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Thread: home made comm cutter/truer

  1. #1
    Join Date
    Oct 2005
    Location
    monroe twp nj
    Posts
    63

    home made comm cutter/truer

    I am planning to make my own home made comm cutter/truer, my funds are limited, that leaves me out from buying one of those ready made ones, so does anyone have any ideas.
    I have afew variable speed electric drills to chuck the arm in, so I can make a mount for it, its the cutting tip and the carriage for the tip to ride on.
    I have lots of materials like brass tubing, music wire, odds and ends of hardware to work with.
    So if anyone out has any ideas, I'll be very greatfull.


    Thanks Orangecrate

  2. #2
    Join Date
    Aug 2005
    Posts
    307
    I feel your pain. I'm in the same boat. I think that your better off living without one, and sending your arms out every so often. You can have an arm cleaned, re-balanced, stacks ground and re-dyed, and the comm cut for $5.00 an arm plus shipping. They'll even put it in an arm tube before they ship it. There are a bunch of places to send them too, so I just keep watching the boards for a deal, and send them out in the meantime. Just my opinion.

  3. #3
    Join Date
    Jan 2005
    Location
    Used to be Keystone, PA
    Posts
    406
    The ONLY!!!! alternative to buying a dedicated comm lathe is to use a small lathe, like a Sherline or similar, chuck up a ball bearing in a dead center chuck, mount a diamond bit on the tool post, check the runout. The only way you could build your own is if you have access to precision machine tools, and if you gotta buy them it'll cost you a ton more than a comm lathe'
    Improving performance one hazardous material at a time.

  4. #4
    Join Date
    Jun 2002
    Location
    Victorville, CA
    Posts
    1,725

    Accuracy is a must!

    Allow me to amplify on Steve's comments!

    DO NOT chuck the armature in anything if you expect it to actually produce a comm surface that is both round, and more important, concentric to its shaft.

    The basic 'rubber band' lathes used for comm truing are actually very accurate because the arm is located on immobile surfaces. The only way to lose concentricity is for the shaft to be bent or worn.

    Additionally, the typical comm lathe has adjustments for taking up slack in the slides and screws, which allows you to constantly tune it up to avoid chatter. If you buy carefully, these little wonders can be had brand new for under $250 INCLUDING the diamond tip bit. Not cheap, perhaps, but very inexpensive considering the precision involved.

    If you manage to build something but it can't hold concentricity within .0002 or so, you'll do more harm than good.
    A clean slotcar is a happy slotcar!!

  5. #5
    Join Date
    Jun 2002
    Location
    Wesley Chapel, FL.
    Posts
    1,385

    Thumbs up $$$ BUT WORTHIT.......



    I know the initial outlay is $$$......BUT how many times do you redo an arm...Do you wait till it really slows? Always complaining your motors are slow....... I have seen where it took more than .015+ to clean a comm!

    I found that after 2-3 races & practice, depending on how soft the comm & how hard the brushes were, I could take up to a .002 cut on a comm and sometimes not get a full clean surface. I took the extra time to take as fine a cut as needed only. I know that it takes much more time but its worth it to me! I am able to get more fast time out of my arms. I would scrape the brushes and still do a water or naptha breakin.

    After 4-5 cuts (8-15 races) I would rebalance those that were balanced before. For ME it paid for itself in less than a year..

    MY $.25 WORTH
    PHIL I.
    Last edited by Phil I.; 06-26-2006 at 09:29 PM.

  6. #6
    Join Date
    Oct 2005
    Location
    monroe twp nj
    Posts
    63
    Guy's, thanks for the info on the comm truer and save up some $ and buy one.

    Thanks again

    Orangecrate

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