Another of the machine put back together (I took the cover off the Z-axis mechanism for a reason ill mention later).
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Once the motors are installed back on the machine and you hook up your controls the first thing you really need to do is tune the Mach4 end of your motor control. This primarily consists of calculating you Count/unit value which is the amount of steps your encoder will count per unit distance. My controller is setup for inches so that means how many steps go by per inch of travel. This is a product of your steps/rev setting I mentioned before, your gear reduction ratio in the belt drive units, and the pitch of the ball screws. You enter that in the motor tuning tab under configuration>mach in Mach4. Your curve should be a trapezoid as shown here:
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You can see in that pic Mach will automatically calculate your rapid traverse speed as well (mine is about 220 Inches per minute, which is excellent for a machine like this). Once you have this sorted out you'd be best off to check your results. The easiest way to do this is put an indicator on the spindle in the direction you want to test and zero it, command the desired axis to jog a specified amount (.001 for example) and confirm you see an equivalent movement on your indicator. That setup is shown in the following pic, I was testing the x-axis travel.
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Also you need to test the movement over longer distances. I don't have pics but I tested down to .0005 movement with a dial indicator, and up to .900 with a drop indicator in every direction. Once I was happy with that I moved it 8" in the X-axis, and 8" back into the indicator. If it still hits zero after that much movement then your good to go. I made that movement via the following very simple line of code.
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Also, that was the first line of code that this machine has run for me, good times!
EDIT: the reason the z-axis is partially ripped apart in that first pic is because I was having trouble dialing in the z-axis movement, and actually I'm still having an issue. Somewhere i'm loosing .005", I hesitate to call it backlash, Because the ball screw setup alone has no measurable backlash. The difference occurs between the ball nut and the bracket that attaches it to the spindle. At first I had like .030" play which is ridiculous, I pulled it apart and found the bolt that attaches to the spindle ram was loose. After tightening that I still had .005 play. I know you can compensate within the program for backlash so I should be able to work around this but really it shouldn't exist at all. Fortunately it's only in the Z-axis so it'll only effect my depth's. The X has ZERO backlash, and I really mean nothing. And the Y-axis has about .0005" backlash, which is no problem.