All the cuts I’m discussing in this post we’re done in the center of work area.
I picked up the Maslow kit, had it running. But the vertical accuracy was off. Percision was good, all the lines were clean enough. But I was losing almost 3/8" in the vertical. Horizontal was bang on.
Then I fried my v1.2 shield due to a unattended jam. @Bee was a friggin lifesaver and FedEx overnighted me a TLE5206 v1 he had(couldn’t wait for the new one).
So now I’m back up and running. I start the calibration. I extend the chains. I hook the other motor. Retract. Bam. Chain pops off sprocket. Again. Same thing. Next time I left it too loose. Third time I got it to grab and hold.
It set my measurement at 3000.71. So then I tried to understand how the calibration works. If the Maslow received no info from motors. Correct me if I’m wrong @bar but does that mean this number is based on only the fact the chains didn’t pop off?
Not satisfied with that measurement. I 3D printed a tape measure holder with magnet that attaches over the motors axis. With a tape guide and center point on the other axis. My measurement was 3006.50.
With that I cut my sled again. Last sled was an 18" circle. That was more like 17 5/8 x 17 7/8. This new was was like 17 15/16 horizontal and 17 13/16 vertical!
We’re moving in the right direction!
So where do I go from here? Do I keep cutting sleds and measuring? What other settings can I mess with?
In my case, made a new sled following the “by hand” instructions, which improved things considerably. My chains do not match in length, so I purchased a long enough section that I can get 2 pieces from one lot, which hopefully will result in a matched pair. Since I am replacing the chain, I also raised and widened the top beam to 12’ using heavy duty super strut from HD. This weekend I will find out if all this helps.
Maslow does receive information from the motors through the encoders so it is using that information to make the measurement.
This is the big outstanding question right now. We know that the chain will consistently measure a few mm different than a tap measure, probably due to the accumulated play in the chains adding up, but we have not found a good way to correct for it that consistently improves accuracy.
Here’s another question that I’m sure a solution to could improve the accuracy of my machine: my sprockets on the top motors have a little play in them. I have the set screw on the flat part of the motor shaft and tightened as much as i can by hand without fear of bending the Allen wrench but both sprockets will still rotate a degree or 2 each direction. I can’t help but think when trying to get one tooth perfectly vertical during calibration that my accuracy is suffering.
So the question is this: is the play normal? If it’s not any suggestions on getting rid of it?
There is a small amount of gear lash in the motor box, but the fact that the weight of the sled exerts a constant pull in the same direction cancels it out. This assumes that the tension on the ‘slack’ end of the chain is less than the tension from the sled, though. Using a strong bungee cord or a large counterweight in the slack management setup could spoil that assumption and bring the gear lash into play.