I’m thinking calibration process issues here.
I’m using a top-mount kit like the one pictured.
I just did a full calibration using v1.02. I checked that the motor spacing (3365.37mm) under load matched the motor spacing at rest.
That is a little wider than a stock frame (just over 11’), but not unreasonable.
whenyou say the spacing under load matches the spacing at rest, do you mean that
the distance measured here matches what you get from a tape measure, and that
there is no difference between under load and at rest ith the tape measure.
The rotation disk radius after the calibration (116.815mm) is the same as the previous time I did the calibration. This calibration gave 1905.2 on the first cut.
This value for rotation radius seems odd, as David’s esitmate for the value as 133.35mm or 136.525mm.
that is odd, 116.815mm is 4.6" and the horizontal links in the kit are 5"
This is an impossible value for this kit and means that something else was
measured incorrectly, and the ‘calibration’ is trying to correct for the error
(see more details below)
I’d like to see a diagram that shows just what is being measured here.
The rotation radiuks is the distance between the end of the chain (more
precisely the center of the hole for the pin at the end of the chain)and the
center of the bit. With this kit, this is 5" (the length of the horizontal arms)
plus 1/4" (the length of the master link that’s added to the chain)
but it’s not actually being measured, what’s happening with the current
calibration routine is that it makes cuts that should match if the yoffset
height and motor spacing are correct, and then ‘adjusts’ the calculated rotation
radius to counter whatever error you find. If the motor spacing isn’t correct,
then the rotation radius that’s calculated won’t be correct (I suspect that if
the yoffset value, the height of the motors above the work area, is wrong, that
will also throw off the calculations)
At any rate, the calibration test passed, so the machine should be accurate.
yes and not, it’s introducing error in one measurement to counter errors from
other measurements. The fact that it ended up with an impossibly small rotation
radius for this kit means that something else is off.
As a test, I ran 20" up from the center position and made a mark, then 40"
down and made another mark, then back to the center position. It returned to
the center position precisely. The upper mark, though, was 19 15/64" above the
center, and the lower mark was 19 47/64" down. Moving 37.5" to the left and
right to make the same pattern yielded similar though slightly different
results. The bottom marks lined up across the sheet, the left and right center
marks were 5/64 above the center mark, the left and right top marks were
19/64" above the center top mark. I pulled the sled down and vewrified thatn
then center of rotation for the
and this confirms that something is off.