# Vevor Tailstock



## lesrhorer (Sep 27, 2021)

The tailstock which came with my 250 x 750mm lathe was really terrible.  If I can find a good replacement for sale, I am thinking of just ditching the old one.  Meanwhile, I am slogging through trying to fix this one.  The mating surfaces between the top and bottom section were a mess.  They weren't even close to being flat.  I am atlking about 5 thousandths out of flat, here, not 5 tenths.  Not only that, there was PAINT on some of the mating surfaces!  I indicated the prism channel to within 0.0002" of being perpendicular on my mill, and milled off the Z-axis seating surface (which had paint on it) and surface milled the horizontal face by .006".  One corner is still low, but after hand lapping the block, more than 95% of the surface is within 2 thenths, so I am going to call that good enough.  Of course, now the tailstock spindle is a little low, but that is easy to fix with some shims.  The spindle is still not parallel to the lathe bed, however.  It dips by 0.004" over the 5" length of the MT spindle.  I am going to set that up on the mill, and surface mill the top mating surface to get the unit parallel to the lathe bed.  Since all of the holding surfaces are cast, it's going to be a little bit of a challenge, but I think I can do it.

The bigger issue is the prismatic channel.  Althouh acceptably flat, it is too wide, by almost exactly 0.0120" perpendicular to the way face.  This means the taillstock does not register properly along the Z-axis when cinched down.  At the tip of a jobber length drill bit in the drill chuck, this amounts to more than 0.050" variation off center.  It really just does not even work.  The prismatic way is supposed to be just a bit wider than the channel, not 0.0085" narrower along the X-axis.

I have chewed on this issue for a couple of days.  As I say, if there is a high quality compatible tailstock out there for a reasonable price, I might be best suited to get it and scrap the one that came with the lathe.  Barring that, however, I am thinking of gluing a 12 thousandths shim to the block on one side.  And no, I am not very happy with the solution, but CA is quite thin, and I think sufficient to the task.  I can then scrape the surface to get the stock parallel to the headstock spindle axis.  I think.  Opinions?  Am I just chasing my tail, here?  Does anyone know where a compatible tailstock can be had for a reasonable price?

Another possibility would be to machine a new base.  It is not a very complex piece, except that I think the prismatic ways are not 90 degrees.  I don't have a good way  to measure them.  Is there a standard for the angles of the prismatic ways?  If so, where could I get a chamfer mill with the proper angle?

Perhaps I could surface mill the bottom of the base, effectively narrowing the prismatic channel?

The specs of the lathe are as follows:

Height from flat ways to centerline: 109mm
Total flat width (outside of outer flat to outside of inner flat): 80mm
Gap width: 27.2mm
Width of individual flats: 17.7mm
Narrow prism width: 9.7mm
Wide Prism width: 14.1mm
Edge of narrow prism to outside of interior flat (i.e. - maximum width of tailstock base): 57.4mm
Total width 99mm


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## OldFatMan (Sep 28, 2021)

I don't know of a replacement but I'll be watching this for responses.  I have a similar machine and the tail stock on it is/was horrible but I was fortunate that I traced most of the problems to various high spots that I was able to eventually scrape down and attach some jack bolts to align the halves to get it reasonably close.  It was out .020 to .030 or so every way- elevation, angularity and parallel to the bed. I've now got about .001 (my indicator capability) run out on the 5" travel and a bit less in concentrically as far as I can tell to a stub turned in the chuck.  More work to do I think but I'm clueless what I'm doing- just trying things as I read them on this a a couple of other forums.  I understand the lathes are from the Preenex?? factory but I've not had any success in finding a way to contact them- I need a manual for mine.  Hope you find some support for yours. I think I will be disposing of this one pretty soon. Going to pick up a small Logan my dad picked up for me in a couple of weeks.


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