Axis Configuration Questions

Use can the below moves to adjust your SCALE.
Use numbers that work on your machine and the range of your dial indicator.

G1 X-1
G1 X0 ;SET DIAL INDICATOR
G1 X1 ; READ DIAL INDICATOR

The first move G1 X-1 set things up.
The second move G1 X0 moves X into position to test with any backlash in the positive direction taken out.
Use the third move G1 X1 to check how far X really moves.

Keep adjusting your scale and repeating the above until you are satisfied the SCALE is set correctly.

When they are the fourth move G1 X0 should move X back to the exact starting point, if not the backlash is the difference between where you sent the axis and where it stopped.

To check for missing steps mark a location on your axis, make a number of moves at different speeds and then return to the mark if there is a difference you may be losings steps.

Rick G

Thanks guys, it'll be a couple days until I get some results. I'll keep you posted.

Thanks again.

Alrighty, its been about 2 weeks since I last posted. I was waiting for new pulleys to show up. The old ones weren't centerd drill properly. I got new ones that are drilled out to my motor shaft. The second thing I did was designed and added a few parts to create a belt tensioner. The X and Y axis is tight but not too tight. I did the LinuxCnC demo with a pen and all the lines are stright and the pen alwasy comes back to where it would start the letter hence it looks good. I also purchased a dial indicator and performed some test with the X axis setting, I adjusted the scale so that everytime I move it 1" it would go 1" in either direction I want exaclty.

Here my questions,

1.) Is there an easier way to change the scale during the stepconfg wizard (That were I'm changing the values)? Can I change the scaling in the main program?
2.) I can get the X axis to travel 1" in either direction perfectly everytime without losing steps. But using the scale that I calibrated for 1", if I want to travel 0.5", it would only move 0.4" eaxctly everytime. I know I'm not losing steps here (I think I'm not) because its repeatable, I modified a g-code demo to move the X axis 0.5" and back to 0 100 times and each time it would move it 0.4" and would return to 0 exaclty everytime. Am I suppose to calibrate the cnc for the capable distance that the X axis can travel? I thought that if you can get it to 1" perfectly then it should work out.

Any help would be greatly appreicated. Thanks again.

scale values can be changed directly in the ini file on a per axis basis SCALE =xxx shown under each axis heading
I notice in your previous posts your using 16th microstepping why so high ? . lower the microstepping and you may find a difference
people wrongly assume high microsteps gives better resolution .. , lower to 1/4 or even half and you may see a difference .

0.1" is a long way out , i'd recheck your microstepping value and confirm you have it correct .
slow everything down and recheck , it's best to check distances over 4 - 6" than shorter 1" , as the error accumulates the further you travel
so calibrate using at least 50% of your travel and see how you go .

belt driven i'd expect to get to within 0.01" reasonably well

Alrighty, been awhile. I got rid of the crappy chinese driver board and got a gecko g540. I performed a test to check for backlash and it was very minimal(.01).
So the question i have now is that if i can go 0 to 0.1 thou without any deviation and if i go an additional 0.1 thou and the dial shows its out what does that mean? Does that mean my scales out?

cncbasher wrote:

scale values can be changed directly in the ini file on a per axis basis SCALE
=xxx shown under each axis heading
I notice in your previous posts your using 16th microstepping why so high ? . lower the microstepping and you may find a difference
people wrongly assume high microsteps gives better resolution .. , lower to 1/4 or even half and you may see a difference .

0.1" is a long way out , i'd recheck your microstepping value and confirm you have it correct .
slow everything down and recheck , it's best to check distances over 4 - 6" than shorter 1" , as the error accumulates the further you travel
so calibrate using at least 50% of your travel and see how you go .

belt driven i'd expect to get to within 0.01" reasonably well

So the question i have now is that if i can go 0 to 0.1 thou without any deviation and if i go an additional 0.1 thou and the dial shows its out what does that mean?

Did you go -0.1 then 0 (to take out backlash)
set dial indicator
then go 0.1
read indicator
then another 0.1?
As cncbasher pointed out make large moves to check first.
If your table has say 12" of travel
G1 to the center (X6)
G1 back -5" (X1)
G1 forward 1" (X2) Mark that spot
G1 forward say 6" (X8) measure the distance traveled
Try at different speeds,
You can adjust the SCALE right in your config file without having to run Stepconf again.

As a side note you may be able to get more accurate micro step moves and smoother operation by adjusting the trim pots.

Rick G