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Can I use ABS plastic for 75 RPM bushings?

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  • Can I use ABS plastic for 75 RPM bushings?

    I'm building a prototype mineral jig. I plan on making and selling these units. They are made of ABS plastic. It would simplify my work to be able to use the ABS for a couple of bushings. Is that workable? Would the working life be acceptable? The bushings would be 1/2" I.D. and 1/2"-3/4" long. Steel shaft.
    Thanks,
    Jim

  • #2
    Hi,

    What's a mineral jig?

    I would think if the tolerences don't need to be very tight or operated in gritty conditions they should last for a while. Question is, how long do you want them to last?

    Dalee
    If you think you understand what is going on, you haven't been paying attention.

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    • #3
      Jim,

      I don't know the particulars of your application but I have had poor luck with ABS as a bearing. Maybe if it were flooded with some type of lube it may work but at the first hint of junk or contaminants it falls apart and will self destruct. It's just a real poor bearing medium, even at that low RPM...IMHO that is~!

      Stuart

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      • #4
        No, nylatron would be a better choice or teflon
        The difficult done right away. the impossible takes a little time.

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        • #5
          Thanks for the help, guys. Is there a plastic that would work that could be glued to the ABS?
          Jim

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          • #6
            Originally posted by dalee100 View Post
            Hi,

            What's a mineral jig?

            I would think if the tolerences don't need to be very tight or operated in gritty conditions they should last for a while. Question is, how long do you want them to last?

            Dalee
            Here's a link to a video of my personal jig in operation....the new one will be a bit smaller, and different construction. The conditions will be gritty and possibly wet, too. Tolerances aren't real tight.
            http://www.youtube.com/watch?v=iLoqfj9-yXI

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            • #7
              Jim,

              What a bunch of kool stuff. Did you invent it and build it? I don't see where the dirt, etc is introduced to the bearings but if there is a 'nasty' zone, don't forget to think about wood bearings, things such a Lignum Vitae.

              Stuart

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              • #8
                Acetal works nicely, it is hard and slippery plastic, a.k.a. Delrin. Machines very nicely.
                Amount of experience is in direct proportion to the value of broken equipment.

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                • #9
                  Originally posted by atomarc View Post
                  Jim,

                  What a bunch of kool stuff. Did you invent it and build it? I don't see where the dirt, etc is introduced to the bearings but if there is a 'nasty' zone, don't forget to think about wood bearings, things such a Lignum Vitae.

                  Stuart
                  Thanks for the kind words, Stu. Yup...I just had the idea in my head, and started building. It just sort of came together. I did it a couple of years ago. I added the auto-feeder last winter. The whole thing is 12 volt, so nice and quiet.....I hate loud noise when I'm out in the outdoors....LOL The new model, I'm doing more thinking about, but still sort of planning while I'm building. Since I want to sell them, I'm trying to keep the cost down, but still want to sell a quality product. It also needs to be simple to repair and maintain. I had thought about wood for a couple of other parts, but hadn't thought about it for the main shaft bushings. It's a really good idea.
                  I'm going to look into that.
                  The dirt isn't really all over, but the unit is used in the outdoors, and there's water around, so there's dust, and you know, maybe a bit of mud....it gets into things, despite the best efforts to keep it out...ha!
                  Jaako.....thanks for the acetal idea...hadn't thought of that, either. What I liked about Stu's thought on wood bushings is they can be glued into the ABS body easily. That way I don't have to use mechanical fasteners.
                  Jim
                  Last edited by IdahoJim; 11-13-2013, 12:19 AM.

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                  • #10
                    Just for us city folks, what does it do exactly? Does it wash gravel to see whether there's anything nice hiding in there?

                    Igor

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                    • #11
                      Originally posted by ikdor View Post
                      Just for us city folks, what does it do exactly? Does it wash gravel to see whether there's anything nice hiding in there?

                      Igor
                      What it does is separate minerals by specific gravity. Generally, gravel has a SG of about 2.5. Gems range from 3.54 (diamond) to 4.2 for garnet. So what happens is the gems end up on top of the screen at the bottom of the screen box. The rest of the material goes to waste. You can also set them up for gold, or platinum. For that you put steel shot on top of the screen.... about a 1" inch layer...maybe 1/8" or 1/4" diameter. The metals go right through the steel shot, and through the screen, and end up in the hutch..the main box, where they can be drained out periodically. Jigs are really handy, as they can be used to separate about anything..according to SG. They also handle a lot of material for their size. The one in the video can handle about 300lbs/hour of washed, classified material for gems...a bit more for gold. The downside of jigs is their cost to build.
                      Jim

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                      • #12
                        If you were going to consider wood for bushings, I offer these thoughts:- 1) lignum vitae is now quite scarce, (translates into EXPENSIVE!)
                        2) It has to be kept wet all the time or it cracks.
                        3) In the days of wringer-type washing machines, the wringer roll shafts turned in wax-impregnated hard maple blocks. These were unaffected by hot soapy water and were subject to tremendous pressure.
                        4) To make the blocks, first machine to size, then oven-dry and soak in a pot of hot parrafin wax, (canning section, grocery store.) Remember, the waxed blocks wont glue to ANYTHING!
                        Duffy, Gatineau, Quebec

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                        • #13
                          Use either type 901 blue nylon, or white uhmw (ultra high molecular weight) plastic for your bearing surfaces if you want to stick with plastic of some form---and no, I don't think it can be glued to anything. It has to be attached mechanically.---Brian
                          Brian Rupnow

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                          • #14
                            I bought some Delrin to try. I was afraid the wood would swell and bind. The Delrin can be glued, too. Should work OK...we'll see how it goes. Hadn't thought about the peraffin treatment. Not a bad idea, except for not being able to glue it. This model is a prototype, so I don't mind changing things as I go. Heck, IU might even learn something...LOL
                            Jim

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                            • #15
                              that would work great for fine gold. maybe you should sell plans.
                              san jose, ca. usa

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