Thread: bearing pre load

I see you got the lathe?
Sorry i didn't help haha, someone else will probbably no something about its, but it might have to ware it in abit?

Cooper

Hi Mike,

Temperature rise is a reasonable guide to whether the pre-load is right, I wouldn't worry about stopping time, a slight temperature rise is a good sign. If it was too hot to touch you might worry a little.

Regards
Ray

I've recently been educating myself about this as well. Basically, what Ray said. If it's done a lot of miles it might get loose. This can cause chatter. Too tight shouldn't happen unless someone has messed with it. If it's not too hot to hold, it's not too tight. Find something else to worry about.

Thanks Ray

I wasn't sure . It does run smoothly . I would hate to damage those bearings as they are damn expensive to replace . The guy I bought it from had packed the bearings with heavy grease and the motor struggled to turn it over on cold days , the motor overload would cut in until the temp. warmed it up . Cooper, no, it's not that lathe you were offered. It is my original Sheraton, a different machine. MIKE

Hi Mike
+1 for what Ray and Bryan say about the spindle bearings.
Have you checked the belts aren't to tight or the motor bearings?
Thought the belts would have to be damn tight and motor bearing normally make lots of noise.

Stuart

Originally Posted by Stustoys

Hi Mike

Thought the belts would have to be damn tight and motor bearing normally make lots of noise.

Stuart

Yeah the motor itself is the noisiest part of the whole machine . It's fitted with a newish single phase motor, a blue thing . 1/2 hp I think. It's a wonderful machine for its age really . With 16 speeds from 60 up to about 1200 . I fell on my feet buying it as I could easily have bought a junk heap .The only down side is changing the belts around , it's slow and fiddly . MIKE

Originally Posted by morrisman

The guy I bought it from had packed the bearings with heavy grease and the motor struggled to turn it over on cold days

Mike

Thats been resolved now? Rinsed out or cleaned up?

Phil.

It's been monkeyed with, so all bets are off. Take Phil's advice. He knows what he's on about. But it can't hurt to find out what the maker recommended for lube and preload. Someone must know, or have a manual.

Originally Posted by Bryan

It's been monkeyed with, so all bets are off. Take Phil's advice. He knows what he's on about. But it can't hurt to find out what the maker recommended for lube and preload. Someone must know, or have a manual.

At a pinch you could have a look at the pre-load used on the Hercus roller bearing lathes. Hercus give a detailed description on how to do the check, and I would think they would probably be relatively similar. Of course you need to loosen the belts and keep them clear so they're not influencing the reading. Presumably you've already done that and just tried turning the spindle by hand to confirm the resistance is in the spindle bearings and not motor/countershaft etc?

Pete

hi Pete

I flushed out the grease using a plastic squirt bottle filled with light oil... I removed the nipples and inserted the nozzle straight into the hole .... takes a while but nearly all of the grease becomes a semi fluid mixture of oil and grease and it oozes out . The plastic bottle filled with the thin oil applies some hydraulic pressure to the whole bearing assembly. It's odd , because there are two grease nipples fitted above the bearings where you lube it , indicating that grease is used. I don't know how the Hercus is set up AS FAR AS LUBRICATION GOES. But I will read up on the Hercus if I can find that book. Yes I loosen the belt from the C/shaft before checking the pre load. I read somewhere that you can use standard lower-precision Timken bearings for hobby use ( like auto wheel bearings ) , and that's OK ?? The special class precision bearings are so expensive ..more than the lathe is worth . MIKE

Just because there are nipples doesn't mean it should be greased. I've heard of machines with nipples and instructions to use only oil. You can put oil through a grease gun apparently.

Originally Posted by morrisman

It's odd , because there are two grease nipples fitted above the bearings where you lube it , indicating that grease is used. MIKE

Mike I'm not sure about your model of lathe so can't speak with any real authority on it ... nor anything else come to think of it, but it's possible you're mistaken regarding the "grease nipple". Many machines use these Zerk fittings, and yes they're typically used for grease in other applications. However on machines they are used for OIL and NOT grease. I cannot emphasise that enough, as I have 3 Hercus machines and every single one of them was mistakenly filled with grease by previous owners when in fact they should have used oil for lubrication. I needed to strip each machine to get the grease out and it was a thorough PIA. The grease really gets in there and plugs up the works, so while it may appear that the oil has flushed out the grease, when I fully disassembled each machine I found that in fact there was still a lot of grease still in there that would have affected proper lubrication.

I found a normal grease gun that takes oil without leaking, and once my machines were stripped I now use that for regular lubrication. I'm away at the moment, but hopefully a search here will reveal the brand as it's been discussed before. Alternatively search for "pom-pom" oilers as that's another type that will do the same job. I know on my milling machine removing the bearing caps was a very simple process to thoroughly clean out the bearing, and I'd expect your lathe would be similar but I'm only guessing.

Mistaking the zerk fittings as being for grease is a very common mistake, I've even seen machines with labels on them next to the fittings saying "USE OIL ONLY" .... filled with grease

Pete

Edit: sorry Bryan you posted before I submitted this, so I've simply echoed what you said.