OK
Thanks!

If you don't have a PanelDue connected, you can have the Arduino feed the GCode command into the PanelDue port. Either use a 3.3V Arduino, or level shift the signal from the Arduino down to 3.3V. By default the port uses 57600 baud and it requires line numbers and checksums on the command lines.

@Dougal1957:

Nice work but what with the banana lol

Obscure reference to reddit.

And, when you zoom in, it really does have a scale…

There's no risk.

Yes that looks current for a single PT100 sensor used to measure the hot end temperature.

Try 1000, and if that works well try 2000.

Great, thank you.

Hi Daniel, I have never seen a shorted heater cartridge, but it's not impossible and they are relatively high current, so the effect would be fairly unpleasant and possibly expensive (new duet board).

So it is worth avoiding, use some resistors in your sensor circuit or some other more sophisticated electronic protection (not really my area of expertise).

If you can crack the challenge of an affordable, conductive build plate then you have a winning product on your hands. Imagine a kit, in it there is a conductive printing surface which connects to a small PCB providing some protection, a trigger output to go to your controller and nice LED's, there is also a wire to connect to your heater block. Neat yes?

Conductive PEI is available but scandalously expensive. However other conductive sheets that you can print onto such as polycarbonate (with appropriate sanding) might be worth pursuing. Indeed most of these things have quite high resistance so the risk from a short is probably lower. One such conductive PEI can also be used as a bed heater, now we are talking convenient, but very expensive at this point in time.

That display should be electrically compatible with the PanelDue controller if you order it with the resistive touch screen; however the pinout of the 40-pin connector is different, so it is complicated to wire up.

I've been testing volumetric extrusion rates from 1.6 through to 3.4mm3/sec.

I'm beginning to think the opaque appearance is the polymer overheating. I had a filament jam late last week that was cause by over extrusion on the first layer blocking the path out of the nozzle for the polymer on the second layer. With a bit of a shove it started feeding again for the third layer, but in a white colour and almost frothy.

I'm currently thinking that;

Running slowly increases the time the polymer spends in the nozzle and it over heats and begins to bubble slightly giving an opaque appearance to the think walls, and white to the parts.

Running fast reduces the time in the hot end and so reduces the ultimate melt temperature, and makes clearer parts.

I've been increasing the nozzle temperature to reduce polymer viscosity, but perhaps the polymer is just particularly crap at taking heat from the hot end. Maybe a longer melt zone at a lower temperature would have the same effect without risking over heating the melt?

I had shear thinning floating around in the back of my brain but at the higher speeds, particularly on the thinner walls the parts didn't only look bad but there were holes in the walls, so if that was a thing for this polymer and I hadn't reached the extrusion rate where that occurs it was well in excess of where I am working.

Edit: Recommended processing temps were 230-250°C and the polymer does ooze out of the hot end at 230°C.

Edit 2: I think I may also be suffering with the polymer having next to no melt strength.

Brilliant! So glad it is fixed. And, now I have something to watch carefully when reading config files.

Like I said, I have one of those (with original controller) and Duet on other printers. So if anything else crops up, ask away.

Sharpie:
Duet boards run this specific RepRapFirmware: https://github.com/dc42/RepRapFirmware

See https://duet3d.com/wiki/Using_mesh_bed_compensation. If you are not using G32 and the bed.g file for anything else (e.g. delta calibration, auto bed levelling using multiple leadscrews, or the manual bed levelling assistant), you can put the G29 command in bed.g if you wish instead of G30 commands.

WOW!!!!!!!!!
I'm delighted about the electronic board and what you're doing!

The 5" screen displays a little more info than the 4.3" screen. The 7" is the same as the 5".

Let me get this clear.

If you select as tool (e.g. T0) and do a print, it extrudes correctly;

If you select the same tool T0 and then press the Extrude button on the web interface, it retracts filament instead of extruding it; and if you press Retract than it extrudes filament instead of retracting it.

Is that what you are saying?

Cool. Thanks

It has been suggested on the RepRap forum that I may have corrupted the EEPROM which certainly seems likely, that was the only thing which I had messed with before the trouble began.

The reply post simply said "… Run the 'clear eeprom' sketch in the arduino tools ... " , but I'm unable to find that in the Tools and it appears from Googling that it's not too tough to brick an Arduino if the method used to clear the EEPROM is incorrect.

Any tips on this?

Enough with the Arduino 8-bit stuff and Marlin, hard to wait until the machine running the Duet is finished.