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3-Jaw Chuck
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Good evening friends, 1. ?Before I reassemble and lubricate the chuck, how easily should the jaws move in their appropriate channels? Matt |
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1. The jaws should be a snug fit/ they should slide fairly easily but they should not rattle in the guides/ ideally there should be no slack at all.
2. I would avoid all oils, since they are going to get sprayed around once the chuck starts turning. Fine swarf will stick to grease, so I'd avoid that too. I would look at dry lubricants, like graphite powder. If it flies around it doesn't do any harm. Then again I have never lubricated a chuck, and never needed to. |
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Lapping should be a last resort imo. I've ruined a chuck in the past trying to true up the jaws.?
I would imagine your problem is elsewhere, I doubt it would have left the factory all those years ago with tight jaws, they did have some degree of quality control. ? Are the jaws tight in the slot? If it is the slots it might just be burred corners.? |
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G'Day Matthew! Try the chuck ways for fit with chuck disassembled before lapping and if it is the same, try lubricating and if that helps, use chuck as it is, it may work its way by itself after a period of time. One of my Unimat 3, three jaws chucks was very tight and after few months being stiff after lubricating it started behaving. ? Cheers, Dushan On Mon, 6 Apr 2020 at 15:13, Matthew Trump <mjtrump@...> wrote: My jaws are very tight.? I will have to lap each one of the a little bit.? Equal amounts off of both sides. ?? |
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Aron
My original 3 jaw is still very tight to move by hand, I¡¯ve oiled all the parts and the jaws themself and it¡¯s only reduced a little, honestly I don¡¯t have issues holding material I only get push and pull during cuts if I haven¡¯t done it up right, honestly tight jaws can be a blessing as your less likely to get slippage during operation, but to be fair that¡¯s what the tommy bars are for on the original 3 jaw.
you may also have the jaws not set correctly in position, it maybe worth rotating them out and putting back in correct position. This can help a lot, I found that¡¯s reversing the jaws for larger work the manual was no bloody help at all, and you have to insert 3 into 3 2 into 1 and 1 into 2 in that order to work... if your problem is tapered cuts from the 3 jaw it could be a number of things like headstock isn¡¯t running true, so adjust the head, the bearings are shot ( really bad chatter during cutting with a sharp bit) or the lathe is not actually level. Believe me it¡¯s easy to correct the lvl issue! the other tapering issues could be too long a work piece in the jaw so it flexes during cutting... ive said all that and honestly haven¡¯t read all the posts but these have been my personal findings since owning a unimat that I¡¯ve had to overcome, but mines now running very well after addressing these issues. |
¿ªÔÆÌåÓýI¡¯m a relative beginner but I would say as long as the chuck is correctly fitted, tight is good. ?The 3 jaw chuck that came with mine secondhand moved freely and I had difficulty getting the precision I wanted. ?I acquired an apparently as new one that is very stiff to move, and have only ever gone back to the original when occasionally I have wanted to mount something head and tail. ?(I use the lathe as often for lining up as I do for turning.)On 6 Apr 2020, at 15:14, Aron <Tugtower@...> wrote:
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I have had a number of 3-jaw chucks pass through my hands. I can offer the following observations.
The earlier ones did not have a cupped washer in the back. The scroll ring on these usually spins freely. Those are the ones I prefer, and have one with very low runout.
Later ones have a cupped washer to take the "slop" out of the scroll ring. Some of these are VERY stiff as they came from the factory. I have modified several by reducing the diameter of the cupped washer, thereby reducing the force it exerts on the scroll ring.
Aftermarket: The Sherline chucks made with M12x1 thread have very tight tolerances. In some case it may be useful to lap these for smoother operation, although I have not attempted this with Sherline. The ubiquitous Harbor Freight Tools M12x1 chuck vary in fit, and are sometimes too tight. I have in fact successfully lapped HFT chucks to work much smoother and accurately.
-----Original Message-----
From: Aron <Tugtower@...> To: Dushan Grujich <dushangrujich@...>; [email protected] Sent: Mon, Apr 6, 2020 10:11 am Subject: Re: [Unimat] 3-Jaw Chuck My original 3 jaw is still very tight to move by hand, I¡¯ve oiled all the parts and the jaws themself and it¡¯s only reduced a little, honestly I don¡¯t have issues holding material I only get push and pull during cuts if I haven¡¯t done it up right, honestly tight jaws can be a blessing as your less likely to get slippage during operation, but to be fair that¡¯s what the tommy bars are for on the original 3 jaw.
you may also have the jaws not set correctly in position, it maybe worth rotating them out and putting back in correct position. This can help a lot, I found that¡¯s reversing the jaws for larger work the manual was no bloody help at all, and you have to insert 3 into 3 2 into 1 and 1 into 2 in that order to work... if your problem is tapered cuts from the 3 jaw it could be a number of things like headstock isn¡¯t running true, so adjust the head, the bearings are shot ( really bad chatter during cutting with a sharp bit) or the lathe is not actually level. Believe me it¡¯s easy to correct the lvl issue! the other tapering issues could be too long a work piece in the jaw so it flexes during cutting... ive said all that and honestly haven¡¯t read all the posts but these have been my personal findings since owning a unimat that I¡¯ve had to overcome, but mines now running very well after addressing these issues. |
Unimat Matt
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