Today we are gonna talk about slicing configuration to properly use PLYUMP.
First thing to know is that i use Skeinforge for slicing. Skeinforge might be not the latest or the easiest, but definitely gives enough flexibility to do almost anything with your GCode.
Important to be noticed too, is that there is no perfect mathematics to get the right configuration; lots of iteration, try and error to get the right prints.
Each material needs its own profile. So i am gonna introduce the steps to follow in order to approach a good configuration (by good i mean decent).
Look for a continuous model with just one “line” per layer (this means completely solid design and with just one part). This is mandatory to avoid worrying (for now) about retractions. I like to use open hardware logo. Also is important to use a model with really small height to reduce the amount of layers, remember that gravity won’t allow big 3d structures unless third party variables come to play (temperature, light, …).
Start from a profile that works for abs or pla.
Disable retraction (Dimension).
Make sure all:
Speed > - Object First Layer -
Equal to 1. This keeps first layer speeds equal to whole print.
Reduce the flow rate to a pretty low value (for example 5mm/s).
Speed > Flow Rate (mm/s)
Try a print. Observe pulsation during the print (discontinuous line).
Start increasing the flow rate until you get continuous perimeters.
don’t worry if once the print is finished the nozzle leaks.
At the same time you need to “adapt” your feed rate to get a “thin” perimeter. “Thin” means getting the right layer height.
Speed > Feed Rate (mm/s)
Obviously you can modify too:
Carve > Layer Height (mm)
But i highly recommend going just for feed rate first. Tweaking two parameters at the same time in Skeinforge is deathly. Especially Carve parameters (which normally affects other parameters).
Next step is working out retraction in order to be able to do different perimeters within same layers without “leaking”. By leaking i mean the tube-reservoir-pressure released after the pump is stopped.
Retraction will highly depend on fluid viscosity, lower viscosity needs more hardcore retraction values.
For fixing retraction a model with letters works perfectly.
Retraction is configured with:
Dimension > Extrude Retraction Speed (mm/s)
Dimension > Retract Distance (mm)
Set speed to 15mm/s. And restart distance to 1mm. From here on is a matter of (again) trial and error.
Once you have fixed “leaking”. After restarting you see pulsation again, increase the next parameter (slowly).
Dimension > Restart Extra Distance (mm)
To get an infill, we cheat. The reason to cheat is because i actually never measure how many liquid volume is print. For perimeters doesnt matter because the difference is just a thinner or thicker perimeter. But for infill it does.
Infill > Infill Solidity (ratio) = 1
You would understand what i mean.
How to go around this issue. Increase infill slowly steps of 0.05. Until more or less you have a total infill. Use infill line grid type.
if you see that you are deforming perimeters without getting a proper infill. Try giving negative values to:
Infill > Infill Perimeter Overlap (ratio)
/*** NOTE ***/
If you want to actually properly quantify your print and get a proper dimensions for everything i recommend starting from:
Carve > Edge Width over Height (ratio)
Carve > Layer Height (mm)
Don’t expect perfect results, start step by step (TRIAL&ERROR). Properly setting up the slicing parameters is by far the most difficult part of using PLYUMP.
I am sorry to not have come up with a better solution for this, i hope future improvement does. All this problems i hope it will be solved in future versions.
Ok, next post will be the last one! Conclusions and further development!