Clausing-Colchester Lathe Question

Machine Shop
#1

I need to turn an 8.25" piece of round material.

Can anyone tell me how large of a piece of material the 3-jaw chuck can hold?

Thanks,

Phil

#2

If the jaws are reversible (I don’t know if they are) it might work, but for work that large I really recommend the four jaw chuck since it can hold it MUCH more securely. The additional time centering is well worth it for pieces that large. Also, if the piece is longer then a couple of inches, I also recommend using the tailstick to support the piece.

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#3

Everything Walter said. :+1:

#4

I’ll add, that if you are used to working smaller pieces where the RPM you are comfortable with is always below max SFPM, be sure you figure out your circumference and check the handbook for the material and tooling and be sure you don’t work it too fast.

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#5

Throw it in the large 4 jaw. It will be better in the long run for ya. While we can reverse the jaws, I don’t think there is enough purchase for that size. Additionally if anyone reverses the jaws, they need to be sure to put them back in the right other.

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#6

I don’t think these jaws reverse by winding them out of the scroll, but rather by unbolting the jaw and bolting it back on the other way.

#7

You are correct. The jaws do come out but you don’t reverse them. You unbolt the jaw from the jaw mount.

#8

Phil,

Are you going to need to turn the part that will be guarded by the chuck jaws? Are you planning to turn part, flip the part, then turn the balance? Or are you planning to turn part then part off the piece desired? If this thing is solid you are going to have a tough time parting with our current parting tool, but if it is mostly hollow you might be able to part it on the lathe. I don’t believe that 8.25" round can fit in the cold saw, which is used for steel but not aluminum. The Well saw in the metal shop might be able to do that size in any metal except hardened steel. If this thing is to be a fly wheel or the balance is critical it should really be turned between centers instead of chuck mounting it. Even though there is almost nothing that a determined member can’t get into a chuck, there may be more to consider than getting it into a chuck.

Regards,

Bob

#9

Max on Cold Cut is 4" of mild steel or brass.

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#10

My thanks to everyone that responded. I’ve determined that I’m NOT going to try to do this.

I was thinking about mounting a hollow piece of Aluminum and based on the feedback, clearly the four-jaw chuck would have been the way to do so and clearly at a low speed.

Just to comment on a few items:

  1. I was told during the lathe training that the jaws in the 3-jaw chuck are not reversible, so I cannot advise anyone doing that unless something has changed.
  2. I can confirm that the cold saw has a 4" maximum cut - I was just barely able to get the blade guard to clear a piece of 4" steel stock a few weeks ago.
  3. Bob is 100% correct - there’s way more to think about that “just getting it into the chuck” - part of the reason I have abandon the idea of using the lathe for something that big.

Thanks again to everyone that took the time to respond.

Phil

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