ProfileMaker thoughts…

Looking at Dave’s Profileinator seems really well suited to a stepper extruder.  However, he also suggests adding a “Flow Fudge Factor.”  I just use this set to 1.0, so I’m not sure if I’m using it correctly.

Flow Fudge Factor: I have to enter 1.0 into the flow rate to get 2.0 RPMs on the extruder.. I got tired of doing this math so I added flow fudge factor and set it to 0.5. This doesn’t change the volume calculations – it just modifies the flow rate on the table. If you have a MK4/MK5 extruder with a DC motor, start this at 127.5 to get the PWM value to use

In any case, it looks like by multiplying it by 127.5 you can get the required flowrate for a DC motor.  In printing with a DC motor, I never wanted to drop the speed below 255, because the DC motor had such a small range of speeds.  I could print between about 230 – 255.  Given this, I can understand why so many others, probably using a DC motor, would rather pick their flowrate as 255 and then determine the proper feedrates.

3 Responses to “ProfileMaker thoughts…”

  1. Aaron Double says:

    Flow fudge factor has to do with the weird compression noticed in ABS. For some reason when printing in ABS the material compresses to about 85% volume compared to the volume of the filament going into the extruder. PLA does not have that problem and you should run it at 1.

  2. MakerBlock says:

    @Aaron: That’s what I’ve been using in the new development version. If you’re willing to help test it, I’ll give you a link. :)

  3. Dave Durant says:

    Actually, the flow fudge is because when I tell my extruder to do 1 RPM, it does 2 RPM. Or if I tell it to do 1.5 RPM, it does 3.0 RPM. Rob says it’s a firmware bug but I’ve been too lazy (and damned busy!) to track it down or use a different EC FW.

    Anyway, I set flow fudge to 0.5 and it tells me the values that *I* should use. If you get 1.000 RPM when you set it to 1 RPM, you should use a flow fudge of 1.

    The horrible named “gear swell mod” is for the ABS compression/volume loss/gear grab diameter/etc.. That’s the one that accounts for apparent volume loss.