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'67 Modular Tailstock Rebuild


Feb 27, 2001
Redwood City, CA USA
The tailstock on my recently acquired '67 10EE was badly worn. The quill had about 0.005" slop and the ways were like a banana. The rest of the lathe is practically unworn, so that must be a testament to the pumped lube system in the saddle.

I had the tailstock bore honed by Mike at Micro Honing in San Jose. Despite having to hand-hold the casting, he told me he got the bore to 1.2547 +/- 0.0001. I made a short plug gauge on a rod and probed the bore from one end to the other, and I believe him.

I drew up a new quill in SolidWorks, mostly copying the old one.


I then bought a foot of 1-1/2" dia ETD-150 from McMaster. ETD-150 is LaSalle's proprietary 4140 pre-hard that is supposed to be specially stress-relieved for less warping and I think is resulfurized for ease of machining. I roughed it out using my trusty Colchester Chipmaster, which has a functional tailstock, as shown below. Then, using the 10EE, I drilled in from both ends using a BXA collet block to drive the drill with the saddle. Sure beats cranking a tailstock in and out for a 7"-deep hole!


Next, I used my Deckel FP2NC mill to cut the keyway, oil slot, and Morse taper tang drive slot. (More pictures in the next post.)

Here is a photo of milling the tang drive slot. The old quill did not rely on setscrews for this feature, and the new one doesn't either.

Here is the old quill and the new rough-machined quill:


Next, I threaded the back of the new quill for the retaining nut using the 10EE.

Next, I thought I'd be cute and cut the Morse taper socket from first principles. I set up a sine bar in an angle plate bolted to a faceplate and dialed in the compound to the appropriate angle. (More pictures in the next post.)

to be continued...

Once I had the compound dialed in, I set up the quill, supporting the outer end in a steady. I had to lightly shrink a collar over the keyway so the steady had a good running surface. I put a dial indicator against the stock (which I'd already bumped into concentricity) as I tightened the steady jaws to avoid deflecting the stock. Even with all the pains I took, the taper fit badly when I checked it against a blued male taper. I don't know whether the boring bar deflected too much or what, but I ended up bumping the compound angle around a bit, and then borrowed a taper reamer to make the final fit.


The quill then went back to the Chipmaster for the final OD cuts before lapping, which I also did in the Chipmaster.


The fit came out beautifully. There is no perceptible slop, and a nice axial drag. It may be better than new.

Next, I attacked the ways, which I'll show in the next post.

I put the base on the lathe and indicated it to find out what all was wrong. I found that the nose drooped about 0.0055" in 8 ", and the base was tipped laterally 0.0065" in 8" toward the rear. This meant the V way was worn much more than the flat way, which is not surprising given the Mickey Mouse amount of bearing area on the V way side, especially once you subtract the huge oil grooves and account for the pressure multiplying effect of the relative steep way angle. What were they thinking?:crazy:

I set up the base in my Deckel FP2NC and cleaned up both sides of the V, the V root, and then the flat. I made sure to take 0.0065" more off the flat than the Vees (vertically). I used a sine bar to dial in the tilt angle of the mill for the Vees. This time, the angles came out perfectly. I only had to do the tiniest bit of scraping on the flat (mainly because the face mill couldn't run all the way off the piece), and just enough on the Vees to break up the smooth finish for oil retention.

The final alignment came out great. The quill runs about 0.0005" high in 6" and toward the front a little more. I had to shim the base about 0.014". There were 0.006" shims in it when I bought it. By the way, I do not believe the tailstock offset guideway way was perpendicular to the lathe axis even when the lathe was brand new. It is out about 0.005" in 8", which I think is the OEM condition.

Once I finished the tailstock, I pulled the apron sumps to fix an oil leak, cleaned them up, and siliconed them back on. The last mechanical bit I have to do is realign the cross-slide nut with the screw. The travel binds to the rear, and it's not because the dovetail is worn. If I take the screw out, the dovetail movement is steady and silky throughout the travel.

I tried demagnetizing the QSD relay armature, but it still sticks. That's for a different post.

I hope this helps someone.
I read this thread with a great deal of interest since I have to do the same job. Mine is probably considerably more worn, being a poorly treated '53 MG. Current thinking is to check the contact with the ways, scraping for supporting area, not alignment, then rig a boring bar between the chuck and steady rest, using a ball bearing on the end of the bar held by the steady. I would mount a cutter roughly in the middle of the bar and link the tailstock to the carriage in some manner to be determined. Then I could use the carriage feed to bore the tailstock. Since I have a Sunnen hone, I can clean up the machine marks. I have considered having the quill built up with chrome since we have good hard chrome and cylindrical grinding shops here. Then I would need to recut the Morse taper. Making a new quill might be the better course. Did you cut the ruler marks in yours?

Some of the relays have adjustments, either screws or shims under the coil, to adjust the gap between the armature and pole when it is closed. Increasing the gap should cure the sticking problem.

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Rklopp, good work. I found the tailstock offset guideway on mine to be inaccurate as well. 9100, If I read your post correctly, you are intending to to correct your tailstock misalignment by reboring the tailstock quill hole insitu. If this is the case , my advise is don't. Bore out the quill bore until it is round and true,in relation to the original bore. Your leadscrew bearing housing, etc are all in alignment to this bore. Hone till is really round, straight and true. .0002 max. Either make up a new quill from scratch(prefered) or have a competant hard chrome shop(rare) build it up,and grind it to a .0002max fit. Now that you now have a accurate quill, you can turn your attention to manipulating the ways on the tailstock either thru scraping ,Moglice, to achieve the desired accuracy. Forrest Addy wrote some excellent and textbook advice for tailstock repair in the New general section, maybe somebody will post a link.
I don't see the point of resurrecting an old quill with hard chrome. On my old quill, I'd have to resurrect the OD, the taper, the keyway, and the tang drive slot. By the time I address all those issues, it is easier to make a new one.

I have not engraved the ruler lines yet. I will either do it in the lathe or on the CNC mill. I don't want to inlay a rule or make a flat for the engraving, as I see that as a path for easy dirt ingress. The original quill had a flat for the engraving. The Chipmaster has the engraving on the cylindrical surface of the quill, which I think is better.
All good points. The decision on boring the tailstock depends on how well the back end is still in line. If the leadscrew is still centered, meaning that there is not too much wear on the base, then boring as I said will be a good option because the front appears to be worn at the bottom, making the quill point down. If the leadscrew is out of line, then I will have to deal with that as required. Just honing will not work unless it is some sort of line hone because it will pull off toward the worn side (bottom). Right now, I am embroiled in scraping the cross slide and compound, so I don't need to take something else apart. Re rulers, I agree. My Monarch also has the flat. My South Bend has cylindrical lines on top. My Sheldon has cylindrical lines rotated about 25 degrees toward the operator, which puts them right where you want them when cranking the handwheel. BTW, I was surprised at how crude the workmanship on the quill is. My 10EE, at least, has some real rough spots.

Re QSD relays. I have one that I may or may not use, so I might consider a trade. It is a Cutler Hammer, probably from a Modular. I also rewind, resurface contacts, replate parts, etc, so I can probably fix yours.

A year-and-a-half later, today I finally got around to engraving the graduations on the tailstock quill. I used my Deckel FP2NC in horizontal mode and wrote a little g-code using macros and looping to do the inch, half, quarter, and eighth lines. Due to the overhang, I used a Circle heavy metal shank lathe boring bar as the cutter. I had to think upside down so that the graduations came out right side up once the ram was installed back in the lathe. The photos tell the story.
Rich, it looks great! Nice sharp graduations too, unlike the originals. I assume the program moved X axis to clear the cutter while it was being advanced for the next graduation, or does Dialog 4 have a capability to set the angular position of the cutter?

I assume the program moved X axis to clear the cutter while it was being advanced for the next graduation, or does Dialog 4 have a capability to set the angular position of the cutter?


Thanks Dave. Yes, the cutter was clear of the work during advance to the next graduation. Here's how it worked: I placed the cutter near the start point of a graduation. I turned on "compensation on the contour" using G41, which tells the machine to account for the contact point of the cutter radius on the intended cut contour, rather than accounting for the cutter centerline. Then, I arced into the cut. The arc was such that the end of the arc was tangent to the intended contour at its start point. This eased the cutter into the cut. Next, I made a polar coordinate move of however many degrees around the tailstock ram the graduation was (36 for the longest graduations). The pole was the centerline of the tailstock ram. Once I reached the end of the graduation, I arced out similar to the way I arced in. The Deckel Dialog 4 control did the arcs automatically. I told it the radius of the arc and the endpoint, and it figured out where to start the arc and moved the cutter there accordingly, either via rapid or a normal feed move. Contour compensation is certainly not unique to Deckel.

I programmed the graduation cuts as a set of four subroutines, one for each length of graduation, then repeatedly called them as I stepped incrementally along the ram. I used G91 to do the incremental moves, then switched back to G90 absolute for each cut.

"Nice work, teaching that CNC Metric machine to do Imperial graduations for a old US manual machine must have strained its semiconductors."

Dave E: Could be, but the Deckel was running in inches at the time. It's certainly nice to be able to switch back and forth between measurement systems with such ease.
I guess I missed this the first time around. Nice work!

I would appreciate a little more information on your OD honing operation. Did you make the hone? If so, what's it made of? How did you charge it with abrasive? etc.


For the OD honing I bought a couple of replaceable cast iron hone shells from MSC (IIRC) and made a holder for them copying a commercial design. I used diamond past and light spindle oil. I think I started with 15 micron paste and finished with 1 micron or 5 micron - I forget. You can see the setup in post #3 above.

I farmed out the ID honing to a local honing shop, Micro-Hone, in San Jose. They have a couple of rooms full of Sunnens. The tailstock casting was at the limit of what they wanted to manhandle on a Sunnen, but they got the job done. I assume they used a spiral stone arrangement to bridge the keyway, but don't know for sure. In any event, the bore came out straight and parallel with a couple tenths as best I can measure. The bore is now about 1.254, which is 0.004 oversize relative to nominal.

I suppose one could do the job with a lap or two, but it would be a real slog. It would be better to hold the tailstock casting stationary in a vertical orientation and drive the lap or hone with a low-speed drill motor and U-joints or a flexible shaft. Set up a little pump to circulate oil.


Thanks for the information. I checked MSC and McMaster-Carr and I don't find hone shells. Do you, by chance, have a part number?

Could you post a photo of the holder?

(This information might be useful to others interested in making a tailstock spindle.)


"I farmed out the ID honing to a local honing shop, Micro-Hone, in San Jose. They have a couple of rooms full of Sunnens. The tailstock casting was at the limit of what they wanted to manhandle on a Sunnen, but they got the job done. I assume they used a spiral stone arrangement to bridge the keyway, but don't know for sure."

Most likely.

They would HAVE TO use a "keyway hone", in any case.

Monarch does a pretty good job of building its tailstocks.

Whether the 10EE tailstock design is as robust as we might like is another matter.

However, the tailstock spindle is indeed honed to the tailstock upper casting, and the two should go together.

The upper casting is identical across 12.0" ("old height") and 12.5" ("new height") tailstocks. Only the lower casting is different, although the "new height" lower casting has the same pattern number ("EE-xxxx") as the "old height" pattern.
Here is a photo of the lap shells and holder. The shells came from Helical Lap and Mfg. Co., Fraser, MI, and cost $28.24 each in July 2009. I was able to pay using my AMEX card. For scale, the laps are 1.25" ID x 2.5" long. There is a pin in the holder that engages the slot in the shell to keep if from turning. There is a socket head cap screw to pinch the holder down on the shell and control the diameter. I cut the slots in the holder using a vertical bandsaw.