Sunday, 19 June 2011

Extrudiate!

Don't you just love that healthy smell of burning electronics in the afternoon?

I have been trying to print a pink DALEK all weekend.

I now have a DALEK graveyard, and some very Dali DALEKs as well it seems. Sadly I am not going to get any more done today.

Basically this is all about getting ABS to print.

The pink is not important, just that I have pink and white ABS, that is all, though I have had a request for it in pink...

Anyway, printing ABS needs heat. Lots of heat. The hot end I am running at 245C.

I had to get the tension on the extruder right as the pink ABS is a full 3mm diameter and if squashed through the extruder then it will not feed through the 3mm nozzle in to the hot end, but if not tight enough it does not have enough force to extrude. That took a while to realise and get right, but that bit is now being very reliable.

I made a heat bed, using 25W 6R8 resistors in a 3x3 grid and running off an ATX power supply at 12V. Thanks for Kev for advice on that. Works nicely, though has trouble competing with a fan.

It manages to get to 115C. The ABS sticks well and is actually hard to get unstuck later! So things print all the way, or so you would expect.

I then found that X and Y axis were slipping and so you got a spacial distortion like the poor pink DALEK shown above. I think it may have been the stepper controllers over heating as the whole thing is running a lot hotter with ABS than PLA (115C hot bed, 245C hot end, and running with fans off as well).

So I made heat sinks (not easy). They seemed to work and I printed more of a DALEK but again they seemed to pack up. I put a fan blowing over them, and that worked for a bit.

Unfortunately something else is wrong, and I am guessing this is the root of the problem in fact.

There was a "pop", and sparks, and proper fire...

The stepper controller is no longer looking too well!

So, time to order some more, and start with proper heat sinks from scratch this time. That will be a few days I expect.

Ho hum.

Interestingly, Kev and I wondered if there is any mileage in doing a proper design for both the electronics and the firmware to see if we can make one of these things that is actually running everything within proper margins. Hobby designs works, mostly, and need tinkering and fine tuning. Done properly the whole thing would not have most of these problems. How many boards would we sell? Good question. No idea. I suspect we'd end up needing to publish the design and software really, but tempting if ever I get some spare time!

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