Granville lathe gib-strip adjustment grub screw sizes

Colleagues,

With some trepidation I make my first post, and from metric New Zealand at that.

I recently purchased a Granville CSL2 lathe which I believe can be correctly described being of the Grayson family with many Myford kin. I'm a complete novice with engineering lathes but I'm embarking on a little 'tidying up' before venturing forth.

I'd like to replace the heavily worn slotted gib-strip adjustment grub screws and with a hex type hopefully. I noted lengthy discussion in this forum under https://www.model-engineer.co.uk/forums/postings.asp?th=99448&p=2 circa 2014 in relation to the grub screws for that lathe. I sensed that the consensus was the grub screws for that unit were most likely 2BA vs 3/16" BSF.

I think its a longshot but to assist my purchase, most likely out of the UK, might anyone know the specs for the Granville/Grayson? If it helps in anyway I've gauged it as best I can and it appears to be close to 3/16" 30tpi.

Cheers David

Hi David,

Welcome to the forum. I assume you have checked lathes.co.uk?

Thor

Hallo Thor,

I'd researched that site fairly extensively but not posed that specific question imaging that Tony would be overwhelmed on a daily basis. Will do so if that's the recommended approach.

Thanks, David

Welcome to the forum. Not a common brand of lathe so you might wait a while for specific info.

3/16 BSF is 32 TPI. 2BA is 31.4 TPI. Close but no ceegar.

And thread flank angle is 55 deg vs 60 deg. Which is probably not critical on mass produced fasteners.

You will need a 32TPI thread gauge, or a tap of any diameter with 32TPI and a good magnifying glass.

Or take a punt and buy some BA screws and see if they work. If not, buy some BSF. Or vice versa.

If that was mine and all I had easy access to were metric fasteners I would definitely just run a 5mm tap down the threads and buy 5mm screws and locknuts.

Edited By Pete Rimmer on 31/03/2022 23:30:19

Hi David,

If it is any help I have just removed one of the adjusting screws on my Granville Senior and it is 2BA.

Regards

Graham

Thanks one and all, most grateful. Tempted by the 5mm conversion but Graham's thoughtful advice is just what I hoped for.

What a forum, cheers.

AS Hopper says note the angle of the thread, as well as the diameter and pitch.

BSF, BSW, BSP, BSB are 55 degrees.

Unified and Metric are 60 degrees, and BA is 47.5 degrees.

Not surprised to read that the grubscrews are likely to be 2BA.

You will always find help on here.

Good luck with the restoration.

Howard