New project idea that I’m starting… the LoCoRap

So, you’ve probably heard of the various 3D printer projects as of late, including the RepRap and MakerBot’s CupCake CNC. However, they’re expensive. A RepRap will cost at LEAST $500, and a CupCake starts at $750.

Also, at least the RepRap has some steps that require special skills and tools to assemble – the extruder, for instance, requires a CNC lathe. While I’m a newbie to all of this, it also seems like there are some design decisions on the RepRap that make it more complex, harder to assemble, and more expensive in the long run, although they do make it easier for it to print parts for itself. Case in point, this blog post where a commenter’s main criticism of a possible improvement to the RepRap is that it reduces self-replicatability.

But, why have a $500 machine that can print parts for itself when you can have, for instance, a $100 machine that instead uses readily available off-the-shelf parts with simpler modifications? (And, theoretically, that $100 machine could act as a RepStrap, or a machine that can print the parts required to make a RepRap.)

That’s my project goal – to make a 3D printer using $100 or less of off-the-shelf new parts, that anyone can build. I’m calling it the LoCoRap, for either Low Cost Rapid-prototyper, or Loco (as in crazy) Rapid-protoyper – some people said I was crazy for thinking it could be done for $100, hence the alternate definition.

I certainly don’t mind sharing with the world, and there are some ideas that I’d like to borrow from the RepRap, and if I actually somehow manage to integrate a good idea into this that someone else wants to use, I’d love to see them able to use it. Therefore, looks like I’m licensing this under the GNU General Public License v2.0.

I’ve got some ideas to start out with to reduce cost and complexity while maintaining quality, mainly obtained from the Fat Man and Circuit Girl IRC channel (#fmcg on Freenode.)

I’m not sure if I’m going to use this concept, but Chris Jones suggested using a polar table, rather than an X-Y table. This replaces at least one linear slide with a rotating arm that the extruder is mounted on. His suggestion also involves the table itself rotating, although I have some concerns about how straight lines and such can be done, so if I use the polar idea, I’ll probably have a linear slide for the extruder to move on.

An idea that I’ll almost certainly use for the extruder, however, is an idea that Jeri Ellsworth gave me. Currently, the RepRap project is making their own nozzles, using a process that requires a CNC mill. However, Jeri pointed out that MIG welding contact tips would have a small enough opening (a .023″ tip would be 0.5842 mm, which isn’t quite as good as the 0.5 mm of the RepRap tip, but is still decent,) are threaded, and have a taper. While the taper is all at the beginning, it does mean that I should be able to drill the necessary 3.5 mm hole by hand. Oh, and they’re usually around $1 each.

Tractor Supply Company carries a pack of 5 .023″ tips for some Hobart and Miller MIG welders for $6.99, and I got a 9/64″ drill bit as well. This gives me a chance to mess up.  😉

Once my drill is charged up, I’ll drill a tip, and post photos of the results in this entry.

So, current cost breakdown, including the 7% sales tax, but not including tools in the price:

Money spent:
$7.48 for welding tips

Of course, that’s for 5 tips. Let’s divide that by 5.

Money spent per LoCoRap:
$1.50 for one welding tip for the nozzle

Tools needed so far:
9/64″ or 3.5 mm drill bit

Due to the cost sensitivity of the project, I’m going to post this cost and tool breakdown at the end of every post about the project.

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