- Joined
- Sep 22, 2017
- Messages
- 139
I had made mention a few months back that I was working on making an ER40 collect chuck for the spindle of my lathe. I finished it tonight; however, I am unsatisfied with the result and will make a second attempt at making a better one.
The main reason I think it's a failure was that I managed to cut the internal threads for the spindle a bit too large, leaving more slop in the threads than I'm comfortable with. I've not made many projects on a lathe since high school. It's not a complete failure as I've certainly gained some knowledge and I suspect I can salvage it as a hex collect block.
The bar is oddly shaped, mostly round'ish with some flat spots. Imagine half a hex bar joined to half a round bar, but kinda lopsided and you're close to the shape. The 3 jaw chuck is too small to hold the piece, so I center drilled it for an arbor. I superglued the arbor in place, chucked it up and started working on it.
It was, for the most part, pretty straight forward. I bored out one end to fit the spindle, using a plug guage I'd prepared earlier for comparison. Cutting internal threads was a first for me and while the threadform came out fine, I overshot the maximum for 1 7/16-12 and ended up producing a loose fitting part. I had considered boring it out and sleeving it, but it would have made for thinner walls in a press-fit part than I felt comfortable attempting, so I pressed on knowing that this was now just a dress rehearsal and I'd have to start all over.
I set my compund to cut an 8 degree taper and mounted the collect chuck to the spindle and bored out the other end to accept an ER40 collet. As I closed in on the final size, I checked the fit of a collet and decided to adjust my compound slightly to make a nice fit.
It was also the first time cutting metric threads, M50 x 1.5, so I wasn't sure what to expect. I wrote a ruby script to calculate change gears and settled on 78t, 30t/18t, 66t as the best match, yielding a pitch of roughly 1.501 - close enough. The calculated change gears produced a thread that matches the nut quite well. I was very happy with that part of it.
Now I've got to try this again, this time with a little more experience. The issue with the spindle threads aside, I think it turned out well.
I had repeated issues with chatter, which I think was from my HSS bits being improperly ground.
The main reason I think it's a failure was that I managed to cut the internal threads for the spindle a bit too large, leaving more slop in the threads than I'm comfortable with. I've not made many projects on a lathe since high school. It's not a complete failure as I've certainly gained some knowledge and I suspect I can salvage it as a hex collect block.
The bar is oddly shaped, mostly round'ish with some flat spots. Imagine half a hex bar joined to half a round bar, but kinda lopsided and you're close to the shape. The 3 jaw chuck is too small to hold the piece, so I center drilled it for an arbor. I superglued the arbor in place, chucked it up and started working on it.
It was, for the most part, pretty straight forward. I bored out one end to fit the spindle, using a plug guage I'd prepared earlier for comparison. Cutting internal threads was a first for me and while the threadform came out fine, I overshot the maximum for 1 7/16-12 and ended up producing a loose fitting part. I had considered boring it out and sleeving it, but it would have made for thinner walls in a press-fit part than I felt comfortable attempting, so I pressed on knowing that this was now just a dress rehearsal and I'd have to start all over.
I set my compund to cut an 8 degree taper and mounted the collect chuck to the spindle and bored out the other end to accept an ER40 collet. As I closed in on the final size, I checked the fit of a collet and decided to adjust my compound slightly to make a nice fit.
It was also the first time cutting metric threads, M50 x 1.5, so I wasn't sure what to expect. I wrote a ruby script to calculate change gears and settled on 78t, 30t/18t, 66t as the best match, yielding a pitch of roughly 1.501 - close enough. The calculated change gears produced a thread that matches the nut quite well. I was very happy with that part of it.
Now I've got to try this again, this time with a little more experience. The issue with the spindle threads aside, I think it turned out well.
I had repeated issues with chatter, which I think was from my HSS bits being improperly ground.
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