Need chuck thread cutting Wadkin Bursgreen BZL

Simples: they can't be. Your Dad has got his mate's advice mixed up somehow.

He should be able to screw the 1'' BSW LH taper tap into the thread in the chuck by hand, on the bench. It should go something like a third or half way in before much resistance is felt. He should be able to wind it in further with a tap handle (or shifting spanner if he has no tap handle). All it should need to do is clean up the thread flanks to match the BSW 55deg thread form, which is actually less than the 60 deg UNC threadform, so should pretty much wind right in. Once he has wound that one through the chuck therad, should be able to repeat with the intermediate tap and finally the plug tap. No need to set it up in the lathe to clean out an existing thread. It should only be a matter of removing a few thou of metal. The tap should follow the existing thread, pretty much like screwing a nut and bolt together.

Then if the chuck will not screw on the spindle, it is a matter of cleaning up the thread on the spindle to fit in the cleaned-out chuck thread. This can be done with a fine file, or with a 1" BSW LH die.

Edited By Hopper on 08/11/2016 12:02:00

Edited By Hopper on 08/11/2016 12:03:15

Wonderful. Thanks Hopper. Thanks for clearing that up in my head. Will have to report back to him...

Weell, I read it a the friend at the engineering place was simply going to make an adaptor for mounting the die to some machine! It only needs to be hand held, shirley? Taking naff all off an already formed thread?

Or is it really a metric bsw/unc/totally unknown thread which will be messed up completely by yet another guesser?

The face plate should be cut to fit the spindle. Every time. A basic principle. Do it right. Job should have been done right in the first place - the spindle should have gone to axminster(?) in the first place.

Exactly yes. My dad & his friend are clearly confused about something, yet to clarify it with them.

We 100% know what the threads are. The chuck - UNC. The spindle - BSW. So we are indeed taking hardly anything off, and it can be done by hand, as Hopper pointed out.

I've cut threads from scratch before on my small lathe, and it's quite straight forward. So if he gets a new faceplate etc (although I believe the chuck has a faceplate adapter that fits on the front), he / we / his friend can do this properly aligned on the lathe...

... BUT as it is, not too complicated...

I have a similar problem but the opposite ,i have two good chucks that need back plates for a south bend 1 1/2 x 8 UNC spindle , problem is the chucks that came with my lathe had nice backplates but they were threaded for a boxford at 1/1/2 x 8 BSW and dont thread on properly.

Ive done some external threading on the lathe but how does one redo the same threads only with a unc single point cutter (ie the treads already in the back plates which will be internal) .??

The lathe has a gearbox and thread dial indicator.

The first photo is of the four jaw chuck back plate showing how little the chuck will thread on.

The second two photos are the 5" 3 jaw chuck  showing the internal threads.

At the moment im using the 6" 4 jaw temporarily fixed to a south bend dog drive plate which does have the correct thread but is less than ideal.

By the way the taps for these are like gold dust and cost upwards of £100 second hand on ebay due the amount of south bend owners in the US and elsewhere.

Edited By mark smith 20 on 10/11/2016 15:19:52

Edited By mark smith 20 on 10/11/2016 15:22:04

Edited By mark smith 20 on 10/11/2016 15:24:10

Richard

Not an answer to your question I'm afraid but a " thank you" for posting that image of the lathe. When I was a lad ( back in the days when Adam was too) my Dad had a woodworking business. He purchased a lathe just like the one you have posted ( although his was grey) and, when he worked weekends, I would often go with him and "play" on the lathe. I still have a fruit bowl and table lamp somewhere around the house!

Happy memories

Norman

Edited By NJH on 10/11/2016 16:45:26

Hi Richard ,did your dad get it sorted out???

I posted above about my problem with BSW 55 degrees back plates and needing them to be UNC 60 degrees.

Well i just done one by picking up the threads using a homemade cutter from a broken centre drill ground to 60 degrees . It was fiddly to set up being an internal thread and clearance etc... but i took a very little off and the result is my back plate goes on perfectly.

I watched a you tube video on how to pick up the threads ,as i had never tried it before and it was very easy.

Edited By mark smith 20 on 12/11/2016 13:16:10

Looks a lot better as well.

Edited By mark smith 20 on 12/11/2016 13:31:51

Edited By mark smith 20 on 12/11/2016 13:33:47

Oh excellent, glad to know it was sort of in some way helpful. Well done for working out the problem!

Yes, are are now sorted. Just this evening.

It took them 1 month to work out what we all agreed on here within a matter of days. Painful.

They had this idea of making an adapter, but eventually agreed it was far too much work. Which it obviously was! It would involve cutting several threads and making parts that fit together. They then got very worked up about the whole thing - I don't know why. It 3 weeks later, this chap he gave it to finally mounted it and put the tap through it. He was concerned that it had only just grazed it...

... and of course, he took it home this evening and it fits perfectly.

All fine now. Thanks for all your help!

You're very welcome Norman! I may try and get some more photos of it if we make something over the Christmas period.

UPDATE:

So I actually saw the lathe over christmas and noticed it isn't actually setup right. Ugh.

The chuck on the outbound side - that has caused this massive faff - isn't on all the way. It's threaded on fine, feels nice and snug, but it's just sitting on the threads. It doesn't go all the way onto the "cuff" part of the spindle... if that makes sense? Do you know what I am trying to describe?

I've had a look and the chuck isn't very deep, so I am not sure boring out the inside of the chuck would work very well., or at least, it may not take it all the way in deep enough. We need around 12mm to get it all the way onto the cuff.

Is it acceptable to cut off the end off the threaded part of the spindle? So that there is less threaded part, and it will slide onto the unthreaded / flat part of the spindle?

Or should we start by boring the chuck first?

He noticed it because he had bought some large donut type jaws with small rubber buttons, so you can hold a bowl and finish the bottom of it more easily. With the larger diameter, there seems to be a pronounced wobble on it. But, it is quite minimal to my eye, for wood turning.

I also just looked at his chuck on the inbound side, and the fit is absolutely atrocious. I do not know how he is still alive, or how he didn't think this was unusual. The amount of play on it as you screw it in, there must be at least a 2-3mm difference. Luckily, that chuck has a simple backplate, so it would be easy to swap for a thicker backplate, and then thread it properly.

Richard

Do not attempt to modify the spindle in any way - it is probably hardened in any case. The "cuff" that you refer to is the register and, whilst the threads on the spindle and chuck draw the two items together it is the close fit between the registers of chuck and spindle that ensure alignment. The end of the chuck backplate should be bored such that it is a close fit on this register.

Norman