By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Allendale Jan 24th

Chuck fitment to dividing head

All Topics | Latest Posts

Search for:  in Thread Title in  
Matt Stevens 118/01/2021 17:58:08
avatar
96 forum posts
11 photos

So i have a Southbend 9" lathe which has a spindle thread of 1.5" x 8 TPI. I have 3 and 4 jaw chucks for it.

Recently i got a dividing head which also has theoretically the same thread. The problem is that the chucks do not screw onto the dividing head?! They go tight within a quarter turn or so....

Any ideas? It would be a pain to have to machine new backing plates and keep switching them between chucks etc.

Michael Gilligan18/01/2021 18:09:36
avatar
18761 forum posts
922 photos

I suspect that one is Whitworth thread-form and t’other is Unified.

... easy to check, at that size, with thread pitch gauges.

MichaelG.

Howard Lewis18/01/2021 18:21:33
5241 forum posts
13 photos

It could be that the thread forms differ, or even worse, the pitch.

Reading lathes UK, it looks as if the Mandrel thread is 1.5 x 8 tpi USF, so would expect to be 60 degree thread form.

If the Dividing Head has a 1.5 x 8 tpi WHIT form (55 degree ) thread, that might account for your problem.

Male Whit form threads do not screw easily into Unified female threads, even of the same pitch; they jam!.

I would check the thread on the Dividing head with thread gauges, to establish the thread pitch and form.

Howard

DC31k18/01/2021 18:39:47
557 forum posts
1 photos

If it does turn out to be as Michael suggests and if you can live with the increased stick out, make an adapter that is 1 1/2" - 8 Whit. form internally and 1 1/2" - 8 UN form externally. The chucks will then screw on to it and project a bit further from the face of the head.

Does the dividing head have an internal taper? It is possible to buy 2MT to Myford spindle nose thread adapters, so you could make something that does the same job (but nothing can poke out the back of the chuck).

Pete Rimmer18/01/2021 18:40:19
1053 forum posts
69 photos

Offer the dividing head spindle thread up to the South bend spindle thread. If the pitch is the same then the threadform must be different. Get a 1.5" - 8 TPI UNS die and run it down the thread on the dividing head, then your chucks will fit, and so will any Whitworth ones.

Dave Halford18/01/2021 19:09:46
1682 forum posts
19 photos
Posted by Matt Stevens 1 on 18/01/2021 17:58:08:

So i have a Southbend 9" lathe which has a spindle thread of 1.5" x 8 TPI. I have 3 and 4 jaw chucks for it.

Recently i got a dividing head which also has theoretically the same thread. The problem is that the chucks do not screw onto the dividing head?! They go tight within a quarter turn or so....

Any ideas? It would be a pain to have to machine new backing plates and keep switching them between chucks etc.

I've heard that one too. My Rockwell Delta 10" takes Boxford thread backplates, but not my BS0 dividing head backplate

Matt Stevens 118/01/2021 21:11:59
avatar
96 forum posts
11 photos

Hi All,

I will check the threads against one another per your suggestion...thanks.

I suspect ordering a 1.5" 8TPI UNS die will be pretty expensive for a one time use, assuming i can find one. ANyway, i will get to the group with my findings.

P.S. It does have an MT2 taper.

Pete Rimmer18/01/2021 23:25:51
1053 forum posts
69 photos

You could remove the spindle from the dividing head and single-point the thread, so long as it's not hardened.

Dave Halford19/01/2021 11:30:06
1682 forum posts
19 photos

Are we sure this isn't the problem ?

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Latest Forum Posts
Support Our Partners
Warco
cowells
JD Metals
emcomachinetools
walker midge
rapid Direct
Dreweatts
Eccentric July 5 2018
Eccentric Engineering
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest