UHMW bushing help / advice
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  1. #1
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    Default UHMW bushing help / advice

    Next week I am suppose to make a couple hundred bushings ( washers?) out of 1 inch diamter UHMW. I have not seen the print yet, but the material came in today and is rather soft and flexible. Material is in 4 ft sections and rather "bendy".

    I have never used solid UMHW that is this small, most of what I had done was with 2 inch and larger tubing. I am concerend with the dimesional stability of the material and how much it will push and whip when using it in a 3jaw chuck.

    I was told that the final pieces will be .960 (+0/- 0.010) inch diameter, have a clearance hole for a 5/16 pin drilled through the center, and the piece will be 0.094 (+/- .010) inch thick.

    I have read that the material should be turned or drilled with hss and a surface speed of 600 to 1100 fpm. I also read that it materials "grows" after machining and that the material will "suck" the drill into the body of the material.


    My initial plan of attack is to turn down 6 to 8 inch sections at a time, then start with a Q drill and work up from there for the clearance hole, then part off the pieces.

    I am wondering if the pieces will grow overnight? I am trying to get a little piece to experiment with over the weekend.

    So any suggestions for feed/ speed, procedure, tool bit shape, etc. will be appreciated.

    Thanks,

  2. #2
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    We use this stuff regularly. Fast rpm s, hss cutters. Cuts like butter. It is quite forgiving material.

  3. #3
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    yes nits true that the material will move after you machine it but if you only get rid of 0.040 od and you drill a hole it should be fine on this point. i personally find out that running 1" at around 1200 1500 do a relay nice shop with a HSS cutter. make it realy sharp and finish the grinding with a fine stone. for the drill its not like Delrin or Nylatron thos one will eat your drill if there is already a hol;e in it but iof you are doing the hole 1 shoot deal with a drill its going to be fine.

  4. #4
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    Quote Originally Posted by Krovvax View Post
    yes nits true that the material will move after you machine it but if you only get rid of 0.040 od and you drill a hole it should be fine on this point. i personally find out that running 1" at around 1200 1500 do a relay nice shop with a HSS cutter. make it realy sharp and finish the grinding with a fine stone. for the drill its not like Delrin or Nylatron thos one will eat your drill if there is already a hol;e in it but iof you are doing the hole 1 shoot deal with a drill its going to be fine.
    I totally agree, and as far as bar whip why not machine a ring to fit the stock and the spindle dia?

  5. #5
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    I'd suggest finding a drill, or grinding one, that will get to one size in one shot. Going back for a second cut is a bad idea, it will grab and the drill won't move, the material will. Like everyone else said, sharp HSS with generous radius and, at least in my experience, feed the tool like you have a lady waiting. I get fantastic surface finishes that way.

  6. #6
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    Regarding the parts growing after machining, I would recommend machining just a few pieces and allow them to stabilize over night. Then you'll know if any compensation is needed.
    Regarding bar-whip, we use spindle liners.

    Brian
    Last edited by Neslob660; 04-19-2012 at 10:52 PM. Reason: spelling

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    Machining is the easy part. It's deburing that will make you pull your hair out!
    We use our hardinge DSM/DV 59's for deburing. SUPER SHARP tooling. set your stops and take quick jabs at it, if you go slow like machining steel you will just push the material around. Good luck, cause until you get it perfect it will suck.

  8. #8
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    Thanks for everyone's help. The material cut like taffy and I my pieces were covered the whole range of tolerances but at least it it over.


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