Extrusion % Chage between layers

[simplifyguy]

Hello Everyone.
I have a printer with a bed that changes in elevation by more then 0.01" between the two ends. This can't be adjusted. What I found is that if I print the first layer at 120-150% extrusion I get a solid adhesion to the bed and the parts come out great. This process requires changing to 100% extrusion once the first layer is completed.
To the question:
Could I get help with the code required for my printer to do this change on its own?
The process would be.
Set extruder to 150% and start printing first layer as normal.
Shift to layer 2 change extruder to 100% and continue printing.
Finish print.

Thanks

[brian442]

If you have to extrude more for the first layer, than that means your nozzle is starting too far away from the bed. I would recommend just using the global z-offset on the Gcode tab. Enter -0.1mm or -0.2mm to move the nozzle closer (which will fill in the extrusion lines)

[upsm]

I have a printer with a bed that changes in elevation by more then 0.01" between the two ends. This can't be adjusted.

What frame are you using? Cartesian or delta? This can usually be fixed with minor changes if the frame is not bent, if you have warped print bed or bent axis then it gets very hard to fix.

Set extruder to 150% and start printing first layer as normal.
Shift to layer 2 change extruder to 100% and continue printing.

Did you try with width/height of the first layer? (First layer settings on Layers tab)? Setting first layer width to 150% and height to 60% or something similar might solve the problem of uneven print surface. Generally the solution for uneven print surface is RAFT, you print raft that's able to survive uneven surface and then you print your object on raft. The bottom surface is not as perfect but it gets flat.

If the width/height/speed of the first layer don't work (I think it should, I had similar problem and was solving it with 10mm/sec 150% and 80%, then I straighten my axes and put glass on bed so don't have the problem any more) then you have to inject the code to change e-steps-per-mm into G-Code after the G-Code is generated. You can use replace function of Simplify3D postprocessing or do it manually (there's visible comment when the layer1 start, layer2 start etc, search forum for REPLACE you'll find examples) so depending on what firmware you use you need to insert different commands. For example if you are running Smoothieware (or Marlin, Sprinter, Repetier) something like this in postprocessing script should work (assuming your E steps per mm originally is 100):

Code: Select all

{REPLACE "; layer 1," "M92 E70\n; layer 1,"} 
{REPLACE "; layer 2," "M92 E100\n; layer 2,"} 

It will inject before first layer M92 E70 to lower your steps-per-mm for extruder axis so firmware will send more impulses to stepper driver and extrude more plastic, then before layer 2 it inserts M92 E100 to return your steps-per-mm for extruder to 100 ...
You, of course, have to first find what your steps-per-mm for your extruder are now so you know how much to lower for layer1 and to what value to return for layer2. Some firmware's (RepRapFirmware for e.g.) will return this value if you send blank M92 without parameters, some, like sprinter, support M93; on others you can read this from config file or send M503.