Moire?

Using DRV8825 in 1/32 to drive extruder with MK8 gear. Running 24V supply. Could this be the decay issue with these stepper drivers?

Notice how the first 4-6 layers are perfect. The rest are messed up.

Edited 1 time(s). Last edit at 04/20/2016 12:02AM by MrBaz.

That can be anything really, is the print quality better at lower speeds?
What board are you using Mega, Duo, something else?
The Mega is pretty much limited to 10000 steps/s, with your high stepping rate you might need a faster CPU for decent speed.
What is your stepping per mm?

Great photo! What did you use to make it?

That looks a lot like the stuff caused by the 8825 decay mode problem others have reported. Try adding the diodes and see if it goes away.

It may also be over-extrusion. See if reducing the extrusion multiplier changes the way it looks.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

This was printed on a Delta at 50mm/s. Rumba electronics.

Took the picture using my cellphone believe it or not. It is just a 100% crop.

I was thinking of trying to force the driver into fast decay mode.
How does the diode mod (I've read the blog about it - very interesting) differ in performance to the fast decay hack?

There is a link to the article on #26 on this page that talks about it what fast decay can do, and the diode fix. Not sure if that's the same article you've read.

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My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
Can you answer questions about Calibration, Printing issues, Mechanics? Write it up and improve the Wiki!

So I tried the diode fix, but something is not connected correctly. The extruder doesn't work at all now. Which woes do I connect the does to?

You want a set of diodes in-line with each coil, so as long as you get different coils it doesn't matter exactly which wires you use. I used the two outer wires when I did mine.

Quote
JamesK
You want a set of diodes in-line with each coil, so as long as you get different coils it doesn't matter exactly which wires you use. I used the two outer wires when I did mine.

This is exactly what I thought. I made sure they were on two separate coils, which also happened to be the outside two wires for me as well (Black and Blue).

The rest of the printer moves. I can home it and move it around just fine.

When I tell the extruder to do any movement (forward or reverse), all 4 motors make a weird ticking noise that can be 'felt' when touching the other motors. What is this? I used 8 1N5408 diodes per stepper motor (just like his config where I have a counterparallel of two in series per phase/coil).

Do the 1N5408s provide too much resistance? Should I try just hooking up 2 diodes in counterparallel per phase?

Should be fine. I've had it working with 1N5404s and with 1N4001s (even though those are under-rated for the job). I managed to mis-connect the diodes once, putting them in parallel instead of anti-parallel. That had symptoms that sound similar to yours, so maybe worth double checking the configuration.