Hi, I have set up my configuration.h file, and all my axis are pretty accurately set; X, Y and Z all move 100mm when I press the '+100' button on the print page. I also set up my extruder to extrude 100mm when the length slider is set to 100. However, when I tried to print a minimug in celebration, loading it into Repsnapper and letting it produce the gcode, the extruder went crazy! Pumped huge lengths of plastic, and eventually pushed the Bowden cable out of the extruder with the pressure. Looking at the gcode, it expects to have extruded 271mm of filament by the end of the first layer. This is obviously far too much. What settings should I be using, or where have I gone wrong? I'm using Repsnapper r352M Darwin i386 on Mac. Is it expecting the length of extrusion to be 100mm, not the input filament to move 100mm?

I have just found the 'printer settings' on the 'print options' tab. I think this is where I can control this problem from. Any suggested settings?

I gave up letting Repsnapper create the Gcode and now create it with Skeinforge41 as it is so much more tunable and I get much better results. The settings I am currently using are

Skeinforge 41 settings
Here are the settings I am now using with a little help from various people on the Reprap forums and via IRC chat. I am currently printing myself a complete new set of gears so that I have a spare set.

Profile type – Extrusion
Profile selection – No 4 (I have several I just kept cloning them so I could keep track of changes)
Search
Version – 11.04.26

Craft

Bottom
Activate Bottom –– Yes
Additional height over layer thickness (ratio) 0.7
Altitude (mm) 0.0
SVG viewer webbrowser

Carve
Add layer template to SVG – Yes
Extra decimal places (float) 2.0
Import coarseness (ratio) 1.0

Infill in direction of bridge – Yes
Layer thickness (mm) 0.4

-Layers-
Layers from (index) 0
Layers to (index) 912345678

Mesh type correct mesh – Yes
Perimeter width over thickness (ratio) 1.8
SVG viewer webbrowser

Chamber
Activate chamber – No

Clip
Activate clip – Yes
Clip over perimeter width (ratio) 0.5
Maximum connection distance over perimeter width (ratio) 10.0

Comb, Cool
Activate – No




Dimension
Activate dimension – Yes
Absolute extrusion distance – Yes
Extruder retraction speed (mm/s) 50.0
-Filament-
Filament diameter (mm) 2.8 (measured with digital callipers)
Filament packing density (ratio) 1.0
Retraction distance (mm) 1.0
Restart extra distance (mm) 0

Export
Activate export – Yes
Add export suffix – Yes
Gcode small – Yes

Fill
Activate fill – Yes
-Diaphragm-
Diaphragm period (layers) 100
Diaphragm thickness (layers) 0
-Extra shells-
Extra shells on alternating solid layer (layers) 2
Extra shells on base (layers) 1
Extra shells on sparse layer (layers) 1
-Grid-
Grid circle separation over perimeter width (ratio) 0.2
Grid extra overlap (ratio) 0.1
Grid junction separation band height (layers) 10
Grid junction separation over octagon radios at end (ratio) 0.0
Grid junction separation over octagon radios at middle (ratio) 0.0
-Infill-
Infill begin rotation (degrees) 45.0
Infill begin rotation repeat (layers) 1
Infill odd layer extra rotation (degrees) 90.0
Line – Yes
Infill perimeter overlap (ratio) 0.15
Infill solidity 0.25 (good for PLA) Nopheads preferred setting
Infill width over thickness (ratio) 1.5
Solid surface thickness (layers) 3

Fillet, Home, Hop, Inset, Jitter, Lash
Activate – No

Limit
Activate limit – Yes
Maximum initial feed rate (mm/s) 75.0
Maximum Z feed rate (mm/s) 3.0



Multiply
Activate multiply – Yes
-Centre-
Centre X (mm) 100
Centre Y (mm) 100
-Number of cells-
Number of columns (integer) 1
Number of rows (integer) 1
Separation over perimeter width (ratio) 15.0

Oozebane
Activate oozebane – No

Preface (can’t be turned off)
-Name of alteration files-
Name of end file – end code.gcode
Name of start file – start code.gcode
Set positioning to absolute – Yes
Set units to millimetres – Yes

Your start and end codes are kept in the Skeinforge alterations folder

Raft
Activate raft – Yes
Add raft, elevate nozzle, orbit – Yes
-Base-
Base feed rate multiplier (ratio) 1.0
Base flow rate multiplier (ratio) 1.0
Base infill density (ratio) 0.5
Base layer thickness over layer thickness 2.0
Base layers (integer) 0
Base nozzle lift over base layer thickness (ratio) 0.4
-Interface-
Interface feed rate multiplier (ratio) 1.0
Interface flow rate multiplier (ratio) 1.0
Interface infill density (ratio) 0.5
Interface layer thickness over layer thickness 1.0
Interface layers (integer) 0
Interface nozzle lift over interface layer thickness (ratio) 0.45
-Object first layer-
Object first layer feed rate infill multiplier (ratio) 0.4
Object first layer feed rate perimeter multiplier (ratio) 0.4
Object first layer flow rate infill multiplier (ratio) 0.4
Object first layer flow rate perimeter multiplier (ratio) 0.4
Operating nozzle lift over layer thickness (ratio) 0.5
-Raft size-
Raft additional margin over length (%) 1.0
Raft margin (mm) 3.0
-Support-
Activate support cross hatch – No
Scale
Activate scale – No

Skirt
Activate skirt – Yes
Convex – Yes
Gap over perimeter width (ratio) 5.0 (prints a perimeter makes sure plastic is extruding)
Layers to (index) 1
(Initially I wasn’t getting a decent extrusion on the first layer of my prints so I added a skirt 10mm out from the print to solve this issue)

Speed
Activate speed – Yes
Add flow rate – Yes
-Bridge-
Bridge feed rate multiplier (ratio) 1.0
Bridge flow rate multiplier (ratio) 1.0
-Duty cycle-
Duty cycle at beginning (portion) 1.0
Duty cycle at ending (portion) 0.0
Feed rate (mm/s) 30.0
Flow rate setting (float) 30.0
Orbital feed rate over operating feed rate (ratio) 0.5
-Perimeter-
Perimeter feed rate over operating feed rate (ratio) 0.4
Perimeter flow rate over operating flow rate (ratio) 0.4
Travel feed rate (mm/s) 40.0

Splodge
Activate splodge – No

Stretch
Activate stretch – Yes
Cross limit distance over perimeter width (ratio) 5.0
Loop stretch over perimeter width (ratio) 0.11
Path stretch over perimeter width (ratio) 0.0
-Perimeter-
Perimeter inside stretch over perimeter width (ratio) 0.32
Perimeter outside stretch over perimeter width (ratio) 0.1
Stretch from distance over perimeter width (ratio) 2.0









Temperature
Activate temperature – Yes
-Rate-
Cooling rate (C/s) 3.0
Heating rate (C/s) 10.0
-Temperature- (I have been playing around with these
Base temperature (C0 210.0
Interface temperature (C) 200.0
Object first layer infill temperature (C) 220.0
Object first layer perimeter temperature (C) 220.0
Object next layers temperature (C) 220.0
Support layers temperature (C) 200.0
Supported layers temperature (C) 230.0


Tower, Unpause, Widen, Wipe
Activate – No







My start code is
G21; metric is good
G90; absolute positioning
G92 X0 Y0 Z0 E0; zero the extruded length axes

My end code is
G91
G1 F70
G1 E-10 F30000; sucks filament back quickly to stop ooze
G1 Z7 F70; lifts nozzle 7mm from finished print surface
G1 F2300
G1 X-100 Y100 F2300; moves print bed out for easy job removal
G90
M104 S0; turns off extruder

Thanks for the reply, I saw your settings in another thread but haven't got around to playing with Skeinforge yet as I work out the kinks in my build. Also, the Mac version seems a bit temperamental, so I'll have to install it on a WinXP Virtual Machine. I have managed to get the extruder under control now, and tried to build the mini-mug. After the first attempt (left of the three) I rebuilt my hot end and tightened up the belts, but something is still slipping. Any suggestions? Here's today's efforts:

are you slipping, or trying to move your X axis too fast, thus causing loss of steps?

Al...

Hi Al, thanks for the reply.
I'm using the Repsnapper's defaults for speed of 2300mm/minute (38mm/sec), no acceleration, which I don't think is too fast. This problem is caused by the X-axis somewhere, the Y axis seems stable. I need to check the belt isn't slipping, and remake the X-axis motor mount, as it is a bit low so pulling in one direction makes the belt tighter - because I'm not using toothed belts, belt crawl could be an issue. I could increase the current to the motor using the trim pots on the Gen6 board, but I only have a simple volt meter, not an ammeter - all trim pots are at the half setting, it seems, as supplied. Is it likely to make any difference if I turn it 1/8th of a turn?

I would say that it depends on the weight of your axis... increasing stepper current on Gen6 will have an effect, but the amount to move the pots is quite small, otherwise you need to actively cool the chips...

If you had toothed belts, I would have said you were not slipping belts because of the small offset of the layers.... but un-toothed belts are unconventional... I'd say too risky for FDM printing myself...

depending on your axis weight... It's possible you are skipping steps at the speed you are trying for... turn the speed down by half to check...

Al...

Thanks Al. I take the point about untoothed belts being unconventional! The X-axis is very light, as I'm using a Bowden cable, which causes it's own problems with ooze and hysterisis. I'm going to try homing and zeroing against the endstops on each layer first (damn, that means installing the endstops!), if that doesn't help I'll replace the belts and pulleys for toothed.

There are really good forums over at the wiki site as well. I have been using htem in conjunction with this forum

Same here, I've been posting in both.