Page 1 of 20 12311 ... LastLast
Results 1 to 10 of 195

Thread: My Taiwanese Shenwai SW-900B Lathe Clean/Repair Thread

  1. #1
    Join Date
    Jul 2018
    Posts
    154

    Default My Taiwanese Shenwai SW-900B Lathe Clean/Repair Thread

    I'm sure most of this kind of stuff is common knowledge to most of the members here, but I thought I would make a thread of my trials and tribulations as I try and get this thing back into working order. Also maybe someone thinking of buying one can get an idea of what may be wrong, and the work involved when hashing out a price. I have lots of experience repairing cars, and have taken on repairing just about anything with a motor, jacks, hydraulics, but with off the shelf parts. I took a couple of semesters of machine shop back in the stone age(well, the 80's, so not that long ago), I know a little, but I'm mostly flying blind when it comes to anything past threading shafts, and making bushings. I am ready to learn though, and if anyone has any useful info, it's welcome. I have a pretty thick skin, so criticism if I'm doing something stupid is fine, and of course, nomenclature corrections.

    This thing was never oiled, so I'm going to go though and clean/check/lube everything. The grease on this thing has degraded into a hard glue, and the cosmoline was never cleaned off. I'm not going for a resto, just a clean up and get it running. The gear box has a drip system with a piece of felt to slow the flow. The gears were packed with grease when I got it, as some alternative to oiling, so the shafts and bushings just went dry. Starting with the lead screw, it was impossible to turn by hand. I had to use a puller to get the end block off, and it was galled with a piece of metal that had come off the shaft and ground around in the bore. I knocked down the burr on the shaft with a small file, and the burr in the cylinder with a few turns by hand with a hole lap. Lead screw turns freely now.




    Other 2 shafts just held on with pins. The set screw on the lead screw did not release it, so I just removed it with the box to get a better angle.



    Flat way has some dings on the inside that almost look to have been surfaced over. The carriage does not bind or slow here, and it is flat with the opposing sides with a straight edge, so I'm not going to worry about it. I can still see the grind marks on all the way, so I don't think there is much wear there.



  2. #2
    Join Date
    Jul 2018
    Posts
    154

    Default

    Gear box came off with 3 bolts. I don't know what the selector gears/handles are called, but the shaft came out by taking off the snap ring, and pushing the opposing bearing out with the shaft(vise grips on lead screw have copper inserts, in case anyone was wondering)




    There is a snap ring on the end of the center shaft, and it pushes out the opposing bearing, right through all the gears.




    The driving shaft comes out with 3 bolts. The lead screw shaft comes out when the center shaft is removed, and the gear goes back far enough to get the shaft key out.


  3. #3
    Join Date
    Jul 2018
    Posts
    154

    Default

    The set screw on the lead screw shaft holds on a collar that was really stuck. Had to use a puller to get it off. Its also the race for the thrust bearing. It reveals a pin that releases the lead screw.



    Damaged gears



    Box disassembled.



    Metal transfer from 2 of the bronze bushings. Looks like this got dry and hot.



    Small spur gear, one of the transfer points, gear is good, but bushing spun in the bore, and oil hole is no longer aligned.


  4. #4
    Join Date
    Jul 2018
    Posts
    154

    Default



    One of the damaged gears, and the other transfer point on the shaft. Again, spun bushing.





    The drip oiling system, bone dry.



    The two bad gears. They are one piece with bushings in the center. Not sure how to go about these, as I do not have any gear making equipment.

    Last edited by junkaddict; 03-08-2019 at 01:26 AM.

  5. #5
    Join Date
    Jul 2018
    Posts
    154

    Default

    Carriage off



    Half nuts look good.



    Snap ring came off under pressure of the gear seizing.




    Gear is stripped and bent.

  6. #6
    Join Date
    Jul 2018
    Posts
    154

    Default



  7. #7
    Join Date
    Jan 2004
    Location
    Missouri
    Posts
    31,565

    Default

    Dunno for sure, but it kinda looks as if the honked-up gears other than the one bronze worm gear could be brought to working condition with a careful job of filing on any deformed teeth. That's if there are no actual missing teeth on the others, and I did not see any in the views above except for the bronze gear. Maybe I missed them , maybe they are on the other side, or maybe no teeth are broken off.

    The bronze gear will need replaced, yes. But if it is for crossfeed, as you said somewhere above, it is not essential, and you can go for years without it. Boston Gear may have something that will work, or maybe the Grizzly folks have parts, since someone suggested there was a very similar Grizzly machine. ( "The two bad gears. They are one piece with bushings in the center. The other one is for the worm gear drive on the power cross feed. Not sure how to go about these, as I do not have any gear making equipment. ") I think you edited the pics and removed part of that statement while I was composing this.

    Looking again at it, it is not a real worm gear, by the look of it, and should be fairly easy to find. Looks like a plain spur gear in several of the pics.

    The spun bushings can be pressed out and replaced, either with ones you make, or possibly with "oilite" type pre-oiled bronze bushings. McMaster-Carr has metric sized oilite sleeve bearings, which I suspect those may be. If they are inch size, of course they have those as well.

    The oilite would not need oiling through a hole like that, although light oil will not hurt them.

    The machine looks well-designed and made, it's issue is having been operated by a low-grade barbarian.
    Last edited by J Tiers; 03-08-2019 at 01:56 AM.
    1601

    Keep eye on ball.
    Hashim Khan

  8. #8
    Join Date
    Apr 2017
    Location
    Kelowna BC
    Posts
    2,570

    Default

    The two gears that need repair were done on a gear shaper.
    You might be able to make new ones, if you can bore out the bigger gear till the small one fall's off. Then make the small one the regular way gear cutting with a wheel cutter, plus a shoulder, then press into the big gear and tig weld together.
    The bronze one looks easy to make..

  9. #9
    Join Date
    Jul 2018
    Posts
    154

    Default

    The one where the small gear is damaged, a couple of the the teeth are cracked at the base.

  10. #10
    Join Date
    Dec 2016
    Location
    Helsinki, Finland, Europe
    Posts
    3,617

    Default

    Quote Originally Posted by 754 View Post
    The two gears that need repair were done on a gear shaper.
    You might be able to make new ones, if you can bore out the bigger gear till the small one fall's off. Then make the small one the regular way gear cutting with a wheel cutter, plus a shoulder, then press into the big gear and tig weld together.
    The bronze one looks easy to make..
    Looks to me that you can get one good gear out of the 2 bad ones by cutting them in half, boring and inserting over sleeve. They seem to be made of steel so you don't need to worry about wall thickness like with cast iron gears.

    With a bit of luck the gears are some standard size and you don't need to cut your own. Folks here can help fiquring out the type if you get enough measurements form the gears.

    Crossslide bronze feed gear could be more difficult to find and some speciality size but you can easily live even without crosslide power feed. Many if most garage size hobby lathes don't have one in any case.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •