Incorrect GCode From All Programs!

I have got to be doing something wrong here as I have tried to print the _40x10.stl for calibration and get:


Slic3r 0.7.2b & 0.9.7 (both produce the same output, just different paths):
- Feedrates for all axis and extruder are WAY to high. I have the default settings in the speeds section (30mm perimiters, 60mm infill) but the gcode is asking for F1800 on extruder, F7800 on Z and F1800 on X/Y.
- Not nearly enough filiment is calculated for the layer (between 3-5mm for each layer of _40x10.stl)

ReplicatorG - 0040:
- Feedrates are still to high on extruder (F1200) and Z (F3000) but xy is more reasonable at (F450)
- Way to much filiment in code (around 50mm per layer on _40x10.stl)

Skinforge (Latest from their website):
- Exact same as issues as ReplicatorG

My machine is running Marlin v1.0 with these settings:
HOMING_FEEDRATE {50*60, 50*60, 4*60, 0}
DEFAULT_AXIS_STEPS_PER_UNIT {24.6154,24.6154,1260.0000,405.2509}
DEFAULT_MAX_FEEDRATE {500, 500, 5, 100}
DEFAULT_MAX_ACCELERATION {2500,2500,50,1000}
DEFAULT_ACCELERATION 1000
DEFAULT_RETRACT_ACCELERATION 1000

Extruder is an accessible wades feeding 3mm filiment via a bowden tube to a 0.5mm makergear hot end.

So how the heck do these programs know how to calculate the extrusion speed to print speed ratio without knowing the speed parameters of your machine? I'm sure I could extrude at the requested F1800 if I was running a nema34 motor and a 240V hot end but I'm not and how does it know that??

Anybody know what I can start with? Thanks!

HOMING_FEEDRATE {50*60, 50*60, 4*60, 0} is mm/minute

DEFAULT_MAX_FEEDRATE {500, 500, 5, 100} is in mm/ second

change DEFAULT_MAX_FEEDRATE {500, 500, 5, 100}

to
DEFAULT_MAX_FEEDRATE {60, 60, 2, 45}


these are conservative values.

I think you are interpreting the values wrong. For a start I'm pretty sure F values are in mm/min so 30mm perimeters is F1800. Z speed should be limited in firmware so it really doesn't matter what slic3r spurts out.

Can you post a small section of your gcode, it will make it easier to explain.

[pastebin.com]

mm/min makes since that their that high. I figured it was /sec as that's what the program wants and the firmware uses...

As you can see from the link above my extruder is only putting out a tiny amount of filiment. I can extrude continuously as 220deg at my firmware max of 100 and it is calibrated correctly. I used Printrun and ran 80mm at 100 without a single skip.

A back of paper calculation shows those values to be reasonable enough. It's extruding about 0.02mm of filament for a 0.5mm move. So that's 0.02x1.4^2xpi = 0.123mm3 (1.4=filament radius)
Track is 0.5mm long roughly that wide and high so 0.5^3=0.125mm3

I'd recommend printing thinner layers than that for best results. You should print thinner than your nozzle diameter. Try 0.3-0.4mm layers

So I set my layer height to 0.3mm.

I can not print the 40x10.stl calibration object AT ALL. I barely get more than a few whisps of plastic layed down no matter what my settings. I measured some of the filament that oozes out of the nozzle and its 0.42mm,

So I switched over to one of the pieces from pocket tactics. I can get the first 5-6 layers to print before their isn't enough material to stick too and I stop the print. I measured the infill thickness (printed at 60mm/s) and its 0.25mm

I got my hot end unlabled so I think it could be a 0.35mm one? So I changed my slic3r settings to 0.35mm nozzle and 0.3mm layer heights and now after 5-6 layers the extruder just stops moving completely! I verified in the gcode that its asking for filiment but what the heck is going on now...

I personally would slow the print way down (10mm/s), turn of retract and stick to calibration objects until you can print successfully.
Once you can print reliably slowly, you can figure out what tweaks you need to make to print faster.
It's way easier to solve one problem at a time.

Are you printing PLA?
if yes do you have a fan blowing air over the thermal break of the hotend?
if no then that would be the first thing you should address, it is common for PLA to mushroom inside a hotend if the thermal break is not cooled resulting in it jamming.

I have a first successful print!

I had a fan on my hot end but it was causing my hot end to cool down between layers and the firmware was stopping extrusion. Once I turned the fan off I can print without much difficulty.

I got the pocket tactics "Cear" base piece printed with 0.2 layer height, 30mm perimiter and infill speeds, and 1.1 extrusion multiplier. It took exactly 60min to print.

Now the only issues I have to work out is the stringiness, which I think is going to be very hard with a bowden. And the gcode has the end of layer with the hot end on the one side of the part across all the layers so that one side has slight blobs and the PLA is discoloured.

i would active cool feature if you have it. slow down print , slow down print if more than 20 seconds a layer in this case, slower if your bowden allows it (usually only if retraction enabled) this will allow your print to cool while printing slowly at the top. also your exturder rate is slightly too high, and temp should be lowered a little more. i can tell because the upper layers were still too hot when completed. Also be sure fan is as close to pla cooling as possible.

to keep hot end from cooling down you can purchase some wool insulation door liner at a hardware store, and some high end electrical tape, the high end tape wont melt on the outside of the wool, the wool will provide a great temp barrier, wrap the wool around the exposed hot barrel and nozzle area, then tape it with electrical tape. if you have it tape it with kapton after that. you may need to change PID integral because heat loss will be slower. but it will keep warm if a fan is on it.

Edited 3 time(s). Last edit at 01/17/2013 12:59AM by jamesdanielv.

I took your advice, summery below.

- I got some fireplace door insulation and wrapped my hot end and kapton taped it up. Regulates the nozzle a lot better in general.
- Put a fan directly blowing on the part being printed, made a HUGE difference I think.
- Slowed the prints down to 30mm/s and printed two items at once so each layer would have a cooling break.
- Lowered the temperature 4 degrees

Below is my latest results: (left is newest)


The left most one was printed at 0.25mm layers, 1.1 extrusion, 210 degrees, 20mm/s and by itself. Almost no strings! only on the inside and their easily removed. It looks like I need to bump the temperature up to 212 degrees though as the middle section is a bit white and rough. The part next to it had a belt skip and was printed at 215 deg, 30mm/s and with a second object.

Anything else to recommend from what you see? And thanks for all the help, I was getting really frustrated...

if you are using slicer, up the flow multiplier for the bridge setting to say 1.3, also increase solid layers and set it to 4. it may be best to even slow it down more , it looks like the feedstock may also be slipping, if this is the case another thing to try. set first layer height to 0.3mm, set speed to 20% for first layer, and then set layer height to 0.2mm. this will also reduce flow rate, and also possibly improve the layer resolution. best of luck, glad it is working better for you!

Well I did some final tweeking and got an awesome print. I sanded it a bit to just even it out and its good enough I might even try giving it a paint job.

I tried printing some of the game tiles tonight and that did not go as well. I can print the 6 layer base perfectly but the patterns on each tile are a different matter. Slic3r's toolpath is so random that the head has a tendency of knocking off whatever tiny wall it had previously printed because the extruder likes to print in the middle, then a bit on the right and a bit on the left and a bit over there....

Oh well, I am happy I can print large objects without a single issue now. The detailed and small prints will take some more fine tuning.

Thanks again for all the help!

Just a thought, but 210 °C sounds very hot for PLA (although every colour/type of filament is different).
Could be that your thermistor reading is not accurate and you are infact extruding at a lower temp, but the white bubbles may be evidence of overheating the PLA.

To find the lowest extrusion temperature, try to hand feed the filament while increasing the temperature in 5 °C steps. Start from around 160 °C, which is usually fairly stiff. Note when the force needed goes down noticably. About 5-10 °C up from that point should be a safe ball park figure; not too hot, and not too cold. To fine tune, Triffid Hunter's advice is likely solid (I haven't tried it myself yet, but most people seem to agree).

/Andreas