Help with Kwik Way SV valve grinder chuck runout.

bugman53 said:

Looking for ideas to replace the chuck on a Kwik Way SV valve Grinder

The chuck has .002-.006 run out. It is the 6 ball style. I replaced the balls with new .531 balls and no change. It is not repeatable. If I chuck up a drill rod and rotate it or re chuck it the high spot is different every time. The chuck shaft itself indicates in within .0002-3. It does have wear on the ramps that compress the balls. It looks to be evenly worn on all the ramps I was hoping to get lucky with new balls but that did not happen.

I am looking to get the run out less than .001". Hopefully less than .0005.

I am not going to use this machine more than once or twice a year so if I have to indicate each valve in each time that is not really a problem. but it is not worth it to spend several hundred dollars on a new chuck no more that I use the machine.

Does anyone have any ideas for a cheap way to replace the chuck? I was thinking machining the existing to fit an ER32 Colet Chuck. But with out a way to adjust it no guarantee it will be much better.

It seems something that is adjustable would be a good idea to dial it in. Any ideas? I like the idea of an er32 collet mounted with some kind of adjustable mount.

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moonlight machine said:

I converted mine to ER collets. Best thing I ever did, that ball chuck was a real POS. I welded a ER collet holder to a piece of bar stock a bit larger than the original chuck shaft. To turn the shaft true to the collet I put the biggest collet and a 4" piece of shaft in the collet and held the other end in a 5c on my lathe and turned the shaft to size. It chucks a valve stem within .0002, it's great for those tiny valves with tight guide clearances that you see on Jap 4 valve motorcycle engines.

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bugman53 said:

That sounds like a plan, I used to build race engines for a living. They were typically Modern 1000cc Jap sport bike engines. I still occasional build one although most of the stuff now has hard coated titanium vales that can’t be ground but it is nice to have the accuracy if needed.

What I am thinking of doing is get an ER32(or ER20 as it still has plenty of size range) collect holder with a smaller shaft than the OD of the spindle IE 1.000 or .750 " The OD of the spindle is 1.250. bore the original spindle or machine a new one with a bore slightly larger than the Collet spindle shank then drill for set screws to pass through the spindle to the inside bore to hold the collet holder. It would have two rows of setscrews one at the very front and one at the back of the collet spindle, 4 opposing at each end. Then spot face the collet spindle with flat spots to match up with the setscrews.
This way I can use the set screws like a 4-jaw chuck and dial in the runout after it is mounted. Also, if I have a really critical valve to do, I could install the collet of that size and dial it in perfect. I am sure 8 decent sized set screws would have plenty of strength to hold the collet adaptor. I can do a stress analysis on it in cad or break out some calculus but I don’t think that is required. The torque on the valve would be minor from the grinding wheel.

Any thoughts on the above plan?

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