I was reading one of the other posts and it reminded me of a trick that I use when trying to use a holesaw to cut a round hole through thin sheetmetal. If you've ever tried this the holesaw grabs the metal and the drill in the center of the holesaw cuts this odd shaped guide hole that no longer acts as a guide and the hole that you are trying to cut with the saw comes out all shitty and out of round. So here's what I do instead (I hope it hasn't been posted before). When I need to use a holesaw I find the center of the hole and center punch and drill it with a 1/4" drill bit (or better yet use a sheetmetal step drill, because it makes a cleaner hole). Well, most holesaws use a 1/4" drillbit in the center and this drill bit is usually removable (unless it is a cheep doorknob holesaw), I take out the drill bit and insert a piece of 1/4" cold rolled round stock and let it stick down about 1/2 to 3/4" below the cutting edge of the holesaw. Now as the holesaw tries to grab, the centering hole doesn't get oggered out of round and your holesaw cuts a nice round hole. So there you have it. I hope it helps someone out. Sorry I don't have pictures but I think you can figure it out. Good luck.
Good trick! When possible I have clamped a piece of wood behind to give the guide bit something more to hold it in position.
I've done that myself. a backup of a piece of plywood also helps. I've also tacked in a small piece of 1/4 flat scrap when using a big saw. I then drill my pilot through the 1/4 and sheet metal. It really helps the hole saw from grabbing or going crazy.
Here's another method. Use the holesaw to bore a hole in a piece of wood. Plywood at least 1/4" thick works fine. Clamp the wood to the sheetmetal in the location where you want the hole. Drill the hole with the holesaw using the hole in the wood as a guide. Perfect holes everytime.
Another trick I've used, similar to Frisco's, where the wood can't be clamped to the sheetmetal, because of clearance or other issues.... Take the wood circle you just cut out, & attach IT to the metal with a couple of screws...it has a 1/4" pilot hole, & the circle itself also locates the hole saw. You may need to move the pilot drill farther back into the holesaw in order to let the wood circle "start" the holesaw properly. Only caveat: if you need to drill several holes in this fashion, you will probably need to cut more than one wood circle pattern, as they wear down & won't guide the saw properly after a while.
Broken- sometimes it works, sometimes not...depends on the bit length & the pilot length needed. Often the set screw would have to tighten against the drill fluting which is a no-no, for me anyway. I've done it on occasion in the field, but usually keep the stock handy.
Sounds like a pretty neat trick. I usually pinch thin metal between a couple of piecs of wood with the right sized hole cut through them but you idea looks dooable so I'm gonna give it a whirl next time.
A better alternative to a hole saw is a good knockout punch set. If you know an electrician he will have one. You don't have as many hole size options but they work great on thin sheetmetal. Good tech post on holesaws though! Brad
Good tip. I have also found that a little chain lube/wax sprayed on the metal, and a light touch with the drill works wonders too.
Good idea. Back when I used to install a lot of radio speakers I would run the drill in reverse to cut through the upholstery so the hole saw would not rip it to shreds.
The Jalopy Journal
