Am making a rear bumper for my 2002 Ford Ranger using a piece of 6" channel iron - maybe 1/8" thick. I need to cut/drill two 1 3/8" (35 mm) holes for the original Ford license plate light fixtures. Drill bits that size run about $110 but I don't possess a drill press anyway (and I think it probably stupid to try that with a 1/2" drill). Can I cut those with a bi-metal hole saw (about $9.00 each) or a carbide hole saw (about $17 each)?
Yes, the hole saw is the proper tool. Keep it oiled and stop if it smokes. If you don't overheat a hole saw, even a bi-metal one will make a dozen or more holes in 1/8 steel.
You try cutting a 1 1/8" hole in steel plating with a reciprocating saw. We'll wait. And it better be round, too.
Have a look at the Uni-bit. http://www.irwin.com/tools/drill-bits/high-speed-steel-fractional-hole-enlarging
If there was a Uni-bit that could cut that large of a hole, I imagine it would be a pretty spendy piece.
You could be right, BB. The good news is you own it (like a hole saw) and they are pretty handy for other projects. Looks like 1 3/8" is as big as the Irwins go, but there are other brands and prices out there too.
We use the hell out of Uni-bit's at work, mostly the smaller ones, and usually to get through sheet metal. The big boy (13/16-1 1/8") is over $80. For bigger holes we use hole saws.
I have them up to 2". The big ones are expensive though and I wouldn't use one on something that thick. I use the big unibits on thin metal and plastics and the like that won't hold a pilot bit properly. You also have to turn the big one slowly.
Alright, used a 1 3/8" Lenox bi-metal hole saw. Kept it submerged with oil - easy after I got a grove started. Worked extremely well at least on this standard construction 6" channel iron. Thanks guys.