Roller headstock bearings. Go for it.

I agree with Jason, Our Harrison M300s recommend making a low feed rate selection and then:

3 hours @ 540Rev/min

2 hours @ 800 Rev/min

1 hour @ 1200 Rev/ min

1/2 hour @ 1700 Rev/min

so you can make a good judgement for your particular machine

Regards

Lofty

Without doing it as formally as Jason suggests, what he recommends is pretty much what I did when I first started my WM250V.

It was as much a matter of familiarising myself with the controls, with the sounds and feel of the lathe running. I fiddled with the headstock gear train too, to see how it was put together and how to get the backlash right.

After a few months' use, I took up the headstock bearings a little, and haven't touched them since.

Thing to avoid is engaging power feed when the slide can't move – the shearpins seem stronger than is ideal. About a month after installing the 250, I engaged the longitudinal feed when I meant crossfeed, against a hard-locked saddle. The shearpin held, everything got locked solid and the saddle drive pinion shaft got bent – the one that engages with the bed rack. Eventually I freed it off, and lived with the tight spot caused by the bent pinion for a year before I discovered how to straighten it with the tail of an ordinary crowbar… No more trouble with that since. Nearly 3 years now, and in use most days – I wouldn't go back to the Myford I used to have.

Edited By Mick B1 on 23/02/2018 09:11:36

There are no stupid questions! I was puzzled by 'backlash' as well. I'll stick my head over the parapet and suggest Jason means you should adjust the mesh between the change gears for quiet running. Because change gears can be changed, you have a choice about how close together the meshing teeth are positioned. They shouldn't be rammed hard together, nor should they be a sloppy fit.

When assembling change gears I trap a strip of thickish A4 printer paper (or a doubled over strip of thin paper) between the gears as they are meshed together. The paper serves to set the gap. Then, rotate the chuck by hand and remove the paper; at the same time check that the gear train turns smoothly throughout. There shouldn't be any tight spots, nor should there be much taking up of slack when you reverse chuck direction. When all seems good, replace the gear guard and run the motor. Don't be surprised if it takes practice to get the meshing 'just so', and don't worry too much if it's a bit slack. Much better to be too loose than too tight.

Hope that;'s right!

Dave

Edited By SillyOldDuffer on 23/02/2018 10:47:41

The idea is simply to ensure there is no actual preload between the teeth – ideally there would be zero gap between them but unless you can demonstrate that there is some finite gap, there would be no way of knowing for certain. So different thicknesses will be recommended for various reasons. Some people recommend cigarette paper.

When measuring gears, you mesh them against a "master" (hardened super precision reference) gear with a spring preload (ensures zero gap) and then measure how much radial movement results when you turn them. Ideally there would be no movement if they are perfectly made involute gears. If you deliberately introduced a gap you'd screw up the operation but for a gear train on a lathe it's hardly going to matter.

Murray

There was a guy selling a load of DP master gears on the homeworkshop site recently but I doubt many people would be aware what they were for.

Edited By Muzzer on 23/02/2018 14:19:14