Excessive runout on Sheldon Lathe

[mikey]

Thank you for the advice, friend is willing to let me borrow a test indicator on Monday and will check the spindle again. Hopefully I can get that takeup nut tightened tomorrow.

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May I suggest you take your concentricity readings before and after adjusting your spindle bearing preload?

I don't know how to adjust preload on a Sheldon lathe but I'm sure Ken does. I did want to relate how Emco does it on their Austrian gear head lathes in hopes that it will give you another option.

They put the lathe in neutral - out of gear and with the leadscrew and feed screw gears disengaged. With a 3 or 4 jaw chuck mounted, grab one of the jaws and give it a strong spin. Adjust the preload until it gives you one revolution with that spin, not more and not less. This comes from an Emco engineer at the factory so as simple as it sounds, it works for them. My lathe runs cool at the bearings and has zero run out so it also seems to work for me.

 

[B1akeM]

May I suggest you take your concentricity readings before and after adjusting your spindle bearing preload?

I don't know how to adjust preload on a Sheldon lathe but I'm sure Ken does. I did want to relate how Emco does it on their Austrian gear head lathes in hopes that it will give you another option.

They put the lathe in neutral - out of gear and with the leadscrew and feed screw gears disengaged. With a 3 or 4 jaw chuck mounted, grab one of the jaws and give it a strong spin. Adjust the preload until it gives you one revolution with that spin, not more and not less. This comes from an Emco engineer at the factory so as simple as it sounds, it works for them. My lathe runs cool at the bearings and has zero run out so it also seems to work for me.

Good point, I don't mind waiting until Monday. I imagine using the chuck to gauge tightness can get you pretty close but on the Sheldon there are 2 nuts that can be adjusted. I am not sure how to tell how tight each bearing is, and if I'd run the risk of overtighting one. The bearings run cool right now too.

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[wa5cab]

I strongly suggest that you not just arbitrarily tighten up the spindle bearings until you have read the procedure for checking whether it needs to be done and how to properly do it in the manual on your lathe. If the bearings are too loose, tightening them will probably fix it. But if they aren't, the only thing that tightening them is going to accomplish is to make them run hot.

With your dial indicator set as in one of your photos, push and pull on the spindle nose without touching the indicator. If the needle moves, they are too loose and should be tightened. If it doesn't, they probably aren't.

 

[4GSR]

Good point, I don't mind waiting until Monday. I imagine using the chuck to gauge tightness can get you pretty close but on the Sheldon there are 2 nuts that can be adjusted. I am not sure how to tell how tight each bearing is, and if I'd run the risk of overtighting one. The bearings run cool right now too.

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There is only ONE nut to adjust. Read my post above and follow! The adjusting nut only needs to move about a 1/16 of a turn. Anymore than this could make your bearings too tight!!! And run hot and damage the bearings!!! These Timken bearings are UNTAINABLE at any price, unless you want to put wheel bearing grade bearings in your headstock!

 

[B1akeM]

Ok, thanks for letting me know. I understand that spindle bearings are very finicky, and would not try something without confirming it here first. I was just making sure that the nut closest to the right was the correct one to adjust. I have a fraction of the service manual that I got when I purchased the machine, but most of it is completely illegible. It looks like it sat somewhere wet. Where can I find another one?

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[4GSR]

Here's a link to the manual for the 15" Sheldon lathe. The only thing it will not cover is the turret and carriage assembly for the turret lathe. Everything else is exactly the same. I haven't yet found a service manual for the turret lathe. You can contact B & K and see if they have a manual or any maintenance information for the turret and carriage for the 3R lathe. Probably cost you upward around $150 for a 12 page manual!

http://www.hobby-machinist.com/reso...s-manual-for-15-precision-sheldon-lathe.3184/

Ken