05-18-2016, 12:01 PM
C'mon Ed, just make your own Greenlee punch. It'll only take an afternoon. 
Since we're talking about hole saws, I have a few hints & kinks I'll share. I use them all the time in my mill.
First off, the rattly ill-fitting arbors which they sell with hole saws are wretched, the work of the devil, IMHO, and contribute to the saw jamming in the cut.
I made some 3/4" arbors for hole saws. They look a little like a slitting saw arbor. I went to my friendly local fastener distributor and bough 2 sticks of all-thread which are the sizes for large and small hole saws. 5/8-18 and 1/2-20. I tapped the arbor for a chunk of all-thread, and slit the end of the all-thread so I could remove it with a screwdriver if it ever gets buggered up. I started with a 1 1/4" bar, and left the mating surface as large as possible after a light clean up on the outer diameter. This arbor is sufficiently stiff to run without a center drill, and to take a half-circle out of tubing (try *that* hand-held!) The plan is to make a fistful of them so I don't have to switch saws on the arbors. (maybe I'll make some R8 arbors!)
I run hole saws very slow, about 80-120 RPM, depending on size. I use heavy sulfured cutting oil, very liberally from a cleaning supply spray bottle.
Here are three great tips regarding the actual hole saws.
1) the mating face between the arbor and the saw is rarely true. This results in cutting only on one tooth which gets dull quickly, then just drags and makes heat. If you chuck the saw up in a 3-jaw chuck you can put a light facing cut on the mating surface and the saw will run significantly truer.
2) the sheet metal saw body is often too thin, and becomes thinner after facing which can allow the saw to bend or strip the thread. The solution is to cut a 1/4" thick disk and weld or braze it to the back of the saw. The key technology is to put the teeth in a shallow pan of water to keep from damaging the hardness when you weld. Also, the paint is NASTY - you'd do well to use paint stripper to remove the paint from the back and inside of the saw prior to welding. Once the disk is affixed, chuck it up in the lathe again and face the surface, and re-cut the threads.
3) If you want a precision hole, and the hole saw is cutting oversize, you can clamp a belt sander on the mill table and adjust the size by sanding the OD off.
Since we're talking about hole saws, I have a few hints & kinks I'll share. I use them all the time in my mill.
First off, the rattly ill-fitting arbors which they sell with hole saws are wretched, the work of the devil, IMHO, and contribute to the saw jamming in the cut.
I made some 3/4" arbors for hole saws. They look a little like a slitting saw arbor. I went to my friendly local fastener distributor and bough 2 sticks of all-thread which are the sizes for large and small hole saws. 5/8-18 and 1/2-20. I tapped the arbor for a chunk of all-thread, and slit the end of the all-thread so I could remove it with a screwdriver if it ever gets buggered up. I started with a 1 1/4" bar, and left the mating surface as large as possible after a light clean up on the outer diameter. This arbor is sufficiently stiff to run without a center drill, and to take a half-circle out of tubing (try *that* hand-held!) The plan is to make a fistful of them so I don't have to switch saws on the arbors. (maybe I'll make some R8 arbors!)
I run hole saws very slow, about 80-120 RPM, depending on size. I use heavy sulfured cutting oil, very liberally from a cleaning supply spray bottle.
Here are three great tips regarding the actual hole saws.
1) the mating face between the arbor and the saw is rarely true. This results in cutting only on one tooth which gets dull quickly, then just drags and makes heat. If you chuck the saw up in a 3-jaw chuck you can put a light facing cut on the mating surface and the saw will run significantly truer.
2) the sheet metal saw body is often too thin, and becomes thinner after facing which can allow the saw to bend or strip the thread. The solution is to cut a 1/4" thick disk and weld or braze it to the back of the saw. The key technology is to put the teeth in a shallow pan of water to keep from damaging the hardness when you weld. Also, the paint is NASTY - you'd do well to use paint stripper to remove the paint from the back and inside of the saw prior to welding. Once the disk is affixed, chuck it up in the lathe again and face the surface, and re-cut the threads.
3) If you want a precision hole, and the hole saw is cutting oversize, you can clamp a belt sander on the mill table and adjust the size by sanding the OD off.