MakiBox A6 Pellet Drive Improved Output

2021-06-22 20:29 by Jonathan Buford (comments: 0)

MakiBox A6 Pellet Drive Improved Output

After revising the nozzle assembly to prevent it from melting the body of the drive, things are looking pretty good.




We still don't have the final output speed or consistency, but it looks like that can be fixed with some changes to give more torque to the drive and with cooling off the output on the way out of the nozzle.

In the printer, this will be feeding into a Teflon tube that leads to the hot end extruder, so that may give us enough to help shape and make it more consistent, but we will try and get the output consistent in just the free air first.



dionstorage responded:
Nice progress. from what i read, you plan to feed the pellet drive output to extruder. why not fuse them together? i mean the extruder become one with the pellet drive. because i think to have the pellet heated twice is not so good.
Evan responded:
@dionstorage - if you do that, then the extruder becomes extremely large. Especially with pellets that can't really be pulled from elsewhere (like filament can), you really need the extruder to carry the entire bin of pellets with it. This substantially slows down the printer (much, much more weight to move around), increases power consumption, increases wear, and reduces build space.

The Bowden extruder was designed specifically to get around this problem - it leaves the drive system (including the heavy stepper motor) in a fixed location and just feeds the filament up to the extruder through a Bowden cable.

As you've said, the need to melt, solidify, and re-melt the plastic is a bit of a problem; this is one of the main reasons that nobody has done an all-in-one pellet-based printer yet. Hopefully Jon will make the Makibox the first to achieve this.

Jonathan Buford responded:
Either way, the plastic will be heated twice, and as long as the critical temperature is not met, most thermoplastics will be in good shape for minor heating and solidifying.

If we were feeding it filament, it would have gone through the same cycle to become filament, as all plastic starts its production life as pellets.

As Evan said, for the A6, it would be too cumbersome to make the hot end handle pellets directly. It would be possible to do so with a larger machine.

secondsky responded:
Actually I'm using a ultimaker, and i have to say that the Bowden extruder is a good theory but a very unreliable true, most of the time.
In particular, it needs extremely regular wire diameter to not jam every five minutes.
I think I'll buy for sure a makibox, that seems to be a very well made 3d printer, but I do not understand all this research on pellets when, in my opinion, would be much more important to realize, first, an extruder and fit it to do some printing test, directly on the xy axes.
Then, design an accessory to create your own cable, separated from the printer.
There are currently many models, I think the biggest problem of this technology is that is not very reliable, and would be nice to be sure to finish all the print we start to print, before have a super accuracy and speed ( in this sense I think it's a very good idea don't use belts).
Jonathan Buford responded:
It is likely we will be putting a sensor to monitor the movement of the filament at the hot end, but there is a chance with thinner and tighter cable assembly that the accuracy will be good enough for a reliable print.

We could have simply printed with existing filament a while ago, but that would not have really helped much in this case as we needed to print using everything that we would be able to reliabily ship in quantity.

The simple fact is what you outlined, the supply of filament is a real problem. From a business standpoint, using filament has many additional costs and adds a significant lead time over a pellet supply. We want the MakiBox to be the printer that enables making something at home to be an economic choice, not just a choice because it is interesting. That is the only way to take the technology mainstream and witness real potential of it.

secondsky responded:
I understand and appreciate the idea. only, I would see as a good option to have a separate machine to produce your own cable as an optional and parallel choice, also because in this way would be nice to use this pellet/wire converter for other printers and not only for the a6.
However, I will continue to follow you and I hope everything works well, as I tell you I got a ultimaker impressed by its accuracy but it is a problem when you have to keep up with each print to avoid to missing the cable at 90% of the process.
I think you have solved very well the mechanical part but extrusion is a very delicate question.

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