MakerBot Thoughts 2

I have ideas written on note pads and paper plates scattered everywhere I might have a thought. Again, I’m just going to post them here for myself and hope that others find some inspiration.

XYZ Platform
-Encoding. Phil from FUBAR Labs pointed out that we don’t necessarily need encoding along the whole range of each axis to do continuous printing via the belt method. We just need a way to determine when the nozzle is at the right height for each print. We might be able to do this using the endstops.

Extruder
-Heat a thin filament and put it through an atomizer-like device to spray the material. Spray in layers to build an object. This probably doesn’t need to be a filament. This could be cool for a freeform fabricating lathe.
– I want to eliminate the thermal barrier retainer. We shouldn’t need a thermal barrier if we make a heater barrel with a thermal gradient such that the tempreture at the top never reaches a bad tempreture for the acrylic extruder body. We could have a captive nut in the extruder body that the heater barrel screws into. A few washers can be at the top of the heater barrel to act as a heat sink.
– Frostruder. There are decorating frosting tubes you can buy at most supermarkets. They have the basic shape of a toothpaste tube. If the back were cut off it would make a cylinder. This is pretty close to a pre-filled syringe.
– Instead of a flat-edge timing pulley as the pinch wheel, we might be able to use a pulley with a curved profile or a V profile. The pulley may not even need to be toothed if the filament fits in there right.
– Bowden extruder. Place an encoder at the heater barrel end to monitor the entering filament. A valve in the mechanism at the head can regulate the flow.
– the larger the pinch wheel and idler pulleys are, the more surface area they will have to contact the filament. More teeth in the filament means a lower force per tooth to achieve the same total force. We want to keep the force per tooth well below the shearing force of the material.

Slicing and Dicing
– During infill the extruder leaves gaps at the end where it turns around. The ends should be a dog bone shape to fill this in rather than a perfect U-turn.

Materials
– Let’s make a henna extruder! We can give ourselves temporary tattoos.
– Feed plastic ribbon into the extruder rather than a round stock. This could give more surface area for the extruder to grip. Maybe a triangular profile, which can fit into a V-grooved pulley. A triangle profile would probably work really in Zach’s twin drive extruder.
– Is there a glow in the dark material we can extrude?

Other Parts
– Use a capstan-like device for loading the filament.

Questions
– What is the shearing force per tooth on the pinch wheel and the twin drive extruders?

Macheining Notes
– To bore a hole through brass threaded rod to make a heater barrel I need to buy a “high-speed steel” bit. It should be “long length”. It’s okay if it’s parabolic.

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One thought on “MakerBot Thoughts 2

  1. I don’t own a makerbot or reprap, so I don’t even know if resolution is a problem, but I had some ideas about it:

    a) use water to regulate the height of the build platform. You then only need a way to pump water with enough “resolution”.
    b) (theoretic): let the build platform move alongside the extruder – this way you would control the delta between the two with two different movements, which might give more resolution.

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