Wobbly spindle

[Rich Harkrader]

Hey all,

I have a PSI Turncrafter Commander 12" mini lathe and am having issues with pieces wobbling on the spindle. Not so much when I have anything in the headstock taper, but when I have something threaded onto it like a chuck. I'm talking a visible, noticeable wobble. Makes it difficult to truly round anything like a bowl or box. I'm on the second headstock since I bought this machine last month. I returned the first headstock due to the same issue. I'm wondering if it's possible that something with the motor could be causing this? Any ideas? PSI's tech support is something less than helpful. Thanks!

Rich;)

[Rich Harkrader]

I should mention that I still have my old Harbor Freight 10x18 lathe and can move a chuck that's wobbling on the Turncrafter to that lathe and it'll run perfectly true, so I'm pretty sure the issue isn't my chucks.

[Richard Coers]

Motor has nothing to do with it. Unless there is a gross mistake with the threads, that's not it either. It's the shoulder on the spindle that sets the runout. Do you have a dial indicator? You can clamp that on the bed of the lathe, put the indicator on the shoulder, then turn it over by hand. That will measure runout. No indicator? Then bring up the tool rest so it jsut brushes the shoulder. Turn the lathe over by hand and see if it rubs all around. You could use paper as a feeler gage to see how much clearance you have if there is runout. Another possibility might be bearings. Loosen up the belt, and see if you can hear the spindle rattle when you try and lift the lathe by the chuck. There should be zero play when you try and rattle the shaft.

[Wally Wenzel]

check and make sure your chuck is seated well against the shoulder on the spindle. Wally

[Thom Sturgill]

Richard and Wally pretty much nailed it. Are you using one of those plastic washers? They can cause wobble too, by keeping the chuck from seating against the shoulder properly.

[Rich Harkrader]

I did the tool rest thing and there is a section about 1/2" that doesn't touch. Any way for me to fix that which doesn't involve another month spent doing the runaround with PSI tech support?

[Jeff Nicol]

Rich, It is doable but you will have to make a jig to hold a piece of HSS tool steel that will be used to cut the face of the shoulder true. You would be able to do this best if you have a crossslide table like on a metal lathe so you would be able to move the cutter in both directions that will allow you to take very fine cuts until the face is true. I have done this a couple of times and it will work. If you don't have a crossfeed table a similar thing can be made so long as the cutter is parrallel to the face so you don't end up with a chamfer or a recessed angle on the shoulder.

It may be more than you want to do, but my brain always thinks this way, if you want some more info send me a PM and I can help figure it out.

Jeff

[Rich Harkrader]

Thanks Jeff! That helped me a lot. I ended up just using a carbide tool with a square insert and using that to flatten the shoulder, which solved my wobble problem. :-)