MakiBox Pellet Drive 3rd Iteration Initial Test and Dissection

2021-06-21 20:38 by Jonathan Buford (comments: 0)

MakiBox Pellet Drive 3rd Iteration Initial Test and Dissection

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Yesterday we fired up the current pellet drive and had some good initial results. So far the output is looking a lot smoother and with less air bubbles. We had some problem with the heat conduction being too good with this brass nozzle, so we are working on modifying it to prevent the body of the drive from heating up enough to melt it.

In the mean time, let's look at the changes that have happened over the last few generations of this design. The above plastic was pulled out of the first generation nozzle that we tested. It has been cut open using the milling machine so that we can see what the structure looks like internally, and it is pretty obvious that there is a lot of air trapped in the middle, just before the output.

This is the current generation. Now, there wasn't enough material pushed through yesterday to flush out everything that was in the nozzle as it got up to temp, but you can already see that there are much less air bubbles to start with. On the end where the pellets are fed in, where new pellets were pushed in after the melting zone was established, there is a solid layer with no air trapped. It looks like when the drive is run until the plastic has fully been replaced in the nozzle with pellets added at the running temperature, then the air bubbles will go away. 

This is a video of the first run. The mechanism is limping a little as the nozzle is getting hot enough at the base to melt the supporting plastic (which is what we are modifying now).

This is a quick walkthrough of the various generations and talking about the differences seen in the melted plastic.

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