Need chuck thread cutting Wadkin Bursgreen BZL

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UNC is not metric, even though it shares the basic 60 degree thread form.

It's 1" x 8tpi - therefore imperial. Ditto for

BSW.

Edited By Hopper on 29/10/2016 13:12:22

Edited By Hopper on 29/10/2016 13:13:09

Edited By Hopper on 29/10/2016 13:15:21

Sorry Hopper, I was referring to the new chuck from Axminster. Did we not think that was metric?

edit: Apologies, my mistake. Just re-read Jon's post and he did indeed point towards it being a UNC threadform. 

edit: So hang on, are we saying both the Axminster chuck & the spindle thread are a 1 x 8 UNC LH thread? But for a more or less unknown reason doesn't fit?

Edited By Richard Harris 5 on 29/10/2016 13:49:39

Edited By Richard Harris 5 on 29/10/2016 14:02:40

I don't know if this is of any help, but last year I had dealings with Peter Child wood turners' supplies regarding a chuck and thread converters both LH and RH for my Myford ML8 and they were very helpful. Sadly they are no longer trading but their website remains accessible here with info about available headstock threads: www.peterchild.co.uk/chucks/threads.htm

Don

Richard

I can do it with the existing chuck/faceplate but that involves making a stub thread to check the existing faceplate then modify (if needed) the new axminster chuck...it would be better with the spindle

Ian

Why not buy this, put it through and see, it just might work?

**LINK**

Buy one of those quick...its a bargain if you have a lathe with that nominal thread

Hello there, Sorry to read of your pain! I have a BZL, great lathe, the outboard thread is 1" x 8 tpi lefthand whitworth thread form. These threads have a rounded thread form, I got my tap from Tracy tools.hope this helps

regards Paul

Where in Shropshire are you?

I don't know if its been verified that the Axminster chucks are UNC or BSW. You probably should chekc with Axminster. Either way, a UNC thread should screw onto a BSW thread of the same TPI.

Your Dad's measurements indicate that the diamter of the spindle thread is oversize (1.001". That is the most likely reason it does not fit. Until you run a file over that thread and clean off the tops of the threads to bring them a few thou under 1.000", nothing standard is likely to fit on there. Usually the OD of a nominal 1" thread will be something like .995 or even .990" to allow clearance.

The 1" thread on the spindle of my old Drummond is .980". Chuck location is done by the plain register behind the thread, so it matters not how sloppy the thread fit is, within reason.

Could you elaborate on what you mean by the other side?

Here you go. Other side of the headstock. Other side of the spindle. Maybe I should have written other end of the spindle.

Not rocket science. PresumabLy (again) there is a right handed thread on that side? Youcould use some engineering blue to determine where the unecessary contact is being made if it is not obvious by measurement.

In my admittedly limited experience of cutting screw threads of this general size, eg to fit my ML7, there is not very much difference between "Won't fit" and "goes on". This means that when screw cutting you need to take quite small cuts as you approach the final size...of course that is not possible in this case, but does suggest to me that either the spindle or the chuck needs a tiny bit more taken off. Iit is a bit of a pain cutting things to fit the ML7 Spindle anyway, because you probably can't get at it to try the fit while the job is in the machine and you don't want to disturb the job while screwcutting. I made a dummy spindle nose that just fits a chuck so as to have something to test the fit with, and successfully made a backing plate for a collet chuck using it.

Ideally whoever is cutting the thread in the chuck should have the spindle available to try the fit, but this would mean dismantling the lathe.

John

Thanks Don. I had came across Peter Child's site before but unfortunately he doesn't list our model.

Thanks Ian, very kind of you. All makes sense. Will discuss this properly if it comes to this. I'm giving him a call this evening to see what route he'd like to take...

Thank you Mark. It seems confirmed that it's a BSW thread now so I'm reluctant to buy a UNC tap. But I guess the difference is extremely small, as has been touched upon. If we go that route, I don't think my Dad will mind paying a little more for the BSW tap.

Oh thank you Paul, wonderful to hear of someone else using this machine. Doesn't seem so commonly written about at least. You point to what many have suspected, the Chuck was cut with a metric thread and the original spindle is imperial. I think we'll be getting a BSW tap to remove a little material from the chuck.

Just a passing comment about these taps, will they be comfortable cutting through the stainless steel of the chuck? I don't know much about it's hardness or material tbh. I trust a gentle back and forth action should do the job safely enough...

My Dad is 1 mile outside of Much Wenlock in Shropshire

Thanks John. I'll pass this over to my Dad when I discuss it with him later as well. That's sort of encouraging to know. Hopefully this tap threading idea will work out okay...

Thanks Hopper. I guess I'm just suspicious as to where it really is oversized, given that I got a different measurement to my dad when I was there .

Thank you to everyone who has helped. I think we'll be able to tackle this reasonably easily now. I'll update you, hopefully with positive news

Understood, there were a few BSW taps as well for a little more, still very cheap compared to buying new.

Such as :

**LINK**ssPageName=STRK%3AMEBIDX%3AIT