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Thread: Trueing up chuck jaws
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22nd January 2014, 08:22 PM #1SENIOR MEMBER
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Trueing up chuck jaws
Here's an interesting comment I received for a video I posted showing how to true up jaws with a TPG:
" I hone my chucks with a homemade brass hone impregnated with 200-300 mesh diamond grit (very easy to make and they last virtually forever). I chuck up the hone in a meticulously trued tailstock, oil up the hone & chuck jaws, tighten the jaws lightly onto the hone, run the headstock at a hundred RPM as I hone the jaws with an in and out action by the tailstock. I do this a few times until the jaws run parallel. The clamping force upon the hone is crucial to getting the clamping surfaces of the jaws parallel. I use the same technique with brand new drill chucks.
I don't care who makes the chuck, until you hone them, they always run untrue. And index the chuck to the headstock with a number or other mark. A sweet & true machine you will have (unlike my wife)."
I like the idea, but couldn't find any info on how to make the diamond hone. The poster hasn't responded to my request for more details.
So how to do the impregnation side of things ? Maybe dip a cylinder in two pack expoxy and roll in diamond grit on a flat surface ?
Ideas ????
Cheers
RobThe worst that can happen is you will fail.
But at least you tried.
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22nd January 2014, 08:54 PM #2
All i see is that if the chuck is overtightened even just a little it will push the brass bar out of alignment and you will only make things worse. Also with such a soft pre-load on the jaws they may not end up correct anyway.
Better to put a ring in the back of the jaws and do it with the TPG or that little die grinder...
Ew1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.
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22nd January 2014, 08:56 PM #3GOLD MEMBER
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Not so sure I like the sound of that, but then I havent tried it.(I'm pretty sure my tail stock is out far enough vertically that I wont be trying it any time soon)
To charge a lap you roll the brass lap on something flat(thats harder than brass) with the diamond grit on it. The grit will end up embebded in the softer material.
Stuart
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22nd January 2014, 09:19 PM #4Philomath in training
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I think your respondent is getting confused with two different things -
- Any chuck that you grind with a TPG should end up with jaws that are parallel. No need to then hone them. In terms of metal removal, a hone is going to take a long time compared to a TPG.
- Honing jaws as described will work fine for a piece of stock exactly the size of the hone. However, due to the way that a 3 jaw chuck works there is no guarantee that a differently sized piece of stock will be exactly centred as the scroll is not perfect. 3 jaw chucks are widely recognised as not being the most accurate way to hold things anyway - he should be using a collet chuck or dialing in a 4 jaw.
Sounds like someone who has come up with a way to do something they think is pretty good and now is trying to convert the world to that way of thinking. Was there any mention of then having to strip the chuck down to remove the diamond grit and then putting it back together having lost that "in-situ" accuracy that was previously honed in?
Michael
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23rd January 2014, 09:04 AM #5SENIOR MEMBER
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The quoted comment was all I got.
It's an interesting method I've never heard of, but the tailstock would definitely have to be true or you'd go bell mouth on the jaws.
I was more interested in how to make diamond hones than the actual suggestion.
Anyone made hones like this and used them ?
RobThe worst that can happen is you will fail.
But at least you tried.