Extruder calibration

Hi,
I am trying to calibrate my extruder. Does anyone know what length of extrusion the Extruder button on the Extruder control tab of the Rep-Reprap host software is programmed to eject?

thanks

Bob

No but whatever it is it will be a time or volume rather than a length. When extruding into mid air the diameter is a function of nozzle size, plastic viscosity and the flow rate so cannot be predicted by the software. The software controls the rate the feedstock goes into the extruder. The output will the same flow rate but the length will be determined by the diameter.

Only when it is being deposited on the bed at a particular head speed to you get a width and height defined by the software.

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[www.hydraraptor.blogspot.com]

on my system it seems to extrude for 5 seconds...

however i'm not sure if its setup by time or volume...

Hi,

Thanks for your replies. I was hoping to calibrate the extruder in the same way I did the axes. For these I measured how far the head moved when told to go a set distance, and made the appropriate adjustments.

In the configuration file there is a value to set the number of steps per mm of extrusion. If I knew how many steps were sent to the extruder by the extruder button, and moving the carriage horizontally so the filament was not dangling in the air, I was hoping to get a reasonable measurement of actual steps per mm.

I am assuming that during printing the extrusion rate = movement rate, ie the extrusion is not compressed or stretched. Is this correct?

thanks

Bob

It is usually stretched a bit so that it will span gaps. A good rule of thumb is to stretch it back down to the nozzle diameter. If you move slower than the extrusion rate it will form a wiggly line instead of a straight one.

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[www.hydraraptor.blogspot.com]

For me the best way to calibrate the extruder is to print a single walled test piece like [www.thingiverse.com], and measure the wall thickness.

Hi,

Many thanks to all for your advice. I will definately look at the wall thickness

Bob