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4 Jaw Chuck
- Thread starter NCjeeper
- Start date
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- Nov 18, 2012
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- 1,352
Yes...sort of. I have a 3 jaw Jacobs spindle chuck that goes up to just over 1/2", anything larger is my 4 jaw independent. With two keys I can centre pretty quickly for most work and pull out the dial indicator for real accurate stuff. Small accurate stuff I use ER collet system.
David
David
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- Sep 25, 2014
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4 jaws chucks work great. Certainly for certain irregular shapes, or if you need a piece offset from center - they also hold better, less tendency to distort hollow work. With a bit of practice, you'll get much quicker. I still recall my first awkward efforts (probably took me 15 minutes) - now it is a routine task (perhaps it takes a minute?).
I have not used the 2 key method (I'm used to a method that works well for me). Number the jaws, locate your dial at the top of the work piece (the mag base on the cross slide so you can move the whole dial back and forth to get the pointer on the high point), then work the jaws in pairs (i.e. get 1-3 close, then work 2-4, repeat), ignore the dial reading between the jaws - just dial the 4 quadrants (the space inbetween will sort itself out).
Regards, DavidC
I have not used the 2 key method (I'm used to a method that works well for me). Number the jaws, locate your dial at the top of the work piece (the mag base on the cross slide so you can move the whole dial back and forth to get the pointer on the high point), then work the jaws in pairs (i.e. get 1-3 close, then work 2-4, repeat), ignore the dial reading between the jaws - just dial the 4 quadrants (the space inbetween will sort itself out).
Regards, DavidC
- Joined
- Dec 27, 2014
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- 658
I use the 4jaw more than the 3jaw.
I never understood why people avoid them so much.
DavidC laid it out perfect. They hold better, distort less, and have less rotating mass and stick out.
Dialing in to about a thou takes maybe a minute, just work jaws in pairs. If I really mess up the initial centering, I use two keys to get it close. Then I just use one key. It is not rocket science, you just tighten the "high" jaw by 1/2 half the runout.
I do use my 3jaw, I just find the 4jaw more useful over all and so it tends to live on the lathe more than the 4jaw. Mostly I use the 3jaw when I am cutting parts off the end of a long bar that is run through the headstock. Hard to beat a 3jaw in that application.
I never understood why people avoid them so much.
DavidC laid it out perfect. They hold better, distort less, and have less rotating mass and stick out.
Dialing in to about a thou takes maybe a minute, just work jaws in pairs. If I really mess up the initial centering, I use two keys to get it close. Then I just use one key. It is not rocket science, you just tighten the "high" jaw by 1/2 half the runout.
I do use my 3jaw, I just find the 4jaw more useful over all and so it tends to live on the lathe more than the 4jaw. Mostly I use the 3jaw when I am cutting parts off the end of a long bar that is run through the headstock. Hard to beat a 3jaw in that application.
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- Jun 12, 2014
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Kinda a little of both depending on the project. If I was removing a piece frequently, 4 jaw gets to be a pain unless you use it a lot. I really like my 4 jaw combination, kinda the best of both worlds but they are very uncommon.
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- Dec 6, 2012
- Messages
- 2,677
My 10inch Powermatic/Logan came with a 4jaw. That's all I had.
Never did figure out the two wrench thing.
Now the only reason I keep the 3jaws for my other lathes is that it may make the lathes more saleable- someday....
Daryl
MN
Never did figure out the two wrench thing.
Now the only reason I keep the 3jaws for my other lathes is that it may make the lathes more saleable- someday....
Daryl
MN
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British Steel
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Call me spoilt, I have three 4-jaws of various sizes (the 10" Pratt-Burnerd with matching to lathe serial number stamped on the back..., a 8" Fuerda and a 5" Bison), swap them to suit the work as the lathe spindle has D1-5 engagements, not a thread.
I find the 4-jaws pretty quick to centre to within a thou" or less with a decent DTI (finger type, not plunger - I don't use two keys either) and use them in preference to the 3-jaw (an 8" Pratt-Burnerd, also matching s/n) even for quick jobs, although it's very good for a 60-year-old chuck, within a couple of thou" still! It may wind up permanently attached to a rotary table?
I also have the rare-as-rocking-horse-droppings native collet set (Holbrook parts are more than scarce and generally don't match up to any others!) and drawtube for up to 7/8" for less-than-tenth accuracy...
Anything really awkward goes on a faceplate firmly clamped, that way if it clears the ways it can be turned
Many seem intimidated by faceplate work, but with some attention to clamping, balance and *keeping the speed down* it's a good way to hold really oddly shaped work that you'd otherwise have to bore on a mill.
Even more run from between-centres machining, but I think it's the only way to reliably turn anything that needs to be taken off the lathe and e.g. checked for a bearing fit or measured. Does shallow tapers nicely too!
I WOULD like a 6-jaw self-centring chuck for thin-walled tubes etc., but I haven't found one in my price range yet... and I need to make a D1-5 spindle nose to go on one of my rotary tables!
Dave H. (the other one)
I find the 4-jaws pretty quick to centre to within a thou" or less with a decent DTI (finger type, not plunger - I don't use two keys either) and use them in preference to the 3-jaw (an 8" Pratt-Burnerd, also matching s/n) even for quick jobs, although it's very good for a 60-year-old chuck, within a couple of thou" still! It may wind up permanently attached to a rotary table?
I also have the rare-as-rocking-horse-droppings native collet set (Holbrook parts are more than scarce and generally don't match up to any others!) and drawtube for up to 7/8" for less-than-tenth accuracy...
Anything really awkward goes on a faceplate firmly clamped, that way if it clears the ways it can be turned
Many seem intimidated by faceplate work, but with some attention to clamping, balance and *keeping the speed down* it's a good way to hold really oddly shaped work that you'd otherwise have to bore on a mill.Even more run from between-centres machining, but I think it's the only way to reliably turn anything that needs to be taken off the lathe and e.g. checked for a bearing fit or measured. Does shallow tapers nicely too!
I WOULD like a 6-jaw self-centring chuck for thin-walled tubes etc., but I haven't found one in my price range yet... and I need to make a D1-5 spindle nose to go on one of my rotary tables!
Dave H. (the other one)
- Joined
- Sep 28, 2013
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- 4,319
had only a 4 jaw for 2 years, so it's nice to have a 3 jaw at last That said, it's a very handy thing to have when you need it.
That said, it's a very handy thing to have when you need it.
- Joined
- Jan 14, 2013
- Messages
- 290
My first encounter with a 4 jaw was in the 7th grade.
We had to remove our project at the end of class, If we didn't the next day we had to get it out of the trash, so we got good real quick. Sink or swim
My first encounter with a 3 jaw was like how does this thing work no mater which hole I stick the key in all the jaws turn together ROLMAO
Just remember tighten on the high loosen on the low
Numbering the jaws may reduce the chance of confusion also.
Tomh
We had to remove our project at the end of class, If we didn't the next day we had to get it out of the trash, so we got good real quick. Sink or swim
My first encounter with a 3 jaw was like how does this thing work no mater which hole I stick the key in all the jaws turn together
ROLMAO Just remember tighten on the high loosen on the low
Numbering the jaws may reduce the chance of confusion also.
Tomh