In progress - hotend

More fiddling today, I added a fan cooling shroud to put the active cooling where it makes more sense - on the heat sink. The carriage/extruder layout wasn't designed with this in mind, so things are a bit crowded and non-ideal, but it's enough to try out the idea.



It seems to work pretty well, but there's a lot of back flow coming from the fan, so I think I need to increase the space in the heatsink to allow more airflow.

I somehow managed to damage the thermistor. It didn't fail out right, but gradually was giving lower and lower readings. Fortunately I have some spares so I replaced it. I've just taped it to the heater wires instead of using the screw in case it was the screw that caused the failure.

Fiberglass plus silicon tube works up to 300 °C.PTFE is limited to 250 but has the enormous advantage of having one of the lowest coeficient of friction.

I have been thinking about ceramic too, the kind you can machine, but these a hard to get for a hobbyist.

Edited 1 time(s). Last edit at 03/06/2016 11:04PM by MKSA.

Do you have the drawings with dimentions? I would like to do this hotend.

Quote
Pampajcs
Do you have the drawings with dimentions? I would like to do this hotend.

The design is in OnShape. I've not tried this before, but it looks like this link should get you to the document:

[cad.onshape.com]

If that doesn't work let me know and I'll export the drawing as some sort of image. Next time I make one I plan on deleting the fixing screw for the thermistor and adding a second thermistor hole on the opposite side so that I can use the block as either a right or left handed version in the dual extruder setup (I can't just flip it as the screw head for the heater clamp gets in the way of the part cooling fan shroud).

Edited 1 time(s). Last edit at 03/21/2017 09:31PM by JamesK.