I’ve been struggling in this days.
First, here my nice Z axis delrin nut. This was supposed to be split type, but I get (luckily) a perfect fitting so it wasn’t required. I grind my own threading bit, not bad for free hand.
Turning the Z axis knob feels very soft, better than my manual mill. I’m not interested in measuring backlash by now, so please don’t ask. I also did a delrin nut for the X axis… but I’m still pissed because a stupid error, so I will not show it (seems to work well, though). Just remember…. when threading, always check a table with drill sizes for both, steel and soft metals, like this.
Later, when I test X and Z axis, an annoying idle-motor noise made me pissed again (not near like this, luckily). All the world says that microstepping it’s noisy and you should live with it, but what annoys me was the fact that when I connect only one motor, there was no noise at all. After some fighting with a hammer against my crappy controller, I was able to eliminate the noise (better said, doing it almost inaudible) doing two simple things:
First, I connect the ground from the 5V supply to the ground of the 24V supply (brown cable). Seems I misunderstood STK672-050 datashet, which says you can use separated grounds for logic and power supply.
Second, I add a ferrite bead to the supply wires of every board. Seems to work better with at least a turn. I will bought a bunch on eBay (not snap type, just plain toroidal).
Nevertheless I should note that I’m driving the motors at 2.5A, not 3A as it should be, so maybe I find some noise later, but it’s ok for now. Please remember, I’m talking about idle motor noise; running motors will always do some noise.
I was easily able to get 70 IPM’s, seemingly without losing steps. I hope to do more testing once the whole thing get finished.
Just a last thing… using a laboratory regulated supply I found that when I set a current at 2.3A, the current draw from the supply, for the Z axis going up, was 1.25A. Not a surprise, but an interesting empiric data.