Saturday, November 21, 2009
Moving towards production
The Java driver software now handles multiple part printing reasonably well, though wrinkles remain. This tray of Mendel parts was printed on my old Darwin in six hours (my new Mendel is still, as web pages say, Under Construction...). Erik and Nophead's experiment of reversing the extrude motor at the end of each write has led to minimal PLA string.
Ages ago Zach defined an XML multi-part file format for RepRap (and Fab@Home) that should be pretty easy to implement that would allow one to store a whole tray of parts like this in a single file. (The G-Code file generated to build all of them is also a single file of course.) I have a few immediate things to do on the software/firmware front (like having an M code that sets the temperature and waits till the extruder gets there, as opposed to returning immediately - one needs both), then I'll implement that. That in turn should mean that Mendel is represented by between four (Mendel) and six (Darwin) files that one just has to load and print...
Labels: factory, fast production, reproduction
Friday, August 24, 2007
RepRaps by the ton
We (and especially Zach) have been devoting quite a bit of thought to how to get people started with RepRaps - when a lot of people have them, then they can all make parts for each other, but when hardly anyone has them then they can't.
In Bath we've had a visiting student over the summer: Nishad Sohoni. He has really come up with something special. Here are the parts for the standard RepRap polymer extruder (quick-swap version) stuck to some sticky tape:
The sticky tape will form a mould split line. Here are the same parts in a box with some risers and runners added:
And here's what you get when you pour silicone rubber in under a vacuum (to eliminate bubbles):
Then Nishad cut the silicone to the split line with a scalpel and took the original parts out:
Note the use of a few silver steel rods as cores for deep through-holes in the parts to be made.
Then he put the mould back together with a load of elastic bands and poured in a resin (no vacuum - the resin stays liquid enough for the bubbles to float out of the risers before it sets). The resin we used was the "water-clear polyester casting resin" from e-bay here. Here is the result:
We're obviously going to make it into an extruder and test it...
The neat thing about this process is that, while you need a vacuum chamber to make the original mould, the making of the actual parts can be done in ordinary (well ventilated...) conditions. So we can make moulds and send them to people, who can then make kits for the RepRap store (or elsewhere).
In Bath we've had a visiting student over the summer: Nishad Sohoni. He has really come up with something special. Here are the parts for the standard RepRap polymer extruder (quick-swap version) stuck to some sticky tape:
The sticky tape will form a mould split line. Here are the same parts in a box with some risers and runners added:
And here's what you get when you pour silicone rubber in under a vacuum (to eliminate bubbles):
Then Nishad cut the silicone to the split line with a scalpel and took the original parts out:
Note the use of a few silver steel rods as cores for deep through-holes in the parts to be made.
Then he put the mould back together with a load of elastic bands and poured in a resin (no vacuum - the resin stays liquid enough for the bubbles to float out of the risers before it sets). The resin we used was the "water-clear polyester casting resin" from e-bay here. Here is the result:
We're obviously going to make it into an extruder and test it...
The neat thing about this process is that, while you need a vacuum chamber to make the original mould, the making of the actual parts can be done in ordinary (well ventilated...) conditions. So we can make moulds and send them to people, who can then make kits for the RepRap store (or elsewhere).
Labels: fast production, moulding
