hotend assembly

I’ve commenced work on the hotend. I had to drill out the 5mm hole in the Al heater block to take the >6mm  5.8 ohm resistor. In addition I had to drill a hole for the 0.8 mm thermistor. Not having a 0.8 mm drill bit, I turned to my trusty laser which did the job nicely.

laser drilling of Al heater block (material ejection and plasma emission visible):

laser drilled hole + thermistor alongside:

After that I followed Arcol’s excellent assembly instructions – hope he doesn’t mind 🙂

Resistor in heater block:

thermistor + fire cement:

I’ve left the fire cement to set overnight. There’s probably too much of it but I was trying to encaspsulate as much of the crimped section as possible for strength. I’ll test it tomorrow. One worry is that the resistor protrudes from the heater block. I’m afraid of hotspots where the temperature rise outside the block may exceed the limit and fry the resistor… but we’ll see tomorrow.

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