Best posts made by DigiD

@DigitalElf
I realize this post is 3 months old but thought for other CNC users looking to isolate their NPN Axis End Stop switches this might be of use , protoboard and opto isolators cost $15 , this is for a duet2 wifi

opto isolator x 4 on my Delta , allows you to use what ever voltage the sensor works best with ( in my case 24volts) , isolates the high voltage from the low , decouples any kind of line noise from steppers etc and doesn't toast the board if you plug it in backwards

in config file use

M574 X2 S1 P"!xstop" ; configure active low endstop for high end on X via pin xstop !prefix

@reFlexlab

opto isolator x 4 on my Delta , allows you to use what ever voltage the sensor works best with ( in my case 24volts) , isolates the high voltage from the low , decouples any kind of line noise from steppers etc and doesn't toast the board if you plug it in backwards

in config file use

M574 X2 S1 P"!xstop" ; configure active low endstop for high end on X via pin xstop !prefix

First I reckon everyone that has Duet board and is building a printer should have a decent multi meter with a K type thermocouple ( bead type preferred)

If you have a decent meter and thermo couple you can try this method

Loosen the screw that keeps the thermistor captured in the heater block . Slip the bead of the thermocouple under the washer and tighten slightly . You want good contact .

Pick your temp range of interest, for me it was 180 to 235 C

In Duet control Set 180 ,220 and 235 and with the meter measure actual temps for each value

You know the Steinhart model values as used in the Config file .

For each of the set temps calculate the resistance the Duet is trying to reach for each temp set in the controller using that model

see attached excel file

with calculated resistance and the correct measured temperatures goto the ThinkSRS page and recalculate R and B

It worked for me . for 180 to 235 temp deviation is only about 1 degree , originally at top end it was 10 . Room temp is a different story that's out by 10 , I get 35 instead of 25 and for me that doesn't matter

would be interested to know if this method works for others.

Steinhart temp to resistance.xls

@alankilian
This is the system used by shopbottools cnc

Pretty well exactly as you described

https://www.orientalmotor.com/stepper-motors/alphastep-closed-loop-stepper-motors.html

@fcwilt

This is the method I used , probably could be refined a bit but for me it was close enough

https://forum.duet3d.com/post/191523

This looks similar to a problem experienced in the UV ink print industry when printing older new media vs fresh new media ( both never used and in sealed bags) plastizers in the older media migrate to the print surface causing unexpected print results .

Turns out PLA uses all kinds of plastizers as well and they also can change wildly over time depending on what plastizer is actually used , which may explain what your experiencing

I went down a rabbit hole of info , this one was an interesting read

Printability, Mechanical and Thermal Properties of Poly(3-Hydroxybutyrate)-Poly(Lactic Acid)-Plasticizer Blends for Three-Dimensional (3D) Printing

@remopini

The slider in the Trium has a fair bit of play or backlash in its construction or mating with the groove or bed in the extruded tower .

I found that there was a lot of roll when the stage got out to the edges of the bed , the two closest towers tended to roll in towards the stage and then when moving to the other extreme rolled out . Not so noticeable when printing in the middle though they did wiggle when doing rapid moves .
( this can really effect the offset probe)

The sliders also have a bit of yaw and pitch . Those two can be fixed by increasing belt tension considerably more than what we were told to do.

I didn't realize how light my tension was until I ended up with one belt wearing out a bit and it started riding on top of the gear rather than in it . Causing all kinds of ghostly print issues as it came and went . It increased the travel distance at random on the X tower

To increase tension set the idle or continuous side of the belt to greater than 40hz at least ( mine is at 44hz) it should twang a bit like a bass string. Use the Iphone App EasyTension , it has a frequency meter for belts!

attached is a picture of what I did. Which pretty well stabilized the slider

Orange blocks are outriggers backed with adhesive teflon sliders (furniture hardware leg protectors)

Gray block made the belts parallel and virtually eliminated pitch and yaw

The green arrow is my disposable tension device a heavy duty tiewrap which is walked closed with a pair of pliers while twanging the belt

@fcwilt

LJ12A3-4-Z/BX Inductive Proximity sensor NPN (OMRON and no name brands seem to work equally well) , very common on Ebay about $3-4 AUD each

4mm sensing distance , best results using mild steel as a target that is close to the diameter of the sensor . derate sense distance for stainless .7 and Aluminium .4

been in the printer for a few years now with out any issues

I use first pass fast coarse and second pass slower accurate for homing