Rostock firmware, uneven extrusion

Dear fellow rostock users,

I have just pulled off bodging up my slightly oversized Rostock Mini. I am running RAMPS 1.4 with the A4988 drivers and a G3D display.

I am running the latest firmware from [github.com], manually patched up with code from [github.com] to be compatible with the G3D display.

Everything seem to run fine BUT my extruder. The extruder seem to run in pulses. I don't really know how to explain it. Yet I'll try. Instead of an even ...step...step...step...step...step... motion of the extrusion motor, where it follow the motion of the extruder head, it runs umm.. a bit like ................step-step-step-step...............step-step-step-step..............

The overall amount of extrude seem to match my builds, the hysteresis of the filament coiling up within the bowden cable leads to a somewhat even extrusion after all, but the stepper motor definitely does not step evenly.

Anyone else experienced this, and knows how to hack the firmware to circumvene it?

Finally, attached is a photo of my Rostock Mini on steroids. 200x200x515 mm effective build envelope. Printing must be done fairly slow to avoid vibrations with such oversized platform. (15-20 mm/s while extruding, 100mm/s fast moves)

Is it just the extruder or also the axis motion.
The Marlin delta code does have an issue where for slow moves it tends to jerk horribly because it generates way too many small segments, and I think the motor interrupt starves the other processing. But this affects all of the axis not just the extruder.
Repetier also has a similar issue, but it's much harder to trigger.
In general the delta support in Repetier is better IMO.

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My blog [3dprinterhell.blogspot.com]

Dear Polygonhell,

I tried to reduce the computational load by decreasing the segments/second, but it did not alter the extrusion behavior. -Alas.

Another thing I've noticed is that my acceleration is quite fast. Slicing with Slic3r with a low acceleration, ex 500 mm/s^2 does not seem to alter anything. Is that because the firmware tries to accelerate to full speed over just one delta movement segment?

In terms of changing to repetier, as far as I can read on various forums, people have trouble getting the G3D LCD running. Especially the SD reader of the module, so that seem not to be an option.

Thanks for your input
David