Ball Screw Errors

[dnunner]

I have a question re: ballscrew errors. I purchased two 5tpi ball screws and nuts for my new X and Y axis. I would expect that to move the nut 1 inch they would have to turn 5 revolutions. That would translate to 5 times 200 or 1000 steps per inch. I have a Xylotex drive set to microstep 1/8 so now need 8000 steps per inch. I have used a digital caliper, a 1/2/3 block with a dial gauge and find that if I move 3 inches the actual move is only 2.95 inches which requires that I need to provide approx 8130 steps from Mach 3 to move the full 3.0 inches. Both the X and Y axis are the same. I can only guess that these fairly expensive ground ball screws are not exactly 5tpi. Is this common or am I doing something wrong? Any answers would be appreciated. Dnunner

[neilw20]

Mach3 can do Screw Mapping. This may solve your problem.
Measure it over 6" and see if you get 5.9". Is it a scaling problem or a linearity problem?

[Zappautomation]

Just to check the screws, manually turn them ten turns and measure the distance.

Originally Posted by dnunner I have a question re: ballscrew errors. I purchased two 5tpi ball screws and nuts for my new X and Y axis. I would expect that to move the nut 1 inch they would have to turn 5 revolutions. That would translate to 5 times 200 or 1000 steps per inch. I have a Xylotex drive set to microstep 1/8 so now need 8000 steps per inch. I have used a digital caliper, a 1/2/3 block with a dial gauge and find that if I move 3 inches the actual move is only 2.95 inches which requires that I need to provide approx 8130 steps from Mach 3 to move the full 3.0 inches. Both the X and Y axis are the same. I can only guess that these fairly expensive ground ball screws are not exactly 5tpi. Is this common or am I doing something wrong? Any answers would be appreciated. Dnunner

[dnunner]

I have fixed the problem, an easy fix when I found out that the ball screws were not 5 TPI at all but 5 mm. dnunner