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Calibrating 9" Model A With Tailstock Alignment Bar

mcload

Hot Rolled
Joined
Nov 5, 2007
Location
Houston, Texas
I'm certain this has been covered far too many times on PM, but just thought I pass this by
the experts. I had not aligned the tailstock since rebuild, so it was time. I purchased an
alignment bar from Edge Technology as well as a new live and dead center (the old ones were fairly
used).

So I got everything assembled and lined out between centers, and first started with the horizontal tailstock adjustment.
Eazy-peezy to zero it out using the setscrews in the tailstock. I should mention here that the EDGE tool was a bit more
difficult to work with, that being because the two calibrated ends have a step in them (as opposed to just being smooth
metal from one end to the other. It was easy enough to come off of the step, but when I reached the far end, I had to use
a little jewelers screwdriver to lift the indicator end to get over this step. (Or maybe I just had the wrong end piece
on the indicator). Oh well.

After aligning the horizontal, I moved the indicator to measure the vertical drop between the two centers (at 12").
I did this a few times and came up with a drop of about 12 thousandths (despite what the photos may show).
Since I had some 12 thou shim stock, I decided to shim the bottom "ways plate" under the tailstock at all four corners.
I had to first back off the setscrews and hit the edge with a rubber mallet to separate the two pieces.
I carefully put it back together after shimming, brought it over to the lathe, and cranked down on the tightening nut.

I then did another vertical drop measurement, and the shims got it down to two thousandths over 12". Not perfect, but better
than it was. Of course, I had to then go back and re-aligned the tailstock horizontal placement to zero.
Now all I have to do is work on 12" long projects and I'll be okay. Any tips from the pros would be appreciated.
(Maybe I'll go back and try to get it to zero).

PMc

BTW, my orig spindle cover is buggered up, so I used one of those plastic ones...any port in a storm!

View attachment 289691 View attachment 289690 View attachment 289692 View attachment 289693 View attachment 289694
 
Are you sure that your vertical drop isn't due to tailstock droop? (Wear of the cast iron TS housing from the spindle.)

Put your indicator on the extended TS spindle and try to lift the spindle. See how far you can lift it. I'll bet that most of your problem is there.
 
The chance that the tailstock base is worn evenly over the entire base is next to nil. Everyone I have ever seen was worn more in the front than the back. Just flip it over and look at it. You can sweep it on a surface plate for even a more accurate measurement if you want. Also, like it was mentioned in the post above, what is the bore and spindle wear of the tailstock? Even the taper bore?
 
The chance that the tailstock base is worn evenly over the entire base is next to nil.

+1, All high mileage lathes like that have the tailstock bore low, and pointing down, and it's standard to shim them to
correct for those errors as well as possible. Within a few thou is considered good.

Did not hurt to buy it but you really did not need the fancy test bar.
 
+1, All high mileage lathes like that have the tailstock bore low, and pointing down, and it's standard to shim them to
correct for those errors as well as possible. Within a few thou is considered good.

Did not hurt to buy it but you really did not need the fancy test bar.

I got one of those bars too and did a quick check when it arrived. My TS was reading .01 low also but I put the thing away since I was too busy to get into it at the time. I made a mental note that at that distance my apron also moves the smoothest so probably some way wear too. It seemed to me like more to figure out and research than I was after but after seeing your shim pics I will probably attempt this also.
 
Thank you all for the great responses and feedback. I've been reading through some prior threads just for research and self-education on tailstock (and other) lathe wear. However large or small the wear is, let's face it...a lathe made in 1946 is going to be less than ideal for doing high-tolerance precision work. As far as I know, this particular lathe has never been used for repetitive production work....that's not what my Dad did. (He probably bought it used from some guy in Dallas around 1951. What it was used for in those first 5-6 years, who knows).

But a 76 year old 9" SB lathe is going to have wear issues almost everywhere, and I have little doubt that the tailstock is worn evenly at its base, not to mention the quill/spindle being cranked back and forth a bazillion times. So no, I haven't put an indicator on those particular moving parts. And my guess is that there is very little I can do about it either within reason and without opening a can of (expensive) worms. If I needed to do super-precision work for a paying client, I'm pretty sure I'd be calling on my friends that run a CNC machine shop. But I manage to do okay in hitting the desired specification by taking my time; using dial indicators on sliders; and keeping a very sharp tool for the last 10 thousandths. (I usually always work with HSS).

I'm attracted to the precision of metal-working machinery and all the parameters, knowledge, and experience that goes with that profession. Most great machinists are underrated and taken for granted if you ask me. (For what it's worth, I never worked for a machine shop, but learned how to run lathes and mills in my teens). Metal shop in Jr. High was a breeze.

So, to get to the point, I purchased that alignment bar for this '46 lathe and the '59 that waiting for me in the wings. It didn't cost all that much and I wanted a quality tool...probably could have found a cheaper one. But there was no reason for me to be turning tapers with offset centers as that is completely avoidable with just a little effort on my part. And same is true with the amount of drop between centers. If all it takes is to insert some shims here and there, then why not? No reason for me to be lazy about it.

But lack of parallelism or squareness on the tailstock base (or carriage) is another issue entirely as the causes are compound issues from 70+ years of use. I could just give it to my CNC guys for total machining of all surfaces along with a check for 10 grand if money were not an issue. And when its all said and done, it would still be a manually operated engine lathe as opposed to computerized. So I'm just doing what I can just to tweak her up a bit. I also realize that making everything "true" a foot away from the headstock isn't going to be the same as 6" away from the headstock.

I hate it when a drill doesn't seem to land squarely in a center hole I just made. Does the MT in the quill need a touch-up reaming? Absolutely. Could I use a new Jacobs chuck and MT shank? You bet. It's on "the list" but I'm not holding my breath. And I would probably prefer another good lathe to do the MT touch-up as opposed to a one-time use hand reamer.

When I was doing the drop measurement at the tailstock end (on the bar), I noticed that the indicator number was getting smaller as I tightened up the quill clamp (of course). But at some point, I got it as tight as I was ever going to ever get it under normal use, and that the quill wasn't going anywhere...but I still felt like the indicator would have still kept going a bit had I continued with some really hard tightening (past what I was comfortable with). I'm not sure what exactly was up with that or able to translate what I was seeing.

So to end this post...and my apologies for its length...I don't mean to be a defeatist when it comes to ultra-alignment of my lathe, but I'll do what I can within reason. Thanks again for your input.

PMc

View attachment 289802
 
you know you are in houston and theres usually one of Richard Kings scraping classes every few months?

with some knowledge,instruction,and basic tools its an evening job to scrape in a small tailstock base....even if it take a weekend...its worth it,
 
you know you are in houston and theres usually one of Richard Kings scraping classes every few months?

with some knowledge,instruction,and basic tools its an evening job to scrape in a small tailstock base....even if it take a weekend...its worth it,

No, never heard of him or the classes. I just sent him an email to see if/when he is going to have
a class in Houston. I'll also watch his videos next.
Many thanks!!

PMc
 
No, never heard of him or the classes. I just sent him an email to see if/when he is going to have
a class in Houston. I'll also watch his videos next.
Many thanks!!

PMc

I just heard from Mr. King. He won't be anywhere near Houston until Feb 2021.

PMc
 
No, never heard of him or the classes. I just sent him an email to see if/when he is going to have
a class in Houston. I'll also watch his videos next.
Many thanks!!

PMc

He's pretty well known in these forums, but mostly hangs out in the "machine reconditioning, scraping, and inspection" section of the forums when he's active.

His classes are usually held at another forum member's shop, Steve Watkins, who reconditions machines, ways, besides other things. Steve is occasionally active on South Bend forums, but floats around the forums a bit. One his great threads and a good read here:
https://www.practicalmachinist.com/...rockford-planer-beast-317291/?highlight=beast

About your alignment I had a few questions. I'm not familiar with 9a's or that particular aligning device.

1. The shims on tail stock. You are shimming on four corners. Are they 4 different thicknesses ? I can see spindle side and hand wheel side being different, to tilt up or down. But are you changing height side to side as well ?

I don't know that is a problem or not, but my knee jerk feeling is I want spindle side one long shim/shims all the way across, and hand wheel side the same, long shim/shims covering all the way across.

I'm not sure that you'll gain stability/rigidity, but maybe, and I'd prefer not having an air gap under spindle. Also if you can shim all the way across, I think you are less likely to have long term warp-age or distortion of base plate, from when tail stock is locked down.

2. Have you aligned headstock independently ? I ask because thread title, and the nature of this tool.

I find this tool interesting, and have not used it. But I think I would use it as a secondary, or final checker. The reason is, it uses dead centers at either end. So either or both, head stock and tail stock might be pointing up or down, and/or right or left, and the tool won't show that.

This tool draws a straight line between the two centers. So it can help measure your accuracy of saddle to work, or more directly, lets say cutting tool to work.

This tool does not actually show alignment of head stock or tailstock to ways though.

Test bars that shove directly into tapers are a more direct extension of each piece.

My suggesttion would be to use test bars first, then use this tool. I don't know for sure, but its my understanding that head stock uses mt3 and tail stock mt2. If that is correct, test bars are fairly cheap:
example mt2:
https://www.amazon.com/Factory-Test-Lathe-Alignment-Precision/dp/B07L4TX7GF

example mt3:
Mt3 (335Mm) 3Mt (Morse Taper 3) Lathe Alignment Test Bar Mandrel | eBay

I'd align head stock first with test bar, locking down head stock down tight during each check if adjusting.

Then back and forth, I'd use a tail stock test bar and current tool for dialing in tail stock. It'll probably take several incremental adjustments using both tools on tail stock to get dialed in. Lock down tail stock on each test.
 
For visual representation of what I mean, I drew a pic. Yeah, quit laughing I'm not an artist, lol:

171.jpg

With the current tool you are measuring a straight line between two centers.

In the exaggerated pic,I'm showing the left side out of whack, and the difference in finding it out of whack with your current tool, verse test bars.

Either headstock or tail stock, or both, could be out of whack. But you won't get a true alignment with current tool alone. You are just adjusting to get a straight line with current tool.

With test bars, you get alignment first. Head stock first. Then use current tool to help the straight line with tail stock, while swapping back and forth with tail stock test bar.

With test bars, use dial indicator on saddle also. Run the length of test bars. Get a reading at 12 oclock for up/down tilt adjustment. And get a reading at either 3 or 9 oclock for right/left turn adjustment.

This will really help improve overall accuracy in work, including facing cuts.

Edit: another fyi, you don't need to jump your indicator on the two end caps of your current tool :D. Just run up and down the purple section. Spin the tool while reading indicator on each end (stay in purple), and in the middle to check its true-ness.
 
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For visual representation of what I mean, I drew a pic. Yeah, quit laughing I'm not an artist, lol:
With the current tool you are measuring a straight line between two centers.
In the exaggerated pic,I'm showing the left side out of whack, and the difference in finding it out of whack with your current tool, verse test bars.
Either headstock or tail stock, or both, could be out of whack. But you won't get a true alignment with current tool alone. You are just adjusting to get a straight line with current tool.
With test bars, you get alignment first. Head stock first. Then use current tool to help the straight line with tail stock, while swapping back and forth with tail stock test bar.
With test bars, use dial indicator on saddle also. Run the length of test bars. Get a reading at 12 oclock for up/down tilt adjustment. And get a reading at either 3 or 9 oclock for right/left turn adjustment.
This will really help improve overall accuracy in work, including facing cuts.
Edit: another fyi, you don't need to jump your indicator on the two end caps of your current tool :D. Just run up and down the purple section. Spin the tool while reading indicator on each end (stay in purple), and in the middle to check its true-ness.

Thanks TGS; you bring up some very valid points that I had not considered, those being if the two centers are pointing directly at each other, and true, the alignment bar will not show or indicate that. And no, I have not aligned either HS or TS to the ways. I thought they were "self-centering" since one side sits in a factory cut groove. Frankly, I'm not sure I understand how either can be "rotated" because of the grooved way. I can see shimming the flat, but that doesn't address rotation.

In regards to the tailstock lower plate, I naturally assumed that all four corners are level and equal in height to one another.
From a technical standpoint, I really should have checked the depth of each.
After looking at that pic, I too wondered why the heck I didn't just cut a "full" sheet to cover the front and one for the back as opposed to 4 little bits. So no, all pieces were from the same sheet (.012) I'll probably go back and redo these shims for a neater installation.

Good point about using the purple part of the bar too!

I greatly appreciate the time and effort you went to in posting the two replies; and the drawing was great! Give me some time to absorb and think about all of this. Thanks for the links too. I was not aware of these bars quite frankly. The taper in the HS on a 9" is quite short...I read somewhere that SB considered it a "proprietary" taper. I always thought that using a good straight
test bar in a collect would be accurate as well. Perhaps not.

Thanks!

PMc
 
I know for a fact a SB 16 HS taper is a special SB proprietary taper. 9a im not sure. But i know and recommend a company that makes test bars for SB tapers, I'll look them up tonight, to post their link.

But you have a good point on collet. If you use a test bar with collet I'd be happy with that. You can roll head stock by hand with indicator to check how true that setup is. It'll be close im sure.

The main thing is use the taper on both sides. Even if tapers have some wear, they will be dead close to true to their respective spindle.

Getting them both pointed at center will buy you all kind of forgiveness on various wear on machine.
 
Unless there is something I'm missing, I don't see how the headstock or TS aren't centered in relation
to the bed ways (and therefore each other) by virtue of the V-notch in each piece. I don't see
how either can be rotated and shimmed to bring into alignment if they are off.

PMc

View attachment 289870
 
Unless there is something I'm missing, I don't see how the headstock or TS aren't centered in relation
to the bed ways (and therefore each other) by virtue of the V-notch in each piece. I don't see
how either can be rotated and shimmed to bring into alignment if they are off.

PMc

View attachment 289870

Sitting on vee ways you wouldn't think so. But both HS and TS can have a slight right or left turn.

As an example to correct HS. If it was pointed slightly left. . . To correct you would shim chuck side only, and only on right side of vee way. When HS is tightened down, it will pull right.

Thats just an example, might vary in details, depending how for it needs to go right or left.

Tailstock i would probably try to adjust right or left from upper half, not base. But i'd need to look at it.
 
The overall goal with a worn machine like this is to achieve as much of the original factory accuracy as possible.

1) the headstock on high mileage machines never moves in relation to the bed, there is no wear there. So no need to do any
shimming or turning other than being sure there is no junk between the headstock base and the bed. Leave it ALONE otherwise.

2) the tailstock base slides along the ways so the base wears. As mentioned the tailstock bore (number two morse btw) will point down,
and be low in relation to the headstock bore. Unless you are doing a full richard king rebuild, the goal is to insert shim between the
base and the upper part such that the ram is parallel to the bed in the horizontal plane, and the bore lines up with the headstock bore in the vertical direction.
The best indication this is done correctly is a small center drill will enter stock cleanly without forming an oversize hole. This is another
good way to ajust the set-over once it is close.

3) the bore in the tailstock casting, and the OD of the ram, wear over time, making the fit sloppy. This means loss of rigidity and
the ram will typically lift a bit when the clamp is tightened. The solution is to hone the bore and plate up the ram. Typically not
done, this is a wear issue that one lives with.

4) the bed ways have the carriage riding on them, so they wear over time. Again, absent a full rebuild, the typical approach is to
use the two-collar method to adjust the bed so the machine turns and bores true, over as long a distance as possible, near the headstock.
Even badly worn machines can turn straight within a thou or two, within ten inchs of the headstock.

Note that none of these checks or adjustments require anything more than a micrometer and some stock.
There is no need for test bars, levels, taut wires, lasers, or dial indicators.
 
Okay guys; absolute great information and very must appreciated.
I agree that the HS should have zero wear as it never moves...and I know its clean underneath.

I was going to ask if I needed an indicator with much finer graduations, but you answered that
question. Starting to split atoms! But the info is very helpful and will motivate me putz around and get
it dialed in as best I can. This is prob helpful to many others as well.

PMc
 








 
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