Wednesday, November 16, 2011

Sumpod Adventures - Part 3

Now for the extruder and hotend. There are a couple issues with the extruder. The first is that there is no way to put the pulley on the motor, and the other is affixing the bowden tube fitting. For the motor, I drilled out the hole to 1/2" so that the pulley can be attached to the motor and then the motor mounted to the extruder. You can see in the pic below how the hole is now 1/2" all the way through. Before, it was only most of the way through and then had a small hole for the motor shaft. This provided no way of accessing the set screw as it is down in the hole. And the motor shaft is too short to mount the pulley the other way. Also in this picture is the modification to the top for the bowden tube fitting. The fitting does not screw into the included M10 nut. I'm in the US, and found that I could use a 3/8-24 nut which has a smaller outer diameter, but the inner is about the same, and allows you to screw it in about 1 thread, just like the M10 nut. This means less modification to the extruder. I just carved out a little bit on each side (about 1/16" per side) until the nut fit with both halves together. I hope that the single thread is enough to hold it.

As for the hotend, this is where my parts differ from the instructions at http://renaissance-engineer.net The main issue here is that the nozzle is different, and no longer fits correctly. The nozzle that came with my kit is a single piece with the threads for the bowden tube fitting integrated with the nozzle. This means that the fitting is now about 1/2" taller, and it interferes with the screw that holds the heatsink to the X axis. To fix this, I drilled another hole in the small aluminum block that is closer to the edge, so that the bowden tube fitting is now beside the screw.
Also, the two screws that hold the small aluminum block to the heatsink won't work. The holes in the heatsink aren't tapped, and are larger that the screws. The screws also aren't long enough to go all the way through. So I got some longer screws and ran them all the way through to the other end of the fan. We'll see if this poses a problem with the heat melting the fan. I hope not :)
There was one more small issue, the holes in the aluminum block were not drilled perfectly straight, so the nozzle is slightly tilted. I hope it doesn't affect anything. If it does, I guess it's not a big deal to make a new one.

I've now got the machine mostly assembled, all that's left is the wiring. I'm hoping to get that done tonight and maybe test it out!

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