Marlin intermittent extrusion problem [SOLVED]

Hello guys,

I've just uploaded Marlin firmware to my RAMPS 1.4, configured it and tried to print something.
However I've ancountered a strange issue - everything works, except that extruder not extrudes all the time. I.e. when it draws line it extrudes some plastic, then stops for a couple of seconds (but carriage keep moving), then extrudes some plastic again and so on.

It's not mechanical problem, because the same occured even without filament. And if I issue command like G1 E100 it will rotate very smoothly without any interruptions.

Any clues? Thanks.

Here is my axis steps: {78.7402, 78.7402, 200*16/1.25, 638.23}.
And this is an example of G-code:
G1 X84,820 Y83,550 E1,01119
G1 X85,060 Y83,360 E1,01829
G1 X85,320 Y83,180 E1,02562
G1 X85,580 Y83,010 E1,03283
G1 X85,840 Y82,850 E1,03991
G1 X86,120 Y82,700 E1,04727
G1 X86,400 Y82,570 E1,05443
G1 X86,690 Y82,440 E1,06180
G1 X87,260 Y82,210 E1,07605
G1 X87,540 Y82,100 E1,08303
G1 X87,830 Y82,010 E1,09007
G1 X88,120 Y81,930 E1,09704
G1 X88,420 Y81,860 E1,10419
G1 X88,720 Y81,800 E1,11128
G1 X89,020 Y81,750 E1,11833
G1 X89,320 Y81,720 E1,12532
G1 X89,630 Y81,700 E1,13253
G1 X89,930 Y81,690 E1,13949
G1 X109,850 Y81,690 E1,60139
G1 X110,150 Y81,700 E1,60835
G1 X110,450 Y81,720 E1,61532
G1 X110,750 Y81,750 E1,62231
G1 X111,040 Y81,790 E1,62910
G1 X111,340 Y81,850 E1,63619
G1 X111,950 Y81,980 E1,65066
G1 X112,260 Y82,050 E1,65802
G1 X112,570 Y82,140 E1,66551
G1 X112,880 Y82,240 E1,67306
G1 X113,180 Y82,360 E1,68055
G1 X113,470 Y82,490 E1,68792
G1 X113,760 Y82,630 E1,69539
G1 X114,040 Y82,790 E1,70287
G1 X114,230 Y82,900 E1,70796
G1 X114,450 Y83,030 E1,71389
G1 X114,660 Y83,160 E1,71961
G1 X114,870 Y83,310 E1,72560
G1 X115,070 Y83,460 E1,73139
G1 X115,270 Y83,620 E1,73733
G1 X115,400 Y83,730 E1,74128
G1 X115,590 Y83,900 E1,74719
G1 X115,780 Y84,080 E1,75326
G1 X115,960 Y84,260 E1,75916
G1 X116,130 Y84,450 E1,76508
G1 X116,300 Y84,650 E1,77116
G1 X116,440 Y84,820 E1,77627
G1 X116,630 Y85,060 E1,78337
G1 X116,810 Y85,320 E1,79070
G1 X116,980 Y85,580 E1,79790
G1 X117,140 Y85,840 E1,80498
G1 X117,290 Y86,120 E1,81235
G1 X117,420 Y86,400 E1,81951
G1 X117,550 Y86,690 E1,82687
G1 X117,780 Y87,260 E1,84113
G1 X117,890 Y87,540 E1,84810
G1 X117,980 Y87,830 E1,85514
G1 X118,060 Y88,120 E1,86212
G1 X118,130 Y88,420 E1,86926
G1 X118,190 Y88,720 E1,87636
G1 X118,240 Y89,020 E1,88341
G1 X118,270 Y89,320 E1,89040
G1 X118,290 Y89,630 E1,89760
G1 X118,300 Y89,930 E1,90456
G1 X118,300 Y109,850 E2,36646
G1 X118,290 Y110,150 E2,37342
G1 X118,270 Y110,450 E2,38040
G1 X118,240 Y110,750 E2,38739
G1 X118,200 Y111,040 E2,39418
G1 X118,140 Y111,340 E2,40127
G1 X118,010 Y111,950 E2,41573
G1 X117,940 Y112,260 E2,42310
G1 X117,850 Y112,570 E2,43059
G1 X117,750 Y112,880 E2,43814

Edited 1 time(s). Last edit at 11/10/2012 04:54AM by alik.

What temperature are you extruding at? marlin stops extruding when it thinks it is too cold to do so safely, so it's possible it's that. See if there's any chatter on the serial port. It could also be dodgy wires to the stepper. I had the same problem where one corner of my bed couldn't be printed in since that was the only place where the dodgy wire was stressed.

james glanville, I've commented out PREVENT_DANGEROUS_EXTRUDE to eliminate this possibility, and extruding at room temp (about 23C degrees). There is no strange messages in the console.
Also wires seems OK, but I'll doublecked.

It seems like when it need to extrude very smal amount of filament it not extrudes at all. I've also tried to set dropsegments to 1, but this has no effect.
I'll probably put some debug messages to figure out where is the problem.

Thanks for your response.

Finally I've figured out where is the problem.

The problem is in G-code - decimal fractions here is separated by comma symbol (',') but when Marlin parses number it expects point cymbol ('.'). So only first part of number (before comma) is accepted, and extruder rotates only when integral part of decimal fraction is changed.

G-code was generated by Slic3r, and I believe it generates commas because of my locale settings (in our country we are using comma as separator in decimal fractions). I've opened an issue about this.

Huh, good detective work, and something I never would have thought of.

James, thanks

I've also figured out that internationalization settings causing even more problems in Slic3r, the biggest one is that rectilinear infill generated as somplete mess.
As a temporary solution I've made simple script to start Slic3r with "correct" locale (I'm using Slic3r-git from AUR in Arch Linux):

#!/bin/sh
export LC_ALL=en_US.utf8
/usr/bin/vendor_perl/slic3r.pl

Hope this might be helpful for someone.