A4988 Black edition?

Hey everyone,

I just burnt out a stepper on my RAMPS trying to get my z-axis moving. Rookie mistake, but thankfully the drivers are easy to swap out. What I was wondering is if anyone has tried the "Black Edition" of Pololu's A4988 stepper, as described here. They're an extra $4, but it would be nice if they really are noticeably cooler than the standard ones.


Thanks a bunch,
Chris

Well, since I haven't heard anything, I went ahead and ordered a few. I'll report back for anyone who's interested.

In case anyone is curious, I have been playing with the drivers for the last hour or two, and I've been pleased. As promised, they're drop-in replacements, and can run a bit faster without overheating. I've been able to bump up my z-axis speed from 1.5 mm/s to 2.5 mm/s without having issues with the thermal cutoff from the chip. I've turned up the pot so that the voltage at the tap on the PCB for the stepper reads 0.90 V (with a fan blowing on it), and at that level the green A4988 will burn out (trust me). It's not a big enough difference that I'm going to replace all my drivers at the moment, but for now it's a great replacement for my z-axis, and I have a backup if one of the others dies.

Ive been looking at some of these or the new purple ones from pololu. Ive burnt out a couple of mine recently, I had one spare, now I'm 1 driver less then what i need.

At +$4 or even +$8 per stepper driver its a small price if the risk of burning out a stepper driver is significantly reduced.

There are a few other driver around though that also interest me including Royco's stepsticks at Panucutt, again better heat dissipation and more copper in the board.

What was the time like between order and delivery for the pololu's and how far did they have to come?

As an interim measure I have ordered a set of stepper drivers from RRD because they were cheap and I knew they would get here quick, but if I keep burning them out because I like to print fast, and there isnt much room for error once they get over hot, then I will probably buy beefier ones next time,

FWIW RRD (reprapdiscount on ebay) have refunded my money on the purchase and are sending more stepper drivers, personally I am pretty sure it was my action that burned out my drivers, but he is still willing to replace them for me free. A supplier who stands so solidly behind his products is a rare thing, I will certainly continue to recommend him to any who ask me.

GaZ

Edited 1 time(s). Last edit at 11/18/2012 10:44PM by gazob.

I think the purple ones with the Texas Instruments chip are not quite drop in replacements, but I seem to recall reading somewhere that the modification to be able to use them is minimal--if I remember to look it up tomorrow I'll post the link here for reference.

As far as shipping is concerned, they were wicked fast. Shipped within 24 hours, as promised on their site, and shipped from Nevada. There were a bunch of shipping options, and Postal Service Priority was the second cheapest, so I went with that. It got here (all the way across the country to the Carolinas) in two days, so the turnaround is nice and quick.

Also, it's worth noting that the voltages I'm running at are a bit above the rated max voltage for an uncooled chip--I am using the Ultimachine heat sinks and a small fan to cool them.

what voltage are you running?

Testing the voltage on the small tap on the boards I get 0.60 V for the green controllers, and 0.90 V for the black editions. From what I understand from reading the Pololu catalog page about the boards (the section on Current Limiting here), this means the current limit for the motors attached to green controllers is 1.5 A, and for the black 2.25 A. Which, as I was double-checking this, I realized is slightly over the rated max for the IC.

Crap.

After Turkey Day I'll double check all this and make sure I'm not sending my sparkly new stepper drivers to an early grave. Luckily I'm not printing yet, so I haven't run it extensively at this speed; I've just been tweaking Pronterface settings and making sure I understand all the different gcode commands.

oo ... black edition ... the 1 with dual VR? yes?

well my cheapo china A4988s dont work well with my motors. it happens that A4983 with 0.2ohm sense are so much more reliable in terms of very nice 1/16steps achieved. in terms of heat sinking, i have managed to improve heat transfer by super-gluing the heatsinks instead of the stock tape etc. anyway. i have destroyed 4 A4988 from RRD, and i dont think i will use anymore of those from them.

have any of you using A4988 tried testing the 1/8 or 1/16 step resolution? this is what i did to test the stepping

i be interested to know if any1 try to recreate their own stepping test.

Edited 1 time(s). Last edit at 11/23/2012 11:38AM by redreprap.