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Thread: lubricant for use with west system epoxy

  1. #1
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    Default lubricant for use with west system epoxy

    Hi All, building a set of wheels for my dinghy, axles are wood and sleeve bearings are polymer, since I don't want the wooden axle to swell I'm planning on coating it with epoxy.

    So I need a lubricant that won't eat the epoxy, ptfe is supposed to be the best lube for the bearings, will it play nice with the epoxy?

  2. #2
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    Default Re: lubricant for use with west system epoxy

    Epoxy is pretty resistant to just about anything you typically might want to lubricate it with. You do want to be sure though that you have enough epoxy to seal the wood well - which is usually two coats if you don't intend to sand it smooth, or three coats if you plan to sand it after it hardens. Any end grain should get as many coats as it will absorb. Proper coating thickness is what will keep the wood from absorbing water and swelling.

  3. #3
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    Default Re: lubricant for use with west system epoxy

    How about adding some graphite powder to the epoxy?

  4. #4
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    Default Re: lubricant for use with west system epoxy

    You can, but you want to keep the ratio of graphite to resin pretty small (like 10% by volume) and you generally don't mix any graphite into the first coat for maximum adhesion to the wood. A higher percentage of graphite might be slightly lower in friction, but it is a double-edged sword as higher amounts tend to yield softer, noticeably less abrasion resistant epoxy. This can be countered to some extent by also adding some Cabosil or similar to help make harder epoxy, but at a certain point all this screwing around with different mixtures seems pretty pointless when plain resin and some simple lube can probably do the job just fine.

  5. #5
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    Default Re: lubricant for use with west system epoxy

    The polymer sleeves shouldn’t need any lubrication, adding lubrication will attract sand and grit that will scour the faces.
    Larks

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  6. #6
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    Default Re: lubricant for use with west system epoxy

    Thanks everybody

    I'm planning on 4 coats of epoxy, sand to 400 grit and then one more thin coat so I'm left with that nice shiny finish running on the bearing sleeves.

    I guess I'll try it without lubrication and see how it goes, if I have any trouble with wear I'll rotate the sleeves and try the PTFE lube, it dries hard and is hydrophobic so it might help keep grit from washing into the bearing with seawater.

  7. #7
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    Default Re: lubricant for use with west system epoxy

    You would be better off to sand to 600 grit and polish it with polishing compound if a smooth finish is the goal. Epoxy resin is not paint or varnish and does not go on smoothly like paint or varnish will. If you sand all the way up to 400 grit and then add another coat of resin you will just obliterate the sanding you just did with a layer of shiny, but lumpy epoxy.

  8. #8
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    Default Re: lubricant for use with west system epoxy

    Or you could avoid a lot of trouble and use axles made of some durable material. Like galvanized steel, bronze, etc.

    Jeff

  9. #9
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    Default Re: lubricant for use with west system epoxy

    Neither wood nor neat epoxy will wear well as a bearing material.
    The polymer bearing will serve well if the other surface is smooth.
    How about stainless or bronze or even copper rod or pipe?

  10. #10
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    Default Re: lubricant for use with west system epoxy

    Prepare to do the joint over again if you rub on epoxy, with anything in it.
    Friction will raise the temp at the epoxy surface, the epoxy will soften , stick, and get worn quickly.
    Put a metal sleeve over the wood for the "polymer" to rub on.
    What kind of polymer?

  11. #11
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    Default Re: lubricant for use with west system epoxy

    thanks everybody

    I've considered other materials and ruled them out for various reasons, too heavy, too expensive, salt water corrosion, not available, etc.

    I hadn't considered heat softening the epoxy, I wheel the boat about half a click each way so they'd definitely get warm.

    acklands grainger just listed the bearing material as "Polymer"

    how about paraffin wax, boiled linseed oil, or bees wax as a wood sealer/lubricant? if heated and soaked into the axles for an hour or so they should keep the water out, and I could burnish them after to smooth them, I suppose I could burnish them first but I'm not sure they'd soak up enough wax/oil if I did.

    only other thing I can think of is split bushings made from abs pipe between the axle and sleeve bearing.

  12. #12
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    Default Re: lubricant for use with west system epoxy

    Quote Originally Posted by minno View Post
    thanks everybody

    I've considered other materials and ruled them out for various reasons, too heavy, too expensive, salt water corrosion, not available, etc.

    I hadn't considered heat softening the epoxy, I wheel the boat about half a click each way so they'd definitely get warm.

    acklands grainger just listed the bearing material as "Polymer"

    how about paraffin wax, boiled linseed oil, or bees wax as a wood sealer/lubricant? if heated and soaked into the axles for an hour or so they should keep the water out, and I could burnish them after to smooth them, I suppose I could burnish them first but I'm not sure they'd soak up enough wax/oil if I did.

    only other thing I can think of is split bushings made from abs pipe between the axle and sleeve bearing.
    Or two polymer type bearings against each other, one fastened to the axle and the other in the wheel. You could simply countersink a couple of screws in the axle side one to fasten them. If you can’t find ones off the shelf to suit it’d be a fairly quick and simple job to get any local machinist to turn one up on a lathe from acetyl. (Any machinist based around a marina or otherwise involved in the industry will - should - have acetyl sitting on the shelf for turning into bearings).
    Larks

    “It’s impossible”, said pride.
    “It’s risky”, said experience.
    “It’s pointless”, said reason.
    “Give it a try”, whispered the heart.

    LPBC Beneficiary

    "Keep away from people who try to belittle your ambitions. Small people always do that, but the really great make you feel that you, too, can become great!"

  13. #13
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    Default Re: lubricant for use with west system epoxy

    I think that ‘polymer’ bearings are tough low-friction plastics like Delrin or better. At low speeds, they’ll be OK.

  14. #14
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    Default Re: lubricant for use with west system epoxy

    Bond a piece of copper tube over the axels with West epoxy.
    The hard surface will run smooth against the polymer bearings, heating will be reduced and the heat will be spread evenly so the epoxy will not be at risk.

    I know it might be hard to get the right sized tube, but this will work for a long time.

    Good luck whatever you do.

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