Been playing with the extrusion multipliers for the Migbots..

3D Printing
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Been playing with the extrusion multipliers for the Migbots… I think this is close enough… xD

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What exactly is an extrusion multiplier? I’ve been checking dimensions with my printer and am finding that all dimensions are about 0.2 mm greater than requested.

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Exactly what it sounds like, it cuts the amount of filament extruded. Instead of pushing 100% if the value, it can push more or less depending on what you set it at. Mine was about the same, cut it to 95% or 0.95 and that’s the result… shame about the Z, which is about 0.3 out… but I’ll sort that later.

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Calibration of the extruder will eliminate the need for the basic extrusion multiplier.

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@Keith_Applegarth
Even with perfect calibration of E Steps filament diameter will vary enough from spool to spool to warrant fine tuning the multiplier for that specific spool.

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@Keith_Applegarth ​ all my printers are within 0.5 mm, sure I could get it exact, but desktop 3D printers aren’t precision machines. You’re also better off using the stock values for steps on X & Y due to the fact what could be 0.2mm on a small print will be greatly inflated on a large print. EG, if you take the X & Y steps down by enough to bring a cube to 20mm, you could end up under-stepping on a large print. This is why it’s better to use the extrusion multiplier over setting the steps/mm on X & Y.

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Ideally you want to measure the diameter and flow of filament leaving the nozzle for accurate extrusion calibration.

That’s not practical so we measure material feed ingoing and use an assumed relationship between the filament and nozzle diameters to calculate extrusion values.

Relying on those relationships and E-steps to establish extruder output is not entirely accurate. The use of an extrusion multiplier to compensate for this error and shrinkage is often required for high precision prints.

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@Ax_Smith-Laffin Fair enough. I haven’t experienced that myself on either of my printers… so I guess it’s YMMV…

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If you measure the block at a cooler temperature, will it be spot on 20.00?

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@Fred_U Not that I’m aware. That was a cooled block

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@Ax_Smith-Laffin I think it is labelled ‘Flow Rate’ on my printer display. Normally set at 100% and adjustable up and down. Thanks.

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Keep calibrating :slight_smile: I have a spreadsheet that calculates it for me. https://plus.google.com/+MichaelScholtz1/posts/MmewnNRtes5

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Good Job!

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A desktop 3D printer Homer Simpson can print a new gut as long as he gives up the donuts.