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Mjolinor
12-22-2013, 06:50 AM
Why do none of these DIY printers use plastic chips / powder / scraps in a hopper.

It seems to me that you could push plastic bits quite easily using a drill bit on a stepper motor in the same way as the filament extruder things.

Anyone with some actual printing experience can tell me before I waste hours of my life trying to work it out for myself?

Gadget
12-22-2013, 07:39 AM
I think the chips would be hard to regulate as far as flow rate goes. It would be hard to compensate for how dense or loosely packed the chips are. With filament you have a very precise measure of the material going through the tip.

winterfalke
12-22-2013, 09:53 AM
I would agree with Gadget, you would need a fairly precisely made screw extruder to compact and solidify the loose material onto a uniform mass with no voids before it went into the print head, and that is a lot of cost and complexity. For continuous printing, I would prefer to see a screw extruder feeding filament directly into the print head, but by simply putting the filament in a coil on the machine, you can let someone else pay for the extruder. Having an extruder directly on the print head would be impractical, you would make it too large and heavy to move effectively. Now a horizontal style machine, with a stationary print head and a full 3 axis table, could easily have an extruder feeding the print head directly, but that is a pretty big jump in cost and complexity for most users. And the added difficulty of printing sideways limits your material choices.

MatthewBasaraba
12-30-2013, 07:44 AM
Wouldnt need to print sideways, just a very large area for the table to move in X and Y.

I think it is feasible to make a machine that would create its material out of pellets while printing but I think the space requirements would be more than most would be willing to give up plus the extruder would need a custom design to feed constant and with no "Filament" it would be hard to "PUSH" the material unless you had a very precise tube where it was forcing the material through and stopping the flow would be an issue in itself.

Now if you could GRIND the pellets to very very small sizes and an auger to force it through a heating element it might work.

bobc
01-04-2014, 10:37 AM
Same reason for any division of labour really, in works out more practical. Cost, size, mass, better control, modularity etc.

A DIY pellet extruder might look like the filastruder Filastruder | The Premier At-Home Filament Extruder/Maker (http://www.filastruder.com/). That is a lot of stuff to mount on a desktop printer. You either need a huge gantry or a huge fixed head system.

Paragon Spirit
01-21-2014, 08:55 AM
I agree with the above re:cost & complexity.

I think the division of labor point is valid, but figure we should be able to extrude our own filament from bits of material. Reduce waste and scrappage by grinding and re-extruding rather than buying another roll.