Saturday, May 06, 2006


No Disassemble Number 5....

Following a multiplicity of jams, the concrete-bodied extruder assembly has been rigorously disassembled for post-mortem purposes - I've pulled it to bits.

The reason for the jams is now quite clear - a sleeve of frilly plastic protrusions inside the central hole, just above the point where the brass heater barrel terminates. These are firmly glued to the concrete and don't want to shift; they probably got there when I unjammed it. I will bake it with the Sunday roast to see if the plastic can be vapourised.

To be frank, I've spent enough time on this and I need to get some real work done, so I'm switching back to the PTFE-bodied extruder until that hits gridlock. This does not mean that the concrete body is a failure - far from it. But it does mean that the design needs a little more work done on it. Once I have two extrusion assemblies, this will be easier to do. One planned experiment is a new concrete body, somewhat shorter and with the barrel lined with silicone baking paper.

Sadly also I have other duties to perform, so work on RepRap will be limited for the next couple of weeks. Frustrating, innit?

Vik :v)

***Frustrating, innit?***

Sure is, just when you seem to have discovered that there is a real problem with the control system for the extruder heater. Still, that's how real R&D works. :-)
Yeah, the overheating in the centre is a problem. Still, we can probably figure out a realistic heating curve approximation and work from that.

Vik :v)
Baking the thing in the oven didn't help much. I'll increase the temperature. Here, blowtorch, blowtorch, blowtorch...

Vik :v)
Just reember that that stuff comes apart at 400 F, iirc.
Concrete is good up to 300C (540F) for sustained temperatures. A brief spell at 800C is acceptable but not desired!

Vik :v)
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