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  1. #21
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    Basically, you weld it up and then deal with the problems of straightening it. If the worn areas are right on the ends, then you don't have to straighten the shafts, just build them up enough oversize and machine them straight and true running.

    I hate to do weld build-ups on tiny stuff like that: I'd sooner just cut the end off, and weld on a larger piece of stock (double U joint preparation) some distance down the shaft where it is the full 12mm. Then machine the new stubs and create the new abutments in the newly added stock.
    There are maintenance SS welding rods made to weld dissimilar steels together, yet have quite high strength properties. Some anneal maybe required after the weld to reduce brittleness of the parent material, but 10 chances to 1 the piece will spend a good amount of time at a red heat while welding it. Just don't quench it, let it air cool slowly.

    Another method might be cutting off the 8mm stubs, drill and tap the ends of the rod for an 8mm bolt, and then fasten the bearings on with capscrews and loctite.

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    David M,
    Thats exactly what I am after Dave. Solutions that would automatically pop up in your head won't in mine because of my lack of machining experience. Thank you Dave,
    Jay.

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    [QUOTE=Sparky961;3053653]
    Quote Originally Posted by redlee View Post

    Didn't realize 410 had any special requirements, as I've never had to weld it myself. However, the OP was looking for a temporary fix. I'm sure a TIG welder and some mystery rod would have made it last at least for a shift or two.
    Chances are it would crack and fail in short order.


    The martensitic stainless steels contain 11 to 18% Cr, up to 1.20% C and small amounts of Mn and Ni and, sometimes, Mo. These steels will transform to austenite on heating and, therefore, can be hardened by formation of martensite on cooling. This group includes Types 403, 410, 414, 416, 420, 422, 431 and 440. Both standard and non-standard martensitic stainless steels are listed in Table II. They have a tendency toward weld cracking on cooling when hard brittle martensite is formed.
    Taken from Lincolns page on web.

  4. #24
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    Being food production limits your options greatly.

    You knurled it so try getting some shim stock that can be wrapped around the shaft then bearing pressed over it.

    Next is if there is room for a bearing with a locking collar that locks center to shaft as these are common but maybe not for this application.

    Center punching the places the knurl does not reach along with some sort of epoxy suitable for the application may be best option for emergency repair.

    Then make or buy 2 shafts and bearing sets then given you have spare will never need it.

    In past life condenser fan on remote site would fail in winter and room temp hit 140 with snow on the roof every year...finally placed a spare on site and never again. .we also bought best money could buy as we did repair while the hvac guys did cheap..

    Buy quality parts that will hold up.

    Sent from my SAMSUNG-SGH-I337Z using Tapatalk

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    [QUOTE=SeaMoss;3053658]You could try a Speedi-Sleeve. Can't work any worse than what you already did. .020" is kind of a lot for Loctite but they might have a product for that, too. Worth a look-see ... [/QUOTE]

    Loctite Quickmetal 660. It's full of silver filler and designed to fill big spaces.

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  7. #26
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    Would you be able to cut off the bad end, drill and ream a 7 or 8 mm hole in the end of the shaft, press in a stub, and cross pin it with a roll pin?

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  9. #27
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    I think I would have used the shim stock idea. My go-to shim material is aluminum foil, yes, the common, household variety. It is about 0.0007" thick so about 14 or 15 layers of it wrapped around that shaft would have made up the difference. Some LocTite on top of that would make up any small gap. Other shim stock would also work and steel would probably be best, but you did want an instant fix for that shift and many places do not have a variety of shim stock around. You can probably find the aluminum foil in the lunch room.

    I would not trust it for very long and would be placing an order for the proper parts or making them as the very next thing on my agenda.

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    I used belzona regularly, you can machine it too, I had temp repairs lasting years, in a hot steel mill that's remarkable
    Mark

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    Quote Originally Posted by winger View Post
    Emergency fix: Center punch all around the shaft as even as you can, smear some JB weld on, press on the bearing and let it cure.

    Measure for a new one before reinstalling.

    Dave
    I've also done this with success, although I used Red Loctite in place of JB Weld. The best part is it takes all of about 5 or 10 minutes to do, and the bump raised by the center punch can always be filed, ground, or turned off (or sometimes even tapped back down) meaning the shaft can survive to fight another day, even if it doesn't work.

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    Quote Originally Posted by UKJay View Post
    By the way if anybody can suggest reasons for this chronic shortage I would be really interested to hear. I think the last generation all wanted to do Information Technology and related jobs so there is a shortage of hands on engineers.
    Jay.
    That's an easy one. Money. Let's see, I can work in an oily, noisy, dirty environment for shit pay & no job security, or I can work in a clean air-conditioned place doing something equally interesting for 3X the pay.

    Let me think about that one a while.....

    I can do both - software pays far, far better with a lot less hassle not to mention a tiny fraction of the capital equipment.

    PDW

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    Some great ideas guys, thanks very much . I've never come across speedi sleeve before so just for that alone it was worth posting.
    Cheers guys.
    Jay.

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    Quote Originally Posted by UKJay View Post
    Some great ideas guys, thanks very much . I've never come across speedi sleeve before so just for that alone it was worth posting.
    Cheers guys.
    Jay.
    Speedi sleeves are primarily for covering a worn area where a seal lip has worn a narrow groove into a shaft. Some of the original shaft diameter must still exist on either side of the groove to back up the sleeve. The sleeved area is now OVERSIZE when the speedisleeve is installed.

    You'd be better served (probably) with an epoxy metal, but you've still got the problem of centering the repair so that the shaft runs true with respect to the bearing journal, and that means machining. If you are into machining such a repair, then you've got lots of options. Some shit you can't fix at all, without machining. I've seen all sorts of cobbled up crap done with center punches and shims, and ain't none of it respectable and probably took as long as a proper repair would take. Never time to do it right but always time to do it over

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    To summarize - you have a 12mm (.472 in) diameter 300mm (11.81 in) long shaft with 8mm (.315 in) journals that are 20mm (.787 in) long . . . This sounds like a noodle so likely lots of flexure / bending.

    "Light press fit" bearings that are not designed to provide angular displacement of the shaft . . .

    Sounds like a recipe for fretting / shaft wear (which you are obviously experiencing). I have no idea what food grade constraints might place on your repair but forgetting about that for a second . . .

    Barry Weeks makes the best repair suggestion although I would press the stud in with Locktite and not bother with the pin. Also, the bearing should be a medium or tight press fit to prevent fretting. And, you should consider a different bearing altogether - I would go with a SKF 108-TN9 bearing . . . Self-aligning ball bearings - 1�8 TN9

    SKF 1�8-TN9 Ball Bearing: Amazon.com: Industrial & Scientific

    Figure out what your downtime and repair labor cost is and that bearing will be seen as cheap if it lasts until you retire.

  17. #34
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    Quote Originally Posted by UKJay View Post
    Hi Fellas,
    I'm new to the community and I would like to ask if there are any methods ( accepted or otherwise) to reclaim enough Outside Diameter on small journals ( 3/4 " and below ) on shafts that run in small ball bearings. I was on shift last weekend and was asked to see if I could facilitate a running repair on a check weigher ( for small packaged frozen food packages ) . When I stripped the unit down the journal that was running in a 608 2RS ball bearing had worn about 20 thou and I had no spares . The repair had to last a 12 hour shift. By the way I am not a machinist I am a mechanically biased maintenance engineer. The only thing I could think of was to put a knurl on the shaft but I could not get more than 40 percent of the journal because of the wall of the knurling tool holder. My repair worked for 4 hours then failed so I would humbly like to ask some of you obviously elite machinists ( judging by reading many threads ) are there any other methods I could have employed?
    Thanks in advance fellas,
    Jay.

    There is a video around somewhere showing John Stevenson welding up worn bearing surfaces on electric motors, and turning them back to size.

    He is in Nottingham, I would drop him a PM and see if he could fix your shafts, if they are easy enough to ship.


    Edit check you PM I have sent you a link to explain more.

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    Guess I would turn it to a press bushing even made of CRS, turn it to the next catalog bearing perhaps inch or metric, fill it with a shim and Loctite it, perhaps needing a tickle to fit.
    Yes think these were mentioned...

    12" long part if not many features could be made of drill rod or CRS for a temp shaft in a couple hours.
    but not seeing the job hard to tell what would be best.

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    Once again guys thank you for all your thoughtful suggestions. They will almost certainly be used as there are probably half a dozen of these small check weighers and I'd be surprised if the others are not in some kind of failure mode regarding bearings. I'm often asked to try some kind of running repair as I'm in of a Saturday night on my own and they run a shift of a Sunday. Like nearly every firm these days they go outside for all their machining needs. There are no in house skills at all regarding machining . Unfortunately none of the guys there can clock a shaft on a lathe. No disrespect to the guys , they have not had the training.
    Thanks again fellas,
    Jay.

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    PS I did post a question the other week but it ended up on the Metrology forum. Basically I was asking if there were any way I can speed up my machining skills ( basic practice drills, books, you tube channels etc. ) There is an old lathe, milling machine, grinder and drill press in the machine shop. I have basic maching skills but I'm keen and I've always worked to close tolerances and always really liked machining but I've always worked at places where there have been dedicated machinists
    Cheers Guys ,
    Jay.

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    Quote Originally Posted by UKJay View Post
    PS I did post a question the other week but it ended up on the Metrology forum. Basically I was asking if there were any way I can speed up my machining skills ( basic practice drills, books, you tube channels etc. ) There is an old lathe, milling machine, grinder and drill press in the machine shop. I have basic maching skills but I'm keen and I've always worked to close tolerances and always really liked machining but I've always worked at places where there have been dedicated machinists
    Cheers Guys ,
    Jay.

    Check out Keith Fenner on You Tube.

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    Thank you Lionelt, I'll check his channel out today bud,
    Take care,
    Jay.

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    Quote Originally Posted by UKJay View Post
    Thank you Lionelt, I'll check his channel out today bud,
    Take care,
    Jay.

    Two more I have added to my favorites are.


    Abom79
    Oxtoolco


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