Drive centre remover for Wadkin RS

[merlin]

All of my old drive centres are easy to remove as they all have flats machined onto them, I am now using Steb centres quite a bit so to get them out I have made a threaded remover.

I dare say newer lathes already have a similar method but as an RS has a solid spindle it is more difficult to remove the centre.

All I have done is find an old 1 3/8 BSW nut and fitted a thick washer on the face using grub screws when it was fitted I drilled out a hole to suit the Steb centre.

Merlin

 

[Phil Hansen]

Very nice idea.
As 1 3/8 x 6 is not a standard BSW size where did you find a nut?
Thanks
Phil

 

[J-G]

Very nice idea.
As 1 3/8 x 6 is not a standard BSW size where did you find a nut?
Thanks
Phil

I didn't see the original post in March but reading it today also sounded 'alarm bells' at the statement 1 3/8 BSW.

The glib (and incorrect) use of the standards designators ('BSW', 'UNC', 'M' .....) is rife, and while it might be understandable in general conversation, on an engineering forum ought to be decried.

Of course it would be possible to make a nut with a 1 3/8" nominal diameter and with a Whitworth 'form' thread - whatever tpi you wish but since BS84 never listed 1 3/8" Ø in the course pitch series it should never be described as 1 3/8 BSW. There is a listing in the fine series (BSF) at 8 tpi but even that is deprecated.

If the nut is 6 tpi (merlin doesn't say) then I suspect that it is actually a 1 3/8 UNC - which is a standard at 6 tpi - and that also suggests that the spindle thread is also UNC - so I suspect that merlin simply didn't think about (or measure) the thread form before sending the original post.

It is also possible that Wadkin did make the spindle nose thread 1 3/8" x 6tpi Whitworth form but it should still not be described as 1 3/8 BSW - and (if that is the case) the chance of 'coming across' a 1 3/8 x 6 Whit Form Nut NOT made by Wadkin would be unusual in the extreme

 

[Phil Hansen]

It is also possible that Wadkin did make the spindle nose thread 1 3/8" x 6tpi Whitworth form but it should still not be described as 1 3/8 BSW - and (if that is the case) the chance of 'coming across' a 1 3/8 x 6 Whit Form Nut NOT made by Wadkin would be unusual in the extreme

Thanks J-G
Never thought to look at the UNC specs. For that sort of use the difference in angle would not be a problem.
Now to find a nut that size in darkest Africa :|
Phil

 

[merlin]

I'm sooo sorry.

Merlin

 

[Phil Hansen]

I'm sooo sorry. Merlin

No problem. Learning is part of the game.
You gave me a very good idea to work on.
Could also be useful for a few jigs.
Finding the nuts here will not be that easy though.

 

[J-G]

Thanks J-G
Never thought to look at the UNC specs. For that sort of use the difference in angle would not be a problem.
Now to find a nut that size in darkest Africa :|
Phil

The difference between 55º and 60º could be a problem. Assuming that the Spindle Nose and the Nut are made to 'size' then there would be a 7 thou interference on the thread flank (3½ thou each side). Because it is standard engineering practice to reduce the depth of thread in a nut to 5/8 of the full depth there wouldn't be interference at the root. See the attached drawing and note the 'Yellow' sections on the flank.

If the nut were made oversize by 15 thou - ie instead of 1.375" Ø it was 1.39" Ø - then it would just clear the spindle - see the second drawing.

I'm talking about finding a 1 3/8" UNC Nut in the hope that you might be able to fit it to a 1 3/8 x 6 Whit form spindle. If you can find someone to make a nut, then you might as well have it made with the correct 'form' to fit the spindle you have.

That surely shouldn't be much of a problem in South Africa?

 

[Phil Pascoe]

If you can't find a nut a forked, tapered drift between the spindle and the front of the centre should be OK - it's not as if the centre will be jammed in.

 

[Phil Hansen]

Thanks J-G nicely explained.
Thanks phil.p another simple solution.
Phil

 

[J-G]

Thanks J-G nicely explained.

Thanks for the feedback Phil. Sometimes my explanations are too technical and I forget to whom I'm addressing them

I must apologize to merlin
- I thought I was replying to an issue on the 'metal-working' forum where knowledge of thread standards should be de rigueur. - - - hardly necessary on a WOOD-turning forum.

Thanks phil.p another simple solution.
Phil

.... and very much easier to manufacture !

 

[Phil Hansen]

J-G.
I found 1 3/8 x 6 UNC nuts.. The first time I threaded them on there was a little of friction.
After that they were fine. That answers that concern.

Merlin,
Your idea works well. Got a few spare nuts to make some face plates and other future jigs.

Thanks to the both of you for the idea and comments.

Phil

 

[J-G]

J-G. I found 1 3/8 x 6 UNC nuts.. The first time I threaded them on there was a little of friction.
After that they were fine. That answers that concern.

That's good. It may well be that the nut is marginally over-size and the spindle marginally under-size in which case the 'interference' I spoke about might well be overcome with sufficient 'welly' applied on first engagement. Once the nut has been on the spindle, both will have been 'worn' by the effort.

I would make sure that the spindle was lubricated each time the nut was screwed on - at least for the first few times - and both items cleaned after each removal, just in case there is some material rubbed off either. If there is, then that could cause a 'jam' when taking the nut off.

I'm ever cautious since I had a collet closing nut jam which meant that I had to sacrifice it to retrieve the collet ... and they were the same thread!

 

[TFrench]

Very nice idea.
As 1 3/8 x 6 is not a standard BSW size where did you find a nut?
Thanks
Phil

I didn't see the original post in March but reading it today also sounded 'alarm bells' at the statement 1 3/8 BSW.

The glib (and incorrect) use of the standards designators ('BSW', 'UNC', 'M' .....) is rife, and while it might be understandable in general conversation, on an engineering forum ought to be decried.

Of course it would be possible to make a nut with a 1 3/8" nominal diameter and with a Whitworth 'form' thread - whatever tpi you wish but since BS84 never listed 1 3/8" Ø in the course pitch series it should never be described as 1 3/8 BSW. There is a listing in the fine series (BSF) at 8 tpi but even that is deprecated.

If the nut is 6 tpi (merlin doesn't say) then I suspect that it is actually a 1 3/8 UNC - which is a standard at 6 tpi - and that also suggests that the spindle thread is also UNC - so I suspect that merlin simply didn't think about (or measure) the thread form before sending the original post.

It is also possible that Wadkin did make the spindle nose thread 1 3/8" x 6tpi Whitworth form but it should still not be described as 1 3/8 BSW - and (if that is the case) the chance of 'coming across' a 1 3/8 x 6 Whit Form Nut NOT made by Wadkin would be unusual in the extreme

I was searching for wadkin RS nose thread info the other day and came across this thread. This post in particular got me very worried as I'd already ordered the 1 3/8" BSW tap set to make my chuck backplate. I checked with a thread gauge and it is actually whitworth. Panic over. Confirmed when the taps arrived and they fit perfectly in the existing faceplates. Thought I'd add this correction to save anyone else the worry!