Watchmaker's Lathe Overhaul (WIP)

Discussion in 'Non-audio related DIY' started by ghazzer, Feb 4, 2018.

  1. ghazzer

    ghazzer Sansui addict Subscriber

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    I managed to get the motor refurbished and running, so now it is time to finish overhauling the lathe.

    This is a Wolf,Jahn 8mm Watchmaker’s lathe, made in Germany, probably in the early part of the 1900s. My goal has been to carefully disassemble it clean it, lubricate it and put it back together so that it works, and not be damaged during use. This has been completed for everything except the spindle of the headstock.

    P1060185.jpg
    I found two nice books on these lathes: “The Watchmaker’s and Model Engineer’s Lathe” by Donald de Carle and “Restoring This Old Lathe” by Robert D. Porter. They have been informative and helpful, but either they left out a step on taking the headstock apart or the pulley block has been glued to the spindle. The set screw for the pulley block has been completely removed, but the pulley will not budge. I have used some cleaning fluids but have been reluctant to use anything stronger because I do not know the composition of the pulley block and don’t want to risk damaging it.

    This is a pic of the head stock, with the drawbar removed from the left side.
    P1060196.jpg

    This shows the back cone removed from the spindle. It was on the left in the previous picture, under the dust cover.
    P1060238.jpg

    Here is an exploded drawing of the head stock. The spindle (bottom piece) is supposed to slide out of the bank of pulleys after the set screw is removed.
    Lathe Drawings-AK.jpg

    I bought a spray can of Liquid Wrench’s Penetrating Oil. It hasn’t freed anything up yet, but I had to buy another can of “febreze” (NA) for the workshop.

    I'm just hoping that someone has had experience with one of these and can offer some constructive suggestions about how to get the spindle out of the block of pulleys. There was key/pin inside the spindle to hold the collet in place. It is missing and I need to get in there to see if there is some way to get it replaced.

    Thanks - - -
     
    Last edited: Feb 6, 2018

     

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  2. grillebilly

    grillebilly Empty Head Subscriber

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    The spindle needs to be supported in the headstock as well as whatever fit it has on the gang of pulleys. I'm assuming it's in bushings or bearings. Make sure nothing is keeping the spindle from moving there. Try to find out if and where there is an interference fit, key or set screw in the assembly. You don't want to force it if it's still being held.
    Heat is helpful when using penetrating oil. I think I would try submerging the entire assembly in oil, if possible. Obviously you can't get a gallon of penetrating oil, so look for the lightest oil you can find. Maybe warm it up in the oven, then submerge. Leave it overnight. To get it loose you will need to "shock" it. Use something SOFTER than the spindle to whack it, like a brass hammer. A no-bounce won't shock it, has to be metal. Repeated heating and cooling cycles in the oil bath should help. Just don't overdo it with the heat. I'm thinking 200 degrees should be plenty safe.
     
  3. Chip Chester

    Chip Chester Super Member

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    What are you planning to make/repair with it? Reason I ask is I have a similar lathe, and while it's great to run thru its paces, its capabilities don't really match what my needs are. No leadscrew, rudimentary toolholding/cross-slide. So it's currently sitting in the top of my Gerstner chest (it's that small) awaiting its next dusting. Still pretty much OK by me, though.

    I have used some of its collets in my larger lathe -- seems they fit nicely in a 3/8" 3C collet, and the fingers pinch things down nicely if you line them up collet-to-collet. And there are some pretty darn small collets with it.
     
  4. John James

    John James "Bob's your uncle" (Stolen) Subscriber

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    grillebilly is on the right path. It may take several days if the problem is corrosion.

    I have had flutes that I had to leave over night/all day, heating several times during the work day, to finally loosen up.
     
  5. ghazzer

    ghazzer Sansui addict Subscriber

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    Cold shock didn't help much. I put it on the back porch for four hours when it was 6°, then heated it up with a hair dryer. The heat gun is probably too hot.

    I have been using a mallet turned from a piece of hickory to tap on the spindle. The pulley is Bakelite and will crack unless I wedge a popsicle stick between the pulley and the base before tapping.

    Guess I should look up the physical properties of Bakelite so that I don't over temp it. To the best of my knowledge there is nothing but Bakelite and metal involved so I don't have to worry about damaging some other material.
     
  6. ghazzer

    ghazzer Sansui addict Subscriber

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    My research indicates that these spindles are machined as a single piece. The inside tapered cone on the right is where a collet is inserted to hold a rod of a matching size. (#29 collet holds a 2.9mm shaft.) This picture was taken with a lamp shining down the tube of the spindle. It shows some kind of break or transition that is ~15mmfrom the end. It also shows the remnants of the pin that should be there to align the collet. This may be the only spindle ever made as two pieces joined together, but that still doesn't resolve the pulley stuck to the long barrel of the spindle.
    P1060244.jpg

    This pic shows the groove in a collet that the missing pin/key would ride in to keep the collet from spinning when the drawbar is screwed onto the threads.
    Groove in collet.jpg
     

     

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  7. ghazzer

    ghazzer Sansui addict Subscriber

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    Grillbilly: The spindle is supported by cone bushings in each of the support arms of the base, matching cone bushing on the spindle and the one that I removed on the other end. I think this will need lots of oil during use. I think I have removed all mechanical links, but am proceeding cautiously.
     
  8. ghazzer

    ghazzer Sansui addict Subscriber

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    PROGRESS!!!

    Today I gave up on the hair dryer and broke out the heat gun, on low of course. I used the temp function on my 5 in 1 DMM to monitor the air temp near the head stock and used a glove to turn the pulley to get even heating. I kept at it until the DMM was reading 95°F and the spindle was just too hot to touch (140 to 150°?). A few taps with the mallet and the pulley was loose on the spindle. I was able to pull the spindle out of the base and the pulley appears undamaged. Well, except for the chip that broke off the first time I followed the book's instructions to remove the spindle. I cleaned it u before taking these pics.

    Here is the drawbar, the back cone, the spindle, the pulley block, and the base. The pulley was seated over the hole that you see in the spindle that takes the set screw.
    P1060253.jpg


    This is the cone end of the spindle, showing the remnants of the collet pin, sheared off on the inside, and the set screw hole to the left..
    P1060256.jpg

    This is the back cone sitting on the side of the base,
    P1060258.jpg

    and the back cone fitted into the base.
    P1060259.jpg

    Next action is to finish cleaning this up then see if I can find out how to get the ~2mm pin replaced. Also need to research gluing a chip back into the Bakelite pulley.
     
  9. gadget73

    gadget73 junk junkie Subscriber

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    Its probably just a solid steel pin that you can drive out with a punch. Thats what the equivalent part in my South Bend is anyway. Mine also needs to be replaced but since I have no drawbar it hasn't been a priority. The pin is only there as an anti-rotation device so the collet doesn't spin when you tighten the bar up.

    If you drive it out, just make sure the spindle is well supported or its liable to bend.
     
  10. ghazzer

    ghazzer Sansui addict Subscriber

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    I agree, and I promise that I am being careful. This mutha is quite small, and I am trying to research the pin to find out if it is tapered, or just small and short.

    This lathe probably won't work without the drawbar holding the collet tight.
     
  11. sol7

    sol7 Super Member

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    Usually, tapered pins are in a through hole. It has to be punched out from the small end. They don't use them in blind holes. I would consider that spindle a blind hole since you really can't punch it out from the inside the spindle. But then, it could be a tapered pin that fit loosely in the hole and the pulley would hold it in place when mounted on the spindle. Or does that area ride in the bushing?
     

     

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  12. ghazzer

    ghazzer Sansui addict Subscriber

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    That area rides in the bushing. Seems like that would be too easily pushed out and damage the surface of the bushing. ?????

    ConradH has convinced me that the pin may not be essential, so I am going to put it all together and try to turn a shaft. First I need to work on the cutting tools, face them up a bit and fine tune them with a hone.
     
  13. sol7

    sol7 Super Member

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    Yeah, scrap that loose pin idea. I'm sure you can hold the collet by hand to keep it from spinning, while tightening the drawbar.
     
  14. ghazzer

    ghazzer Sansui addict Subscriber

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    Yes, I can tighten the drawbar enough that I cannot turn the shaft by hand. It is more difficult to loosen it, and there is virtually nothing to clomp on to. I am concerned about whether or not hand tight will be adequate to turn against the tool.

    Right now I am devoting more time to supporting my wife's decision process for buying a new stove. And that is MUCH more fun than working with the lathe . . . .
     
  15. gadget73

    gadget73 junk junkie Subscriber

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    Collets with a reasonable taper do not need to be extremely tight. The taper is what holds it, not the pull from the drawbar. If you look at the size of the handwheel to run them on, thats an indication that you're not supposed to have to reef on it. If you have slipping problems often that means the collet or the bore that it fits into is worn. Using some bluing compound to see what the contact patch looks like will tell you.
     
  16. ghazzer

    ghazzer Sansui addict Subscriber

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    I have regressed. The motor overhaul did not hold up, so I am back to this thread. I'll go back and troubleshoot the old motor after I get the lathe running.
     
    Last edited: Mar 5, 2018

     

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  17. ghazzer

    ghazzer Sansui addict Subscriber

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    Looks like there is a problem with the brushes in the original motor, so I'll go ahead with the sewing machine motor for now. I'm designing a sled to interface the SMM to the base of the lathe so it can be held steady, and parallel to the axis of the lathe. I ordered some T-track and should be able to use that to keep the motor square and adjust the tension on the drive belt.
     
  18. ghazzer

    ghazzer Sansui addict Subscriber

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    As usual I have over designed this thing. I hope to get to the woodworking shop tomorrow and cut two parallel dados for the T-track to ride in.

    The going rate for name brand T-track bolts and matching knobs seemed exorbitant. The local H/W store had a set of lawnmower handle nuts& knobs for ½ a saw buck and all I had to do was some selective grinding on the bolt heads so they would fit the track. It's a good thing I don't have to pay very much for my time - - -
     
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  19. ghazzer

    ghazzer Sansui addict Subscriber

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    This week I finished the sled interface and mounted the sled interface. Here is a pictorial of the process.


    Lathe-1.jpg


    1. Blank Borel plate that lathe is mounted to.

    2. Interface plate on Borel plate

    3. Two T-tracks mounted to interface

    4. Dadoes cut into underside of slide, with holes for T-bolts


    Lathe-2.jpg


    5. Better view of dadoes

    6. Slide riding on T-tracks

    7 & 8. T-bolts holding slide to base. I would have put the tracks further apart but that was limited because of the existing holes in the Borel plate. The sled could probably be held in place with one T-bolt, but if one is good, two is better. If the knobs and bolts look familiar, think nuts and bolts for holding together the two pieces of handlebars on a lawnmower. Cheap and readily available at your local H/W store.
    The second set of holes for T-bolts were added in case I later have to add a set of pulleys to reduce the speed, and need more space between the lathe and the motor. The sewing machine motor turns at 6,000rpm and the original motor is only 3,500rpm

    P1060270.jpg

    9. Sewing machine motor mounted to slide

    P1060271.jpg

    10. Motor secured, aligned and ready for checkout.

    Now I am almost ready for a trial run at turning a shaft, but first I need to have a better knowledge of what I am trying to do. I have contacted a local watchmaker and he offered to give me some tips, dos and don'ts, before I grab a graver and start making little metal chips. I'm thankful that this lathe is very portable and I'll be taking it to his shop next week for a learning experience.
     
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  20. ghazzer

    ghazzer Sansui addict Subscriber

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    I spent an amazing three hours in the horologist's workshop, and he has increased my knowledge of this lathe by at least 3dB. First thing I learned was that I had mounted the sewing machine motor (SMM) in the same orientation as the original K&D motor, but that was wrong. The configuration shown in the previous post turned the spindle in reverse. Bill put a twist in the drive belt, adjusted the tension, and we were in business.

    We put a #31 collet in the spindle and inserted a 1/8" (~3.1mm) brass rod and hand tightened the drawbar. That held it tight enough to turn with a hand held 2mm graver.

    I have since reversed the mounting of the SMM and am working on plans for a set of speed reducing pulleys. Electronic speed controllers either reduce the torque at lower speeds, or do not function correctly with motors smaller than 1/3 HP.
     
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