[bbrown2005]

I HAVE MACH 3 MILL ON A BRIDGEPORT MILL I CONVERTED IF I GO TO SET AXIS IT MOVES EXACT WHAT I ASK. WHEN I GO TO MDI LINE AND MOVE AXIS IT DOES NOT MOVE THE DISTANSE I ASKED. I CAN GO BACK TO SET AXIS AND IT IS SET EXACTLY. I DONT KNOW WHAT TO DO. THANKS

[ger21]

What is set axis? What are you typing in the MDI? Can you give an example that explains what you're seeing a little better?

[bbrown2005]

sorry about that. On the mdi line I type in y.5 and it will move .45 i can type y0 and it will go to 0. I have a digitial dail indicator set up to measure movement. I can move it back and forth and get exactly the same. when i go to set step for that axis and type in .5 for the y it moves .5 every time i do it i get the same.

[ger21]

I don't know what set step is? what screen is it on? If the MDI move is wrong, then your steps per unit is probably wrong.

[bbrown2005]

it is on the settings tab right before the dianostic tab.

[ger21]

You mean the Axis calibration.What happens if you run a gcode file? Sounds like the Axis Calibration may not be working correctly for you for some reason.

[bbrown2005]

i run the surface wizard today i just had to find what my points were with the dro and not what the part measured it done great except the the dro did not match part. it never missed any steps

[bbrown2005]

i tried reinstall mach 3 yesterday and reset every thing it still does the same on my y axis i would ask it to move 8.375 it would move .691 inch to fare every time it was consistent it did not change each time thank you

[ger21]

Then change your steps per unit so it moves the correct amount.

[LeeWay]

That or check to insure that you have no loose connections on the screw. A motor coupler can be hard to find and is a real gremlin sometimes. Ball but carrier is also a source for play.
If all this is tight, you will need to adjust your steps a Gerry mentions until you get what you are shooting for.

[bbrown2005]

i still aint had no luck i checked for excessive backlash i have .0083 on my y axis. im trying the math to see if i can get it were it needs to be. i type in 8.363" and it moves .21" to far thanks

[bbrown2005]

i done alittle math today and came up with 24.26343154246 rev/inch on y and 21.2539851222 on x im using the keeling kl-4030 driver if i have it set to 1/16 micro step would i times 200 x 16 x rev/inch = steps/unit?

[ger21]

yes

[bbrown2005]

could elictrical noise cause this? or maybe my computer when i put in the steps i figured it did not even read close i tried changing micro steps. if i calibrate axis for 4" and then on the mdi type y 4 it moves exact to 4 if i type in y 2 it lacks about .25 if i type y6 it goes past .1. if i calibrate for 6" then six moves exact but only what distance i calibrate for it is driving me crazy trying to figure it out.

[bbrown2005]

thank, i got it figured out it was a bad breakout board. i replaced my cnc4pc brakout board with a g100 i had and it is working great i cut two parts and they was within .001 of want i needed that is a wholelot better thank ben

[Crevice Reamer]

I don't know if rev/inch means TPI to you, but the formula would be 200 X 16 X TPI. (turns per inch) 1/16 micro stepping is very high. Anything over 10 is basically wasted, and 10 may be too high for much speed on rapids.

I agree that you may need to tweak your SPI to get the axes to move the proper distance. If it's falling short, than add a few steps. If it's going too far, then subtract a few steps.

CR.

[bbrown2005]

i am yusing 1/8 step now with the g100 and its working great thanks