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Help, British threads !!!
Darren:
Annoyingly I have have two backplates for the standard size, 1.752 x 8 tpi, came in a box of spares. Dia is a bit small though.
I'll dig them out tomorrow and see if anything can be done with them. Have a better look like....
Darren
bogstandard:
Darren,
Just to prove that yours isn't a standard BSW thread, here is the BSW chart
http://shopswarf.orconhosting.net.nz/bsw.html
Notice that the standard 2" BSW has a pitch of 4.5 TPI.
Metric is always measured by the metric length of pitch.
Anyway, back to your problem.
Those old backplates should be fairly easily opened up to fit your machine, there should be enough meat on them. But again, the spindle would be required for an accurate fit. I suppose a dummy spindle nose could be turned up to fit one of your backplates, but that increases the workload, and because yours is a fairly old machine, the backplates might be worn, and any resulting backplates might not fit your lathe spindle correctly.
I have seen faceplates made using large brake discs, with a hub being made from a smaller piece of cast, and then bolted together, but I don't think I would trust that sort of build up to support a heavy chuck.
BTW 1" = 25.4mm, so 1 thou = 0.0254mm. When doing a quick mental calculation, 1mm = 40 thou (actually 0.03937", but close enough for quickie calcs).
If you are going to get deeper into this, a basic understanding of Imperial is definitely required, as most British and American plans will be in imperial. Over time, you really should be able to think and work in both systems, otherwise major conversion errors can creep in.
There is a bit more to this model engineering lark than you thought. But it seems you are picking all the difficult bits to begin with.
John
Darren:
Thanks John, I'm beginning to realise that you can make any darn thread you want.....and they did !!
A thread type is little more than a shape or angle. BSF & BSW are just two sets of standard pitches of the same shape for a given diameter.
The beginnings of thread standardisation.
The lathe nose is not of one of those standards. Nonetheless, it works well.
Oh and the thou = mm thing, I shouldn't post so late, I got that backwards. I do hope it becomes more natural in time without too much thinking. I'm not getting any younger for all this new language I need to learn :smart:
Anyway, I doubt my lathe nose is too warn, it was set-up as a dedicated capstan lathe using collets. There was plenty of collets with it but no chucks or backplates.
The spindle nose in front of you would be best, but darn inconvenient, not that I've ever removed it.
Quote
"There is a bit more to this model engineering lark than you thought. But it seems you are picking all the difficult bits to begin with."
Oh I do hope so, it should be downhill from there on :D
No worries, I'm in no hurry, might even find a backplate yet, I have found one so far.....
John Stevenson:
Once you get into these items they are all specials.
2" x 8 BSW is the same as 2" x 8 BSF, what they are trying to say is that they are 2" x 8 tpi at 55 degrees thread angle.
Any lathe that needs plenty of attachements needs a spare spindle nose. This in turn is then uses as a master gauge to reproduce new fittings.
John S.
Darren:
Hi John,
Yes thanks, it's starting to become a bit clearer (and simpler).
This is a cracking and very solid little lathe. It does what it was designed for very well.
But thread cutting is not part of that program. Maybe I should be looking for one that has more capabilities in this department.
Not right now though, it'll have to wait a while, got to build a garage first, after some other renovations. I spent the most of yesterday pulling ceilings down. Should give you a picture of where I'm at.....will all come good in the end :D
Main thing is, I enjoy playing with metal, always have. Funny really, so demanding on the resources at times, yet so relaxing....sure makes time fly.... :thumbup:
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