pulley ratios on 3 pulley axis

[Swarfing]

I played around with the ratio tonight and set it to 5.35 which brings it almost correct after some trial and error adjustment. I did this by measuring distance travelled etc. There is no screws on this axis just belts, i've set the drives at 16 microsteps (3200). definitely confident that it is not loosing steps as it will always return to point zero every time. Still managed to cut a few sample pieces which turned out rather nice in comparison to my old machine. I will spend some more time tomorrow playing with the ratio. I will rig up the DTI rather than judge by ruler which is what i did tonight. the belt is 5mm pitch, if you look at the pics it shows the end of the X axis. It runs with belt both sides powered by the single stepper (4amp bi parallel). Using PM542's on a Uniport V2 bob, kept to 5mm pitch screws on Y and Z. The Y has 24T pulleys 1:1 config and these axis are absolutely spot on

[Jonathan]

[QUOTE=2e0poz;22816]I played around with the ratio tonight and set it to 5.35 which brings it almost correct after some trial and error adjustment.

4.5*173.5/150=5.20 which is close to 5.35 ... doesn't make sense to me at this time of night though.

With 3200 steps per rev, and using 26.66mm per revolution as worked out in my last post that's 120 steps per mm.

Oh just notices, 5.35/4.5 is 1.188 ... i.e. very very close to 1.2, which is the factor the 24T pulley adds in. 1.2*4.5=5.4

So in conclusion try 5.4 and I bet it will be right...I'm not going to bet much though as it's getting late

[Swarfing]

Jonathan i tried 5.4 already and it was close but not quite. I will try again tomorrow with the DTI, i think sometimes we can only let the math get us most of the way there then rest is probably a bit of trial and error. i will set out a drawing to draw out markers, I have about 1300 cutting distance which is a large distance to loose on.

[Jonathan]

The difference between 5.35 and 5.4 is less than 1% ... I wouldn't be too surprised if there's that much error in the belt, particularly as it's quite long. I would definately try the DTI, or even attach digital calliper as that gets you 5 significant figures (unless your DTI is digital too). Digital calliper is not perfectly accurate, it will say the tolerances in the instructions. Either way it's better than a ruler which could account for the 1% error.

Note to self Read all the damn thread...........

There was only one post to read when you replied :lol: