Major stepper motor trouble with ramps.

I am having nothing but trouble configuring stepper motors!

I have built a nice p3steel with a e3d v6 hotend. This is my first project of this type, but I have quite a bit of experience with buiding, debugging, hardware, software, etc. I build stereo tube amps and I am a Linux programmer for a Fortune 500. Not my first rodeo. lol

I have an overkill dell power pack capable of 18 amps at 12 volts. I have isolated by hot bed with another once of these power supplies and an electronic relay. I have both the 5 and 11 amp ramps power hooked up.

I have bought a few kinds of stepper motors, my latest exploit is the AMX 3d.
It is a 2amp 84oz hold with a nice cable. [www.amazon.com]
Btw the cable is wired wrong, so I found my coils with both the ohm meter method and the led method. They are correct.

1/32 stepping is too much for the Marlin firmware I am using. A current version downloaded a week ago.
I set my step to 1/16th. Just testing the Y axis belted using the following:

200 steps per revolution 1/16 so 3200
2 mm belt pitch
16 tooth belt

I come up with the following:
#define DEFAULT_AXIS_STEPS_PER_UNIT {100,100,60,60}

Don't worry about the other numbers, just Y.

I am using repetier host, I have the jumpers set to MS3 jumped others open for step, s/b 1/16th step.

I am using the DRV8825 drivers because of the more powerful stepper motors. (btw i used a smaller motor with the same results, fyi)
I set the vref to 1.1 v for roughly 2 amps. Tried other settings.

What I am seeing is that the motor can move sometimes, mostly in the right direction. But really erratic. jumps jerks whistles whines.
I can get it to behave for a bit changing steprate in repetier host. Setting is marlin.

I have replace my ramps board with 2 other version, both Chinese. Identical results.

It is really driving me crazy, as I cannot isolate root cause!
I understand that this is a little like standing on a beach ball. Lots of tweaking and adjusting. I just feel like I am shooting at a moving target.

All comments and help appreciated.

Have you tried to lower the max. acceleration and the speed?

Quote
enif
Have you tried to lower the max. acceleration and the speed?

Yes. It seems to change the things a bit. But nothing really repeatable, still rough starts, some stalls, buzzing.
That is the frustrating part. Going by the book, I should be getting close to a workable solution.
I have even tested the stepper motors on another know working device in my laser cutter, they work just fine and my pinout is correct.

The only thing I have not replace is the Mega 2560 Arduino knock off.
It seems to take firmware perfectly, boots great. But I am running out of ideas!

How far have you lowered acceleration and speed? I remember that the defaults for acceleration used to be way to high. So you should try to start with really small values...

I never had any success with the smaller values and the drv8825.
However, when I went back to a a4988 even on the 2 amp stepper motors, they smoothed right out like butter.
I replaced the big steppers with some .9 amp super high quality japanco stuff that I had on the shelf.

I think that the cheap ramps board never let me set the step jumpers correctly.
Keeping in mind that a4988 is all 3 blocks jumpered. I am of the opinion that when I tried to use a single jumper to set the drv8825 to 1/16th some of the other pins were shorted.

Thanks for the help. I am happy with the result.

If anyone else has an idea on the drv8825s I am all ears!

So it looks like your RAMPS has the same problem as described in this thread.

Yep.
I just checked both boards, unhooked ms1 is shorted on every axis.
Interestingly, ms2 and ms3 are open.
So when I was jumpering ms3 I had both ms1 and 3 both jumpered, effectively.
I could not get the drv8825 set to 1/16th step, just because of that fact.

Thanks for the info!

Actually I don't want to give out any misinformation.
There appears to be resistance across ms1, looks like it is hooked to a resistor and a cap, maybe as the ohm meter causes it to fluctuate as it charges the cap.
Starting of at 1.6m ohms and changing. It has polarity, because the meter reads minus when hooked up backwards.
So they are not shorted.