zondag 3 december 2017

Prusa MK2+MMU

I recently built a Prusa MK2 + MMU (multi-material upgrade), using only PLA parts printed on my T3P3 delta printer. I wasn't entirely sure PLA was going to work for the extruder parts, as the parts that come with the kit are printed in ABS. After more than 100 hours of printing with it, I think it's safe to say that this works just fine, at least when printing with PLA (at around 200 degrees celcius).

The multi-material upgrade is a lot of fun. I had a minor issue at first, where the filament would repeatedly get stuck at the end of the cooling tubes. I decided to ream the filament path(s) below the cooling tubes with a 1.85mm drill, and haven't had an issue since (knock on wood). I love the simplicity of the whole thing, and the ease with which the multiplexer opens up to debug any issues.

For anyone interested in getting a multimaterial upgrade, it's probably good to know that the normal wipe tower settings don't work very well for especially black filament. In order to avoid filaments 'colour bleeding' into each other, I usually had to double the wipe tower size. In combination with constant filament switching, this means you should be prepared for very, very long prints, across multiple days for moderately large objects (with many colors). The large kirby above (about the size of a tennis ball) took 11.5 hours to print. Another thing to consider is that print quality seems to suffer sometimes, I guess because of the bowden setup, especially if a color is only used for a small detail (see for example the eyes of the small omnom above.) Interestingly, it seems that this depends on filament (color).

I will play more with multicolor prints in the future (when hopefully there will be filament available with less bleeding, as well as per-filament settings for the wipe tower!). I will also play more with supports, and hopefully print my SNES controller again with it. I already printed a donkey using BOVH for support, and found out that doubling the wipe tower is also a good idea with supports, or the main part may become brittle:

zaterdag 29 juli 2017

Cleaning Soyabella screen

We recently bought a "Soyabella" soymilk/nutmilk maker. It's a really nice machine, and easy to clean _if_ you clean the soymilk screen right after use. If you don't, and I don't always feel like this or just plain forget about it, it becomes very hard to remove the protein buildup from the tiny holes in the screen. The Soyabella manual also mentions this, but interestingly gives no suggestion on how to actually clean the screen later on..

After trying a few approaches, such as soaking in vinegar overnight, and looking online, but nothing working, my wife went to a chinese search engine, and quickly found out that rubbing salt into the holes makes it actually pretty simple to clear out the holes. Not sure about the actual chemistry of how this works, but it looks like a combination of small salt particles being pushed through the holes and actually reacting with the protein.

So far, I've only used this with a wet sponge, fine sea salt, and rubbing from the inside out.

update: While salt works, rubbing it in is still a bit cumbersome. I now use a small metal-wire brush instead, which works much faster.