Customs how to cut large round holes in body panels?

I need to cut 2 3/8" holes in my 64 Chevy Fleetside C10 to add backup lights. What is the best way to cut holes of that size? It is already painted so I don't want to use a torch.

 

Hole saw???

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Hole saw.

 

Find an electrician and ask to use his 2" conduit knock-out punch. Actual OD is 2 3/8 and if the punch is sharp, will give a nice clean hole....

 

All of the above. The knock out won't be as hard on your wrist as the big hole saw.

 

...And won't skate around while drilling and leave thin edges.

 

Tape it up first...

 

If you tape up the whole area, lay a good line to follow, a good quality jig saw with a metal blade will do a nice job, and nicely controllable

 

Yep,electricians greenlee punches.

 

Come on, man. This is hot rodding. We like to make it complicated.

 

I might even use snips, after drilling a smaller hole. Depends how ambitious I feel. But when I had to poke a 7/8" hole in the nicely painted dash in my Chevy II yesterday, I just used a hole saw.

 

Back it up with a piece of 3/4" plywood or a block of 2x6. If you can't clamp it, get someone brave to hold it for you. This gives the pilot bit something solid to go into, and will help prevent the hole saw from "walking".

 

Jim, smaller hole saws aren't too bad at 'wandering', but the bigger they are, the worse they wander. Even with 'backing' you can still have issues (wait until the pilot bit breaks and you scar the paint around your hole...) And the bigger saws just don't leave a 'clean' hole. As a retired electrician, I used both saws and punches more times than I can possibly count and always preferred to use a KO punch where possible. No sharp hot metal chips, no burned paint at the edge, just a cleaner deal all around. Actually, for holes up to about 1.125", a step bit works better than a hole saw on sheetmetal.

 

Which is fine, if you have access to knockout punches, and step bits...the few knockout punches I have are always the wrong size. But they will definitely leave a nice hole!

 

Can you rent a set? That's what I'd do here in the UK - would cost about $25 for the weekend. Better to spend some money on renting a punch than risk having a big hole saw wobble around and do $$$$ of damage to your paint. Do you have tool hire shops in the US?

If not, I'd tape up, mark out and then chain drill using a 3/8 drill inside the line. Then join up the dots with a pad saw. File to finish. Job done.

 

X2 on the knockout cutters. I bought a cheapo harbor fright set and they even work.

 

Get this guy to help ya.

 

I would use a fresh 2-1/4" hole saw with band saw stick lube and carefully file to final size. Any small irregularity should be under the gasket for rage light.

 

Greenlee punch is 1st choice , 2nd Holesaw low speed

 

If you use a hole saw, drill your pilot then remove the bit and either flip it around, or replace it with round bar.

It helps keep the bit from wollowing out the pilot hole and prevents some of the hole saw walk.

 

A radio "chassis punch " ( knock-out punch?) is good if it's new or sharp, otherwise drill a small pilot hole (3mm), holesaw on low speed and lube it while you go.

 

You can do it the hard way. Tape up the area, draw your line, take a drill with an 1/8" to 1/4" bit. Drill lots of holes just inside that line. Knock out that piece and file it until it is the right size.

Well somebody and to say it!

 

I was looking for a better way to punch holes/flare them (besides a HoleSaw), and decided to buy a Greenlee punch set (along with some individual ones on Ebay)-while the quality is first rate, I found that the sizes offered did not correlate (at all) with my hole flaring set-obviously, they are made for the Electricians of the World (which I am not), and, I found that there are at least two different designs of the Cutters ( I think the newer ones are ok)-

What I didn't like was the hole that was left-usually there were "ears" left (which, admittedly could be filed), but I was less than impressed (anybody looking for a nice Greenlee Punch set? )-

I get along pretty well using a Holesaw (like others), but I've always wanted to buy a set of these:

http://www.hougen.com/cutters/sheet-metal-hole-cutters/Carbide-Holcutters.html

 

I have used all of the mentioned tools over the years and they all have good and bad points. Lately I have found the small air saw made for panel cuts works really well. It is basically a cylindrical jig saw.

 

Yeah, those carbide cutters are the cats meow... But just as expensive as the KO punches if you buy a set, and they do wear out.

As to Greenlee-type KO sizes, there's 'other' sizes available (non-conduit-sized round, square, rectangular, and 'specialty' types) but they can get pretty pricey. While I got my sets in the course of my work, you can find the cutters/dies at swap meets, yard/garage sales and usually fairly cheap as most people don't know what they are. You can buy new drawbolts. Enerpac also makes KO cutters and sets that are almost identical to the Greenlee sets and the cutter and dies will interchange. There's also offshore-made sets available these days for pretty cheap, if you limit them to no thicker than 14 gage mild steel they'll hold up plenty good enough for 'hobby' use.

 

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Are you cutting holes the flat panels on the end of the bed?
http://www.fellionautorestoration.com/images/GM/1964_chevrolet_pickup/1964_chevrolet_pickup002.jpg

 

in sheet metal? the best/fastest way is to make the opening, then use a hole saw a size smaller, file the opening out to the marks. done and no damage to paint.

 

Having flashbacks of installing a rear antenna in a buddys freshly restored 57 chevy convertible.........he was very careful, cut the hole undersize, was fileing it out when he pulled the "rat tail" file a lttle too far and.......ran it down the panel........you know this isn't gonna end well......right? Be Carefull and tape up the panel before starting

 

X2 on the knockout punch mayby from a rental place.

 

I say you don't need back up lights. Leave it "as is".