While Plan B already better than expected, there are still a few things that probably could be better. Also there are some technologies that were not that interesting to pursue while plan B was still in progress, but are not that it works.
Improvements on Plan B
- Get the top surface out of the design. While is does give a nice platform to work with, the top surface serves no real purpose in strength or function. Removing it would safe a considerable amount of money on the frame.
- Carriage cable paths are not really working. The cables get there but it looks very flimsy.
- Add acceleration to the movement. Plan B does not use any acceleration on any of the movement (except for the printing swipe movement). This severely limits the speed of the printer. When acceleration is added all movement will be smoother and max speeds will be higher. Acceleration is planned to be added but it requires a complete rewrite of all movement functions.
- Add pause function. Plan B has no pause during printing. While it is not a necessary function, it is a handy function to have. Pausing the print is already functional, resuming it however is still a problem, making the pause function kind of useless.
- Place the nozzles closer to the printbed. The optimal gap is several millimeters. Plan B has a gap of several centimeters. This causes a decrease in accuracy and variable gaps between lines. The C6602 is not made for 3DP printing and the carrier of the cartridge is in the way, so to fully implement this improvement a different cartridge is needed.
- (Selectable files). All files to be printed have to be on an SD card with the name print.txt. The .txt part will not be fixed because of the limitations of the used libraries, but the print part needs to be fixed. A function needs to be added that allows the user to select a file from the SD card.
- More efficient Nozzle commands in Plan B code. While Plan B code currently gives no problem, it will when better cartridges (C51640 for instance) are used. Toggling 100 nozzles on currently has to be done by selecting ever nozzle (N0 N1 N2 N3….. N97 N98 N99 N100 X15.22 T1). A better way would be to be able to select a range of nozzles as well (N0-N100 X15.22 T1). For now it is not necessary though, so it will be added later.
- Better Plan B converter. Plan B converter works, with that everything is said. It glitches with some files and it needs another slicer to actually convert the STL file to something usable. It would work way better if it simply sliced the STL file itself.
- Add insulation to the buildbox. The buildbox is made of aluminum and loses a lot of the little heat it produces to it’s surroundings.
Additions to Plan B
- Better cartridges (piezo inkjets instead of bubblejets). Plan B uses A6602 cartridges which are bubblejet cartridges. They heat a small portion of the ink to expel a droplet. C6602’s were chosen because there is documentation available. Bubblejet physically heats the binder and give very little control over the droplet size. Piezo inkjet cartridges are harder to control and more expensive, but don’t produce any heat and give a much greater control in droplet size.
- Test the HP C51640 cartridge. It has roughly the same functionality as a C6602 but has 300DPI instead of 96DPI. It also has around a hundred nozzles instead of twelve, so even though it has a higher DPI it also has a wider band. The only drawback is that the nozzles are multiplexed and require additional electronics and more calculating power. A solution might be a dedicated controller just for the cartridge control.
- Having a CISS (continuous ink supply system) cartridge in stead of the old fashioned reservoir cartridges. Ciss has an external tank and supplies the ink to the cartridge via tubes. This gives more control over what goes into the cartridge (because ciss tanks are easily refillable or replaceable) and gives a safer binder supply. It doesn’t even cost much more than an ordinary cartridge, so there aren’t many drawbacks. I have found a supplier, but I will have to look into this.
- More open source printing materials. Powder printing is owned by only a few companies and there is a limited amount of cheap or open source materials. More research in materials needs to be done to get increase the amount of available materials. Open source gypsum, USG HydroPerm, ceramics, sugar and graphite are things I want to test.
- Rough pistons. For FDM printing a smooth printing surface is desired. With this in mind Plan B was designed. However at thin layers, the powder slides across the printing surface, deforming and breaking up the layers. For the best result, a rough printing surface might work a lot better.
- SHS. Selective heat sintering. It is not 3DP printing, but it is quite an interesting technique. There is 2 ways this can happen. The first way is to have a row of tiny controllable heaters (or a single heater), selectively heating a plastic powder to sinter it (the name seems quite explanatory). This can perhaps be done with a thermal printer head normally used for receipts? The other way is more relevant to Plan B. It is inkjet printing with a IR absorbing liquid (such as black ink) and then moving a big IR heater over the powder. The black ink will absorb the radiation, heating up to near or above melting point, but the un-inked white will absorb a lot less, thus heating up less. This technique can create parts which are at full strength immediately. From what I have seen with the Blueprinter, prints do require quite aggressive depowdering, but this is no issue. This might be an interesting direction to test, using finely controlled low power components to modify IR absorption and then using a crude high powered heater to heat everything. This as opposed to carefully controlling High power.