The build guide says to adjust to square using the pull off parameter in FluidNC, I am thinking why not use the adjustment screws on Y0 min, Y1min belt holders?
Is there an advantage of one method over another?
You can use the screws. But at the end you will still have to adjust the pull off to get it as close as possible. Most likely anyways.
Because you can use fractions of a mm to set the pull of by firmware. I guess it is really difficult to ve spot on by turning a screw
If you know the thread pitch (I think the M3 screws are 0.5mm/thread), then it is super easy to adjust by fractions of a mm.
1 full turn is 0.5mm, 1/2 turn is 0.25mm, 1/4 turn is 0.125mm, etc.. So if you need to adjust by 1.75mm, 3 full turns and one 1/2 turn will get you as close as you can get with the pulloff.
I used this method to check my belt tension. I issued a command to move the full length of the axis (from XMin to XMax, and from YMin to YMax, and measured the actual distance travelled.
Doing this, I found that my Y travel was about 2mm difference between the rail side (exactly correct) and the non-rail side (2mm short). I tightened the non rail side belt by 4 full turns, and both sides moved exactly the desired amount. I couldn’t tell just by feeling the belt tension that there was a difference in tension between the two.
Thanks all for the advice, I will start with screws and see how it goes from there, I would never have thought about calibrating Y belts so will double check that also.
The instructions should say use the screws to get you under 2mm, from there software might be easier.
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