Missing Features in LCNC for FFF/FDM Printers

More
27 Aug 2021 19:10 #218935 by Roiki
That's because the extrusion rate is set in the code generation, just like feed rate in cnc. Both klipper and duet have overrides for extrusion factor overrides and speed overrides.

Please Log in or Create an account to join the conversation.

More
27 Aug 2021 22:27 #218943 by Doogie
FWIW, it's kinda nice having LCNC controlling the 3DP and laser cutter and eventually my CNC.  Sorta like: one ring to find them, one ring to bind them, One ring to rule them all.  Unless you like different control systems for all your different machines.  Just a thought.

Please Log in or Create an account to join the conversation.

More
27 Aug 2021 22:29 #218944 by scotta

I could think of some more drawbacks of Duet and Klipper and Marlin, but right now i am fighting the extrusion rate and that is something you can not change while printing, or at all as it requires stopping>slicing>start over>throw the partially printed part
Pretty sure that could be done in LinuxCNC during printing.

Why not use an external offset? I've been toying with the idea for pressure advance but we could monitor the A axis command and add / subtract a %. 
The following user(s) said Thank You: tommylight

Please Log in or Create an account to join the conversation.

More
27 Aug 2021 23:09 #218945 by tommylight

Pretty sure that could be done in LinuxCNC during printing.
Why not use an external offset? I've been toying with the idea for pressure advance but we could monitor the A axis command and add / subtract a %. 

That is exactly what i was thinking, on both accounts, but pressure advance would also require a delay between extruder and XY motion, not much important for direct drive but required for bowden as soon as you pas about 20 to 30mm/s depending on the length on the tube.
So sending the commanded position for X and Y through an adjustable delay should be easy enough.
Or am i overthinking this ?
P.S.
@Scott
I was just checking what else i need to print to finish your printer, started waaaaay back and bumped into some rail size issues ! :) Building a small one at 160x160x??? .

Please Log in or Create an account to join the conversation.

More
28 Aug 2021 09:06 #218973 by AlessandroT
Hello,

I actually manage the extrusion feedrate through a pressure control.
I linked the extrusion feedrate with the xyz nozzle speed, and I removed the A coordinate from the gcode.
Actually we are considering only the prints in spiralize (aka no retraction ) with this method, if not the post processor for the gcode should be more complicated.
The worst barrier in my opinion about lcnc and 3d printing is the trajectory planner that doesn't have the look ahead option for more than 3 axis.
The pressure control act as a workaround for it, reducing the number of axis from 4 to 3, but absolutely we need to develop a better tp for this specific aim.
I'm waiting with anxiety the Grotius job. I saw that he was working on a standalone version of tp that maybe could be the best solution for this.

Please Log in or Create an account to join the conversation.

More
28 Aug 2021 12:28 #218991 by tommylight
I think Andy mentioned somewhere using A axis as Z and using the Z axis for extrusion, should work perfectly but i do not have time to test it.

Please Log in or Create an account to join the conversation.

More
28 Aug 2021 12:53 #218994 by AlessandroT
This swap between A and Z axis should work if you are not printing with the spiralized method ( as we do because of very large nozzles) where the Z value is increasing constantly or in some fancy prints where you slice the object along curved surfaces instead of planar surfaces.
In general we need to use a different "tp" to solve this problem at the root, also because interruption or not smoothie extrusion behavior acts as very bad prints quality and strongly increased printing time.

The extrusion feed override is really useful, especially with different materials suppliers and differents material behaviours.

Please Log in or Create an account to join the conversation.

More
26 Sep 2021 00:28 #221592 by MartyJ

There pretty much no point in using lcnc when duet and klipper exist.

I have a Voron 2.4, but I also have a large CNC router. I would love to be able to throw an extruder on this machine and make some large 3d printed parts. Yes, it would be slow, but I know it's reliable, and it's paid off. And the ability to print on a 5-axis machine with LinuxCNC opens up some incredible print quality and topology optimization opportunities.
The following user(s) said Thank You: tommylight

Please Log in or Create an account to join the conversation.

Time to create page: 0.095 seconds
Powered by Kunena Forum