Comm Lathe Questions?????TY

Discussion in 'RC General & Getting Started' started by rdandy5875, Feb 11, 2004.

Thread Status:
Not open for further replies.
  1. rdandy5875

    rdandy5875 New Member

    So I bought a comm lathe on ebay and it came today. At least it came with a few goodies, no instructions though. I googled a few how-to's over my wait, and followed their instructions on cutting the comm precisley.

    I think the bit is dull though because I got what I would call chatter and a pretty rough cut.

    I made a few passes with the bit barely touching the comm, all was good some of the black marker I put on the comm was warn or cut off and some wasn't, and then increased the feed to one increment. I don't know exactly what one increment is because it had no instructions, and try as I did I wasn't able to quickly find instructions for this lathe, which is a Trinity Pro 3. I was going to check how much was cut off by one increment once I made a few passes, but the arm or the bit seemed to chatter, and then seemed to really dig into the comm, more than I thought it should. I made a few passes with some loud cutting or rubbing, and checked the comm, pretty rough, lines, the burrs were really built up inside the spaces. The diameter still reads .287 or so, it read .290 or so when I started.

    So basically I think my bit is fubar, possibly the arm too??? Although the arm isn't cut to what I was told the absolute minimum, of .270. Was this all besause of the dull bit? And where can I find info on SHIMMING the bit. All of the popular how-to's say to refer to the manual? I know minimal shimming info.

    I'm going to get another armature either way, I would also like to get a new bit new orings and some instructions on the lathe but I'm going to have to contact trinity to get that. It would be nice to be able to reuse the older arm as well.

  2. Steve M

    Steve M Member

    Try looking on the Hudy web pages for their instructions.

    The tip of the bit must be slightly higher than the middle of the comm you are cutting. I use a Hudy Tech lathe and a diamind bit to cut my motors.
  3. mastmec

    mastmec Member

    Also make sure that your arm is spinning in the right direction. The arm should spin toward or against the blade tip.
    One increment on the handle is too much to cut at a time, I never cut more than a 1/4 of one increment at a time. If the comm. is chattering, your cutting to deep and/or the arm is not spinning smooth, if it rides on bearings make sure they spin perfect, if just in grooves, put a little oil on the shafts to lube it so it will spin easy. Also put motors shims on the shafts so that the arm can't slide side to side but without binding.
  4. timrock

    timrock Active Member

    you guys really think it is necessary to cut coms on a lathe?i know most competetive racers do that but...everytime i change brushes,i clean up the com with fine steal wool.if there are any microscopic,imperfections,the new brushes will wear/break-in to shape the comuntator perfectly,as i always imagined.and the motors run smooth,like new and there is no arking.

    i have been into electric powered RC for 15 my opinion, it isnt necessary to cut coms.though i had mine cut for me several times over the years because a friend had one and did that but the motors didnt run any better doing it that way.
  5. mastmec

    mastmec Member

    I do it to get the most use out of every motor and brush. I can't afford to buy alot of brushes and motors when they just wear out so I rebuild them to last a long, long time. And I'm kind of a perfectionist too, so that doesn't help either. It's like when you do a brake job on your car, if you just put pads on without truing the rotors the pads don't last as long because they are being ground down by imperfections on the rotor. Same with the comm. on the motors.
  6. timrock

    timrock Active Member

    well,like i said,when i change brushes i clean up the com with steel wool and it is ,virtualy perfect.when i used to run only 6 cells,my motors would last forever as long as i serviced never seemed to make a difference by cutting the com.

    maybe if you have a serious burn mark on the com,you may be able to save it by throwing it on a lathe and cutting it out but other than that i dont think it is necessary.
Thread Status:
Not open for further replies.

Share This Page