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DoN. Nichols
 
Posts: n/a
Default SMART & BROWN 1024 - should I purchase?!

According to SC :
Hiya all, first post here - have to say this seems a strangely 'nice' group!

Anyway onto the point. I have the opportunity to purchase a Smart & Brown
1024 lathe.


I was not familiar with this -- so I looked it up on
lathes.co.uk. It is a *beautiful* lathe.

ttp://www.lathes.co.uk/smartbrown/page5.html

[ ... ]

Lathe I've looked at - well I've fell in love with it! Serious bit of kit
with just a couple of problems. Slides are great (as new even) but their
screws are worn - well, not the screws but the thread in the block. Due to
the heavy construction I was unable to see if the thread is actually cut
into the slide itself or into a block which is fixed to the slide. I'm
guessing the former (in every case?). I've been mulling solutions over in my
head - there is currently about 1/4 turn of play - seems a lot - can it
really be the block thread that is worn? If it is I'm thinking along the
lines of sacrificing some travel and welding some new blocks with freshly
cut threads onto the ends - if you follow!


That should not be necessary. Normally, both the leadscrew and
the nut into which it threads are consumable parts -- they are
*expected* to wear out, so they are designed to be easy to replace.
Typically, the nut is of bronze, and is attached to the underside of the
slide in some manner. In the case of my 12x24" Clausing, the format
of the nut is a cylinder of bronze joined to another one at right
angles, making a stubby 'T'. The upright is upside down, and passes
through the cross-slide, providing an oiling point in the middle of the
cross-slide. It is held in by an Allen setscrew from the side of the
cross-slide.

Based on my experience -- both the nut and the leadscrew wear,
and probably should be replaced at the same time. My Clausing had
enough wear so there was about 0.070" of backlash in a 0.100" per
revolution dial. Some backlash is expected, and a good machinist learns
how to work around that -- but this was sufficiently extreme in the
middle of the travel that the Acme thread, which should look like this:
_ _
_/ \_/ \_

actually looked like this:

_/\__/\__

and presumably the inside of the nut was equally worn -- but hard to
examine.

Anyway -- this looks like an excellent machine -- and it should
be possible to replace both the nut and the leadscrew to bring it back
to original condition. You *might* have to make your own leadscrew and
nut if you can't find ones from somewhere

From the web site which I posted above, the machine was made up
until the early 1990s, and:


================================================== ====================
A 'Spare Parts List and Full General Arrangement Drawings Set' and an
'Operating & Maintenance Manual' are available for this model
================================================== ====================

which apparently needs you to create an account to access them. I would
say that would be quite worthwhile.

But I'm thinking that is not the problem.

But I'm sure I'm wrong! What a quandry!

So - anyone have experience of these machines - where the fault may be
found?

The handle to screw has 0 play (and is geared)...


Almost certainly a worn leadscrew and nut -- but this is not a
disaster. Replacements can be made if not purchased -- possibly by
using the lathe itself to perform the task.

But it is remotely possible that whatever screw secures the nut
to the cross-side may be loose.

I would suggest that you go for it. It looks like a lovely
machine, and I would love to have it.

Good luck,
DoN.
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