I’m using a ramps 1.4 for my build and my Z axis has 3 motors. Does anyone have a method to run 3 Nema 17s steppers off 1 driver? I’ve got it running now, but I had to turn the driver down drastically so it wont over heat (extra big heat sink and 100cfm fan already set up).
My current set up uses 3 geared steppers to adjust the bed level and move 1/4in tempered glass up and down.
This low current is hindering my z axis speed. I’m looking at 1mm/second. With Auto level compensation, a slightly off bed makes the print run slower than a turtle stuck on a glue trap!. On top of that, It’s a pretty large set up. 17in x 17in x 12in.
Depending on your supply voltage and the voltage of the steppers, you might be able to run all three in series instead of the more common parallel setup. The stepper drivers can then supply the full amperage to all the steppers. It will divide the voltage between them but if you have low voltage motors it should work.
I’m doing half step right now, may just go to full step. They are 19:1 on a 4 start lead screw.(8mm per revolution). Keeping them in sync is mostly just luck. With it being the z axis that doesn’t move much at a full step only throwing it off .002mm, I’m not to worried about it.
My PSU is a 12v. I wouldn’t mind pushing it higher, but I know I’ll need to mod the ramps. I also don’t know if the relay I have for my heat beds will operate off higher voltage. I’ve got 4 heat beds running off an HP proliant server PSU. It is cycled on and off with a relay from a Dodge neon lol
I’ll also need to check the specs on my motors before making voltage changes. But if I can, it may be best. I’ve added a 2nd motor to my x axis. This is belt driven on gt2 with a 16t gear, and would be more prominent to losing steps.
I’ll be keeping the x axis in sync after I make a couple of 5mm pillow blocks.
Edit*. I bought that controller for $12.99. I also had ideas of running stepper drivers in parallel. Dunno how well that would work out. If I recall, only 1 pin communicates back, and that’s due to over heating.
With an electronic that has extra drivers (at least 6 in total, X,Y,Z1,Z2,Z3 and E) and software that supports it, you could autolevel trough the 3 Z axis motors, that would be “real autoleveling”.
But to actually answer your questen, you could also “mirror” one z axis to the last driver (if you use a 1 extruder setup), this way you would have 2 steppers in parallel on one driver and the 3rd stepper on the last driver. The feature can be found under mechanics/z-achis stepper in the repetier online configurator, look for “Mirror motor signals to other stepper driver (FEATURE_TWO_ZSTEPPER)
Mirror motor signals to third stepper driver (FEATURE_THREE_ZSTEPPER)” https://www.repetier.com/firmware/v092/
I’ve got a dual extruder set up going on. The drivers in parallel would be… well all doing the same thing at the same time. I’d be nice if i did have individual control over the Z axis. I thought of methods to do this, with another Arduino that can control all 3 motors independently, but that would require communication between the 2. That shouldn’t be to difficult. But it’s beyond my ability.
Primary ardunio says move z 3 steps down, 2nd arduino tells the 3 drivers to move 3 steps down.
True auto leveling would need the communication between the both or a 2nd z axis probe/end stop. Letting the 2nd controller handle the z end stop would be simplest. It receives a signal, it replicates signal out and into the primary arduino. This would help keep it all running happy. The primary arduino would be none the wiser to this method. Of course, you wouldn’t want to leave it basic. If your already communicating between the 2, then you can have checks. “I sent you end stop information, did you receive that?”, If no, resend, if no again. pause/stop operation so you don’t crash.
@Mark_Rehorst Those drivers are not very reliable when it comes to small movements. I used that kind of setup with 3 motors, and it was a disaster. Spend a little more money on a leadshine digital stepper driver, and bob’s your uncle.
@Mark_Rehorst Well, I discovered this a while ago, when I noticed my printer didn’t do very well in printing the right height.
I was surprised to find out that when calibrating with a movement of 10 mm everything went perfectly well, and even movements of 1 mm turned out good enough. But after noticing oval holes in my prints, I tried moving the bed with steps of 0,1mm. 10 steps should be 1 mm, right?
Turned out to be only 0,8 mm. Most steps were less than 0,1 mm, and some more than 0,1mm.
First I thought it had to be a mechanical problem, but could not find anything… I switched from simple threaded rods to trapezium rods, but this did nothing. Checked everything, found nothing. Rotating the motors 200 steps at a time got me perfect 360 degrees rotation. Every time.
I rewired my 3 stepper motors from parallel to a serial configuration, which I should have done in the first place.
Tried all kind of settings in the firmware, but the problem persisted.
After a search on the internet I learned in a large CNC group that this kind of problem is common with those cheap Chinese drivers.
There is nothing wrong with the TB6600 chips, but that can’t be said of how they are implemented.
There are ways to improve the behavior of these drivers, which involves replacing some smd resistors, rerouting power lines an adding a lot of capacitors, but it is far cheaper and easier to buy better ones, like digital Leadshine drivers. Even cheap 4988 drivers are better.
Thats good info to know. I know my code is correct, the 8825 drivers are moving everything to the correct height. Once i get the new TB6600 driver, I’ll get it all wired up and check to see if everything moves accordingly. If not, I’ll tossing everything in series. If that doesn’t work, I’ll do my research on modifying it… AND if that doesn’t work, I’ll shell out the $55-60 for thew single driver.
With this thing moving half/full steps, i don’t think I’ll have much trouble. Even a cheap drive should be able to handle a full step.
It seems I’ve been giving the blame of my troubles with my Z-axis a little bit hasty.
After switching to other drivers, it seemed better. But it isn’t.
Something is wrong, but I don’t know what. I’m getting suspicious about the whole ramps/ arduino board setup.
Maybe it’s time to switch to something different. 32-bit. Or give up entirely.
I’m still waiting on that tb6600 to show up. As for the wiring, I assume i just use jumper wire from the ramps to the tb6600, matching up the signal to the ones listed on the 8825 datasheet?
I’ve tested the accuracy of mine a couple of different ways. Test cube, and a depth gauge/calipers. Set it to move 100mm and verified that it moved 100mm. Check it on each corner of the bed.
I received the tb6600, but have no idea how to wire up part of it. Connecting power and the motor’s isn’t a problem. Connecting it to the ramps 1.4 where the DRV8825 sat is where I’m lost.
The pins that get me are:
dir-
dir+
pul-
pul+
en-
en+
Also, will i need to modify any of the code? If so, which part? I’m currently running marlin.
You connect dir(action), pul(se), and en(able)- all to ground. The others should be obvious? Just compare the print on the DR8825 with wat you need to determine what pins you need.
Marlin does have some settings for Toshiba drivers, but experimenting with them never gave me better results.
I’ve got the stepper driver hooked up, but I still cant get it to move any faster than 1mm/second. It makes a grinding sound and doesn’t move.
I’ve tried changing the microstepping, nothing helps. I even tried increasing the step pulse to 10us, no dice(unless i did it wrong). I’m using Marlin.
On a side note, There’s no over heating drive anymore!
I’d imagine that either higher voltage, or less gearing would do the trick. I’m running 12 volts and this 19:1 gear reduction on those lead screws are probably just to much.
I haven’t dealt with the cross talk yet, I’ll get them twisted. Other than running next to each other for an inch or so going into the driver, they are separated.
The motors are connected correctly in parallel. At low speeds, everything in in perfect sync.
I believe the motors are rated for 1.6amps, so I’ll need 1.28a per motor, or 3.84 coming out of the stepper driver. Means ill have to mod the driver. Chinese driver.
