This is my first post on this forum.
I have built a "home built CNC" from ply-wood. And this may not even be the place to ask for help. But I have about run out of ideas. I tried the other forum sites and have not found an answer to my problem. My CNC is a Blacktoe V4 2X4 w/ chain drive on the X & Y axis. Z axis has a 1/2" 10 x 5 start lead screw.
I have been having a problem getting my motor to run smoothly. And keeping Z axis motor from stalling.
Saturday, I setup a simple gcode to test the motors as listed in Mach3 manual. The gcode runs in a loop and moves the gantry X axis up & down the table 50 times. I also added more moves to the gcode. Giving it a move across the 'Y axis', a move across from X0,Y0 to X20,Y12 and a move in the 'Z axis' of 4 inches up & down. Here's what it was doing while making an air cut. Everything was running fine, with just a small knock once in a while. Then the shocker, when the Z would try to move from Z0 to the + it would move about 2 or 3" and stall making a loud buzzing noise then start moving again. I tried changing the Velocity & Acceleration settings up & down but could not stop the Z motor from stalling. Of course when the Z motor would go into a stall it would throw the rest of the gcode off and start at a different spot in the code. When I stopped the program and returned to "Home" 0,0,0, it would be way off of 0,0,0 and 'Z' would drive into the table top. NOT GOOD!!!
The Z motor stalling has been going on sense day one, I kept thinking that the anti-backlash nut would work its way in, but still, it is not that tight. And YES I have been lubing it.
I tried changing the velocity & acceleration. After experimenting with the settings, the only way I could come close to having the steppers run smooth was to lower the setting on the velocity from 700 which what the math says it should be, to a lower setting. Set X= steps @ 1420.682271 which is the setting that were set by the auto "Set steps per unit" by Mach3. Velocity @ 400, acceleration @3, step pulse @4, Dir pulse @5. Set Y= steps @ 1422.456593 (set by Mach3) velocity @ 450 acceleration @ 3. . Z= steps 1602 velocity @ 100, acceleration @ 10. I would let the loop run an air cut for a while and listen to the motors. I air cut this loop program about 15 or 16 times. Most of the time they were running smooth, but then there would be a noticeable bump and knock like a motor skipping a step. The knocking sound has been very persistent. And the knock and bump is coming sometimes from the X motor and sometimes from the Y motor. There is no pattern to the bumps. When I would stop the loop and go to home zero. 0,0,0 would be off, sometimes by as much 0.18 to X+ side. And a couple of times at 0.06" to the X- side of Zero.
Here's the question: Is it likely that I have motors that are undersized and or bad? They should be 382 in oz. but here are no markings on the motors. Just a small paper tag with a couple of numbers. I put markers on all the sprockets and lead screw, and there is NO movement.
I had noticed before that sometimes when the gcode made a change in the 'Z' level is when the trouble would start.
The photo shows how much the X axis moved is one of my test cuts. Good thing it was scrap wood.
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