M305 Thermistor Values for the Duet Maestro on the Ender 3 Pro?

[Veti]

@punamenon said in M305 Thermistor Values for the Ender 3 Pro?:

The equation you gave me uses the 4700 value.

that is correct because the marlin table is for a resistance of 4700 which is present on nearly all 8 bit boards. so to convert it you use 4700

[Veti]

@punamenon said in M305 Thermistor Values for the Ender 3 Pro?:

M305 P0 T97700 B4619 C9.743561e-8 R4700

again you specified R4700. that is incorrect for the duet maestro

[punamenon]

@veti @dc42 @deckingman

Thank you all for your input and help! Here is my conclusion for anyone else finding this thread and needing an answer:

The following settings using veti's method work:
M305 P0 T97700 B4619 C9.743561e-8 R2200
M305 P1 T97700 B4619 C9.743561e-8 R2200

The following settings using dc42's numbers also work:
M305 P0 T98801 B4185 R2200
M305 P1 T98801 B4185 R2200

I'm guessing that anyone using run of the mill thermistors from China (purchased on ebay or aliexpress, etc) with a Duet Maestro board will find these settings to be functional. I notice little difference between the settings from dc42 and the ones from veti. They vary from each other by only about 2°C at the high end (ABS printing temperature), and they completely agreee/match at room temperature. I'm going to go with dc42's numbers as he explained he was correcting for a rounding error, so potentially more accuracy there. All of this is assuming that the original numbers from the Marlin table were accurate.

Disclaimer: I'm measuring the bed temperature using an IR thermometer which gives varying readings +/- 1.5°C. The accuracy of the Thermometer is also questionable (+/- 2.5°C?). I have no way of accurately measuring the temperature of the hotend. To gauge this I'm manually forcing ABS Filament through the nozzle. While I haven't gotten my fingers calibrated recently, I am comparing the feel of this to the same filament going through my other printer which is properly calibrated for temperatures, and has the same size nozzle. Given these constraints, my conclusions are more of an art than a science.

[bugsysiegals]

@dc42 said in M305 Thermistor Values for the Duet Maestro on the Ender 3 Pro?:

B4185

I'e just installed the Duet Maestro for Ender 3 Pro and am having issues with something in the layer change corner on my calibration cube ... https://forum.duet3d.com/topic/10623/duet-maestro-upgrade-calibrations-cube-issue/7

Besides that issue, to add to this discussion, my bed is working perfectly using M305 P0 T98801 B4185 rather than M305 P0 T100000 B4138 R4700 which I originally found on https://www.youtube.com/watch?v=HxEk7-6RriQ&t=1031s

That said, when using either M305 P1 T98801 B4185 or M305 P1 T97700 B4619 C9.743561e-8 R2200 my hot end measured ~160C when set to 200C. I was hearing slight clicking noise from the extruder when it was retracting and perhaps because the filament wasn't hot enough. Using the oversample/temp values above, a value of 2200 rather than 4700 since I'm using a Maestro, plugging the results into the spreadsheet dc42 linked, and using those values in my gcode, M305 P1 T45731.91 B4161.08 C10.817155e-8 R2200, has resulted in the hot end measuring 177C of 200C.

I moved my IR all over the place to get the max temp from the hot end while it was stationary. It's difficult to measure but seems correct. Hopefully I will not cause any damage with these values? Is there anyway to better measure the hot end? It doesn't matter which way the hot end wires connect +/- correct? I'm trying to understand why the temp is so far off while the bed is working perfectly.

[dc42]

@bugsysiegals, have you seen the recently-published Ender 3 guides at https://duet3d.dozuki.com/c/Duet_2_Maestro ?

It's not possible to measure the hot end temperature accurately using an IR thermometer because the target area is too small.

[T3P3Tony]

@bugsysiegals The guides that @dc42 mentiuons do not show up if you are not logged into the documentation site because they are "inprogress". the direct links are here:

https://duet3d.dozuki.com/Guide/Ender+3+Pro+and+Duet+Maestro+Guide+Part+1:+Wiring/37
https://duet3d.dozuki.com/Guide/Ender+3+Pro+and+Duet+Maestro+Guide+Part+2:+Configuration/38
https://duet3d.dozuki.com/Guide/Ender+3+Pro+and+Duet+Maestro+Guide+Part+3:+Commissioning/39

from the configuration guide:

[tompoper]

@dc42 Math has never been my strong suit. I tried to follow along with your recommendations above to no avail. I upgraded my ender 3 about a year ago to the Duet 2 Wifi. I cannot get the right settings on my heaters. I printed ABS with the stock ender 3 board (probably why it burned up). Since switching I can't get the hotend hot enough to print ABS. It is not hot enough to get a good flow rate through the nozzle. Please help!

[Veti]

be careful the ender 3 hotend has the ptfe tube down to the nozzle. printing at abs temperatures can cause the ptfe to start giving off harmful gases.

[Phaedrux]

@tompoper you may have a temperature limit set which prevents it from getting hotter. But as veti says it's not really a good idea to print abs with the stock ender 3 hotend unless your abs will work at the lower temp range. Perhaps switching to a different filament would be best? There are some lower temp ABS out there. Or maybe petg would suffice.

[tompoper]

@Veti and @Phaedrux, thanks gents. I appreciate the advice about the off gassing from the ptfe tubing at higher temps. I am aware of this issue. I have a well ventilated area in which I print. I am in the process of swapping over to a hyper cube evolution, fully enclosed with a VOC filter installed. I just have a few more prints to get through. One of the reasons I need to figure out the temp setting on the Ender 3.