@rcarlyle It looks like it would work really well, but I just couldn't justify dropping $65usd on a filament sensor.

I would strongly avoid anything that website sells, they are marketing a 12v relay as able to switch 220v mains.

"Ideal for silicone beds up to 450W approx. (max up to 40x40cm)

We also leave the connection of the pins for use with 220V beds:"

Mechanical relays in general are much more prone to failure in addition to being noisy.

I strongly suggest you do a lot more research into working with an AC bed before you proceed any further, as mains voltage can be deadly. There are many relevant topics on the duet forums in the past few days that at the bare minimum I suggest you read.

@dc42 I'll second this, I set up firmware retraction on my delta two weeks ago, you really need to use post processing in order to get the G10 and G11 commands inserted into the right spot.

The script is pretty simple, just use a known speed and distance and then post process to replace those moves with G10 and G11.

http://thrinter.com/using-firmware-retraction-with-simplify3d/

This will work well, but he's using absolute extrusion distances, so you'll need to edit his script a small amount.

Just open a gcode file you've sliced in a text editor and double check the post processing has been done properly.

Hooray, I'm glad you got things sorted, the duet is a fantastic board, as for your fans there's plenty of posts regarding hooking 12v fans up to a 24v system. Basically you can use a buck converter to go from 24v to 12v and feed that into either the middle pin of the fan selector jumper or into the + lead on a fan, as long as you're connecting the - to the fan connector of your choice your fans will work.

E3D also makes brass nozzles down to 0.15mm

https://e3d-online.com/nozzles-v6-brass

Hooray, I'm glad you got things sorted, the duet is a fantastic board, as for your fans there's plenty of posts regarding hooking 12v fans up to a 24v system. Basically you can use a buck converter to go from 24v to 12v and feed that into either the middle pin of the fan selector jumper or into the + lead on a fan, as long as you're connecting the - to the fan connector of your choice your fans will work.

@mrehorstdmd As I have mentioned before, most self resetting fuses do work this way, power is cut but a small amount of leakage current prevents the fuse from self resetting until the issue is remedied. By all means run multiple fuses, but you can save yourself effort by having the initial cut out be a self resetting fuse, that way if the SSR fails the heatbed stops heating and you replace the SSR without needing to do any actual wiring work to the heatbed.

https://en.wikipedia.org/wiki/Resettable_fuse

@dc42 I'll second this, I set up firmware retraction on my delta two weeks ago, you really need to use post processing in order to get the G10 and G11 commands inserted into the right spot.

The script is pretty simple, just use a known speed and distance and then post process to replace those moves with G10 and G11.

http://thrinter.com/using-firmware-retraction-with-simplify3d/

This will work well, but he's using absolute extrusion distances, so you'll need to edit his script a small amount.

Just open a gcode file you've sliced in a text editor and double check the post processing has been done properly.

@pro3d if you're using an e3d hotend @DjDemonD sells the pt1000s on his web store.

https://www.precisionpiezo.co.uk/product-page/pt1000-sensor

Is your SSR hooked up the right way? When I first set mine up I had the polarity backwards and it wouldn't heat when I tried to tune it. I flipped the leads going into it and it's been fine ever since.

As a slight aside I spent most of my Saturday setting up pressure advance on my delta, part of that included using firmware retraction.

I use S3D as my primary slicer on the delta and for $150 software it doesn't have a nice checkbox to enable firmware retraction I used post processing scripts I found here:

http://thrinter.com/using-firmware-retraction-with-simplify3d/

I had to turn off relative extrusion distances to get the script to work properly but now that it's setup it seems to be pretty nice.

Only thing I noticed was if I sent all the parameters for retraction distance, speed, unretract extra distance, and zhop together in the same command the zhop wouldn't apply. I added a second command and moved the zhop command to it which seems to have fixed it.

I have all my default retraction gcode in my config.g and have alterations of it in the start gcode commands for different filament if different retraction is needed. Plus the ability to make on the fly changes to retraction is fantastic, I can disable retraction mid print or add more shop if I need, or even print multiple retraction tests at once with different settings easily.

@danal What type of self resetting fuse is it if you know? I kind of regret not getting one built into my bed, Even though I have redundant safety measures as well an extra one wouldn't have been bad.

@mrehorstdmd my example was also worst case, if there's a polyfuse or other latching type resetting thermal fuse it will continue to leak a small amount of current when tripped, maintaining its temperature and preventing itself from resetting until the current is removed. Like you said they are safety devices and are designed as such.

@mrehorstdmd self resetting will just act as a poorly tuned bang-bang.

Temperature will rise above the fuse threshold, open the circuit, this will allow the temperature to cool below the reset threshold, the fuse will close allowing current to flow and the bed to resume heating until the temperature again rises above the threshold and the cycle repeats endlessly maintaining a temperature close to the two thresholds.

It is of course less than ideal as a dead stop in case of a fault is preferred, but depending on how the fuse is wired changing it may not be an easy task.