I need to make two, 1 1/2" holes in a piece of 1/4" steel. They need to be a clean circles. I have a drill press. Is there a bit I can buy at the hardware store that will do this twice? Or.....if you had to do this with a makeshift tool assortment what would you do? Thanks

 

A carbide-tipped hole saw in a drill press might do it if you drill the pilot hole correctly and go slow, with plenty of lube. How precise does the hole need to be on diameter? You need a friend with a Bridgeport mill, or a lathe (if it can be chucked up).

 

I've done it this way thru 3/8, slow speed and patience and a whole lot of cutting oil

 

For clean, round larger holes in thicker metal it's hard to beat rotabroach holesaw cutters: Fractional Rotabroach Cutters
Designed to be used in steel up to 1/2" thick.

 

Sorry for the delay. I had to look up PRECISE in the dictionary. Not in my vocabulary or skillset. If I can get a bit at a local hardware store I would say pretty precise. If I can't or if my measurements are predictably off then I really would just need to remove material. Just trying first to save as much metal around the hole as I can and second avoid having to grind a bunch of metal away from the inside of the hole. For background...I made my own motor mounts for a 302. As luck would have it the mounts interfere with the brake line mounting hardware that comes through the frame I was just going to drill out a matching hole big enough to accommodate a socket big enough to get around the large nut on the inside.

 

For this job, a good bi-metal holesaw from your local DIY store should do the trick. Use a lot of lubricant, slowest speed, and moderate steady feed pressure. Withdraw the saw regularly to cool and flush out the chips.

 

I have never used the 1.5" version of the rotabroach that AX suggested. The kit is . I would think that you would need a good drill press to use it.

I would use a plasma cutter or bridgeport milling machine. If you don't have access to either I'm sure that there is a machine shop near Bakersfield that would do it for less than $50.

These pictures are of the plasma cutter used last week on 5/16" plate steel:

 

I've drilled many 1/1'2" and 2" holes in W-section flanges and well casings. A good quality hole saw works fine: Milwaukee, DeWalt, etc. It doesn't have to be carbide. Use a drill with an extension grip/handle so you don't wrench your arm if and when it takes a bite that is more than it can chew.