Forrest Higg’s vision has just come true! He’s written several times about how he wants to design and build a system that a reasonably bright 12 year old could build. I guess we should have known it would have taken a 12 year old to design such a system in the first place.
My lego prints connect slightly better to other printed legos than real legos. I suspect this is in part to the ridged texture to both parts. This also makes me think that printing legos is a fool’s errand.
While lego nubs are circular, the parts they fit into touch the circular nubs tangentially. For instance a nub fitting into a corner piece would be held in place by two straight sides and held against a circular tube. The picture to the right shows the underside and nubby bits for several lego (lego compatible?) pieces. This system probably works because of the exacting tolerances of real lego parts. I’m guessing they tested the nub heights and contact points to find an optimal mix of most of the same criteria I have for an interconnecting building block system.
Without tighter printing tolerances, I don’t think three tangential points are going to be enough to hold printed parts together. Thus, it may make sense to have taller nubs on printed parts. Then again, the ridged nature of printed parts may allow them to better fit together without having taller nubs.
One benefit to having circular nubs is that you can make interesting components where pieces pivot. But, this is more of a lego-hack than an actual useful feature. I’m not as concerned about this particular usage because I could always design a printable pivoting part.
So, other than that one narrow usage, why circular nubs? Why not circular nubs with circular holes? Why not square nubs with square holes? Or circular nubs with notches in them?
The design question I keep coming back to is “How do I create a reliable interlocking system for blocks?” My criteria for a robust and useful system are:
The interlocking system should allow interconnections in three dimensions.
The pieces should snap/interlock together reasonably well/easily.
The pieces should stay assembled reasonably well.
The pieces should snap apart reasonably well/easily.
The pieces should not require additional tools to be assembled and disassembled.
MakerBlock:“Yeah, listen, I’ve got no technical skills – it was basically a bolt together system.”
Dude: “Seriously?! So, what, when you’re ready to print you just send it an STL file?”
MB: “Um, well, not quite. I have to take the STL, make sure it’s printable, convert it to GCode, and then convert it into an S3G file, and for maximum resolution/quality save it to an SD chip which I then put in the ‘bot and then… Hey, where’d you go?”
The fact that it’s not yet a USB plug-n-play system kinda scared him off. 1 I’m confident we’ll get there some day. And, even if we don’t, I’m still having a hell of a time.
