Tailstock replacement/refurb

I have a South Bend 16x60 lathe that needs the tailstock replaced. Found one through parts works(used in good condition).The way on the lathe are in relatively good condition.Ive heard when you replace the tailstock you are required to "scrape"the ways.Is this correct? if so whats the procedure? and does any one know of someone capable of performing this task? Also the tailstock im removing is it possible to get it refurbished.Any insight would be helpful.thx :

I don't know about having to scrape the entire lathe ways. (i have been wrong before) But you will prob need to match the tailstock base with your current ways. Thats the way it is on a brand new one...Bob
http://groups.yahoo.com/group/southbend10k/

How exactly is scraping on the tailstock base done?

I should have said, filed to fit, maybe. Thats what i was told when i inquired of a new one from SB...Bob

Hi There,

What is wrong with your old tailstock? When your lathe was manufactured, the center height of the tailstock and headstock were the same (actually the tollerance was -.000" to +.003" tailstock to headstock). If you are swapping to another tailstock, the center height of the tailstock may not be the same as the center height of the headstock.

If the replacement tailstock has a center height that is too high (over .003" higher than the headstock) the base of the tailstock should be scraped (if it is just a little off) or machined and scraped to lower the tailstock to specification.

If the tailstock center height is too low, you can place shims between the base casting and the upper half of the tailstock casting to bring it back to specs.

For an in depth explanation of the scraping process, get a copy of Machine Tool Reconditioning by Connely. This book is kind of pricey because it is in such high demand.

Your old tailstock could be refurbished but the person doing the work would need the whole lathe in order to get the tailstock matched-up to the headstock again. This brings me back to my first question. What is wrong with your old tailstock? Is the base worn down? This can be corrected with shimming. Is the quill too loose in its bore? This is more difficult. I have corrected this problem by reboring the upper casting and making a custom quill to fit the new oversized bore. This is an expensive way to refurbish the tailstock unless you can do the work yourself.

So, depending on what is wrong with your old tailstock, replacing it with a good used tailstock may be the simplest and most cost effective thing to do.

I hope this helps. Good Luck!
-Blue Chips-
Webb

The fixed non-moveable bearing areas are known as ways, the bearing areas that move over the fixed ways are known as slides. For example the carriage, on the bottom, has one set of slides for moving over the bedways, it also has the cross slide's ways, on the top, which the moveable cross moves over. The cross has 2 flat slides,1 dovetail guiding slide and 1 dovetail guided slide, which is the gibbed slide. It also has the circular way for the compound rest assmbly.
In your case, I think your buddy was referring to the tailstock slides.
There are 4 tailstock tests that should be performed that will greatly help in pin pointing the problem area(s). These tests are listed in Edward Connelly's book "Machine Tool Reconditioning", and these tests are part of the lathes test card.
There are 2 sets of tests,, and each has 2 parts, and in both cases there is an indicator mounted on the carriage and the carriage traversed. The first test is to check the alignment of the locked extended quill,spindle, or ram, both horizontally and verticall, the second set is to insert a test bar in the ram and perform the same tests on the test bar. These tests will tell you the alignment of the ran and the alignment of the ram's tapered bore as they relate to the bedways. Of course if your bed is worn these test will be less valuable. The assumption is made that the ram is a good fit in the tailstock top, in otherwords a nice sliding feel with no shake. If there is shake, that problem will have to be corrected first.
My experience is that the tailstock's ram will be pointing down, which means that the front ends of the slide have worn more than the rear ends. If you place shims at the front to bring the tailstock into vertical alignment, chances are you will also have to place additional shims in the front and the rear to bring the ram's alignment in line to the headstock's spindle. This is potentually a bad situation; think of what is happening to the tailstock's top when you tighten the bed clamp.
Before the use of shims, the tailstock bottom should be scraped into alignment, both horizontally and vertically, then you can use one constant shim thickness to obtain alignment with the headstock spindle.
You can check headstock-tailstock alignment by using a test bar between centers, preferred, and/or sweeping the tailstock's ram with an indicator, less exact but do-able.
By all means get Connelly's book, strongly recommended, there is a lot that hasn't been discussed, I've basically hit the high points. The book is in depth study of scraping, the tools needed,the alignment procedures and problems, and takes one through the reconditioning of 5 machine tools.
Harry

Well the lower base has alot of wear on both the flat and vee ways.plus the quill bore is pretty sloppy.my center height is low .024 and horizontally is out .015(when the quill lock is tightened). If I can get away with shimming I would,wasnt sure if the base could be shimmed or not. as for the quill bore Is it possible to shim the bore? I have a new quill currently installed.I did find a refurbished unit supposed to be here today but regardless I would still like to refurb the old one. Thanks for all the great info.

You can adjust the horizontal alignment of the tailstock using the alignment screws on the tailstock (whew, i guess that isn't very helpful, is it now...). There's one on the operator side and one on the opposite side.

As for vertical alignment, if that's direct reading it's actually 0.024/2=0.012" low, since you likely zeroed the indicator at one of the extremes.

Tailstocks can be shimmed up to deal with vertical alignment.

As for paralellism to the bed ways, you cand scrape the tailstock slides to the bed to adjust that alignment. This isn't easy, however. As said by others, if you gdet a new tailstock you wil have to fit it up to the bed anyways.

Good luck.

I haven't had the slop problem, so I did a search in the Monarch and General sections.
The consensus from what I have been able to tell is to rebore the tailstock top and hone it, take it to a jig borer, and so on.
I'm going to toss out an idea, and see what you think. Set the top up on a large horizontal mill, cross travel will be the biggie here, and make a special boring boring bar held in the spindle and the other end supported in the overarm support and take a clean up cut, followed by a honing to smooth things out. You will have to make a new spindle to account for the larger bore.
You will have to recondition the tailstock bottom before you can actually determine how much of a shim you need to bring it back to center or a little above(I like my tailstocks to be about .001" high, seems to work bettter). As it stands now all you can get is an approximation. One word of caution here; pay attention to the transverse way engagement, you will reach a point of practical limits. If you have a 1/8" depth of engagement,I don't think .020-.030" shim is unreasonable, .050" I think I would get very concerned. This issue is to addressed when you start scraping, don't get greedy, just take off the minimum.
Harry