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Topics - WilliamB79

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General Mach Discussion / Gantry Router
« on: June 11, 2013, 04:26:28 PM »
Hi All,
          I have recently built a CNC router with the idea being that if could build a small router table, why couldnt i build a 8' X 4' plasma table (thats what i really want!)
So, i got to the point where all mechanics were done and its all wired in, excitedley purchased a mach3 lisence...............and for the last 3 weeks have been tearing my hair out (on and off). If anyone would care to read on, and offer any advise i would greatly appreciate it.

Machine: 3 axis gantry type router as below, if the pic uploads.

Mechanics: 16mm linear bearings, 20 x 8 trapaziodal leadscrews with brass nuts, Nema 23 (3.1Nm) motors

Hardware: http://www.ebay.co.uk/itm/261190737455?ru=http%3A%2F%2Fwww.ebay.co.uk%2Fsch%2Fi.html%3F_from%3DR40%26_sacat%3D0%26_nkw%3D261190737455%26_rdc%3D1

48v power supply

The machine works as a whole, so i think i have correctly set the ports and pins etc.......all axis' move on jog and running code.
Drivers are set to: step angle 0.025 , pulse/rev 1600 and on half current
All settings in mach are the same with all axis'. steps per 200, vel 2000, accel 170

Problem: The X axis does not measure up, mach will read 207mm to a physical 200mm its actually travelled, and it seems to grow 7mm (ish) every 100mm it travels
on numerous tests just running the x, with the aid of a digital height gauge on its side, every result (measurement) comes out different, this confused me because the other 2 axis' work great and to quite a tight tolerence.

I have checked all mechanics, they are free moving , tight and inline

I swapped the Z mototr for the X , leaving it so that when i jogged the Z in mach it moved the X on machine, it measured up! i thought it was the motor that had gone, so i bought a new and fitted it, but got the same problem, i then replaced the driver, same problem. I then wired in a motor on the Y axis to the X driver, and told mach accordingly what was going on so the machine would still operate, low and behold the Y motor started playing up!

I know the mechanics are good, its not the motor, its not the driver, its not the parallel port cable.So ive boiled it down to either the breakout board, my computer (which is dedicated to the machine)or its something in mach i havnt done correctly, i just find it very strange that everything is set up the same with good results, yet something is is very badly wrong running through the X path somewhere!

Sorry to bore you all........i really hope you can help, its so frustrating when your so close, cheers

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