Had an idea today. Probably not the first person to do this.
Ok so I have a 1-1/2" hole that I want to be 1-3/4".
Take a 5/8-18 bolt. Cut the head off and turn a shank to fit in my drill.
Chuck that bad boy into a drill. Thread on the 1-3/4" hole saw, stick a washer or two onto the shaft and then thread on the 1-1/2" hole saw
Now i have a piloted hole cutter.
This hole is actually over an inch deep and took a while but it worked.
I have done that with a deep wall socket as the pilot.
Excellent solution to a common problem. Hats off!
Need idea, thanks for the tip!
For others trying to enlarge holes or start a hole saw where there isn't anything to drill into is to tack weld/fasten a piece of scrap metal into the area where the center bit is. This is a fairly obvious trick if you've got a welder, but I'll share it anyway! Here's an image I stole from another forum of a guy doing the same thing when his pilot drill needed something to grab on to:
Bryce
I've done that, although I used the pilot bit instead of the 5/8-18 bolt. I'll have to get a bolt and see if that will work with the pile of Lenox hole saws I have. That would be a good thing to already have ready to go in the drill-bit drawer.
Great idea.
I've just used a burr bit to enlarge holes in the past. Never really worked well.
Another option...
I do this frequently for wood. I see no reason why it wouldn't work for metal.
Take the hole saw of the correct desired diameter, and cut a hole in a piece of scrap with it.
Place the scrap on the finished piece with the hole aligning exactly where the finished hole is to be. Clamp it tight.
Go ahead and drill through the hole in the scrap. The hole saw will be guided by it's perimeter, instead of the center pilot.
This technique also works well to make plugs. Remove the center pilot of the hole saw, and cut perfect circles without a pilot.
I have to remember that....
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