Hi, While i have never tested a belt driven Z axis with a direct brake i did have some very good success with balancing the Z-Axis using a long expander rope. Basically i attached it at the Z carriage, and ran it up and down the entire Z axis a few times using pulleys. With the increased length compared to the Z axis travel, the force is fairly linear, and you can easily calibrate it to be "load neutral".

Cheers!

Hi, While i have never tested a belt driven Z axis with a direct brake i did have some very good success with balancing the Z-Axis using a long expander rope. Basically i attached it at the Z carriage, and ran it up and down the entire Z axis a few times using pulleys. With the increased length compared to the Z axis travel, the force is fairly linear, and you can easily calibrate it to be "load neutral".

Cheers!

Hi,
this may be an odd feature for 3D Printers, but for machines that also use a laser it may be useful, unless there is annother way of doing it already, that i have yet to figure out.

When Laser Cutting and hitting pause, there is a chance the machine stops during a travel move (in my case travels are a few moves, because its referencing the height each time on the material with the z axis prior to a cut which increases the chance of pausing during a travel), which is fine of course, but the problem is that either i setup pause.g and resume.g to turn off/on the laser and compressor as it should when pausing during a cut, but then it will start the laser early if resuming during a travel move.

A simple way to fix that may be to have a g-code that we can issue for times during which the machine may not be paused, so for instance that could be issued prior to a travel move, and then cancelled when starting the cut.

Not sure if this is useful for many people and its certainly not urgent, because after a pausing i can manually alter the resume.g file depending on the machine state, but that can be tedious when debugging the machine in general trying simple square cuts which basically give you a 50:50 chance of pausing during either type of motion.

Anyways, thank you very much for the awesome reprap firmware!

@dc42 said in Advice on adding plasma torch height control:

At the moment it seems likely that I will modify the firmware to support independent Z moves controlled by some sort of PID loop in February.

That would be a really great feature to have and open up a lot of room for experimentation. It may also be useful to be able to override the E-Axis as well through the same system, as that would allow closed loop control of pellet or syringe based extrusion systems where maintaining a constant pressure would be highly desireable.

I know that is not the topic of this thread, but if you do actually decide to implement it for the Z-axis, opening it up to also work with the extruders would be great. I would certainly like to use a feature like this!

Hello,
First off i would like to say a big thank you to the developers of the Duet Board and software. I have now used two Duet2's on fairly standard FDM printers and am most impressed, the firmware configuration and the webinterface are absolutely amazing, and no other option even comes close.

Now for my question,
i would like to drive a laser with the duet, and so far, there is no problem there, as like it has been discussed there are many ways of setting an output to a specific PWM rate for each line. But what i would like, because i have a very sensitive application, is to have a compensation of said PWM value for the current feedrate, so that if the machine slows down for a turn, the laser power is compensated/reduced. I am not sure if the laser mode does this allready, but i could not find a defineable minimum laser power on the g-code page, so that seems to be indicating that laser power is not updated for the actual speed of the machine (please let me know if i have simply missed that).

So basically what i am looking for is something like a "pressure advance" but for the laser. Is there any way of making this work with current stock firmware?

(counting extruder step timing is the only thing i can think of)

I realize this may be a bit of a niche application, but i am sure there is some benefit for people who want to vector engrave for instance.

Anyways, i am really greatful for all the work that you have put into the duet and its firmware!