A few months back I bought a second hand Tevo Little Monster delta printer. I had always wanted a delta, just for the cool motion of the arms as they print. This particular printer came with a bunch of extra parts, which was in fact a second non-working Tevo Little Monster.

I played around with the working printer, but never really got it to print anything more than a simple test print. I found the firmware horrendous; if anything didn't work as planned the printer would just freeze. One time it seemed to be cooking my filament - PLA smells like baking candy when it's too hot. Enough was enough, so I looked for a suitable brain to perform a transplant! What I needed was a Duet 3D brain!

More than one Little Monster has been converted to use a Duet 2 board - these printers are after all quite old. This one is around 7 years. I was going to buy a Duet 2 and convert, but helpful people on the forum suggested the Duet 3 Mini 5+ might be a better choice. So I ordered a WiFi one and went down the rabbit hole...

Figuring my time is actually valuable I decided to upgrade other bits of the printer that were of unknown condition. In the end I replaced the hotend fan, part cooling fans, hotend block (E3D Volcano), heat break, nozzle (now 0.8mm brass), controller fan (Noctua), heater (40W E3D), thermistor (E3D), E3D extruder (but kept using the slimmer extruder motor on the original printer). There was some fabrication of the mount for the controller board and for the WiFi aerial, and I made a new face plate to control air flow better (also blocking off side air to promote air flow under the controller).

The first print had poor adhesion which I traced to too much fan cooling. I was fiddling with 0.55mm layer height. I have since found that I might as well use 0.3mm layer height as volumetric flow seems to be the limiting factor, though I'm using a max of 15mm^3/s and it can probably go higher. Next I want to try the Bondtech CHT 3 into 1 nozzle but like nearly everything, importing this stuff into New Zealand where I live ends up costing a small fortune; a single nozzle will cost an estimated USD$60, landed. Be thankful those who live on large land masses.

The printer is working well. I'm still getting used to a 0.8mm nozzle. Apart form that the only noteworthy thing is that my X and Y don't quite seem to be a 90 degrees to each other. This is a problem as I print electronics enclosures and need accuracy. It does my head in thinking about what I have to change to get this right.

Anyway, here are some photos.

Under the hood... Trying to route cables, always a challenge. Every wire had to be re-crimped to the Molex KK Duet 3D seem to love. I'm very lucky to have access to a genuine crimper which makes a big difference in speed and quality.

Front plate is a 3 layer print; transparent, black, then blue. Duet controller LEDs are visible without impeding air flow. WiFi aerial mounts off the old mount for the LCD display which is no longer used after the conversion.

With 0.8mm nozzle infill becomes quite... thick.

Boat on the left is about what I'm getting. One on the right I increased speed, too far...

Thoughts, questions and suggestions welcome.

@droftarts the parts arrived in due course and here is the made up adapter cable. I'm happy with it.

Note to all, this cable carries mains voltage and should be tucked out of the way and safely covered where you cannot touch it. This photo is with the cover removed for photo purposes.

@KenW interesting. Well it's been about a month now and I haven't had the controller WiFi issue at all since then, so it seems that avoiding allocating Wi-Fi channel 1 on the access point has indeed turned out to be a successful workaround. I mention this for anyone else having issues.

I decided that this was good enough and have ordered another Duet 3 Mini 5+ WiFi for my next Tevo Little Monster upgrade/conversion.

This is not specific to a Duet powered printer, but I thought I'd write about it here anyway.

TL;DR Stop your delta printer effector crashing into the bed at power off using this small part.

For a while I've been tinkering with a Tevo Little Monster that I "repowered" with a Duet Mini 5+ board. The printer uses a BL Touch for sensing bed height. What I have found is that when the printer was powered off, the effector and arms would sometimes start to slide down and hit the print surface with a thunk. This wasn't the end of the world, but when powering the printer back on the BL Touch performs a self test, and with the effector firmly on the print surface this self test fails. The upshot is having to turn the printer off again, raise the effector off the bed by hand, and, while holding it off the bed, reach up and power on the printer.

More recently I modded another Little Monster with another Duet Mini 5+ board, and gave it 1.5m rails instead of the 1m rails on the original. This printer has the same problem when the power is turned off, except now it's even harder to reach the power switch on the top of the machine without raising the effector a long way up. A hassle more than anything. Anyway I wondered about how I could fix this issue and here is my solution.

It's a flexible bracket that has enough resistance to stop the arms falling at power off, but not so much resistance as to stop the arms moving while under power. I position it a couple of mm below the rear carriage while the effector is in the parked position.

As these printers use 80x40mm C-beams the bracket I designed works with those only, however I think the idea could be applied to any other design. It's possible others have come up with something similar, but I didn't find anything in my searching. As is often the case the biggest problem may be figuring out what it's called!

Anyway, here are some photos. I use two screws with T-nuts to hold it on the rail.

Here is a photo of the two monsters, showing the bracket in place.

Hi everyone. I have been experimenting with an Arduino controlled active chamber heater for a Prusa i3. This has been successful and so my next step is to build a chamber heater for my Duet 3 Mini 5+ delta machine. This got me thinking as to how I might control the chamber heater. Presently the Arduino
does everything, so brings the chamber up to temperature and then I start the printer printing. Then later when I see the print is done I can slowly cool the part down. All very manual.

For the Duet I'm thinking there is possibly a better way to do this. So I took a look in the Duet instructions and I see info on how to connect a simple chamber heater with thermistor and heating element. The thing is my chamber heater is more elaborate (Eg. multiple independently controlled fans) and so it would be better if the Duet could somehow tell the Arduino the desired temperature and the Arduino could report back the current temperature. Or something like that. I'm wondering if there is a meaningful way to do this and how. My brief searches suggest that canbus is used by a number of external boards, but if I went down this path would this require changes to the Duet firmware?

On one hand I have experience building and writing code for canbus devices for my day job. On the other hand, I don't want to embark on a massive mission.

@droftarts Ahh! I think I might have found something useful - M118.

Eg. M118 P2 S"SET_TEMP 60"

This looks to send the string "SET_TEMP 60" to serial port 2 of the Duet, which I could pick up using the Arduino. Not sure yet how I could send info in the other direction though; like chamber presently at 53C. Or how I could get the Duet to wait until the temperature hits 60.

I thought I'd post an update on the enclosure heater design. While I still don't have an enclosure for the Duet3D delta printers I've built, I have an enclosure on a Prusa i3 that I do heat, using the same heater controller design.

Splash screen:

The unit measures temperature, current flow through the heater element fan and RPM of the 'mixer' fan. I have only briefly hooked up the serial port and it wasn't working, so something to investigate there. So it's all manual for now.

Driving the mains powered heater element is handled by a separate box using a relay.

I thought I'd post an update on the enclosure heater design. While I still don't have an enclosure for the Duet3D delta printers I've built, I have an enclosure on a Prusa i3 that I do heat, using the same heater controller design.

Splash screen:

The unit measures temperature, current flow through the heater element fan and RPM of the 'mixer' fan. I have only briefly hooked up the serial port and it wasn't working, so something to investigate there. So it's all manual for now.

Driving the mains powered heater element is handled by a separate box using a relay.

@droftarts the parts arrived in due course and here is the made up adapter cable. I'm happy with it.

Note to all, this cable carries mains voltage and should be tucked out of the way and safely covered where you cannot touch it. This photo is with the cover removed for photo purposes.

This is not specific to a Duet powered printer, but I thought I'd write about it here anyway.

TL;DR Stop your delta printer effector crashing into the bed at power off using this small part.

For a while I've been tinkering with a Tevo Little Monster that I "repowered" with a Duet Mini 5+ board. The printer uses a BL Touch for sensing bed height. What I have found is that when the printer was powered off, the effector and arms would sometimes start to slide down and hit the print surface with a thunk. This wasn't the end of the world, but when powering the printer back on the BL Touch performs a self test, and with the effector firmly on the print surface this self test fails. The upshot is having to turn the printer off again, raise the effector off the bed by hand, and, while holding it off the bed, reach up and power on the printer.

More recently I modded another Little Monster with another Duet Mini 5+ board, and gave it 1.5m rails instead of the 1m rails on the original. This printer has the same problem when the power is turned off, except now it's even harder to reach the power switch on the top of the machine without raising the effector a long way up. A hassle more than anything. Anyway I wondered about how I could fix this issue and here is my solution.

It's a flexible bracket that has enough resistance to stop the arms falling at power off, but not so much resistance as to stop the arms moving while under power. I position it a couple of mm below the rear carriage while the effector is in the parked position.

As these printers use 80x40mm C-beams the bracket I designed works with those only, however I think the idea could be applied to any other design. It's possible others have come up with something similar, but I didn't find anything in my searching. As is often the case the biggest problem may be figuring out what it's called!

Anyway, here are some photos. I use two screws with T-nuts to hold it on the rail.

Here is a photo of the two monsters, showing the bracket in place.

@droftarts

As alternatives, and for which I'll use to make an adapter cable, I found these:

https://www.aliexpress.com/item/1005004265820177.html

They are described as 63080 with 6.3mm pitch. This seems, maybe to be something like a Molex Minifit. Maybe. Who knows with Ali Express. I'll have a close look at it when it arrives. I suspect it will be OK for voltage (230V here) and current (surely at most 2A for the TLM heater).

I would have ordered something nice from Digikey, but in the past I have spent a lot of time and almost lost my sanity trying to find housings, both male and female, and terminals to suit the wire gauge, all which fit together properly and for which I have a crimp tool. The Ali Express store RiccoDi seem to have lots of "sets" including male, female, and terminals which really helps with the headache.

This is the last piece of the puzzle for the printer conversion to 1.5m rails. I really hope it works and produces some at least half way decent prints.

@martinv

Ahh rats, I think I found it on Digikey. 6.2mm pitch apparently. Unfortunately it seems to be obsolete.

Molex part 351-43-0201

@droftarts

I measured the pitch again today and get 6.1mm, so maybe it's actually a 6mm pitch. A bit unusual. Notice also the half rounded housing keying. After much searching I've found that the rounded keying is unusual; most keyed connectors seem to use 45 degree angles.

Here's another photo; having real trouble taking a nice shot alas. I'll have a look on Digikey for 6mm pitch housings...

Another thing I could do is instead of making a complete new cable, or splicing the old one with some nasty solder joint would be to use the cable I have to make a short adapter to a new (and importantly, obtainable) connector. Kind of like...

heat bed--->X X<---->known male/known female<------- ... 2m to power supply end.

Hi everyone,

My Google-Fu is failing me. Does anyone have an idea of what connector this is in the photo? My measurement of the pitch is 5.9mm (difficult to measure exactly as it's only 2-way).

For the whole story, I have a Tevo Little Monster delta where I have lengthened the rails. So now I have to lengthen all the cables. For the (mains powered) bed I'd rather build a complete new power cable rather than splice the old one. I could change to a different connector and be done with it, but Ideally I'll keep the original as I have a number of these printers and I'd like the possibility of easily swapping the beds.

@dc42 Thanks for the reply. I took a look at the link, but decided that's quite a departure from the Arduino and would be quite a lot of work to re-implement everything for a new development environment that's otherwise low on my radar. I'll hopefully set up a quick test in the coming days to have a look at the M118 command in more depth.

@droftarts Ahh! I think I might have found something useful - M118.

Eg. M118 P2 S"SET_TEMP 60"

This looks to send the string "SET_TEMP 60" to serial port 2 of the Duet, which I could pick up using the Arduino. Not sure yet how I could send info in the other direction though; like chamber presently at 53C. Or how I could get the Duet to wait until the temperature hits 60.

@droftarts Hmm, having had a look at those two projects as well as generally reading up on PanelDue it looks to me like the Duet sends status information (bed, hotend temperatures etc.) to the PanelDue and the PanelDue sends control information like axis movements to the Duet. So if you're wanting to get in the middle of that, it's all good. I'm not presently seeing how I might use this for a chamber heater interface however. The communication looks to be in the wrong direction, as in the Duet might tell the PanelDue the chamber temperature, not the other way round. Am I missing something?

What I kind of need is a way to see the G-code "as it goes by" to the printer so that I can control the chamber heater. Then somehow to report the chamber temperature back to the Duet. Hmm...