Chuck Run Out

[kwgeorge]

I know since I joined I have not posted much here but I would like to get some long time turners options on a subject that is making me crazy and that is “Chuck Run-Outâ€Â. It is a subject that seems to rear its ugly head quite often on different forums and when it does the opinions start to fly!

I am the kind of guy that likes to try different products so I now own The Vicmarc 3-1/2â€Â, Super Nova, PSI CMG3 and the most recent is the Nova Midi. I also hate stopping to change jaws thus the number of chucks I own.

It seems to me that unless you are planning on re-chucking your work that a small amount of axial run out makes no difference once it is rough shaped and I have had issues trying to re-chuck a piece no matter if it was on a $80 chuck or a $250 chuck. You are just not going to get the exact same hold on the piece as you had originally. It seems to me that if you are worried about that much precision in wood turning then you should avoid an $80 chuck and go strait to the Axminster Precision chuck!

So the question becomes how much run out is acceptable and how would one really measure it? Seems that it would have to be done off the lathe to make sure you are not dealing with spindle run out and you would have to have a piece of round stock that you know to be square on the ends and perfectly round. Then you would need a good dial indicator and a controlled process of measurements to go through. Does not make sense to me after all we are turning wood not German Car Parts.

So what are your thoughts on this subject and how much does it really matter? I have made precision finials and boxes using all my chucks and have not had any problems.

 

[Jeff Jilg]

I have a Oneway stronghold chuck. If it has much runout, it isn't apparent. There is probably over several hundred hours on it - it's a stout piece of equipment.

Lately I noticed a small wobble in the live center that came with my Powermatic and it's enough to make a difference. To me, if the runout in either of those tools is noticeable to the naked eye then I'll replace them. Well... since I'm a cheapskate that really means I'll just use the old tailcenter for roughouts

 

[Dave Daniel]

I'm a tad anal about runout on my equipment. I noticed when turning the outside and foot of a bowl on the faceplate, I was getting an error/runout multiplier when going to the chuck. This resulted in noticeable dimension differences in the wall thickness.
Of course, the easy fix is to do a light slice on the outside once mounted in the chuck, but this created an extra step - correcting a symptom versus the real problem. Since then, I've remilled the face surface on all my faceplates with a noticeable improvement. I've also had the surface of the base and the outer surface of the jaws remilled on my chucks.
The combination now allows me to pull a finished outside/foot off the faceplate, mount it on the chuck and turn the inside with little error between the inside and outside of the bowl. I can also pull a bowl off the chuck and remount it again later without any noticeable runout.

 

[Bob Hadley]

Runout of an item held in the jaws of an adjustable chuck is a combination of factors.

All chuck and collet systems have run-out and lathe spindles do not run perfectly true.

Even the most expensive chucks in the most expensive lathes will not likely run perfectly true. For sure, the better the lathe, the less runout there will be.

I have noticed that the installation of the threaded insert is important. If your chuck body wobbles bad enough to see it by eye (as Jeff mentioned), try removing and reinstalling the insert. Just for yuks, I used a .0005" indicator to measure the installed runout on my Oneway Stronghold chuck. The runout as measured at the body was not bad, about .0025 inch. I did not bother to check the runout with a test bar in the jaws. I figured I would be better off not knowing. Why? Because with wood, it's a losing battle. The material flexes, moves, crushes, distorts and whatnot. So even if the jaws were within 0.002 inch runout (which I seriously doubt), wood will fight it all the way.

In general, multi-jaw chucks for woodworking are made to a "looser" tolerance than metalworking chucks. This does not necessarily mean they are made poorly, only different. Considering the application and work environment (wood movement, dust, jaw profiles, etc.) Nova, Oneway and other specialty chucks are excellent quality. Precision is always good. Ultra precision is better. But the cost quickly becomes a factor.

Check out the Sept/Oct issue of Home Shop Machinist for an article titled: "Things to Know About Three Jaw Chucks" by Forrest Andy. It contains eye-opening information and tips about getting the most out of any scroll-type chuck.

BH

 

[waltben]

Re: Chuck Runout

I've two Nova's, a Super and a Titan. Never had any runout with the Super, with my old Delta, or my new Stubby, but had some at first with the Titan on the new Stubby. Turned out to be the adapter! Teknitool replaced the adapter and it's had no noticeable runout at all.

 

[Steve Worcester]

One of my first Strongholds had quite a bit of runout (a couple of hundreths) and it was the adapter. The adapters needed to be torqued down evenly.

The easiest way to measure is to use a dial indicator on a magnetic base. Put the base onto the ways of the bed and adjust the indicator so it will rub on the face of the chuck body with the jaws removed. The further to the outside the better. You will want to "pick up" the indicator as it skips over the area where the jaws are screwed to.

If you have an insert that screws in, mark the high spot on the chuck, remove the chuck and tighten the screw closest to that marked area. Install the chuck again and remeasure. Continue until you are satisfied with what will now be the acceptable amount of runout.

 

[Dtoggs]

Like what already has been posted,wood does all sorts of things. I would take a cut and then measure with a dial indicator. If within +- .010,alles ist in ordung. JMHO,Paul