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I didn't really need another grinder, but a friend here in Austin did me the favor of letting me have it at a really good price and, after all, who can resist a little jewel like this...
It's a Hermes engraver grinder and will make a very nice addition to my shop. I disassembled it, cleaned it up some, and began to think about what I needed to do to adapt it to my needs. It came with one, 1/8" collet and the collet closer had an m11 x 1 external thread that engaged an internal thread on the back of the collet. Hermes collets are pretty scarce and darned expensive at $60 apiece, plus I doubt you can get anything but round collets. I didn't have an M11 x 1 tap, so I decided to make a new collet closer with a 7/16 x 20 TPI. Here's the old and new collet closer side by side.
Then I set about making a new collet, first just to see if I could and second, to make a holder for 1/4" square HSS tool bits. Here's the old and new collets side by side.
And here it is with the 1/4" tool bit clamped in place.
Making collets does take a little time, but it's not particularly difficult. I started with a 1" diameter piece of 12L14. The big end of the collet is .83" in diameter and the body is .587. I drilled a 9/32" hole through the middle and enlarged the back of the hole to .390 up to about 1/4" from the face of the collet. Then I used a 1/4" square broach to make the square hole. It's actually the only broach I have and I used the tailstock ram in my lathe to push it through the face of the collet which was mounted in my 3-jaw chuck. I used a 7/16 x 20 tap to thread the inside of the collet and a .040" slitting saw to cut the slits in the front of the collet.
Don't know the grit of the diamond wheel that came on the Hermes, but it grinds the HSS tool bit pretty quickly and leaves a mirror finish with a razor sharp edge.
Chuck
It's a Hermes engraver grinder and will make a very nice addition to my shop. I disassembled it, cleaned it up some, and began to think about what I needed to do to adapt it to my needs. It came with one, 1/8" collet and the collet closer had an m11 x 1 external thread that engaged an internal thread on the back of the collet. Hermes collets are pretty scarce and darned expensive at $60 apiece, plus I doubt you can get anything but round collets. I didn't have an M11 x 1 tap, so I decided to make a new collet closer with a 7/16 x 20 TPI. Here's the old and new collet closer side by side.
Then I set about making a new collet, first just to see if I could and second, to make a holder for 1/4" square HSS tool bits. Here's the old and new collets side by side.
And here it is with the 1/4" tool bit clamped in place.
Making collets does take a little time, but it's not particularly difficult. I started with a 1" diameter piece of 12L14. The big end of the collet is .83" in diameter and the body is .587. I drilled a 9/32" hole through the middle and enlarged the back of the hole to .390 up to about 1/4" from the face of the collet. Then I used a 1/4" square broach to make the square hole. It's actually the only broach I have and I used the tailstock ram in my lathe to push it through the face of the collet which was mounted in my 3-jaw chuck. I used a 7/16 x 20 tap to thread the inside of the collet and a .040" slitting saw to cut the slits in the front of the collet.
Don't know the grit of the diamond wheel that came on the Hermes, but it grinds the HSS tool bit pretty quickly and leaves a mirror finish with a razor sharp edge.
Chuck
