Best way to deal with tail stock low by .003"

I am nearing the end of scraping a Rockwell 14 by 40 lathe minus the hardened bedways. I have scraped the tail stock base and got the top of the base parallel with the carriage travel within .0002" However because of the ram wear I had to add couple thou of paper shims under the tailstock in the front between the base and top to get ram parallel. Now I have tested height of TS to head stock and it is still .003" low however parallel. What is the best way to deal with this? I could add shims to front and back. I have read not to turcite under TS cause it won't lock well. What have you all done? Thanks, steve.

I used .005" brass stock under one I repaired once.
Would steel shim be better?...no idea but I had the brass in hand and it was doing fine 3 years later
when I left that shop.

I cut out one piece the same size and shape as the area between the base and top of tail stock.
Kinda like making a gasket if you will with cut outs were needed.

Another vote for shim it up. Worked fine for me.

Shim is pretty much all you can do. I would not use steel I would use brass and order a roll of it so you have enough to change out regularly. Most of the time you may not need to have it dead on.

I just pulled out my "Testing Machine Tools" Book by George Schlesinger the book modern day spec's is based on and it says,...
Tailstock on Lathes up to 15 1/2": (A) Tailstock sleeve (quill) parallel with bed in vertical plane (front Rising) 0 to .0008" in 4" and (B) Ditto in horizontal plane ( front end inclinded toward the direction of the tool pressure) .0004" per 4".

How did you indicate check the quill? . I recommend you turn a test bar down to the same size as the quill about 3 to 4" long then line up the side or horizontal side of the quill and test bar by mounting a mag base and indicator (.0001 to .0005") and eyeballing the center-line and adjust the tailstock so the sides are dead on or .0 to .0002", then lock down the tail-stock down to the bed and lock the quill and check the side of the quill to see which way it's pointing on the side (B). Then indicate the top zeroing the using top dead center check by moving the cross-slide in and out and reading and noting what direction your moving when getting the read. then move the saddle down indicating the top and 4" down do the top dead center test again noting the direction you move it during the read. Did you test it that way?

Another thing one needs to do when scraping the tail-stock is to keep the top of the bottom plate of the tail-stock parallel to the movement of the cross-slide in and out. Just think about if that isn't parallel as you move the tail-stock in and out to line up the center-line and if it is not as you move it in and out it will move up and down as it's moved. Check it then lets talk about how to fix it. Rich

That's exactly what shim stock is made for. I'd say squirt some Loctite in the gap to stabilize it except you'd never be able to offset the tailstock axis.

Thanks for the info guys. I checked the height of the quill with a dial in the 3 jaw chuck offset to get around the quill. I used paper to get it right but will order some brass stock. Now when I lock the quill I am .0005 high (above the HS spindle) but .004 low when unlocked. I guess I will have to lock with doing close work.

Richard, did not test the parallel of the quill the way you suggest but will. I like that method. I put a dial mounted on the cross slide, tip on top of quill extended, and moved the carriage back and forth. I will turn down bar as suggested and line up, and post results. Much appreciated. Steve

Edit: so I guess I have .005" clearance on the quill bore. A rebuild there I ass-u-me would require bore hone, and a larger quill to fit. A lot of work. I will try to live with it. Is that amount of play in the TS common?

To have some fun, mount the mag base on a steel bar or parallel and reach out the indicator rod and indicator the distance you had it extended out from the chuck to tail-stock and put about .020" pressure on the indicator. Pick up the whole thing and turn it over holding over your head and watch the indicator sag from gravity. If you have the time make up a fixture and don't use the mag base and it will probably be the same. This has been talked about in several archived thread on here.
I have seen several Journeymen machinists shocked to see how the indicator bar and indicators sag down do to gravity. Rich

Yeah. Tramming from a horizontal spindle makes for much head scratching and mechanical wonderment.

When the tramming axis isertical, gravity is always in the same sense direction so it has no effect on the indicator set-up. Ina horizontal spindle, gravity is constant while the indicator set-up rotates with the spindle; your indicator reads double the set-up sag plus double the error. This leads to remporary insanity. If you can compensate for the effect of gravity, cool.

Otterwise do as Richard suggests: scan across from a quill sized plug machined in the lathe spindle to the quill.

Oh yeah. Always use a metal shim to space ferrous parts in a possibly wet environment. Paper, any paper, is fibrous and wicks water. Rust. Rust bad.

Rudd said:

Another vote for shim it up. Worked fine for me.

Click to expand...

Sorry, I couldn't help it. I had to like your post.

how about putting a shim on the base, shim tail so it is true and epoxy it to the shim(s)?

Come on guys, this is a machine re-building sub-board. Shims???

The correct answer as anyone knows is, you reduce the height of the *headstock*
to match, by machining five thou off the underside and then scraping for fit to the bed!
When you are done the tailstock should be a few thou *high* as it will wear
in over time. This is how hardinge set their stuff up.

Other trick is, you scrape for bearing, fit, and alignment for the tailstock. Take
as much vertical as you want. Then make a new tailstock ram with the bore
offset the correct amount. This is the cheat when the tailstock is a one-piece
version, not split.

jim rozen said:

Come on guys, this is a machine re-building sub-board. Shims???

The correct answer as anyone knows is, you reduce the height of the *headstock*
to match, by machining five thou off the underside and then scraping for fit to the bed!
When you are done the tailstock should be a few thou *high* as it will wear
in over time. This is how hardinge set their stuff up.

Other trick is, you scrape for bearing, fit, and alignment for the tailstock. Take
as much vertical as you want. Then make a new tailstock ram with the bore
offset the correct amount. This is the cheat when the tailstock is a one-piece
version, not split.

Click to expand...

Thanks Jim, we are all waiting on the photos of you doing this....

Enjoy the rest of your weekend

Charles

jim rozen said:

Come on guys, this is a machine re-building sub-board. Shims???

The correct answer as anyone knows is, you reduce the height of the *headstock*
to match, by machining five thou off the underside and then scraping for fit to the bed!
When you are done the tailstock should be a few thou *high* as it will wear
in over time. This is how hardinge set their stuff up.

Other trick is, you scrape for bearing, fit, and alignment for the tailstock. Take
as much vertical as you want. Then make a new tailstock ram with the bore
offset the correct amount. This is the cheat when the tailstock is a one-piece
version, not split.

Click to expand...

Damn, I thought I was nearly done...

Actually I've done that twice so far. Once for a cataract 59 lathe, and once for the 7"
pratt whitney that I like so much. The small machine's a treat to run now that the
tailstock lines up right. Also in both cases it let me keep the original tailstock rams,
which have proprietary tapers in them, and still set the machine up using MT1 so I
can use standard tooling.

Nobody wants to see those old photos anyway...

Not trying to start an argument here, but there are several ways to skin this cat.

I am waiting for the tests to be done right. I'm not going to get to excited until then. I used to work with Hardinge field service, have taught scraping classes for Hardinge employee's and consulted with the NY Headquarters in the past. Their Tail-stock (TS) is one piece and I never scraped the head-stock in the field as it is perfect alignment and it is a real pain getting everything aligned up as good as the factory can do it with the proper test bars and special dummy* straight-edges. .

I checked it for burr's and put it together tested it with the Hardinge supplied test bars and bolted it down. If the tail-stock was low and it depended on how low, I had some trick of the trade Hardinge rebuild told me to do or I machined off the bottom of the TS and applied a wear-strip material. Usually we used Phenolic or Moglice. I also know some used Nylon and Turcite. If your bought a new bed plate many times it is ground a little higher to compensate for wear.

I would never put in a a brass shim in between the 2 piece tail-stock on a rebuild, but I also would not scrape under the head. He now says the quill is loose in the TS bore. Lets take it one step at a time and be calm about it. I have done temporary repairs using shims if the customer needed the machine to run, now. There is a time and a place for everything. If Low Country is doing a true rebuild then we can discuss the best option for him when he has it tested. I have some idea's that will work for him. But will hold back until we know what the true readings are.

I was just talking to another member today and we both mentioned some of the hobbyists get to excited getting the machine perfect or "like new" get it in .0001"'s when .001" is close enough. Just look at so many machines that are worn out and making good parts... Rich

* Dummy is a special straight-edge factories have that are made to fit production made parts. They resemble the part like the bottom of a head-stock so both sides of the bed is blued together at same time. In the Moore book shows a Dummy being used when they are bluing up the base (can't find my copy now to give page number). Also in the little booklet I give out "Why are they Scraped" by Do-All is using a dummy to scrape the saddle.
Charles, member MUD made a copy of it and added it to a thread. Why don't you message him to send you a copy to add to the top. I have permission from Do-All to republish it.

Just my input, repairs with loose, thin shims aren't a professional repair. You can shim your lathe tailstock anytime you like, but you won't shim mine. Most tailstocks are made in two halves. I'd machine down sections of the lower half and then screw and dowel 1/4" plates onto the lower half. Steel or brass will be ok, cast iron is not so good Do your machining so the plates end up about 0.005" high and then scrape for alignment.

Regards Tyrone.

"...I had some trick of the trade Hardinge rebuild[er] told me to do or I machined off the bottom of the TS and applied a wear-strip material."

That probably also helps with the T/S lockdown problem on the HLVHs.

Packing tape or self-adhesive shims, or just use trig to determine when/how the error would rear it's ugly head on any specific project.

It won't create a taper as much as affect the centerline of the cutter, right?

If the quill is all beat-up, perhaps a new quill with the socket moved .003 off center?

I suspect a clever machinist would just work around the issue.

Send it out for chroming?

Lets stay on the subject of Steve's lathe. We can discuss Hardinge in another post. Makes it easier to archive the information in this new forum in my opinion. I also think shimming between his 2 halfs is not the correct way in the rebuild as I stated. When we have more info lets figure out a way to help him. Rich