So this article, http://hackaday.com/2016/08/29/how-accurate-is-microstepping-really/, made me think about our drivers.
I need to start this saying I have never had an x or y axis power issue. This is just a cool test/explanation.
I have the means to easily test our drivers in series vs the tried and true parallel. The problem we have, and the reason I made the wiring harnesses in parallel is speed. The power advantage goes to series wiring until about 4000 steps /second, and then parallel starts to pull ahead. For us at 32nd stepping this means 20mm/s, above that and parallel is (should be) stronger.
We can very easily up this to 40mm/s by dropping down to 16th stepping. I know all the data says 16th should be stronger anyway, I can not tell a difference and opted to supply the directions and kits at 32nd stepping.
Here’s where some of you are going to not like my little experiment, the rub. To do the test I should have turned up the drivers to 1.4V for the parallel tests, but the drivers at that high of current output get way to hot to ship. So I did the tests like I would want to ship the boards, no active cooling required.
Now that that is out of the way. I chopped up a wiring harness and checked out series. I did it very scientific, almost as much as the article linked above. I put a pulley on the steppers and tried to fight the steppers with my Hercules like Kung Fu grip. Same steppers from the kit, Drv8825 driver set to .7V. I just swapped my doctored up wiring harness for the stock one. At 15mm/s series in very noticeably stronger. I tried it at 60mm/s, they still felt a little stronger. When active and idle they are still much stronger in series. explained by the .7v and not using 1.4V on the drivers.
So now what…Change everyone to 16th stepping and order new wiring harness? Leave it as is, because I have never had an issue? I didn’t expect this to be a very noticeable difference, wrong. Kinda cool that this thing just keeps getting better for no added money though right?
Easy to try yourself. Make sure you disconnect all power before unplugging a stepper, you’ve been warned. See the attached picture.