Wednesday, August 24, 2005


Ready-made heaters

Last night Ash and I fitted our latest EVA nozzle to the Meccano feed mechanism. We've used the nozzle of one of the wrecked glue guns, replaced the tip with a 0.5mm one, and attached the Meccano supports to flanges on the nozzle.

As we've destroyed all the heating elements and are wary of vapourising more PTFE tape we've used 5W resistors as heating elements, holding them on with a hose clamp. Using the standard 12V supply and 27 Ohm 5W cement/ceramic resistors, we generate approximately 10W of heat. If we need higher temperatures, we change the values of the resistors. It's cheaper than buying nichrome and the ceramic bodies can be re-shaped to fit the nozzle body with a tile cutter.

No controlling electronics is required, but we have added a switch and indicator LED for safety.

We still need to re-shape the extruder drive mechanism as the new nozzle is a drastically different shape and size to the old one. The EVA feed doesn't line up properly and the end of the nozzle is too far above the turntable. We'll build a better adjustable support while we're at it.

Vik :v)

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