That has quickly devolved into some weird drama, but for what it's worth... This level of entitlement and lack of gratitude is simply astounding. Duet forums are amazing as far as support goes. I haven't seen any big open source projects where the lead dev is so quick to respond and help users with very mundane problems. Not to mention that the whole project is very much alive, with constant firmware and hardware updates. And both are kept as open source as they can be. Simply amazing, hope you guys can keep it up.

I've finally completed transitioning my second printer to a water cooled hotend setup. I admit that's a bit of an overkill, but I really appreciated the performance of this beauty (https://youprintin3d.de/hotendszubehoer/e3d/wasserkuehlung/792/water-cooled-heatsink.html) on my other machine. Luckily for me, the guy behind it has published .step files, so it wasn't hard to modify it for the Smart Effector even with my level of Fusion 360 skills.

Here's what I got (the water cooled one already has the RC cooling jacket on, didn't thing about taking a picture before I put that on):

I got the thread size a bit wrong (I think the original heatsink has moved to 1mm pitch instead of 1.5mm in beta), but other than that it's a drop-in replacement. So there was no need to change my print cooling setup or the config. Oh and the CNC company couldn't do the lip E3D now does for the push-fit connector, so I had to push in an E3D brass fitting instead.

So far I'm pretty happy with the results - the hotend fan was by far the loudest thing on my delta, my retractions are down and I can reliably use soluble filaments in my switching extruder setup. On the minus side water cooling is definitely another hassle, but I haven't had any leaks with my other machine with a similar arrangement for more than a year.

I'll gladly share the source files if anyone's interested. I did use openly shared models to create this anyway.

I've read about one being in development for a while, but have only recently came across a more or less finished bot here https://www.npmjs.com/package/duet-telegram.

Works really well, I run it on my Pi Zero W along with Motioneye. Very convenient for those of us with really wonky ISPs, in my case that means I don't have to bother with weird IPv6 tunneling issues if I want to keep an eye on my printer during the day.

@ivang Don't use that! It's a mechanical relay that's only rated for 12V. Running 220V at the output is dangerous and has probably just fried the contacts. I'd advise you to get a DC/AC Solid State Relay. I don't know where you are, but you can easily get those off Amazon and e-bay. Just make sure it's the DC/AC type.

If you order from Keenovo, I'd recommend asking them to include a bimetallic switch in your heater. Costs something like 2 dollars, makes the whole thing a lot safer. I've ordered mine with a 155 °C cutoff temperature.

I was referring to the contacts inside the relay - it's a mechanical one, there's a lot more stress on them if they're switching a higher voltage. Wow, I haven't noticed that they actually advertised it as 220V compatible. That's extremely irresponsible and downright dangerous. And I would really advise you to follow the suggestion above, mains voltage is a lot less forgiving.

https://youtu.be/snBZX9P4RBw?t=10m39s. Maybe he'll even test one some day.

@ivang This one won't do. Look closer - it's a DC/DC relay. You need an DC/AC one, like https://www.amazon.es/heschen-Single-SSR-40DA-estado-sólido/dp/B071HP9NJD/ref=sr_1_5?ie=UTF8

I've converted to PEI-coated aluminum. I get mine from clever3d.de, but I'm fairly sure you can find someone who does those wherever you're at.

They cut you a flat tooling plate to size and dip it (I think) into some PEI. The resulting coating in very robust (although you can damage it if you try) and extremely convenient. I now use glue-based adhesive aides only for some exotics. It's also a bit less sticky than your usual PEI sheet, so I don't bother with release agents for TPU or PETG.

@bartolomeus Not to the bed, to the silicone heater - I've bought a tube of high-temp RTV silicone and literally moulded the fuse in. The RTV silicone is very chemically similar to the heater, which makes for a very reliable contact.

@Nxt-1 Oops, haven't visited i the forum in quite a while... Sure does though, here's a link https://www.dropbox.com/s/1xaf4sxdj74tjb7/Waco_V6_modded v2.step?dl=0.

Got to credit the guy who makes the hotend from the link in the reply above - I'm actually using that particular one on my second printer. I ordered mine from Weerg.com, if you choose the same one I could give you the order number so they might possibly give you the "doing again" rate. Wherever you decide to make those, make sure to get them anodized. My anodized one from youprintin3d.de doesn't have any gunk in it whatsoever and my polished alimunium one needed some gentle scrubbing after a year of use.

@misterj With dual drive gears sometimes too much tension could lead to problems. I'd check whether you have adequate cooling on the heatbreak and whether both drive gears are actually aligned.

@singhm29 You need to consider both values when choosing the thermal fuse. I'd advise to go well beyond your normal current rating, something like a 20 A one. The max temp really depends on how high your bed can go and how high you're usually pushing it. I'd recommend bonding it to the silicone with RTV cement instead of a bracket when it comes to mounting it.

I'd second @DocTrucker on grounding - please don't rely on your bed being grounded via the chassis. Unless it's a delta and there are no moving parts in the bed assembly and you've tested that there's a low resistance electrical connection between the bed and the ground of the chassis.

@veti You're absolutely correct! No wonder that my homed height seemed higher than it should have been.
Thanks a lot! Case closed - I've configured steps per mm for 20-tooth pulleys while running 16-tooth ones.

@veti Yes, with config-override disabled for simplicity's sake.

The plot thickens... Once I allow the auto-calibration routine to adjust delta rod length with 9-point calibration, I get decent calibration, with 0.030 deviation and an almost perfectly flat bed on a G29 probe. A 8-point one nets a 0.4 deviation and some monstrous distortion.
I'd be pretty happy with the former if it didn't adjust my diagonal rod length all the way up to 267 mm. Which is really different from the real life measurement of 215 mm. That's getting confusing.

@veti Wow, that's a really nice reference page. I'm running a 6-factor auto calibration, so both endstop positions and delta radius should have been accounted for.

@phaedrux Yep, although 1 thing I haven't done was put springs/rubber between each pair of rods. Not sure if that could cause that much of an effect, but will do that nonetheless.

I've been resurrecting whatever remained of my old trusty Mini Kossel kit to a semi functional state and ran into some issues I'm having trouble to explain/deal with.

Basically, this -

The printer has a set of 3 under bed piezo sensors, so there shouldn't be any influence from the effector tilt. It's clear there's some underlying mechanical issue here, but I'm at a loss what it could be. I've tightened what could be tightened (pulleys, belts, screws, delta arms...), the bed itself is a cast aluminum plate flat to 0.1 mm. If anyone has any ideas what could be the cause of that, I'd be really grateful.

It'd really depend on what exactly do you want to set up. Separate extruders/heater blocks (like E3D Chimera), mixing extruders (Diamond, E3D Cyclops), IDEX carriages, toolchanger, a switching hotend (Prometheus System, Prusa MMU 1)... There are a lot of possibilities, and all of those would require very different approaches.

I've tried 2 approaches.

One was bonding a thermal fuse (I used 140 degree ones) with RTV silicone directly to the silicone heater. Said fuse is connected in series with the heater. In case a temperature runaway occurs, the fuse breaks and everything is well.

The second one and the one I've settled on in the end for both of my printers is odering heaters with bimetallic themal switches built in them. If you get your heater from Keenovo, they do that for a small extra charge (like a $ or 2), or sometimes waive the charge altogether. This approach is a bit less safe - in case my SSR fails short my bed will oscillate between 130 and 140 degrees. While it's a bit worse than the fuse just breaking, the switch will reset afterwards. So you won't have to bother with replacing it if you accidentally overshoot your max temp or after a failure. And since it's baked in the heater, no need to worry about it ever falling off. Although the last one is hardly a problem is you use RTV silicone.

So, the choice is yours. If you already have a silicone heater - get a tube or RTV silicone and a properly rated fuse/switch. If not - I highly recommend ordering one from Keenovo and just asking them to mould in a switch with the temperature rating of your choice.