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hercek
I'm not sure this is true. At the location most far away of a tower, the arm of that tower will have small angle to bed (in ybanrab situation about 24° which is not that small anyway). But the arms to the other too towers will have quite big angle to the bed (about 63°), those arms should take the most of the probing force (which is in the Z axe direction). Maybe this situation may be bad when the pairs of arms going to the same tower are too near to each other, but hopefully all people realize that the distance between arm pair should be as big as possible (within the design constrains of the effector platform).Quote
sheepdog43
Also, if you plan to auto level or auto calibrate, just reaching the edge of the build plate is not enough. The further out you go, the more flat one arm will be, leaving you little to no leverage to depress the probe. Even if you do have a little extra, I recommended not probing more than 75-80% from the center of the build platform to reduce wear and tear as it is VERY hard on your diagonals doing this.
An original rostock here does not have problems probing about 80% away from centre.
All three sets of arms are needed to hold an effector in place horizontally. If one set of arms is horizontal, they are no longer holding the effector flat and the effector can rock. It doesn't take much to throw off calibration. Yes, two sets are holding it down, but we have three sets for a reason. Take off a set of arms and you will see where the problem is.
When you calibrated your printer, remember how the print was bowl shaped? It's not linear, the further out you go, the worse the bowl shape gets.Quote
hercek
I do not understand why bigger printer would need bigger accuracy of parts barring the problems of frame/rod elasticity (probably what you mean by deflection).
So lets say your Kossel diagonal is accurate to within 0.04mm giving you great precision. However, in reality, you probably aren't perfectly flat. There can still be 0.01mm bowl shape in your print, you just can't spot it and it's irrelevant.
That 0.01mm bowl shape at 170mm wide balloons up to 10mm by the time you reach 500mm wide. You need to dial down to something like .0015 diagonal accuracy just to get a .01mm accuracy across the bed at 500mm.