Regarding the “stepper drivers” (I’m way out of my depth here so forgive me in advance if I use incorrect terminology) - What is the advantage of higher voltage? I went to purchase a RUMBA board, saw that there were options for A4988 or DRV8825 drivers - with the latter having 1/32 microstepping (instead of just 1/16) and being capable of higher voltage and higher current. It is described as a “higher performance drop-in replacement for the A4988 in most applications”.
What I REALLY want out of my drivers / steppers is ‘easy setup’ first… THEN ‘best performance’…
Is it worth looking into the DRV8825 drivers? +Whosa whatsis was saying something along the lines of “If your drivers and your motors aren’t matched they will have problems with microstepping properly” - and this may have caused ‘tree rings’ and other artifacts visible in printed parts?
This is the WEAKEST part of my knowledge, mechanics I understand… software I mostly get it… Electronics / steppers, I am starting to understand but, any help / guidance would be greatly appreciated!
Tagging @Whosa_whatsis cause it seems like your tag didn’t take. He explained it to me a while back in more succinct terms, but I G+ search doesn’t seem to search commentary on posts…
I don’t know if it applies directly to your situation, Jarred, but generally speaking, driving stepper motors from higher voltages means faster movement. Higher voltage counters the motor winding inductance. The current has to be limited to safe levels though, so either the pulse is shorter, or commonly a series resistor is used.
this could be fun to read. they were my early forays into what do these amperes and voltage drives mean for steppers. the tests are not exactly NASA standard, but the stepping errors can be seen. http://3roomlabs.blogspot.sg/2013/03/rsenser4-experiments.html
I hear a lot of the “pro’s” talk about using 24V or so, I just assumed it might be more desirable, but, I don’t want to add complexity to the circuitry… It’s sounding like I’ll just go for the stock 12V / A4988 combo. Speed isn’t a BIG priority for me.
I don’t necessarily want a big long post HERE about the difference either, but I can’t find any information that’s in a easy-to-understand format. If anyone knows of a good read related to steppers, drivers, voltage, amperage (relating to steppers, not just general electronics) I’d be very interested in knowing about it!
I’d at least go for the DRV8825’s. They’re more robust, and I’ve seen people pop the A4988s pretty easily. The ones from Panucatt are properly designed, and have the ability to be turned into digi-pot controlled that work with the new Azteeg Pro
People normally use a higher voltage for heated beds. The higher voltage will not change much for the steppers since they are really current controlled.
@Wylie_Hilliard Not true. A higher voltage on the steppers will lower their holding duty cycle (the duty cycle needed to maintain the set current), but when you want to move quickly, you need to be able to increase the duty cycle significantly to overcome phase inductance. The motion of the motor creates a reverse voltage that fights your current driver, so you need excess voltage on the supply side to overcome it.
to make things really simple, just make sure you adjust the trimpot on 4988/8825 to suit your stepper. and you of course need the stepper driver to be in range of your stepper (talking about the current sensing). some stepper drivers are sold to drive higher currents (tiny sense resistor, 0.05ohm?). some are fitted with larger (0.1 ohm? 0.2 ohm?). so basically before you buy, check ur stepper current limit, ask the seller if it is within the SENSE limit (not the drive limit of the chip, this value is a constant). ALL retail versions can drive anything BEYOND 1A, but NOT ALL are made with a larger Rsense resistor to handle/Sense smaller current drives.
(IIRC … i have tried mods up to 0R33 Rsense, the drive is really small but some stepper motors i have tried still could work on it because they are rated at very low current)
a stepstick made to drive/sense 4A (0.05ohm Rsense) is not good choice to drive a stepper that only needs 0.3A. you have no where to turn your VR adjust properly to get to the current you want accurately. a stepstick with 0.2ohm Rsense will allow you to adjust to 0.3A roughly 4 fold better.
@Whosa_whatsis you missed my point completely. While I agree that a higher voltage will allow a higher stepper speed without loss of torque, it is not possible to power many headed beds without a higher voltage power supply due to the rating of the connectors and FETs. Often the voltage of the power supply is increased just for that reason.
So, if someone were to be building an ingentis sized printer they would probably want to run the bed on higher voltage? I’ve ordered the power supply already, they’re not exactly expensive, should I consider a small 24v one just to run the bed?