4 jaw chuck

[snoopdog]

So, looking for a 4 jaw chuck for my lathe, 2.25x8tpi threaded spindle, 8 or 6 in, preferably 8. Looks like I'll have to buy a plain backed chuck and a threaded backplate, if I end up buying new. I have an 8 in 3jaw and backplate that I haven't drilled, because I really haven't needed the bigger chuck yet. That 3 jaw has the 2 piece jaws, and finally I'll get to my question, what are the advantages or disadvantages to that? Is that something I should look for in a 4 jaw? Thanks ahead of time.

 

[bill stupak]

The 3 jaw with 2 piece jaws is nice for a few reasons, you can change from outside grab to inside faster and easier and best of all you can get and use soft jaws. I don't know if 4 jaws come with 2 piece jaws, but a 4 jaw is good thing to have.

 

[snoopdog]

The 3 jaw with 2 piece jaws is nice for a few reasons, you can change from outside grab to inside faster and easier and best of all you can get and use soft jaws. I don't know if 4 jaws come with 2 piece jaws, but a 4 jaw is good thing to have.

I'm not seeing any 2piece in the 4jaws.

 

[C-Bag]

What size lathe do you have?

 

[snoopdog]

What size lathe do you have?

I'm not sure the exact size,

 

[C-Bag]

Hmm, hard to say from the pic. Doesn’t say one the lathe? Just wanted to make sure you didn’t buy bigger than you need or is usable. My 9x20 came with a 4” 3jw, 5” 3jw and 6” 4jw. I have to be careful with the 6” with the jaws opened and clearance to the bed. I think a 5 or 5.5 would have been better but it works. Bigger is not always better.

 

[snoopdog]

Hmm, hard to say from the pic. Doesn’t say one the lathe? Just wanted to make sure you didn’t buy bigger than you need or is usable. My 9x20 came with a 4” 3jw, 5” 3jw and 6” 4jw. I have to be careful with the 6” with the jaws opened and clearance to the bed. I think a 5 or 5.5 would have been better but it works. Bigger is not always better.

I measured it at one time, but not sure now, its close to 14 x 40, 12 x 36 etc

 

[projectnut]

Another advantage of the 2-piece chuck jaws is that you won't lose one or more of the inner or outer jaws when you store them in that "special place". The primary advantage of a 4-jaw independent is that you can remove a part, reinsert it to perform a different operation and still be able to adjust for .000" or less runout.

Several brands of 4 jaw chucks do come with 2-piece jaws. If you do a quick Google search and click on "images" you'll see several vendors offering several brands with this feature.

 

[Jubil]

4 jaw doesn’t need 2 piece jaws because the jaws are reversible unless it’s a scroll chuck. The reason is the scroll gear in the scroll chucks will only work one way. Look inside your 3 jaw, you’ll understand. Or look at the back of the jaws, at the shape of the gear. On 3 jaw or any scroll chuck the gears are curved, on chucks with independent jaws they are relatively straight.

Chuck

 

[snoopdog]

4 jaw doesn’t need 2 piece jaws because the jaws are reversible unless it’s a scroll chuck. The reason is the scroll gear in the scroll chucks will only work one way. Look inside your 3 jaw, you’ll understand. Or look at the back of the jaws, at the shape of the gear. On 3 jaw or any scroll chuck the gears are curved, on chucks with independent jaws they are relatively straight.

Chuck

Yes, the jaws on my 6in 3 jaw are not reversible.