No posts for for half a year... a new job was getting in the way of my hobby.
I decided to build a spare extruder using the old hot-end of my makerbot MK4 extruder that broke a while back. I printed the parts of Greg's hinged accesible extruder, which is variant of the wade extruder which I am currently using. As my printer is not standard, I used a sheet of 3 mm plastic between the extruder and the aluminium frame. I printed the parts in PLA which is not the best option as I found out. The old makerbot MK4 hotend has a metal ring that transfers a lot of heat to the bolts which keep it in place. The bolts are getting so hot that the PLA deforms. I noticed this early enough so no serious damage was done. I guess I could order a new hotend later which has proper (peek) insulation, but I wanted to get this to work now, so I improvised. A special aluminum bracket was created with 2 glued-on m3 nuts to which the hot-end can be connected. The aluminium strip and the hot-end is further cooled by a small fan which I took from an old modem. This setup seems to work fine.
The back of the extruder looks like this:
The bolts which get too hot are the two long m3 bolts (one visible) in the middle:
And the bracket and the fan installed:
The extruder works fine. Of course it needed some serious calibration:
I printed some knurled bolts from thingiverse:
Quality seems to be OK. I am waiting for the delivery of the parts for a heated bed which will allow larger ABS objects to be printed. I also ordered a new stepper motor controller which will allow me to use a more standard software configuration and which will increase the accuracy of starting and stopping extrusion.