Using the LCD knob to change extrusion multiplier on the fly

[gmay3]

Hey guys,

Like most of you, I often print from different spools and it's getting to be a chore to keep all my slic3r profiles up to date for each color since each is a slightly different diameter and I use different slicing profiles (infill variability, support or not support, etc.)

It's usually pretty easy to tell right off the bat if the extrusion multiplier is slightly too much or too little. I was wondering if anyone has tried or thinks it's worth a try to allow the LCD knob to change the extrusion multiplier on the fly.

This could also help with the calibration process by allowing users to get a feel for what happens is the extrusion multiplier is played around with without having to go through a lot of extra PC work.

[sniffle]

Hey guys,

Like most of you, I often print from different spools and it's getting to be a chore to keep all my slic3r profiles up to date for each color since each is a slightly different diameter and I use different slicing profiles (infill variability, support or not support, etc.)

It's usually pretty easy to tell right off the bat if the extrusion multiplier is slightly too much or too little. I was wondering if anyone has tried or thinks it's worth a try to allow the LCD knob to change the extrusion multiplier on the fly.

This could also help with the calibration process by allowing users to get a feel for what happens is the extrusion multiplier is played around with without having to go through a lot of extra PC work.

you know there is a filament diameter sensor in the works :-) i think that will be what fixes your problem i plan on getting one when the become more widely available.

[gmay3]

you know there is a filament diameter sensor in the works :-) i think that will be what fixes your problem i plan on getting one when the become more widely available.

Yeah I've seen a few versions of that type of thing but then my thinking is that I don't need it on the input side as much as I do on the output side. But there's no way to measure the filament diameter coming out of the nozzle.

You'd need a fine camera and algorithms, but I can just bypass all of that by looking at the print and changing the extrusion multiplier or output flow using the LCD knob.

I feel like an home made input measurement sensor isn't the solution as there are a lot of variables at play for what ends up coming out of the nozzle in the end. It would take forever to develop something that had good enough results.

[sniffle]

by having the filament diameter it extrudes a set volume of plastic which makes the filament extruded consistent

[Roxy]

I see some merit in this idea. It would be an easy way to adjust how much is coming out of the nozzle as it is doing different things like outside parameters or inside parameters for screw holes. And I don't see this as mutually exclusive to having a sensor that automatically sensed and adjusted the filament diameter. Even with that, I may decide for a given print I want a little more filament to force things to fuse harder????

Any way, it would not be that much code to do this. It would be pretty straight forward. But I can't help because I don't have an LCD panel. With out the actual hardware to play with, it would be hard to get the firmware working right!

[gmay3]

Sniffle, I agree to what your saying in theory but there's more to it than a single diameter measurement like we are doing with our calipers. Filament roundness, air bubbles within the filament, mismatch of automatic correction delay to filament slipping on the hobbed bolt, slight heat change of the hotend, hotend tube friction etc etc.

It's very possible that a input filament measurement system that changes the extrusion dynamically could make the print much worse then without it. It would be awesome if someone was able to do this with good results, I definitely encourage it. I'm just not going to be the one to do it

[gmay3]

Any way, it would not be that much code to do this. It would be pretty straight forward. But I can't help because I don't have an LCD panel. With out the actual hardware to play with, it would be hard to get the firmware working right!

That's encouraging to hear Roxy! Would the current print speed adjustment with the LCD pot code be found in Marlin? I'm wondering what the name of the variable in the code would be to identify an increase of flow out of the nozzle.

[printbus]

I played around with the extrusion multiplier (flow rate?) a bit on my LCD, but not enough to draw any conclusions from it. I don't remember seeing any difference, but maybe I was trying too small of a change. I seem to recall it was confusing in that there's more than one setting - perhaps an overall one and then one for each extruder if you have more than one? I started to look at the code to better understand how the adjustment factors in, but never got to the point where I had figured that out.

[sniffle]

speaking of... gmay on the devel branch of octoprint there is now a slider for flow rate and feedrate :-)

[gmay3]

speaking of... gmay on the devel branch of octoprint there is now a slider for flow rate and feedrate :-)

Oh very cool! I'd love to see how it works. I wonder if there is a M command to change the flow rate, that could also work.