Help Best way to fix.

It is almost like the jaws on the chuck are ground at an angle or something. Rather than true to the center. I even have a test bar that I barrowed that when chucked up does not indicate properly.
used a piece of 2.5 al and did bump it with a brass trying to get it to shift. Did not seem to really help much.
I will keep working on it, I have seen many on how to grind 3 jaw setups, but not the 4 jaw setups. In fact I had to do a touchup grind on the chuck I got with a Sherline. Once I did that it worked better. But not even sure how to look at doing this one. I will keep working at it. This is a good leaning experience.

Yes did check the bearings for play, etc All new bearings, oil seals etc.
Was new but not sure where it came from, Looks like one of the Grizzly ones I have seen,
the run out is about 0.100 over the 10 inches, Enough that you can readily see it at the end of the shaft.
 
Ok, Got home and decided to number and pull all 4 jaws out at one, Cleaned them up and set them down on a sheet of think glass (it is what I have for now) Then took a square and set up against the face on each, Two were out on the top, and two are out on the bottom. The are just opposite from each other. Think the Jaws were Looking it almost looks like they were ground with something under one side of the chuck. Could this be the problem. And would this cause problems trying to line up the headstock.
 
KVT, if you have a machinists square, check the face of the jaw to the face of the screw side and see if it is square or not.

In theory, they should be square and the slots cut in the chuck body should be square to the axis of the chuck. The back of the chuck should also be square with the axis. Also check the thickness of the chuck body all the way around. This may indicate where some of the runout is coming from.

Ken
 
kvt said:
run out is about 0.100 over the 10 inches
Click to expand...

IF this statement is true, (and we have no reason to doubt it) we're not talking about alignment but chuck runout.

If you mount an indicator on your compound and traverse the length of your rod, and you average each end, it will give you alignment. if you set zero a the chuck and rotating the chuck at the far end get plus and minus .050, you have zero alignment and .100 runout.
 
Ken, Yes checked the face of each against the face of the srew side and they are off when I put a machinist square against the face. They I have run an indicator on the chuck and it is good on the face. Have not checked the slots to see what they are like, but may do that while I have them out. I may also bring stuff with me on Sat, if ok.
Tom, Yea, chuck, cut an alum bar to the same size for 10 inch with less than 1 thou diff on each end then pulled it out and flipped it over and got about the same run out again. Made me start looking at the chuck All the stuff I had been doing prior was real short stuff that I had plenty of extra to take off so did not really notice it until now. Had used a different chuck that was barrowed to do my prior alignment with.
 
Ken,

Bring it all with you, we'll see how bad we can mess it up trying to fix it.:D Seriously, we can mount the jaws on my surface grinder and get them where they all run the same direction and give it try. And if we have to, set it up on the tool & cutter grinder and grind the jaws to match the chuck if I have a arbor we can mount the chuck on if necessary.

Ken
 
My Grizzly four jaw chuck appeared to have had the jaws ground in an external fixture. This is supported by the fact that replacement jaws are available. I reground my jaws in situ, which corrected a serious runout issue similar to yours (when I mounted a 9" bar in the chuck, I could cause a permanent deflection of more than .010" with finger pressure). Having reground my jaws, I numbered each jaw and the chuck face so I can install the jaws in the same position each time.

It is possible that the previous owner ground the jaws in situ and they were subsequently removed and replaced in the wrong order. Someone in a past thread did a complete overhaul of a four jaw chuck and had found some interesting results with the chuck body. Sorry, I can't recall who it was.

Four jaw chuck jaws are usually interchangeable. If you put the matching jaws opposite each other, they should cancel out. You will grip round stock at the front on two opposing jaws and at the rear on the other two jaws but you should get a repeatable grip.
 
You must log in or register to reply here.
Back
Top