Calibration
From Wiki
Process of calibration for RapMan is way of finding a relationship between head speed, extrusion speed and the temperature that will produce the correct thickness of the single filament line wall. You can read more about the process on the Tony's blog post. There is also a simple g-code generator of the test object available on Bogdan's site. It will create a simple 4 side object allowing you to measure wall thickness for the parameters you enter.
Contents |
basics
settings
The following settings affect each other:
constants:
- material used. Even the same material from the same supplier may have very different properties in different rolls.
- noozle-size (RepMan comes with a 0.5mm noozle. You can also order closed hot end that you can drill yourself )
you choose:
Depending on the resolution/print-speed -ration you want values from 0.25 to 0.5 are sensible. 0.35 is a good comprimize. Below 0.25 all sorts of additional problems will arise.
and:
The default of 1.8 is fine. This is how wide the filament should be compared to it´s height.
and either
- Speed: Flow rate = extrusion rate setting - how many RPM of filament get pushed out per time-unit
or
- Speed: Feed Rate - how fast the head moves per time-unit
interdependencies
If Skienforge simply set one filament on top of another, the contact area would be very small as the two circular sections touch only on the circumference. The result would be a very weak object with poor layer adhesion. To overcome this, Skienforge squashes the new layer into the preceding one to give a larger contact area and hence a stronger object. A Skienforge parameter is used to control this;
- Perimeter width over thickness (ratio) : default value 1.8
In this way Skienforge extrudes more plastic into the perimeter of each layer making the outer shell of the final print more robust. Internally the fill will be at 1.8 x layer thickness.
In either case the filament is printed as an elliptical section that has its major/minor diameter = the ratio.
This ratio is not controlled by skeinforge but you have to find a combination of settings that make this ratio hold true.
calibrating
1 read
Read Tony´s post on calibration. BfB made your machine and you should listen to their word on it.
2 calibrating temperature
See the Operations Manual on examples of too high and too low temperatures and how they manifest when printing the test-raft.
This topic is handled in the manuals quite well.
3 calibrating flow rate and feed rate
First position your head to be about "layer thickness" above the bed.
If you cannot meassure the height accurately, see the images in the Operations Manual for examples of prints with the head too high(curling) or too low(smearing).
Then Bogdan's test-object and meassure the wall-thickness of the uppermost layers.
Then meassure the wall-thickness of the upper few layers using a micro-lathe and compare.
It should be "perimeter width over thickness" * "layer thickness" .
If it is too wide, choose a lower flow rate or higher feed rate.
Repeat until you are satisfied.
