Lathe chuck question ??

[dr sportster]

Can a chuck loose ability to hold parts tightly ? I admit sometimes I did not have a great bite, sometimes nylon slipped but it is slippery . Even some steel and brass parts flew out . It is a three jaw chuck USA made in Michigan . Even when you give it an extra crank it seems to loosen too often. It used to hold with little surface area contact to the jaws no problem . Or parts moves in chuck from tool pressure. I always loved this chuck because it had no runout for a three jaw . I even give the chuck key that extra oomph still may get loose ?

 

[leroy in ne]

At former employment. CNC lathe required chuck disassembly, cleaning, coating scroll with special moly paste every 3 months, grease gun lube with special moly grease daily. If these instructions were not followed you could expect it to start throwing parts in the near future. Nothing like a 70 lb. chunk of steel unloading at 1000 RPM. Tends to modify tooling and shields.

 

[leroy in ne]

Note: this was a power chuck. Leroy

 

[Steve@Advance]

It probably needs to be disassembled and cleaned. Note the position of each slide, they have to go back where they came from.

Are the jaws removable or made as one piece to the chuck? If removable, you can probably buy a new set. They do get worn over time and are no longer parallel, tend to let the piece work out.

And eventually a chuck will get worn internally or damaged and need to be replaced. You get what you pay for, a good chuck with removable jaws and an adjustable back plate will be expensive but worth it.

 

[Repairman60]

Not knowing the size but some 3 jaws have three key holes tighten each one may help you.

 

[big jt]

Yes they can get worn if used repeatedly on the same size material. Usually only see it in production machines. I remember being in a guys shop that made parts for antique stationary engines and he had one lathe with a collet attachemnt. I asked him about it and his response was he made so many of the needle and seat kits for M series IHC engines (think 1.5, 3 and 6 HP hopper cooled) that he was wearing out chucks in that size range and that made the colllet attachment worth it. My lathe came from a production facility and had a collet attachment, I use it occasionally.

jt

 

[rlp in Co.]

Which way are you cutting? Cut toward the tail stock.

 

[Mike(NEOhio)]

Three jaws will wear toward the outer end of the jaws and the T-slots can wear causing the jaws to be out of square. It's common to grip the stock near the outer ends, we all do it. The can be refinished if you have a tool post grinder.

 

[markct]

Unless you are in a production shop on double it has worn out, I would disassemble and grease the pinions and scroll plate with a good moly grease

 

[dr sportster]

I traded a Smithy woodwrokers machine for a tool post grinder .

 

[M-MAN]

Sounds like it's well worth the trouble to take apart and clean. It's been a while since I researched it but I'm Pretty sure it takes a special grease in the scroll.