TEVO Little Monster Duet Ethernet Conversion

vsch

It's usually possible to convert 5V optical endstops to 3.3V. Identify the resistor in series with the IR emitter in the slotted opto switch and reduce its value by about 50%. If it's a surface mount resistor and you don't have SMD desoldering equipment then it's easiest to solder a second resistor of equal value on top of the existing one.

Does the Duet Wifi not have the ability to use the Stall detection of the stepper drivers for end stop detection?

I know this is possible according to Trinamic information and also by the Prusa MK3 implementing this exact feature.

This is definitely something I would like to use and if not available to work on the firmware enhancement to make it work.

I hate relying on the optical end stops. They are not as reliable as the trinamic stall detection because the latter will work if an obstruction stops the carriage from triggering the optical sensor.

dc42

See the other thread on the subject of using stall detection instead of endstop switches.

vsch

Just got my TEVO Little Monster printing with Duet Wifi with the LCD interface, and the WEB UI. Wifi seems to loose connection all the time. Sending [c]M562 S0[/c] to disable it then [c]M562 S1[/c] to enable it on the LCD console, reconnects every time. A bit of a pain but I will deal with it later.

The upgrade was not complicated except for a couple of loose pins in connectors that only showed up after a few days of working with the printer.

In the end the real cause of my problems was poor temperature control of the MKS-SBASE controller in the machine, which resulted in the PTFE in the hot-end melting and lining the nozzle (two actually because I switched to a new nozzle hoping to make it work) with thin ribbons of PTFE that would peel off at random and cover the 0.4 mm hole, causings extrusion to become very uneven, sluggish or blocked.

Nothing worked consistently, not the Titan extruder, not the e3d hot end. Only when I cleared out all plastic out of the nozzles by heating them with a hot air gun and cleaning them out with a 1.94 mm drill bit, slowly by hand turning it. Then soaking them in MEK to pull all the crud out. Only then did I realize what the issue was when I saw thin strands of plastic floating around that MEK did not affect.

Now the printer is running and better than before. Finally, after a four week struggle trying to figure out what the issue was.

dc42

I'm glad you have your printer working well.

WiFi disconnections are typically caused by low RSSI (signal strength), but not always. See https://duet3d.com/wiki/WiFi_disconnections_and_AJAX_timeout_errors for guidance.

Ak Eric

Just finished doing this conversion: Huge thanks to Emulsifide for gathering all this info and providing all the config files. Only two gotcha's I ran into, one I have solved, one I have not:

#1: The endswitches wiring is all sorts of different between the MKsBase, the switches themselves, and the Duet. I didn't reailze this at the time, but when none of the switches were working I quickly relized it. Cutting & wiring new dupont connectors solved this.

#2 : I'm getting this error from the web control for my heated bed:
Error: Temperature reading fault on heater 0: sensor open circuit

Any ideas? Everything 'looks' wired correctly:

Thermistor plugged into Duet.
Heated bed output from duet is plugged into the same terminals that would have been pluggged into the MKs Base, that actually connect to the connector in the side of the case.
Those wires run into the PSU, presumably connecting to the SSR, which controls the output to the heated bed, which is also plugged in.

.
Anything I'm missing here?

While I've not printed anything yet (want to solve this last issue), it homes and bed levels like a boss.

Cinpro

You put it with the terminals right beside the BED power wires on the board right?

Also there is a Facebook group for this combo of printer and board; Little MOnster Duet WiFi Ethernet Users Group

Ak Eric

@Cinpro:

You put it with the terminals right beside the BED power wires on the board right?

I'm… not quite sure what you mean by that . I have it wired up just like the pic here shows:
https://thingiverse-production-new.s3.amazonaws.com/renders/8b/40/85/43/2e/03e4de45ef0e423ff95199fd8deccd3b_preview_featured.JPG
The bed-out terminal is on the bottom right of that pic, and mine looks wired just like it.

I'll check out that FB group, thanks.

Ak Eric

Just to follow up: The TLM kit came with an extra thermistor…. so I just tried plugging it into the bed instead: Now getting a temp reading that matches the hotend, only off by about .5c. Shot in the dark: Anyone know by chance what setting to use for it, if stuck on the bed? Since I presume this was a spare for the hotend, should I just dupe my hotend M305 settings? Currently have this, since I just copied what Emulsifide had posted:

[[language]]
M305 P1 T100000 B4138 C0 R4700             ; HOTEND :  Set thermistor + ADC parameters for heater 1
M305 P0 T100000 B4607 C8.950070e-8 R4700   ; BED : Set thermistor + ADC parameters for heater 0

number40fan

I am sure the hotend and bed uses the same thermistor, so you should be safe copying.

Ak Eric

Thanks: Swapping sensors, changing settings, heating it up, and testing with my IR thermometer, it's within just a few deg, so I'll call that a success.

dc42

I'm glad it's working for you. If you are using glass on top of the bed, then it's normal for the temperature on top of the glass to be 5C to 10C lower than the temperature you set.

Ak Eric

@Emulsifide : Any chance you wouldn't mind posting the Simplify3D profile you've been using? I've been tuning mine, and slowly progressing with better results, but would like to have something to compare against.
Thanks!

Ak Eric

@Ak:

@Emulsifide : Any chance you wouldn't mind posting the Simplify3D profile you've been using? I've been tuning mine, and slowly progressing with better results, but would like to have something to compare against.
Thanks!

I'll answer this myself since discussing this with him elsewhere: I totally forgot That S3D provides lots of default profiles, and they have one for the TLM. Derp.

Ak Eric

General question (for Emulsifide or anyone else) : How did you come up with the numbers for the M665:
M665 R157 L397.1073 B175 H525 ; Set delta radius, diagonal rod length, printable radius and homed height
Specifically the L and R values? Was this based on the measurements of your machine, or did you actually find official looking numbers online somewhere?
Just wondering simply because my numbers based on measurements seem slightly different, I'm coming up with:
M665 R155.58 L395.416 B175 H525
Again, just wondering.

ExSerCo

Hi people,

Alot of info I can find here

But I do have a question too.
I'm no expert in wiring (yet), so feeling uncomfortable right now.
Where can I find info/pics/schematics on how to cut/rewire the connectors for the Little Monster?
I've tried googling already, but I'm still confused.

Thank you

Ak Eric

I listed some high-level notes from my conversion here, if they help:
http://www.akeric.com/blog/?p=4325#Assembly_Notes

A Former User

Hi dc42 you wrote
"It's usually possible to convert 5V optical endstops to 3.3V. Identify the resistor in series with the IR emitter in the slotted opto switch and reduce its value by about 50%. If it's a surface mount resistor and you don't have SMD desoldering equipment then it's easiest to solder a second resistor of equal value on top of the existing one." Are you able to explain this in more detail. I have two optical endstops that are 5V that i need to turn into 3.3v. I read another article of your that I will need BAT43 diodes (which I have ordered) but can you show me an image or describe how this works please

dc42

If you convert the endstops to work on 3.3V then you don't need the diodes, they are for endstops that need higher voltages.

If you post photos of your opto endstops then I will try to help.

A Former User

Sorry there not opto sensors, I meant to say proximity sensors.

https://imgur.com/FmQV2nM

dc42

In that case, assuming they are designed to run from 5V, you may need to connect the ground pin of the sensor to ground on the Duet endstop connector, the output of the proximity sensor to the STP pin of the endstop connector via the diode (cathode of the diode goes to the sensor output), and the +5V connection from the sensor to +_5V on the Duet. You can find +5V on the expansion connector. But from reading posts from other users, it appears that some of them got the sensors working on 3.3V.