Friday, November 25, 2011

GT RepRap project update

An update on the 4 GTers that I’m guiding on building 3D printers. I’m building one along with them, so if anyone else wants to just have one without building it, I’ll have one for sale when this is all done, in about 3 weeks. I’ll probably bring it to Capricon for demos, write me a check and you can take it home.
It’s a funny time to build a printer because Prusa just released “Iteration 2″ of the Prusa Mendel printer. It’s got some exciting changes, but it does mean that I’ve probably seemed horribly wishy-washy to these poor folks. The new version of the printer uses less parts, should produce better prints, and be easier to use.
Just yesterday I discovered that the official recommendation now is to use fine pitched timing belts rather than the old T5 (or XL in the US). The recommended T2.5 is hard to get in the US, but after chatting with some of the leading folks on RepRap development on IRC, They pointed me to a supplier but also informed me that it’s actually better to use “GT2″ (how appropriate) timing belt and pulleys – it’s designed to eliminate backlash in this sort of situation.
The old XL belts are still fine, but the new stuff is supposed to produce slightly better prints, and it’s not much more expensive.
I did determine that using really tiny pulleys is really bad. I put on some 8 tooth pulleys and the backlash is horrible. I went back to 10 tooth and it is much better. Looking forward to trying GT2 36 tooth.
The even more exciting development is the elimination of the upper and lower print bed. This reduces moving mass, greatly reduces complexity and also eliminates periodic levelling of the print bed, which is a pain in the rear. Apparently just leveling once during the build by adjusting the frame is good enough. If this works I’m changing my old printer as well, because the print bed complexity is irritating and leveling is a pain in the ass.
There’s an Iteration 2 build party going on in Cologne, Germany on Dec 3-4, more info here. I hope to get good tips and photos to help me put together good instructions for our folks.

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