My MPCNC threaded rod mod build

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This topic contains 7 replies, has 4 voices, and was last updated by Profile photo of David Keranen David Keranen 1 month, 1 week ago.

Viewing 8 posts - 1 through 8 (of 8 total)
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  • #26824
    Profile photo of David Keranen
    David Keranen
    Participant

    This is test run .The build has a threaded rod mod on x and y for milling . Have a beaglebone black with a cramps board running linuxcnc.The cramps board is from pico-systems.This board can also run a 3d printer Everything is printed out of abs

    #26827
    Profile photo of vicious1
    vicious1
    Keymaster

    What are you doing about whip and backlash?

    Remember above 60rpms and you lose torque with the steppers.

    #26828
    Profile photo of David Keranen
    David Keranen
    Participant

    I’m using a nylon bushing Hillman 8804338 tapped for 5/16 thread , it doesn’t seem to have any backlash at all . This is the second CNC machine I used this arrangement on .Made wood gear clocks with first machine .As for the threaded rod whipping about it doesn’t seem to occur on my machine, of course when I purchased it I tried to determine if it was absolutely straight.

    #26847

    Very interesting topic. Please keep us posted, I think it could solve the only issue the MPCNC has (in my opinion): a limited torque.

    I would worry that the threaded rod wobbles quite a bit at high speed though. You should consider some acme rods or ball screws instead, also because the pitch would be longer. I guess your CNC moves pretty slowly with these rods.

    Did you use one or two motors per axis?

    #26875
    Profile photo of WarHawk8080
    WarHawk8080
    Participant

    So need a video of this in action!

    #26923
    Profile photo of David Keranen
    David Keranen
    Participant

    I found the information I needed on google groups for the motors. Charles Steinkuehler I believe designed the cramps board and did the software for it .So there are two drivers for X and two for Y . They called it a gantrykins . So I have 5 A4988 drivers. I think there was someone else on this site that was working on the same thing, but I haven’t found it again.

    Was going to post a video of my machine but I still have issues . It may be caused by vibration. The gear printed about right with the pen but when I tried it with a 4 flute .062 end mill wasn’t good at all. Have to finish my table for the machine and bolt it down and maybe that will solve it . The gears in the picture I did on my first machine but the machine is much heavier . Hope I can get them to turn out on the MPCNC.

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    #26925
    Profile photo of vicious1
    vicious1
    Keymaster

    Yes, you have to bolt it down, and a 4 flute bit is not recommended for such high rpm spindles.

    #26945
    Profile photo of David Keranen
    David Keranen
    Participant

    I had to shorten my z axis had it too long

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