Lathe setup question

Hi, I have just purchased a new (to me) lathe a Denford Viceroy 280. It's installed in it's new home and I have set it level using the adjustable
feet on the cabinet.
Checking the alignment of the tailstock I find that the tailstock center height is about 0.5 mm (20 thou) higher than the center height of the main spindle.
Lateral alignment is exact (as close as I can measure anyway) and the tailstock seems to be paralell to the bed.
The problem is I can see no way to adjust the hieght of either the tailstock or the main spindle ? Is this ammount of misalignment typical ?, Does it matter ?
Chris Cain
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Take the tailstock castings apart and clean out any chips or crud in there, and underneath. Also check the tailstock ram bore for dings or chips.
I've heard that some lathes were sent from the factory with the tailstocks slightly high, to accommodate eventual wear, but .020" is far too much.
Your tailstock being low by .020" would make more sense, as they do lower with wear, but not high. Unless maybe a section of the ways are so badly worn that they are tilting the tailstock.
If your problem is truly the tailstock, scraping will lower it. For .020", might want to mill/plane/surface grind first.
First, though, I'd do the checks above. And, how did you measure the difference? Only really accurate way is to clock the ram with an indicator from the spindle.
Wait a minute - "set it level using the adjustable feet on the cabinet". That's a start, but is not quite what "levelling" a lathe is all about. You might want to check the archives of this group.
John Martin
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"Chris Cain"

tailstock
0.5mm is quite a lot. It will certainly be a problem when trying to drill a small centre hole and it will cause a problem when trying to turn small ( say, less than 8mm diameter ) shafts long enough to need supporting with a centre in the tailstock. This is because the centre height of the cutting tool becomes more critical as the diameter gets smaller - imagine trying to turn a 2mm diameter shaft with the tool set 1mm below centre height. Impossible. With the tailstock height different to the spindle the centre height will vary as the tool cuts along the shaft. At least being too high means you could get a decent machine shop to shave it down for you.
Good luck, Dean.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Cris, Setting up a lathe is a 3 step process. The leveling of the cabinet is a convenience step and not required in the end. The very first step is to level the bed. The second is to make certain the spindle plane is parallel to the level bed. The last step is to center the tail stock. 1) To level the bed, it is convenient to level the cabinet. Then, with a precision level (.0005" per foot), check the bed. When out of alignment the bed is then twisted by shimming the bolts that hold the bed to the cabinet until straight. 2) The second step is to install a test bar that fits into the spindle cone. Then, using a dial indicator (tenths) run the carriage back and forth on the side and on the top of the test bar. Shim headstock until parallel. 3) Then set tailstock to the headstock. Take a test cut at head stock end and at the tailstock end to verify. This is simplified for brevity, but correct none the less. Steve

adjustable
tailstock
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

adjustable
tailstock
For the long term, the exceptional height might be a good thing because as the base of the tailstock wears, center height drops. You should be good until the cows come home!
That amount of height is not good. The place you'll have problems is when trying to ream, if you do, and with small center drills, which love to break off when they are not properly aligned . It would also be a problem when turning between centers. There's more than that, the problems could be endless.
I'd suggest you take the tailstock apart and check if it's been shimmed at the juncture of the top portion and the bottom portion where it slips for offsetting for cutting tapers and otherwise aligning the tailstock with the headstock. That's one place you may be able to make an adjustment to bring it closer to alignment. I'd shoot for no more than a couple thou above center at most. If you don't find any shims, it might be a consideration to re-machine the bottom plate on the top face to lower the tailstock leaving it only slightly higher, about like mentioned above. Do this as a last resort, only. It's a permanent alteration. It goes without saying that if you cut the plate, it should be set up perfectly parallel with the bottom machined surface so you don't tilt the tailstock by cutting an angle on the plate.
This is good advice for the typical tailstock, but I am not familiar in the least with your particular machine, so I can only guess that it is made similarly to most others.
Good luck~
Harold
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Chris, first remove your tailstock and clean it thoroughly, then clean the ways underneath it thoroughly, then reinstall it and repeat your measurement. Maybe you just have a burr under there! - GWE
Harold & Susan Vordos wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

This fixed it, it wasn't a burr but very close. The lathe had been repainted at some time and there was paint between the top and bottom parts of the tailstock on the machined parts. Cleaned it off and reassembled it and it is now just under 1 thou high. Thanks for all the help.
Chris Cain
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The new hardinges come about three thou high, so I would consider that to be the gold standard.
Tailstocks are trickier than first glance would show.
They have to have the ram parallel to the ways, as viewed from above. And they have to have the ram parallel to the ways, as viewed from the side. Then of course the axis of the ram has to be coincidental with the spindle axis.
If the first two are achieved, then one can extend and retract the ram without losing the third.
This is really tough to do when the tailstock is all one piece - the small pratt & whitney lathe of mine had the tailstock bottom all worn out, so I manufactured a new ram with the hole offset to account for the wear, and then I re-scraped the dovetail bottom to fit the lathes bed.
So all of the ususal conditions (three above) had to be met,*and* the bearing for the three bed surfaces had to be right at the same time. That job basically took all winter one year. But I had gotten real tired of the piece of shim stock that I had screwed to the bottom of the tailstock to account for the wear.
Jim
================================================= please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com =================================================
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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.