What epoxy for this gear case repair?
Close
Login to Your Account
Page 1 of 3 123 LastLast
Results 1 to 20 of 41
  1. #1
    Join Date
    Aug 2007
    Location
    GA
    Posts
    939
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    183

    Default What epoxy for this gear case repair?

    Out of production gear case, small approx 8mm od thin roller bearing broke out of the boss at the bottom. Small and hard to access, I'd like to fill the whole bottom with epoxy to support that side of the bearing. Low speed low temp application with grease, not oil. I need about 3 cubic inches of epoxy; wondering what type would be best and where to buy that small amount retail or should I just use some jb weld hardware store stuff. Its an aluminum case, I'd like to use aluminum or steel filled putty, roughen the area and press it in by hand after the bearing is in place, completely filling the area all the way to the case wall, 1/2" deep I could embed some steel struts radially between the bearing and case wall and/or make a crescent shaped piece to fit in there around the bearing too- should I?, but I'm not going to attempt to weld down in there, not enough room (for me anyway).
    Attached Thumbnails Attached Thumbnails pxl_20210831_200222358.jpg  

  2. #2
    Join Date
    Jan 2013
    Location
    Gilbert, AZ
    Posts
    7,375
    Post Thanks / Like
    Likes (Given)
    9930
    Likes (Received)
    9428

    Default

    I've done similar, with success. If you can, remove that roller bearing, and do an aggressive sand-blast down there.
    Clean-clean-clean is what it needs to be if it is going to hold. How thick is the case wall? I would be tempted to make a support for the open side of the bearing.
    Then drill/tap the case wall adjacent. And put a little preload on that support with a screw in the new tapped hole. Then fill around the whole shebang with epoxy.
    You gotta do what you gotta do when you can't buy parts. I've been there.
    But, I feel if it blew the side of that boss out, epoxy alone isn't gonna do the job.

  3. Likes BT Fabrication, michiganbuck liked this post
  4. #3
    Join Date
    Aug 2007
    Location
    GA
    Posts
    939
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    183

    Default

    Good idea screwing a support in from the side; but the bearing shell for the roller bearing is super thin, so thin that I would only be able to run it up to make contact as any pressure would distort it. I might be able to mill a radius matching the bearing od into the face of a nut (maybe the type of long nut used to connect threaded rod if they come that small) and unscrew a bolt from that nut to wedge into the case side. I'll have to think about that...

  5. #4
    Join Date
    Oct 2008
    Country
    UNITED STATES
    State/Province
    California
    Posts
    453
    Post Thanks / Like
    Likes (Given)
    13
    Likes (Received)
    118

    Default

    Wheelieking makes a good point, it did blow out the casting. Your idea of supporting it with rods or a crescent-shaped piece might work. I've used a lot of JB Weld, but recently I tried some West Systems epoxy and I have to say, that stuff is amazing and versatile. Used without filler, it's got the viscosity of vegetable oil. They sell microfiber reinforcement that can be mixed-in in any amount to go as thick as you want it. Pricey, but worth it. They have a lot of helpful documentation their website as well. If you decide epoxy is the way to go, use West Systems.

    Jeff

  6. #5
    Join Date
    Mar 2006
    Location
    jacksonville,fl.
    Posts
    1,554
    Post Thanks / Like
    Likes (Given)
    1526
    Likes (Received)
    532

    Default

    Sounds like you have a drawn cup needle bearing.It is very important that you have a truly round bore with the correct press fit if you want it to last. The drawn cup depends upon the bore to maintain its round shape.

  7. Likes 1yesca, wheelieking71 liked this post
  8. #6
    Join Date
    Aug 2007
    Location
    GA
    Posts
    939
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    183

    Default

    Yes, I'm sure that's the type of bearing it is. I guess I'll have to machine the curved nut and tension it against the side of the case. Not a perfect solution but should be ok for the amount of use it will get here.

  9. #7
    Join Date
    Jun 2006
    Location
    Kansas
    Posts
    1,680
    Post Thanks / Like
    Likes (Given)
    338
    Likes (Received)
    654

    Default

    I would drill and tap some studs in a circular pattern around the bearing. Clean and clean again, I like using spray oven cleaner, yah I know it’s toxic to aluminum but rinse it off good and it will be clean.
    I would rough the outside of bearing so the epoxy can grip it.
    I think the best epoxy is Devcon plastic steel.
    Build a dam using putty around the studs and pour it full.

  10. Likes ernieflash liked this post
  11. #8
    Join Date
    Sep 2009
    Location
    tonawanda new york
    Posts
    300
    Post Thanks / Like
    Likes (Given)
    68
    Likes (Received)
    146

    Default

    In a former life I was a machine repairman in a large forge. We used Belzona. It came in tubs large enough to fill the void. If I was doing the repair I would just get a new housing and save all that time and trouble.

  12. Likes ernieflash, gbent, MetalCarnage, mike44 liked this post
  13. #9
    Join Date
    Dec 2008
    Location
    Vt USA
    Posts
    9,541
    Post Thanks / Like
    Likes (Given)
    1699
    Likes (Received)
    3500

    Default

    Just because we are hashing solutions and not sticking to "what epoxy should I use". (DEVCON LS is Good stuff!)

    But, If I were not wanting to go back in there to repair the repair, I would...

    Mill the damage surfaces "mostly" flat and square. Minimum material removal! Just enough to give good geometry and support.

    Drill and tap for a pair of screws as a logical eye might best locate. (Drill through if possible)

    Make up a repair block from alu. that could be screwed down with the previously tapped holes. Trying for a tight fit across the newly milled surfaces.

    Mount the repair block, locate center and bore for the bearing.

    Disassemble and clean up.

    Assemble bearing and repair block with screws WET with whatever epoxy. I like 3M 2216, Devcon is good, J-B weld has some impressive performance values as well. (Not the Quick set)

    Barring that, I would turn up a sleeve stepped both in and out to suit the bearing and a bored out socket.

    Made of steel, press it in.

    Viola! Better than new!

  14. Likes 1yesca, MetalCarnage, matt_isserstedt liked this post
  15. #10
    Join Date
    Jun 2006
    Location
    Kansas
    Posts
    1,680
    Post Thanks / Like
    Likes (Given)
    338
    Likes (Received)
    654

    Default

    Quote Originally Posted by norb View Post
    In a former life I was a machine repairman in a large forge. We used Belzona. It came in tubs large enough to fill the void. If I was doing the repair I would just get a new housing and save all that time and trouble.
    Belzona is very good stuff but expensive and not as easy to find as Devcon. I think Devcon is as good as Belzona.

  16. #11
    Join Date
    Sep 2009
    Location
    Apex, NC
    Posts
    1,771
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    894

    Default

    I've done similar things and repaired aluminum and cast iron castings with JBWeld, it's good stuff (not the 5-minute or clear versions). If you need it to flow into a cavity easier, just heat it up a bit.

  17. Likes CalG liked this post
  18. #12
    Join Date
    Sep 2005
    Location
    Oakland, CA
    Posts
    3,088
    Post Thanks / Like
    Likes (Given)
    648
    Likes (Received)
    1004

    Default

    McMaster-Carr has 2 part epoxy putty that is pretty good. The putty won't run all over like a more liquid epoxy will.

  19. #13
    Join Date
    Feb 2010
    Location
    ch
    Posts
    3,392
    Post Thanks / Like
    Likes (Given)
    281
    Likes (Received)
    474

    Default

    no idea if such a repair makes sence.

    but:

    - activate the aluminum with some hot lye (oven cleaner?), dry with hot air and proceed immediately
    - if you have some epoxy resin fill it with fine band saw swarf washed in solvent and add dryed silica flower/fine sand for consistency and
    compressive strenghth.
    - if using some common putty i would prewet the surface with resin or at least epoxy glue. you can let it cure a bit.

  20. Likes wheelieking71 liked this post
  21. #14
    Join Date
    Jan 2005
    Location
    The Netherlands
    Posts
    6,837
    Post Thanks / Like
    Likes (Given)
    378
    Likes (Received)
    2030

    Default

    If you can machine it I would bore the hole bigger and flat with the broken out piece
    Then bolt in a excentric steel ring
    Bore a pilote hole centric with the broken out bore and turn a mating shoulder to the underside of the ring
    Just to get the the ring in the right place

    Peter

  22. Likes CalG, henrya liked this post
  23. #15
    Join Date
    Jul 2001
    Country
    UNITED STATES
    State/Province
    North Carolina
    Posts
    2,229
    Post Thanks / Like
    Likes (Given)
    262
    Likes (Received)
    558

    Default

    Use an adhesive with a methacrylate based chemistry for your aluminum case. Epoxides are old technology. Just recommending your favorite brands, you might as well recommend your favorite beer, for all the good that will do.

    -Doozer

  24. #16
    Join Date
    Mar 2005
    Location
    Kansas
    Posts
    8,727
    Post Thanks / Like
    Likes (Given)
    626
    Likes (Received)
    4441

    Default

    If I was going to use any epoxy, I would use Belzona.

    That said, whatever happened broke out a significant piece of aluminum. No epoxy is going to hold up to that. You need a mechanical repair. At minimum, a steel sleeve, with epoxy for a support on the weak side. What is the bottom thickness? I would think about a threaded stud, screwed into the bottom of the case with locktite, with the bearing pocket bored into the stud.

  25. #17
    Join Date
    Nov 2017
    Country
    UNITED STATES
    State/Province
    South Carolina
    Posts
    154
    Post Thanks / Like
    Likes (Given)
    33
    Likes (Received)
    36

    Default

    Could you locate on the remains of the bore.
    Then drill/bore out the hole, then thread it to accept a plug of of either aluminum or steel. Loctite in place the re-machine the bore ?
    It depends on the wall thickness of the main case of course, but it seems you need to add some strength to the original bore.
    Good luck,
    Bob

  26. Likes CalG, henrya liked this post
  27. #18
    Join Date
    Oct 2016
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    469
    Post Thanks / Like
    Likes (Given)
    1182
    Likes (Received)
    298

    Default

    I vote for JB Weld

    Clean are well first

    Apply the JB Weld

    Let it cure 24 hours before you touch it

  28. #19
    Join Date
    Feb 2010
    Location
    ch
    Posts
    3,392
    Post Thanks / Like
    Likes (Given)
    281
    Likes (Received)
    474

    Default

    Quote Originally Posted by Doozer View Post
    Use an adhesive with a methacrylate based chemistry for your aluminum case. Epoxides are old technology. Just recommending your favorite brands, you might as well recommend your favorite beer, for all the good that will do.

    -Doozer
    mma adhesives to my knowledge have no advantage on metal in this application. they excel in production environments and for plastics epoxy cant be used on without expensive prep.
    Last edited by dian; 09-01-2021 at 12:29 PM.

  29. #20
    Join Date
    Jul 2007
    Location
    Missoula Mt
    Posts
    1,442
    Post Thanks / Like
    Likes (Given)
    62
    Likes (Received)
    710

    Default

    Here is the 64,000 dollar question...If the metal was not strong enough to hold the load, why will epoxy be any better?...Phil


Tags for this Thread

Bookmarks

Posting Permissions

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