Maslow Home Maslow Community Garden Newsletter

Okay, I've been calibrating for a month, time to ask for help

So, some backstory, I built the frame and about a week ago found out that my motor offset distances were not the same on the left and right side, but before adjusting it I was able to get down to 2-1.5 mm accuracy in Makerverse 1.1.2

Now I am hard pressed to get 3.5 or better, both distances are the same, waste board is 59.25" off the floor and level at 0 degrees, motor centers are 76 7/16" (76.4375) off the floor and level, so offset is 17.1875" (17 3/16) distance is 118.0625 (118 1/16) between the motors, my 12-o-clock chain length was 23.25", and I am using a metal precision ruler to measure down to the 32nd.

I can get edge calibration down to 1mm but I am consistently getting 0.875 measurements in two areas when they should be 1" +/- 1/32nd, upper left Y measurement, and Lower Center Y measurement.

I checked the holes distance to the floor and they are consistent on the top row at 60.75" on the Y axis,
but the bottom row seems to creep up from (left to right) 14.5, 14.65, 14.75, so I am looking for any insight that may you guys may have as to where I might have gone wrong?

Below is a picture of the last calibration that yielded 3.5mm

It might be worth looking into WebControl and the holey calibration process as a different approach

I gave it one more college try, main issue was I am attaching to brick so moving the board or beam is a bit of an issue, but I made a few new holes in the brackets and decided to scrap my original plan of measuring to the floor to get the distances and heights. Made sure the beam was level and the wasteboard was level and that wasteboard distance to beam brackets was the same, measured from the motor axis to the bottom of the beam, then the bottom of the beam to the wasteboard, got a new offset height of 17.19", ran the chain procedure, and the sled moved to the center point dead-on the money! Now to do the rest of the calibrations (again) and see how I did :slight_smile:

Alright, getting closer, at 3mm now, I noticed on the initial precision calibration both the top and bottom Y axis were both bowed inward, would that mean my motor distance is too short? Or offset to shallow? Or combination of both? So top Center was 0.875” when it should be 1” and same for the bottom

there’s not a 1:1 relationship between the shape and the particular parameter
that needs to be adjusted. (there is a topic ‘sources of error’ that goes into
details of all the possible errors). at one point we had a simulator that would
let you enter an error in a parameter and look at what the resulting curves look
like.

David Lang

The sled drag will cause some errors. Have you waxed it? Also, where are your errors the worst? I expect it to be the lower left and lower right areas where the X component of chain tension is minimal and therefore leading to higher X errors.