Squeaky 7x12 bearings

Starting at 200RPM then fading as I go past 275RPM I get a squeaking/rubbing sound out my spindle. Is this to be expected from the mini lathe or is there something wrong?

I'd say there should be no erroneous noises at all if everything is in working order.....

Has it just started? Have you made any adjustments?

It may be change gears or the high/low gears. Make sure they are lubed. You can remove, lube and replace the headstock without worrying about accuracy as it is located by the inverted V.

Neil

Done the taper roller conversion. Preload is pretty much as tight as I could get leverage, any less gave a poor finish. Threw a handful of grease on the gears on reassembly.

Will start a vivisection now and see if anything looks weird.

Done the taper roller conversion. Preload is pretty much as tight as I could get leverage

That's surely not right, you must be missing a washer or something, or the spindle wobbles in the bearings

High preloading will score the inner surface or flatten the rollers

+1 on this does not sound right. You might need to check to make sure the inner race on the far end of the spindle, the one that moves when you tighten the adjuster nut, is free to move without binding or hitting a step on the spindle etc.

Sounds like dying bearings, then!

If you were getting poor finish it probably meant the bearing races weren't fully seated or misaligned and were shifting creating play once the lathe was used. Roiller bearings need very little preload.

You should only fill the bearings about 40% with grease.

Neil

My Sieg minilathe squeaks from time to time but it's the drive belt. A quick squirt of ptfe lube onto the motor roller silences it.

Rob

Roiller bearings need very little preload.

Depends on the application. Timken used to (maybe still do ?) make a taper roller bearing called a Hydra-rib that allowed the preload to be changed "on the fly" using hydraulic pressure. De Vleig borers used them - in low range (where heavy loads could be expected) the pressure was increased to run a higher preload. In high range a lower pressure was used so bearing heating was reduced at higher speeds & higher stiffness was not required.

You should only fill the bearings about 40% with grease.

Doesn't matter as much with taper rollers. Unlike ball bearings, which "churn" excess grease within the bearing causing overheating, taper rollers "pump" from one side to the other so the grease gets expelled in normal operation. More of an issue with taper rollers is keeping them greased - hence the usual provison of some form of re-greasing arrangement on TR applications where many BB applications are greased-for-life.

I would expect over tight bearings to start to get warm quite quickly, getting uncomfortably hot at higher speeds after longer running. Some MTBs use the headstock temperature after running at a particular speed for a particular time as the method of setting optimum pre-load - too cool, increase - too warm, decrease.

Nigel B

Haven't found the time to take it apart yet but noticed that when shifted into high gear the noise goes away. If the bearings are failing then atleast they are doing it silently. Once I get it open I am guessing it will be the gear select rubbing on the side of the gear

edit: oh it makes the squeak with the gears disengaged. Well thats unexpected

Edited By Rainbows on 21/06/2017 22:32:10