South Bend 9A Tailstock Critique

[graham-xrf]

An evaluation - if you like.
This is the lower part of my SB9A tailstock after a partial cleanup, and an admittedly casual attempt at checking the wear. I used a red highlighter to try and show up the "unworn" parts. (Red highlighters don't work as well on cast steel as they do on paper)!

I used a single edge blade set to straddle the worn bits, and tried to stick feeler gauge shims underneath. I know that there are tailstocks around still doing quite accurate work, having wear somewhat worse than this, but I post it anyway. This is just about making the SB9A as nice as I can within reason, piece by piece, done as and when I can get to it. This machine has to get repairs, some new parts, alignment, a paint job, wicks, drive belt, etc.



The worn parts have score marks, no doubt from chips or dirt getting under there. There is a similar wear ridge, about 1mm wide, on only at the very edge of the vee nearest the feeler gauge where I tried to mark it in red. It progressively thins out, and disappears entirely by the right half of the vee. I guess if there was wear on where the flat way rubbed, then there would be similar wear in the vees, but we can only see one side of the vee wear, because the "other" ridge does not form, it being in the relief slot.

Such as it is, I value any comment. I don't know what is "OK" or "seriously messed up", nor anything in between. I don't know what folk would do to help the state of it somewhat - if i needs it at all.

I can anticipate that if any attempt is made to get the sliding face flat, then it involves also taking care of the vees, to maintain the relationship between the flat, and the prism ways. Of course, if there are any trick tips for improvements - then do tell..

 

[Bob Korves]

What are the numbers on your tapes referencing from? Remember that while flattening the base you also need to also make or keep the quill parallel with the bed, Checking the tailstock spindle center for height and the spindle for parallel with the bed ways first will tell you what needs to shrink and what needs to grow the big picture. The base that you are working on needs to ultimately end up with both top and bottom surfaces parallel with each other and both flat. Shims often help between the upper and lower halves to achieve proper overall alignment.

 

[graham-xrf]

What are the numbers on your tapes referencing from? Remember that while flattening the base you also need to also make or keep the quill parallel with the bed, Checking the tailstock spindle center for height and the spindle for parallel with the bed ways first will tell you what needs to shrink and what needs to grow the big picture. The base that you are working on needs to ultimately end up with both top and bottom surfaces parallel with each other and both flat. Shims often help between the upper and lower halves to achieve proper overall alignment.

At this stage, we see only a first "quick 'n dirty" check. I will attempt to use an indicator on it this weekend. The numbers (inches) are the thickness of feeler gauge I can pass under the razor blade when the blade edge is stood across the worn place. If you hold the blade across from red-marked surface to the other red-marked surface, you can see flashlight light sneak under the blade. That is where I stuck the feelers in.

 

[graham-xrf]

Checking the tailstock spindle center for height and the spindle for parallel with the bed ways first will tell you what needs to shrink and what needs to grow the big picture.

For sure Bob, you are one of HM's posters extraordinaire, and I think you have probably seen it all!

I just look at the tailstock, and I know right away that because it sits on the ways, some of what happened to the tailstock, also happened to the ways, and anything I do had better be considered first with the big picture in mind.

Except for the wrecked quill, which is a separate and worthy project for the SB9C, the overall condition of the SB9A is not so bad. There is no obvious wear ridge at the edges of the main ways. I throw in some caution, because I also have no idea of their history. Maybe there was previous work done on them. I am just carefully picking my way through everything, piece by piece, at my leisure, and figuring our what the treatments might have to be.

The base that you are working on needs to ultimately end up with both top and bottom surfaces parallel with each other and both flat. Shims often help between the upper and lower halves to achieve proper overall alignment.

Sure thing about setting the tailstock at the correct height, using shims, and get it tracking parallel to the headstock spindle. I have gathered enough from the HM site, and various videos, to have discovered the ways to go about it. The awkward bit in there is about the prism vees. Any adjustment at all to the flat rubbing surface has also to take the 45° vee surfaces down with it.

It occurs to me that one has to be sure to get the ways right first. I mean to measure them, and get them understood, leveled, and fixed as needed. I don't have a "Kingway", but I figured this would come in handy..



Once the ways are known to be straight and level, then placing the tailstock base onto them, and using the level across the tailstock base should reveal by how much the vees need to be "adjusted". The plan is flawed! If the flat has been changed, the vees will be slightly "rocked" off their seating from the start.

I have a MT2 + MT3 precision test bar set just waiting to become useful. There is the irony about how much even trying to use one of these bars relies on having first created a new MT2 quill, accurate in it's own right, and checked out for sweet fit with the tailstock bore. I even wonder how good is the tailstock bore. The piece of EN24T (like 4140) has arrived, and it mocks me from where it is on the shelf!

Some basic stuff about the main lathe ways is already known, but I have in mind to measure up properly, so I know the truth of it all. It may end up that there is not much work needed (or sensible to undertake), except continue with the cleanup and assemble. If there is any straightening up to do, it looks like it would be likely be somewhat less than the 0.003, or 0.005 carvings the scraping enthusiasts often get up to.

I am not sure about having the ways ground, because right now, there seems not very much one might have to remove to set it right. I would worry that doing something like that has consequences - like having to rework the carriage leadscrew position, gearbox and all.

We have not yet even mentioned the main carriage. It still has to experience the adventure of traversing the ways while carrying a magnetic base dial indicator set with the business end touching the top of the ways, or maybe onto something flat set across them.

Of course, we all realize that these here are just two (three??) more rabbit holes I am looking at. Various HM folk did warn me..!

 

[Bob Korves]

Graham, I certainly have not seen it all, just a home shop hobby machinist who often talks a way better job than I do. I am an avid reader, and study the reading material, YouTube videos, and Hobby Machinist most of all, and also help friends with projects to learn as well as help. That is all that I know. I was in the machinists union for more than 30 years, but as a parts guy for cars, trucks, big trucks, all kinds of construction equipment, and anything else that breaks or wears out parts, but never as a machinist. I did pay attention and listen carefully to what was going on, and asked lots of questions, but never operated a machine doing that work. Yes, I have a good memory (getting worse as I get older), and do pretty well at visualizing how things work and what might be wrong if they don't work. I can make decent stuff with my machines, but relatively slowly and carefully, with stops to study and figure out what I should be doing next. I am not too afraid, shy, or proud to ask for help. So I get by...

We also have an active and friendly local machinist group and help is easily available, both on the internet and in person locally. It really works well for us all, And also Hobby Machinist, OF COURSE!!!

Your understanding of getting the lathe bed straight and parallel and the tail stock properly lined up with the headstock is flawed. That level will not do the job. If you want to do that work on the cheap, you need to get some training in machine tool reconditioning, learning how to properly test the machine for deviation from the manufacturer's specs. Then, again on the cheap, you should learn to scrape machinery the correct way, which must include some professional guidance as well, until you clearly understand how to test, what to do with the results, and why. Many machines are made worse by those who do not understand the complete details of the jobs they are doing. I have had some professional training at scraping and machine tool reconditioning, and I paid attention. Still, I am a rookie at it, still studying and practicing the craft.

 

[Janderso]

A good read on the subject. Edward Connelly, Machine Tool Reconditioning.

 

[graham-xrf]

Your understanding of getting the lathe bed straight and parallel and the tail stock properly lined up with the headstock is flawed. That level will not do the job.

Ahh .. no. Not to misunderstand. I could have said it a bit differently.
The level is a 0.02mm/m Stiefelmayer "PRAZISION" sold on from a calibration lab. That is 4.125 arc-seconds.
Aside from basic leveling, if placed across unworn way tops, it will measure twist. In all the other ways a level can measure, this one can do it. It's just that the better way to tackle lathe ways measuring needs TWO levels, and a couple of dial indicators also, and some partial setup that does what the Kingway does in more complete fashion.

Slower, but putting a gauge block across the ways at lots of points, and measuring down to the wear surface does it.

So far, I have identified the unworn surfaces on the bed, and measured to the tops of the ways at intervals for the length of the bed, to discover if the tops can safely be taken to be suitable precious "reference surfaces".
For the rest of it, I will be reading just about everything on the subject in this forum.
Once I know exactly the shape of it all, then we decide if the wear is so minimal, we just put it back together, or do we embark on something more adventurous.

The tailstock has been "run in", so to speak. Should I restore the tailstock to "as new" before taking on the rest of the machine? I think, if I do, it cannot be done in isolation. We have to consider giving rest of the lathe similar treatment.

Getting up a sort of Kingway is not beyond the bounds of possibility. Even a reasonably proper one. If I could get hold of a couple of those cross-clamps, and a large ball bearing, the world might have another home-brew Kingway.

 

[graham-xrf]

A good read on the subject. Edward Connelly, Machine Tool Reconditioning.

I do have the Connelly tome. It is not the sort of book to read straight through. I first go for the table of contents, get to the stuff I need, and allow the attention to spread outwards from there. On this subject, for one of the measurements, it seems we can use precision ground dowel rods laid in the vee, and use a parallel over to the flat. More reading yet to do!

 

[graham-xrf]

To quote the ex-country singing girl, "Look what you made me do"!
The upper surface has some (sort-of) scrapes, looking like a few sparse wide shallow crosses.
I resort to a 6" diameter x 1" thick "was-once-an-optical" flat, and some ocre rouge.


and then we flip it over to check out the other side..



What can I say? I will admit that some expressions of an un-moderated nature were used, of the sort darkzero might have had something to say about!

I know the upper surface is never to be seen again, but even so, it disappoints. I guess the pressures of wartime manufacture forced that the best standards were reserved for essentials.

I think if I post a picture of this thing again, it just has to be something made a whole lot better.

It begs the question.. Is possession of a surface plate, and a collection of scraping stuff, something almost all of us have acquired, even if we rarely use it?

 

[Bob Korves]

Ahh .. no. Not to misunderstand. I could have said it a bit differently.
The level is a 0.02mm/m Stiefelmayer "PRAZISION" sold on from a calibration lab. That is 4.125 arc-seconds.
Aside from basic leveling, if placed across unworn way tops, it will measure twist. In all the other ways a level can measure, this one can do it. It's just that the better way to tackle lathe ways measuring needs TWO levels, and a couple of dial indicators also, and some partial setup that does what the Kingway does in more complete fashion.

Slower, but putting a gauge block across the ways at lots of points, and measuring down to the wear surface does it.

So far, I have identified the unworn surfaces on the bed, and measured to the tops of the ways at intervals for the length of the bed, to discover if the tops can safely be taken to be suitable precious "reference surfaces".
For the rest of it, I will be reading just about everything on the subject in this forum.
Once I know exactly the shape of it all, then we decide if the wear is so minimal, we just put it back together, or do we embark on something more adventurous.

The tailstock has been "run in", so to speak. Should I restore the tailstock to "as new" before taking on the rest of the machine? I think, if I do, it cannot be done in isolation. We have to consider giving rest of the lathe similar treatment.

Getting up a sort of Kingway is not beyond the bounds of possibility. Even a reasonably proper one. If I could get hold of a couple of those cross-clamps, and a large ball bearing, the world might have another home-brew Kingway.

Ah, OK Graham, you DO know what is going on... It did not sound like it in your earlier post. Still, using a level to get a long surface flat and parallel is fraught with opportunities to accumulate errors, and so requires other ways to help with validating the results. Good posts, keep it up.