One tool head with independent heaters

helpimlost

Has anyone configured a toolhead to have two independent heaters in the same hot block of the hot end? How would this be set up in config?

dc42

If they are in the same heater block, it's unlikely that it makes any sense to control them independently. In which case, the simple option is to wire them in parallel. Or in series if they are 12V heaters and your VIN voltage is 24V.

BoA

I have a deja vu.

2 heaters connected to 2 outputs and controlled by one thermistor and PID. Sounds familiar to what I was thinking about - define heater using 2 outputs for 2x120W chamber heater.

helpimlost

@dc42 I have one temperature sensor near the top of the hot block and one near the nozzle. I can successfully get a 15C delta between the length of the thermistors. I currently have it set up as two different tool heads but I could wire the heaters in parallel and just have one tool head. Although, I'm more interested in experimenting with independent control of the two different heating zones right now.

BoA

That sounds interesting. Is this tool some kind of pellet extruder with pre-heat zone?

helpimlost

@BoA It's not a pellet extruder. Still using filament. It might be one step before switching over to a pellet extruder.

helpimlost

@BoA A preheat zone is sort of the idea though.

theruttmeister

Unless your hotend is both very long and made from something fairly non-thermally-conductive (like stainless steel), its not worth the trouble.

Bear in mind that most pellet extruders (in the filament production world) are constant flow, unlike FDM. There not much we can or should copy from them.

Its much easier to use the cold-end-hot-end/heatsink - insulator/break - hotend model that most FDM machines do.

dc42

@helpimlost said in One tool head with independent heaters:

@dc42 I have one temperature sensor near the top of the hot block and one near the nozzle. I can successfully get a 15C delta between the length of the thermistors. I currently have it set up as two different tool heads but I could wire the heaters in parallel and just have one tool head. Although, I'm more interested in experimenting with independent control of the two different heating zones right now.

If one heater is near the top of the heater block and one near the bottom, you can set them up in M563 as a single tool with two heaters, and set different temperatures for them using G10.

helpimlost

@dc42 How would I control the heaters independently? I have them set up as one tool head with two heaters now. When I send G10 P0 H1 S50, it sets both heaters, H1 and H2, to 50C. I'm guessing H isn't the correct parameter.