches (if available in those sizes) are very pricey. Best off just hacking them out close with whatever and filing them out the rest of the way?

 

[tdlmomowers]

I used a hole saw to drill my dash for gauges in my 69 Torino. After drilling, I used a flapper wheel on my die grinder to fine tune the holes. Worked great, and the gauges aren't hanging under the dash on an accessory panel. I had room to mount all three gauges side by side, just had to relocate the cigarette lighter.

 

[mfagan]

Just make sure you buy a good quality
Bi-metal blade. Otherwise you'll just worry
the hole to death.

 

[Marvin/TN]

And use low RPM and use oil on the saw. Best to use in a drill press if possible

 

[Ronnie]

You can sandwich the plate between 2 pieces of 1/2" plywood with clamps and then take it to the drill press and get a nice clean hole.

R

 

[Bluebell]

If a chassis punch is not available and a hole saw is the planned method, I would drill the pilot hole, and then use a plain bit of tool steel as a mandrel in the arbor (replace the drill bit with some tool steel) so there is no movement laterally.

 

[Karl Wolf]

You can sandwich the plate between 2 pieces of 1/2" plywood with clamps and then take it to the drill press and get a nice clean hole.

R

What I have done is take the hole saw to a small piece of plywood, clamp the plywood to the dash and use it to guide the hole saw, with the pilot drill removed... The saw cannot wander around...
Works with the dash in place...

A Harbor Freight nibler can do the larger holes (like the speedo)

Karl

 

[PeteVS]

Thanks folks. I particularly like the idea of using a drill blank to pilot the hole saw after using a 1/4" drill to do the hole for the pilot.

 

[Zeke...PA]

Used a hole saw on mine but as you look at the speedometer hole you will notice the jump out that thank goodness is under the trim ring.
Zeke

 

[33cabriolet]

A 2" hole saw will cut a hole a little larger than 2" most of the holes are right at 2/16" or a half round file will enlarge the hole to fit the gauge.
John

 

[36Bill]

Ask an electrician, they should have a chassis punch.

Bill

 

[Cool Hand Lurker]

The two biggest problems with using a hole saw are the enlarging of the pilot hole by the drill and the resulting wobbling of the saw that makes a sloppy hole. I use the method of replacing the drill bit in the pilot hole with a smooth 1/4" shaft before cutting the hole. I hadn't thought of clamping a piece of plywood to the panel to use as a guide but it sounds like a great idea. But I would first cut all the holes in the plywood in their planned position using a drill press so the holes are precise.

 

[felix37]

At the shop we use the trick of removing the drill bit once the pilot hole has been made like the others have mentioned, but I also sand off the outer teeth on the hole saw and it makes for a much more precise holes and for some reason makes older hole saw's cut better.

 

[Ralph Moore]

I'm trying to cut a finishing plate for my steering gearbox mount, outside the frame. I am using 3/16" stainless so that I may polish it. So far I have destroyed three hole saws and I still have no hole. So today I think I will try the plasma cutter, although getting a true circle and straight lines is gping to be difficult for me.
Back on the subject of gauges, I want to put a SW tach in the radio hole in a 36 dash. The hole is about 1/8" too small all around. Any tricks on enlarging an exsisting hole?

 

[felix37]

scribe the correct size around the existing hole and carefully use a dremill tool with barrel sander or die grinder till you meet the scribed line. I use this method all the time at the shop. be sure to keep test fitting the gauge so you don't go to far.The bezel on the SW gauge should cover any minor imperfections.

 

[cmbrucew]

Ralph Moore

Use a circle of aluminum plate @ 1" smaller than the hole you want. Use double sticky tape to position the circle on the stainless, and use it for a guide for the plasma cutter.

Bruce

Works good
Lasts long time

 

[PeteVS]

Back on the subject of gauges, I want to put a SW tach in the radio hole in a 36 dash. The hole is about 1/8" too small all around. Any tricks on enlarging an exsisting hole?

If the dash is #18 gage (.048) or thinner, you should be able to get by with a pair of aviation snips.

 

[GOSFAST]

Using a cutter set as in the photo below (Morse) makes the job fairly easy. A drill press certainly helps. A small flat piece of old plywood as a "backup" is also needed.

You can cut very neat holes with this setup with a minimum amount of "dressing" up. Use slow speed and no lube, for "sheet" (.060") aluminum.

The holes in the photo below measured 3.625", this was using a 3.500" hole saw! Due to the saw's design the holes are always slightly larger.

Thanks, Gary in N.Y.

P.S. The key is to keep everything as stable as possible, as you can see in the photos, the holes came out very "neat".

 

[Pete]

A cheap, easy method of making any large hole, even odd shapes is, drill a series of 1/8 holes all around just inside the the scribed line. Leave about 1/32 between the holes. Then nip the webs with a pair of side cutters. Remove the center and finish the edges with a half round file.
Time consuming, yes, very accurate, yes.
Big advantage, cheap. No expensive hole saws or chassis punches needed.
The holes could be drilled with a hand drill if you are really hard up.

Another method used in the "olde dayz" was the single bit adjustable fly cutter driven with a hand brace.

 

[Cool Hand Lurker]

"I'm trying to cut a finishing plate for my steering gearbox mount, outside the frame. I am using 3/16" stainless so that I may polish it. So far I have destroyed three hole saws and I still have no hole. So today I think I will try the plasma cutter, although getting a true circle and straight lines is gping to be difficult for me. "

I made a compass out of a flat bar of steel to use with my acetylene torch for cutting holes. Just drill two holes half the hole diameter apart in the bar. One hole should be 1/8" or so to match a pivot stud that will go into the center pilot hole drilled where you want your hole to be. The other hole should be the diameter of the cutting torch tip. Then with the bar anchored at the pivot point you can move the torch around in a circle to cut the hole. Go slow.

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