- February 6, 2017 at 12:25 pm #26824
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
Attachments:February 6, 2017 at 12:27 pm #26827
What are you doing about whip and backlash?
Remember above 60rpms and you lose torque with the steppers.February 6, 2017 at 12:40 pm #26828
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.February 6, 2017 at 6:51 pm #26847
Dui, ni shuo de duiParticipant
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?February 6, 2017 at 11:13 pm #26875
So need a video of this in action!February 7, 2017 at 8:26 pm #26923
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.
Attachments:February 7, 2017 at 9:37 pm #26925
Yes, you have to bolt it down, and a 4 flute bit is not recommended for such high rpm spindles.February 8, 2017 at 7:13 am #26945
I had to shorten my z axis had it too long
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