Assuming that it's not the hardened bed, you could buy "machine tool
reconditioning" by Edward Connelly, learn how to scrape and rebuild the lathe.
If it's hardened or you don't want to spend several years on a rebuild
project, you could search for someone with a slideway grinder.
My trade school South Bend has that problem. The alignment is better
with the tailstock spindle minimally extended and the lock tightened.
Center drills wobble a little at first, then snap into line and drill
true within a thousandth or two, as confirmed by boring.
Crude but effective temporary solution: The tailstock 'lump' is in two
pieces, the base being separate from the top. There are machined ways
allowing offsetting of the tailstock for turning taper. On these ways,
between base and top, you can insert a bit of shimstock raising the centre
line of the tailstock barrel. (Front one is a Vee way iirc so you need to be
inventive with the shim.)
However: The bed under the headstock obviously is NOT worn as nothing moves
on it, so the spindle height in space is where it always has been. The
tailstock on a Student slides on different ways from the saddle.
Consequently the tailstock ways should see very little wear and are usually
in pretty good condition even on old Students. Are you sure that your
problem is not tailstock barrel droop from wear in the barrel or bushing?
Thank you all for your your interest and suggestions . The lathe is a student
Mk1. the rest of it is in pretty good condition for its age. I think its just
the bed warn at the chuck of the bed that is where it gets the most use I guess.
My plan I think will be to clock the error over a 4" rod between the chuck and
tailstock determine the exact error and try and split the tailstock and shim as
Thanks again I will let you know how it all pans out!
Classic method of estimating bed wear on a Student is to arrange a dial
gauge in the tailstock, bearing on the flat way that the carriage runs on,
and slide the tailstock gently down it's ways noting any changes in reading.
Then repeat in the side (not top!) of the inverted Vee way. This of course
assumes little wear on the tailstock ways which is usually true. Clean off
the ways first and very very lightly oil with a very thin oil and wipe off
to almost nothing, so the tailstock slides freely but isn't raised
(who's had a few Roundhead Colchester Students in his time <G>)
Another crude one. If the chuck is in fairly good condition you could
span the tailstock barrel into it. Then measure any deveation between 1
the barrel and tailstock, 2 upper and lower part of the tailtock.
Merely as an indication. On my 1937 Fleck&Co all slideways are worn,
even the tailstock ones about a foot in front of the chuck. Reading,
understanding and mastering Connelly's book will take a lifetime and
the actual re-scraping another one..! Overhere a +/- 0,001 mm lathe bed
re-grind will set you back about ?600,-.
Best regards, Dirk
Regrinding the bed is the best way to go, but that's not the end of the
story. The saddle and tailstock need scraping to the bed, and probably will
need Turcite or similar bonding first to bring the level back so that the
feed shaft and lead screw ports back into line. Probably the cross slide and
top slide also should be done. I've had two Students and one Master 2500
reground over the last few decades !
Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here.
All logos and trade names are the property of their respective owners.