Hello everyone I have just brought a AL 54B metalmaster lathe.
I have a 3 jaw chuck set up at the moment.
I took a skim off some 1 inch ally stock so I could spin it around and chuck it up to check run out with my dial indicator.
I wound up with 6 tho runout off the stock spinning in the chuck.
and about 5 tho off the actual chuck body itself.
I would really like to be able to do this test again with some drill rod instead but I dont have any at the moment.
Do you guys think this is acceptable with a 3 jaw chuck?
It will be ok if you finish your item to be turned in one setting. If you take it out and then replace it in the chuck it wont be concentric to the previous turned diameters.
ok thanks for that mate.
I will loosen the 3 bolts off and see if I can get it any better. This is as received from China so it could probably handle some tweaking.
If your looking for a precision groung piece of round stock for indicating purposes you might try some different size hardened dowel pins. You can get them in most hardware stores. I have found sizes up to 3/4" dia and 3" long. I use one when I want to check the chuck in my Clausing 5900. I usually end up with about .0003 spindle run out but that varies a bit with different dia. due to the chuck jaw position and the scroll. I also have a Bison set tru 6 jaw chuck on it. I'm pretty satisfied with that.
0.006" isn't all that bad. One of the brand new Bisons at the school had 0.030".
As malbenbut said, it'll be fine for everything you do in one setup. If you take it out, you'll have to put it in the 4-jaw to get the rest of the cuts concentric.
I always mark the position of the workpiece where where it touches the #1 jaw so I can put it back in like it was, if necessary. You still have to check it for runout, but at least you have a chance of it being very close. It doesn't help at all if you turn it around, though.
There are all sorts of ways to compensate for errors in the 3-jaw chuck, but learning to use the 4-jaw is the best approach.
Sounds American Indian
It would be a good idea if you have not already done so to completely disassemble the chuck and clean everything then carefully inspect internally, externally, look for burrs every where, back, scroll, guides, everywhere.