3-Jaw

bonneblktrk said:
I have a Logan 820 it came with a 4-jaw. And a 4-jaw with independent moveable jaws, which has been useful when switching from internal to external turning large diameters. Do I need a 3-jaw? Is it better for round stock.
Thanks
Tom
Click to expand...

If you do a lot of round stock that's not absolutely critical, a three jaw will save a lot of time.
If you do a lot of round stock that's fairly critical, then a collet chuck and a set of collets will be quick and sufficiently accurate.
If you do some round stock that has to be very accurate, then use the independent four jaw and take the time to set it spot on.


M
 
Most novices do everything in a 3-jaw.
Experienced machiners use the 4-jaw more.

I'm neither. when I need accuracy on a round part, I use collets.
 
Thanks for the response gentlemen. So it looks like I have pretty much the proper chucks. I won't fret over a 3-jaw anymore. Chucks for the Logan seem not too available, what with the threaded spindle. The ones I got with the lathe, I have lucked out. I am low on the knowlege scale, and usually just try to get the best finish and tolerance of .001-.002 maybe I could do better if I knew more. Thanks again. A little picture of my equipment.

Logan Lathe 017.jpg Logan Lathe 028.jpg Shop 002.jpg
 
Tom thats a nice bit of gear there. but that last pic does my eyes in if I look at it to long :drink2:

bonneblktrk said:
....best finish and tolerance of .001-.002 maybe I could do better if I knew more. ....
Click to expand...

Dont forget that if you chuck something up, regardless of how eccentric it is installed, once you have turned it round it should be within 0.0002 on that lathe at the end of the day. None of this helps if you are only turning some of the item, but if you chuck up some material, machine up your part so that all surfaces have been reduced and then part it off, the finshed part will be as good as your lathe can be. The chuck having no impact on the final result.
If you put a test bar in your 3 jaw and machine its length, it should be concentric over the machined section. If it isnt you have problems elsewhere.

Cheers Phil
 
Darn, and I was just about over coveting a new to me larger mill and lathe setup. Then you had to come along and show us this pristine clean shop with all kinds of goodies I want. Now I gotta get over wanting new machines and.... A clean shop. Gee thanks there guy. All kidding aside that is a great looking lathe and a nice looking shop too. Have fun and dont forget to snap lots of pics so I can drool over them too.
Bob
 
Thanks will do. I will get some more pics, now that my son and I are done with his streetfighter motorcycle build.
 
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