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I have a question about lathe alignment

mark_f

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#31
Mark, it seems nobody is willing to comment on your question about headstock misalignment. I've been chasing a similar problem with taper on my old 12" Utilathe, and found some relief by adjusting torque on the four headstock bolts. Also discovered the headstock has been shimmed at some point in the past. Further, doing reasearch on this on a rebuilders forum, I discovered some comments that suggest that headstock bolt torque does indeed affect taper. Which makes sense if you consider drawing the right front edge of the spindle down and away from the lathes true centerline will certainly create a taper in long work.

Can't hurt to experiment with removing the headstock and looking for debris bits underneath, then remounting. Or alternatively, just loosen the appropriate bolts and take a series of cuts to see if you can improve the situation.

Glenn
Glenn,
Thank you. It may be possible that I threw it off tightening the headstock clamp bolts. At least I have a plan now.
 

rgray

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#32
Before I do all this, I was thinking about putting a 3MT test bar in the spindle and using an indicator
I like the "rollies dad method" (google that) for figuring out bed twist. Worked well for me. Requires no precision test bar.
It amazed me how small of an adjustment it took to show an easily measured difference.
 

kvt

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#33
Mark, I was thinking of the floor, Not as a platform but also not knowing what you have your lathe on if it has feet etc, and are placing the weight of the cabinet, lathe, and everything on just those areas. An the areas were not direct on top of the floor joist. Then the OSB can start to give, and I have seen things start to sink into it and punch through. For some reason I do not trust the stuff any more. I would double up the OSB under it, put a piece of good Plywood, or even what one said I about taking and placing 2x4s and putting under it. Then start working on putting a good platform together to mount the lathe. I like the door idea then put your current piece of steel over that for the platform to mount the lathe.

Also the torque on the head bolts, I have actually watch this one on one of my lathes. Was working on the alignment when still had the bar in, then went to torque the head bolts down. As I torqued them down I could watch the gauge move around. My real surprise was how much it moved. But mine did not use a way to keep it in line either. But I remember 4gsr said something about not fully tightening the bolts down on the head for a South bend He had.
 

Technical Ted

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#34
Mark, you've gotten a lot of good information here and maybe even a little bit of information overload! :) Plenty of things to test/try when you're feeling better. The only thing I would like to mention at this point, is if you do decide to buy a test bar, if you buy one with a 3MT everything has to be in perfect shape for it to function as designed. Meaning, your spindle taper, both the internal and external tapers on your spindle adapter and the taper on the test bar have to be in perfect shape, no dings, dents, errors at all or the far end of your test bar has very little chance of running true and will wobble. There are test bars that you can buy/use/make that either go between centers or you can put in a four jaw chuck (or extremely accurate 3-jaw chucks), or even a collet so you can tap the far end to get it to run concentric with your spindle. If using a chuck, clamp up on the very end of the bar using something soft, like aluminum or copper, under your chuck jaws so you can indicate the far end in.

Just a little more food for thought!
Ted
 

Silverbullet

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#35
Permalam beams would anchor the floor and base , those babies are about 3x 12 , manufactured lumber , strong buggers. They should stiffen it up plenty. .
Mark sorry your down bud , ill send some extras to heaven. On your behalf.
 

Splat

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#36
Get rid of the wood. Wood absorbs moisture and will kill any leveling you may have obtained at that time, not to mention its expanding and contracting nature. You need a good foundation., preferably concrete IMO. It ain't gotta be deep either. 3" would be minimum for me. Without the solid foundation you'll be chasing level each time you use the lathe. Good luck and feel better, Mark
 

MikeWi

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#37
Get rid of the wood. Wood absorbs moisture and will kill any leveling you may have obtained at that time, not to mention its expanding and contracting nature. You need a good foundation., preferably concrete IMO. It ain't gotta be deep either. 3" would be minimum for me. Without the solid foundation you'll be chasing level each time you use the lathe. Good luck and feel better, Mark
+1, but instead of replacing or augmenting the floor, treat the building as a ship. Remember you said that the ship is never level and moves around all the time, but the lathe is still aligned to itself right? So build a sturdy frame to go under the lathe. As long as it doesn't flex, the lathe can be aligned, and will stay there (reasonably speaking) regardless of what the floor does.
 

T Bredehoft

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#38
Everyone is talking about leveling the lathe. While a perfectly leveled lathe is awesome, the same result can be achieved with both front and rear pieces of the bed being parallel. Remove the tail stock, put the saddle half way between head and end. Rig a height gage on the front with the indicator on the back, set zero on one end, and put it on the other end. make both ends the same and your lathe should cut straight.
 

eeler1

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#39
Agree with Al earlier, you walk around from the front of the machine to the back and I'll bet it goes out of level (or twist).

Big shops here in the north west often used to have wood floors, but were stable and impregnated with oil. Some had the wood stood on end, maybe 4x6's or larger. No flex at all, and actually durable where the machines were placed.

If you pull the headstock, it's a good opportunity to see about level using that part of the bed that has no wear. But then when you walk over to put the level away it will flex back out.

Maybe put it on springs?
 

mark_f

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#41
To be honest, I think an alignment is off. The lathe cuts consistent. It does not wander when I walk by it or anything. I leveled it 3 years ago and re-leveled it last fall. It still cuts consistently the same and always has. I cant wait to be well enough to go back to the shop and check it.
 

george wilson

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#42
FIRST,KNOW THIS: A 9" SB lathe is a very light lathe,and the bed is quite flexible under the load of a cut. This lathe cannot operate well sitting on a flimsy floor. Especially the longer bed models @ 32" between centers. This is not to say that it is not a good lathe. But it needs to be set up properly. You also need to know how to EXPERTLY grind your cutting tools to avoid chattering,uneven cuts,and other problems. What you NEED to do,is cut a rectangular hole in your particle board floor. Dig a hole 2 FEET DEEP to fit the hole you sawed out of your floor. FILL the hole(in the ground) with concrete. Make the surface of the concrete as smooth and even as you can ! Sit your lathe cabinet on that concrete foundation and it will not move about when you are walking on that flimsy floor. Make sure all 4 feet are sitting snugly on the concrete. If not,shim the leg that needs it with a tapered OAK wedge.Then,you can properly level your lathe.

I doubt that you can swivel the headstock on a 9" S.B. lathe. The V way goes all the way under the head stock. To get the lathe so it makes a true cylinder the same diameter its full length you do not need an expensive level. You need to first make sure the tailstock is perfectly centered on the bed. Put a NEW,sharp pointed #2 MT center in both the headstock and the tailstock. Bring the tailstock right up to the headstock. Get the 2 centers nose to nose. Look straight down on them with a 10X loupe. Adjust the tailstock sideways till you can see that the 2 points are dead aligned. Look sideways at the centers too. Tailstocks can easily get worn,and become LOWER than the headstock,from being slid about. NEVER SLIDE THE TAILSTOCK over DRY ways. It will wear both the tailstock and the SOFT ways on a 9" S.B. lathe. If the tailstock center is below the headstock center,you must loosen the bolts on the sides of the tailstock and lift it so you can put shims under the top half of the tailstock. DO THIS EVENLY EVERYWHERE,or you will end up with a tailstock that may be as high as the headstock,but may be pointing downwards(which is the usual problem). To check for a down pointing tailstock,after you get the points equal in height,with the tailstock quill nearly fully retracted into the tailstock,EXTEND the quill out ,lock it,and see if the points of the #2 MY centers are STILL the same height. If they are not,you need to add shims like you did before EQUALLY on both sides of the tailstock. Do this until you can be sure that the tailstock quill is PARALLEL.You keep checking the height of the 2 MT centers from a sideways view. THEN go back to viewing from above the lathe,and make sure that the centers are perfectly nose to nose.

NOW you are ready to "level" your lathe. Put a bar of steel or aluminum in the lathe. Have it about 18" long. It is a good idea to take sone fairly deep cuts in the center area of the bar,leaving both ends the original,full diameter. Then,take a LIGHT cut off both ends of the bar. If the lathe is aligned,the ends should be the same diameter. If the tailstock end is SMALLER,put a few shims under the FRONT side of the lathe's rear foot..If your bar is too large on the tailstock end,put shims under the back side of the lathe's rear foot. Experiment with shims,repeatedly cutting the test bar,until it is the same diameter on BOTH ends.

It does help a light lathe like the 9" SB,to mount it on a 1/2" thick steel plate. Much thicker than that,and you'll need MUCH HELP even lifting the plate!! I have plates of 1/2" bronze 1' x 4'. Each one weighs 100#. And,you'll have a terrible time drilling 4 holes through a thicker plate unless you can get it onto a drill press. If you have to use a hand drill,make a smaller hole first,then drill your larger hole. It will be INFINITELY EASIER to first drill a small hole first. 1/8" diameter is fine. Removes the pressure of the center of the larger drill. The centers do not cut very well.

If you get both ends of the test bar to cut to the same diameter,try cutting the FULL LENGTH of another test bar. If your test bar is the same diameter at each end,but LARGER (shaped like a wooden barrel) in places,your lathe's bed is WORN,and needs to be re cut,re scraped or re ground. That costs big money. But you can live with it by filing long pieces till they are equal diameter all over. Short parts will likely be o.k.,unless your lathe is really badly worn.

This is the straight dope on how to get the maximum accuracy out of your light lathe.
 
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mark_f

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#43
I "sneaked" (snuck?) out to the shop for a little bit today ( my new test bar came yesterday). I had to try it out.

The first thing I checked is the bed for level. It is still level from the last time I leveled it and there is no twist.

Also, even though I have a crappy foundation, I see no change when walking on the crappy floor.

20170728_154129_HDR.jpg

I put the test bar in the spindle (yes, I cleaned the MT3 taper).

20170728_152656_HDR.jpg
This is the indicator reading at the spindle.

20170728_152719_HDR.jpg
This is 6 inches out and it is linear. I put a flat backed button on the indicator so in case the bar sags a little, it still reads on the high surface.

I was able to get it down to .003" by loosening and re- torquing the two headstock bolts and .002" using the tailstock (which may be off).

So ...... my next step is to take the headstock loose, clean under it, and put it back and see where I am. If good ..... then align the tailstock.
 

Technical Ted

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#44
Just curious... if you revolve the spindle, with the end unsupported (no tail stock) does the test bar run true concentrically both up near the head stock and on the far, unsupported end? This would tell you how good your tapers in your spindle and any adapters you might have to use are running.

Ted
 

george wilson

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#45
If your 9" SB is a short bed one( abt 18" between centers) ,it will be more rigid than the long bed model,and may stand up to being on a non rigid floor better.
 

tertiaryjim

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#46
Did you mark the position of the test bar in relation to the spindle and then after testing rotate the test bar position
180deg in the spindle to confirm whats running out?
 

mark_f

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#47
I think I have it.
20170729_095900_HDR.jpg
This is at the spindle. When I rotate the spindle, I get.0005 TIR.


The other photo won't upload for some reason, but the free end is exactly the same! This is with the test bar in the spindle and no tail stock. When I put the tailstock in, it moves the bar .001", but I know the tail stock is not set perfect.

I also checked the center of the bar and it matches the ends.

What did I do to fix this? I lifted the headstock, cleaned all the surfaces, and lightly stoned the dried oil off all the mounting surfaces and washed with brake cleaner.

I don't think it can get any better. I am going to make a test cut later today.
 

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4gsr

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#51
Mark and others out there, the taper in the 9" SBL is not a true MT3. The taper is off by a few thousandths per inch. So the indicator reading you were getting at 6" out is about right for a test mandrel not fitting the taper properly. Bump it around by hand until you get it running true out on the end.

Like I said in my post earlier in this thread, Leave the bolts loose on the tail end of the bed and somewhat tighten the bolts at the headstock end of the bed. This is the way my 9" SBL has been setup and running since 1949 when it was born. It cuts within .001" in two inches without using the tailstock. With the tailstock, I have not checked it since I recondition the lathe about 15 years ago.
 

mark_f

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#52
Mark and others out there, the taper in the 9" SBL is not a true MT3. The taper is off by a few thousandths per inch. So the indicator reading you were getting at 6" out is about right for a test mandrel not fitting the taper properly. Bump it around by hand until you get it running true out on the end.

Like I said in my post earlier in this thread, Leave the bolts loose on the tail end of the bed and somewhat tighten the bolts at the headstock end of the bed. This is the way my 9" SBL has been setup and running since 1949 when it was born. It cuts within .001" in two inches without using the tailstock. With the tailstock, I have not checked it since I recondition the lathe about 15 years ago.
Well ....... I can now cut 2" without the tailstock and the taper is negligible. I set the tailstock and can cut 6" with less than .001" taper. I will see how long it stays. My lathe bench top is made of 1/8" steel plate. The sides are 1" high at a 45 degree angle. It was designed to run flood coolant.

If the spindle is not 3MT , it must be mighty close because the 3Mt tooling I have fits good, sucks in tight and doesn't move. It doesn't "bump" around.
 

4gsr

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#53
Mark, i eat my words, I was confusing myself with the no. 4MT and not the 3 MT. I went back and looked at the SBL book "How To Run A Lathe" in the back at the table of dimensional data and verified, it is the same as 3MT. Sorry.
 

mark_f

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#54
Mark, i eat my words, I was confusing myself with the no. 4MT and not the 3 MT. I went back and looked at the SBL book "How To Run A Lathe" in the back at the table of dimensional data and verified, it is the same as 3MT. Sorry.
No problem. I thought it was a 3MT, but I been wrong before.
 

4gsr

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#55
What it was, the larger SB lathes, with 1" collet capacity, most of the spindles have a taper that is about 1.625" diameter at the face with a .603 TPF. This is not even close to the taper in my 15" Sheldon lathe. It measures 1.625" at the face, but the taper is equivalent to a 5MT which is .6315 TPF. This is what I was thinking was the difference on a 3MT. As the saying goes, "start brain before mouth!" I need to go eat some more brain food......
 

Technical Ted

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#56
You guys have probably seen this before, but I thought it might be useful for those who haven't. My 1935 15" SB is the same as the 14-1/2" with 3/4" collet in the attached. The taper is the same taper per foot as a #3 morse but is a larger diameter requiring a special adapter to actual morse taper sizes. You can buy an adapter, but I made my own and it works perfectly. It's nice that your 9" can use a #3 directly without the need for such adapter. The more adapters needed, the more room for error and mis-alignment.

Ted
 

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mark_f

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#58
I am putting this here in hopes it maybe useful to someone else.

I bought my South Bend 9 lathe in 2013. It was all original and I new the history of the lathe. It is a 1944 model B. It was a war surplus machine bought after the war by a guy I know and passed to his son and then I bought it. It was never dismantled , restored, or repaired. It was as original and setup and used "lightly" ( they are not machinists. When I moved it to my shop, I set it up and leveled it. I used it for the last 4 years but it always cut that 5 to 6 thousandths taper per 10 inches. I never could figure out why. Over the years I got all kinds of advice as to why and a lot of it made sense but wasn't the problem. The headstock is mounted on a V way and not adjustable. As you can read earlier in this thread, I was tired of fighting the taper. In desperation for a solution, I lifted the headstock. All looked good. There didn't seem to be anything under it. EXCEPT ....some very old oil that had dried and made a brown discoloration on the V way. This appeared as a stain as I could not feel it... just see it. I used some crocus cloth to shine the way and the bottom V on the headstock. Fine crocus cloth will not remove any material but will clean the surface if you rub enough. I remounted the headstock and checked the alignment and the taper is almost all gone. I put a dead center in the tail stock and the headstock to hold my alignment bar between centers,adjusted the tailstock and got the alignment to .0001" over 10 inches.

I have cut several parts since doing this and all parts are no more than .0001" taper and short parts up to 4 inches have no measurable taper. All alignments on this lathe are as perfect as I can possibly get them, and with the recent upgrades to large dials and a graduated dial on the tail stock, this lathe is a dream to use.
20170803_143419_HDR.jpg 20170803_143411_HDR.jpg

One note here. Before I set the tailstock alignment, I used a MT2 hand finishing reamer to "clean" the tailstock socket. At the most I didn't really remove any material. Just any high spots and to polish it a little. The tools don't go in any measurable distance farther. By doing this, it has greatly improved the grip on tools inserted. I also polished the tapers on my tooling with some very fine crocus cloth. I cant believe the improvement holding tooling.

The point here is, an old oil stain that I couldn't even feel, was enough to throw the alignment off.