Validating axis movements

[DLAM]

I measured the pitch of the ball screw with dial indicator. I changed my revs/inch to 1 and commanded a 1" move in MIDI. The measurement was .0985". That puts turns ratio at 10.15228426395939, So I think 10.166766300 number I came up with over 5 inches is pretty close.

[cncsnw]

It is likely that the best answer is 10.1600000. That would be typical for a 5mm screw belted 2:1.

Unless you have a laser to measure travel with, anything else is kidding yourself.

[swissi]

The servo motors are 1:1 to the ball screw. I will have to take the rear cover off the machine to try to measure the pitch of the ball screw.

Something is still not right. You are saying that you are driving the balls screw directly 1:1. Googling the specs for the Emcoturn 220 it looks like the pitch of the ball screw is 5mm and in that case the "Overall Turns Ratio" would be 5.08.

So either you are using a gear ratio of 2:1 or the Encoder Counts/Rev are wrong. What's the Gear Number you have configured in your DYN 4 drivers?

-swissi

[DLAM]

The axis drive is 1:1 I was able to use the original pulleys that was on the Stepper motors. The motor's steps/rev in the motor parameters is 8000. The gear number is set to 2000.

[swissi]

The axis drive is 1:1 I was able to use the original pulleys that was on the Stepper motors. The motor's steps/rev in the motor parameters is 8000. The gear number is set to 2000.

So the "Steps/Rev" definitely look ok but when you say you could use the original pulleys, could it be that these pulleys are actually driving the ball screw with a 2:1 gear ratio and not 1:1?

I think it's highly likely what Marc said that the 5mm pitch ball screw is driven with a 2:1 ratio which would make the "Overall Turns Ratio" an exact 10.16000. These ball screws usually have an error of less than 0.1mm over 30cm so leaving the Overall Turns Ratio at exact 10.16000 as Marc suggests is probably a good idea.

If you are still getting errors that add up, I can only suggest you make a quick video showing how you measure and how the error accumulates so we can have a better understanding what else could cause the issue.

-swissi