Software development for petal infill with varying geometry and composition Part 1: Hardware and firmware upgrades
Abstract:

A popular type of Additive Manufacturing is Fused Filament Fabrication.  Fused Filament Fabrication  heats different types of thermoplastic based filament and deposits the molten polymer on a build surface on a layer-by-layer basis. MP2 uses 3 extruders which feed into the nozzle to achieve localized multi-material composition.  The MP2 has been plagued with freezing, power cycling, bed and extruder heating issues, and filament jamming.  The goal is to add stability and consistency to printing by rewiring, changing the control board and firmware modifications.  These changes were implemented through small modifications followed by testing to make sure the changes being made are producing the correct results.  Wiring was managed throughout the printer to keep it away from high temperature components and add strain relief.  Firmware was modified to allow the use of an expansion board to drive additional stepper motors. The firmware modifications caused a couple of problems such as SD card software interface issues, low z-axis stepper driver current, and eprom errors.  The SD card software interface and eprom errors were rectified using firmware modifications.  Firmware and hardware modifications were used to fix these issues. Multiple successful prints were completed after all these issues were fixed.  All these modifications have produced a more stable system.  Over 10 prints have been completed and there has not bee any freezing or shutting down.  Future work includes adding two additional relays for the heater cartridges and full documentation of all changes, procedures, issues and future updates to both software and hardware.

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Kiana H.
Well done Alan, great explanation and clean poster!

Could you elaborate on where this printer would be adopted (i.e. lab, industry, home)? Are future works being proposed as a manufactured product? What is the largest specimen that can be printed under this capacity prototype printer?

Alan Melendez
Its roots are based in industry with its intention to develop and print synthetic knee components. With its modular design it can be used at home. There are no plansa to produce it as manufactured product but the prints being made with this printer are used and sent to our different industry partners. The printer does take after a Prusa MK3 so its volume is similar to it but due to much bigger extruder carriage we are limited to 190mm on the x-axis, 215mm on the y-axis, and 140mm on the z-axis. The z-axis is heavily limited due to the weight of the extruder carriage.
Colin Bill
Is this a lab made fabricator? Why was the original design so poor, since surely most of the problems could have been predicted?
Alan Melendez
This is a very heavily modified Prusa MK3 printer. The multi-material extruder is lab fabricated, the printer chasis is from Prusa, and control board is from Bigtree Tech. There have been 4 versions of the printer so far and each has addressed quite a bit of issues with it. We have taken an itterative design approach to make sure we fully test after each design. We have learned quite a bit and apply those lessons to the next design. Second, some of the components necessary may not be available at the time. The control board is a good example of this as there are not many companies who develop control boards that can deal with more than 5 stepper motors. So far we have found only 3 companies that develop boards with more than 5 stepper motor capability.
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