MakiBox Pellet Drive Partial Updated Testing

2021-07-03 16:51 by Jonathan Buford (comments: 0)

MakiBox Pellet Drive Partial Updated Testing

Some days things just don't go smoothly. This was one of them. But, we still got some encouraging results from the revised drive mechanism.


After finishing up the nozzle, making a good tip insert, wiring everything up, we started getting random run away temps, which seemed to be tied to the thermistor being a little loose in the socket. One of the problems we have (sorta a good problem) is that our system response is so fast that we can run up into the mid or high 300's if the thermistor is not accurately reporting in a matter of 20-30 seconds once at temp. With this version, it is taking around 1-2 minutes to reach print temp from what I can see, but it may take a little more time for the melt to catch up in the plastic. The nozzle gets to mid 200's in around 1 minute, but it will take some time for that to settle in the system. 

You can see in this picture that the flex circuit around the edges of the heating flange at the nozzle looks a bit dark. That is what happens when the heater hits the mid 300's. This is accompanied by a little bit of smoke, which is not recommended for breathing. But, for something hitting almost 100 degrees over the designed temp, it handles it pretty well. 

A little later on, the extruder heater just turned on full bore when we gave it power, so we need to check out the connections and possibly the board tomorrow to see where the fault is. 

Even with the temperature control having a lack thereof, we were able to start getting some output from this one, although, just a small amount. It at least shows a fair amount of more smoothness in general, and it looks like the increased backpressure is starting to do the job. We may need to increase the gearing more to build the pressure a bit more, but it seems like it is close to what we want. 

The one on the bottom is where the plastic got overheated and the one on the top is from cleaning out the machining oil and other residue, but the one in the middle is looking pretty much like what we are looking for.

 So, encouraging results, let's see what we can do with the gear tomorrow.



gr0b responded:
What is the diameter of the output filament? I know you have already suggested this before Jon but Makibox owners could make filament for other 3d printers.
After looking at the pricing of filament compared to pellet could be a market opportunity for Makibox owners.
Jonathan Buford responded:
The output of this one will likely be smaller than 1.75mm. I'm leaning towards around 1mm so far, but will be testing a range in the next few days. After we wrap up the production design for the MakiBox, I'll be doing a separate extruder design based on this one, but there are some differences if we don't have the constraints of the current box.

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