Casting a Bearing Cap in Iron

Discussion in 'Sand Casting' started by PatJ, Dec 5, 2018.

  1. PatJ

    PatJ Silver Banner Member

    "Treva" on AA contacted me to try to cast a bearing cap for him.

    I am not in the foundry business, and only do this as a hobby, but I need some experience with iron castings, so I am going to try to cast this part for him.

    Apparently he is big into line shaft driven machines.

    As he states, he would make a new pattern for this cap, but he wants to retain the authenticity of the part with the numbers and letters on the top, and so we will try to use the original part for a pattern so we can salvage the numbers/letters.

    Obviously we need Treva to join us over here on this forum, not to take anything away from AA, but I don't have access to AA, and I can't see any photos that are posted there, and don't have any way to interact with anyone there.

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    Last edited: Dec 5, 2018
  2. PatJ

    PatJ Silver Banner Member

    Here are some photos of the original piece.

    What I would propose to do is glue on some think plywood to the flat sides, and build up the curved top surface with spackling compound.

    This approach would allow me to clean up the letters/numbers and salvage them.
    All of the holes in the cap would be drilled after the part has been cast.

    All the additions could be cleaned off the original part to salvage it as an original piece. although it is not very usable in its broken condition, and the welded repair is not really something I would rely on.

    rImg_2506.jpg


    rImg_2490.jpg
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    Last edited: Apr 16, 2019 at 1:41 AM
  3. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    As simple as the part is you might consider just making a new pattern as opposed to fiddling with cleaning up the original part. For the letters, take an impression off the original part with some modeling clay, cast the letters in resin or wax, and then attach them to your pattern.

    I think I could make a lost foam pattern for that part in about 15 minutes!

    Best,
    Kelly
     
  4. Melterskelter

    Melterskelter Silver Banner Member

    I think I would just grind off the extra weld material. Epoxy on a piece of wood to replace the missing portion of the ear and ignore the hole in it as it would be easy to bore out later. Probably would fill the other ear hole and the other holes in the journal with epoxy too as the holes just add complexity. Use the resulting part as a pattern and just put it round side up on the table and ram up the cope. Then flip the cope and dig out whatever sand found its way into the journal and ram the drag. Add the needed runner and sprue and give it a go. Runner could fill from the drag through the ear bosses.

    Cast it and bore out the holes.

    Good luck.

    Denis
     
  5. PatJ

    PatJ Silver Banner Member

    I thought about that, but have never done anything like that, and I am not sure how that would turn out.

    Yes, but that would make a casting that is smaller than the original part, and I want a casting that matches the original part dimensions.
    Granted the shrinkage amount would be small, but if I am going to go to the trouble of casting it, I want it exactly the same size as the original, and I don't want the holes in the ears to have to be drilled in a non-concentric fashion.

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  6. DavidF

    DavidF Administrator Staff Member Banner Member

    I'm with Kelly on this one.
    Would be very easy to knock out a pattern, then use clay to pull the letters from the original.
    You can use 5 minute epoxy to make duplicate letters from the clay mold.
    Or cad model and 3d print the pattern. Did I mention I love 3d printing?? Lol
     
  7. Melterskelter

    Melterskelter Silver Banner Member

    well, OK, getting the part to come out of the sand exactly on size with no warping and holes of correct size , draft free, and correct location with those thin sections of ear around the hole also pouring correctly sounds really hard to me.

    If 40 thou undersize in greatest dimension (estimated as the part looks like it is about 4 inches in greatest dimension) is objectionable, maybe build up the long portions of the part with celastic, pasteboard, Bondo etc and the thin portions (.004 undersize) with a couple coats of spray paint?

    I am sure you will be documenting this fully, so it will be interesting to follow this project.

    Denis
     
  8. PatJ

    PatJ Silver Banner Member

    The cap measures 3.43" long, so the pattern would need to be about 3.48" long.

    If the cap is used as-is as a pattern, then the casting would probably come out about 3.38" long, if I am doing the math right.

    Is that difference enough to matter to most people? Ans: No.
    Is that difference enough to matter to me? Ans: Yes, just as a matter of principle, I don't use a part as a pattern without modifying it to allow for shrinkage.

    Call me stubborn or whatever, but if I am going to make a replica of a part, it is going to have to measure the same as the original part, using a vernier caliper (vernier calipers are not terribly accurate, but accurate enough to get within any original production tolerances).

    As far as the holes, I will fill them with something that is temporary and easily removable, such as spackling compound, so that the part can be cleaned, repaired, and reused if desired.
    Most people don't want original parts modified regardless of the condition, since they are often one-of-a-kind pieces, and I understand that and feel the same way.

    I should probably try the clay and epoxy thing, just so I can get the feel for it, but the letters are not particularly crisp, and so I don't want to lose any resolution on those.
    I have never done any letters of any kind, so my confidence is just not there for me to try and copy the letters for this piece.

    In a perfect world, I would put the piece in my 3D scanner, and pull it into Solidworks, then scale it up by 1.015, repair the part, omit the holes, and then print it on my high-resolution 3D printer.
    Unfortunately this is not a perfect world, I don't have a scanner or a 3D printer; I make all my patterns by hand using wood and/or steel.

    But the hand and eye can be surprisingly accurate with the proper training, and I like learning how to hand-make patterns, and like working with wood and steel.

    Its all for fun, and I would not be trying it if I did not enjoy trying to match it exactly as possible.

    Probably a couple of layers of card stock on either end, and on the bottom would take care of the shrinkage, along with a little filler on the curved surfaces and the top of the ears.

    Edit:
    It is possible that I could clean some of the rust/scale from the letters/numbers, and get a clean imprint of them, assuming the clay pulled off without sticking and/or deforming.
    I am still contemplating at this point.
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    Last edited: Dec 5, 2018
  9. PatJ

    PatJ Silver Banner Member

    Here are some photos of patterns for a bearing.
    These are not my photos, but were publicly posted on ebay.

    Gives you an idea of what are probably typical bearing patterns.
    Nice self-aligning cap feature.
    I am not sure why the patterns did not have core prints on the ends?
    Perhaps the core was just laid in the cylindrical recess in the mold?


    BEARING-04-s-l1600.jpg


    BEARING-05-s-l1600.jpg


    BEARING-06-s-l1600.jpg


    BEARING-A1-s-l1600.jpg


    BEARING-A2-s-l1600.jpg


    BEARING-A30s-l1600.jpg

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  10. PatJ

    PatJ Silver Banner Member

    Here is another example.
    Photos are not mine (from ebay).

    PATTERN-BEARING-01s-l1600.jpg


    PATTERN-BEARING-02-s-l1600.jpg


    PATTERN-BEARING-03s-l1600.jpg


    PATTERN-BEARING-04-s-l1600.jpg


    PATTERN-BEARING-06-s-l1600.jpg


    PATTERN-BEARING-07-s-l1600.jpg
     
  11. PatJ

    PatJ Silver Banner Member

    I started cleaning up the bearing cap tonight.

    Ground off the excess welding and cleaned up the letters/numbers a bit.
    Glued on some tongue depressor sticks to give a little shrinkage and machining allowance.

    rImg_3274.jpg



    rImg_3275.jpg



    rImg_3277.jpg



    rImg_3279.jpg


    Traced out the pattern for the broken ear.

    rImg_3282.jpg


    Found a piece of wood about the right thickness.

    rImg_3284.jpg


    Glued on the wood and added some filler (wall patching compound).
    Did the initial rough sanding on the filler.

    rImg_3286.jpg


    Filled in the oiler hole.
    I will tape over the holes that secure the babbitt in place.
    The holes will have to be drilled in the new casting; I don't have a way to cast them in-place.

    rImg_3289.jpg


    Added final layer of patching compound, most of which will be sanded off.

    rImg_3290.jpg

    The wood and patching compound, wood and glue can all be stripped off if desired, if the old piece is to be salvaged some day.

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    Last edited: Apr 16, 2019 at 1:43 AM
    Tobho Mott likes this.
  12. crazybillybob

    crazybillybob Silver Banner Member

    Could the core be suspended through the two perpendicular cores ton top via a strong back ?
    [​IMG]
     
  13. PatJ

    PatJ Silver Banner Member

    I am only casting the cap, not the entire bearing body, so there is no need for a core.
    I will just let the drag sand protrude up into the area where the shaft will be.

    Here is an example:

    rIMG_3190.jpg
     
  14. ESC

    ESC Silver Banner Member

    Those are probably the core prints so they could go in the drag and position the core. I think this is for two separate castings that will be held together by bolts through the ears, since it would normally have a flat parting line if it were to be cast as one piece. Perhaps a follower, or a match plate that had the core prints mounted.
     

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