Low Speed for 3d Printing application

andypugh wrote:

Doogie wrote:

Machinekit has been all about the Beaglebone Black and derivatives.

They seem to have concentrated on that, but a a fork of linuxCNC it should run on anything that LinuxCNC does.

But don't give up on the LinuxCNC TP getting the upgrade. I am looking in to it.

I looked to Machinekit first and besides not having the rPi port imaged, I could have tried building it as I've created a distcc setup where I was building Machinekit on the BBB and my PC in something like 30 minutes. But the support forums and updates seemed to have greatly slowed down over the past 5 years. LinuxCNC still has a robust support forum and some active development besides having the rPi images. Seems like the place to be with Scott Alfords Remora. And had Scott not had it already set up on his 3D printer, I would have went right for the CNC setup with rPi/Remora.

One guy already has Remora working on his CNC and he's been able to do tapping. High speed spindle control and feedback is being worked on and tested so on the CNC side LinuxCNC/Remora is a big winner. With 3D printer support which works with all the slicers out there would be a big opening to exposing people to LinuxCNC.

So I'm not giving up on the LinuxCNC TP, just have to hold off on promoting it and Remora for 3D printers until something can be worked out to smooth out the warts. If you figure it out, please let me know.

Anything to make a LinuxCNC install and config less confusing for a newbie would be beneficial. Swapping axes is relatively straight forward once you understand the flexibility and configurability of LinuxCNC. But for someone starting from scratch... a disaster waiting to happen.

As for a forum section for 3D Printing. I vote yes. I've been printing with LinuxCNC since 2017 and without Google some of the good info would never be found.

They seem to have concentrated on that, but a a fork of linuxCNC it should run on anything that LinuxCNC does.

I thought that was the case, but robert nelson doesnt seem to be building machinekit on buster, and there is still an open issue in regards to buster on their git. when trying to install linuxcnc on a prebuilt scratch, I still needed to install everything first. It might be how I did/didnt/dont know how to/ configure the build, but it said I had to install tkinter/everything else , despite running machinekit already

IMO the beaglebone/cramps shield should have been the next evolution in 3dp but

But the GUI stuff is tough on the BBB

Everything is tough on bbb. I have a cramps shield from pico and its very well made, same with the bone. One of my machines still uses this setup. The graphics issue always seemed bs to me, so a few months ago I looked into it. The BBB claimed 3d accelerated graphics from the start, it was supposed to use PowerVR SGX530. Turns out there wasnt a driver for it until a few years ago, because closed source I suppose. Recently, one was release, so I thought I would try it out. First problem was machinekit prebuilt images are older than required for the new graphics driver. I wanted linuxcnc anyways so it didnt seem like an issue. First thing I notice, was how long the boot time has become now on buster 5.4 kernel. Some new math takes extra long in the boot, minor details. Then, I needed to change the screen resolution to 800*480, which was already painful to do on the bone. When I tried doing it this time, something with xrandr is broken now with the new graphics stuff/other things. So I couldnt even add a new resolution, which is when I decided to step away for a little.

@andypugh, just wondering if you've found any cycles to dig into this TP fallback to a single message buffer when a rotary axis' are enabled? ie when a 3D printer uses X, Y and Z for motion and A for an extruder.

would you happen to know a way to tell it is working or not?

I saw in the docs it is defaulted to ON if there are no entries in the [TRAJ] section but can't tell if that means no ARC_BLEND... entries or no entries at all and what if there's just ARC_BLEND_ENABLE=1?

Looking for ways to figure out if this is working or not on my Ender3 3D printer and need ways to see this if I were to start fiddling with things. Thanks.

how to tell if 3 axis blending is enabled on XYZ when A is also setup and what happens if instead of using A we used U.

Is the only way to tell if it's working is to create circle out of a ton of segments and look at speed with and without an A axis defined?

Sorry, I'm not but a beginner with LinuxCNC.

I went and created a circle in LightBurn and set it to fill the circle using Offset Fill which basically does a changing radius circle fill. I set the speed to 200mm/s.

I added a move of Z10 to the top of the gcode file to get it off the build plate and put all the ARC_BLEND_xxx defaults in my TRAJ section to be sure it was being told to use arc blending feature of the TP.
G64 P0.010 Q0.015 ; Path Blending to help fix rounded corners

I disabled the A axis in my hal and ini files and ran with arc blend enabled and it was running quite fast with over 110mm/s at the outer/larger circles. I disabled ARC_BLEND_ENABLE and saw it was running noticeably slower and only seeing under 90mm/s speeds on the DRO.

I added the A axis back to the hal and ini files and tested again. With XYZA defined and testing both with ARC_BLEND_ENABLE=1 and 0, what I saw on the DRO display for X and Y speed was under over 100mm/s with ARC_BLEND_ENABLE=1 and under 90mm/s disabled.

With ARC_BLEND_xxx commented out of the TRAJ section it operated as if it were enabled so the default is arc blending enabled.

So the 50 segment TP look-ahead buffer seems to be working for 3D printers(XYZA) unless this is operating this way because there's something I missed.

NOTE: I tweaked the config file for lots of speed and it was screaming fast with arc blend enabled. I used these settings to boost performance:

1) boosting X and Y axis and joints to MAX_ACCELERATION = 4500
2) boosting TRAJ to MAX_LINEAR_VELOCITY = 550
3) boosting TRAJ to MAX_LINEAR_ACCELERATION = 4500
4) boosting DISPLAY to MAX_LINEAR_VELOCITY = 550

fast config, hal file and gcode test file attached.