4 ms·
I like the idea of this sort of thing. Lots of different predesigned parts, cool, cool. But it's axe grinding time. As I recall from digging into STEMFIE a w
by TOGoS 2y ago
I like the idea of this sort of thing. Lots of different predesigned parts, cool, cool.
But it's axe grinding time.
As I recall from digging into STEMFIE a while ago (because I can't find this information on the site), they use some odd base unit like 12.5mm, which I assume is chosen because it's approximately half an inch (12.7mm), but "more metric". Which as far as unit systems goes, gives you the worst of both worlds, in that it will almost, but not quite, fit with your 1/2-inch based construction systems (like Erector Set/Meccano beams), and the metric numbers end up being not all that nice anyway (if you subdivide a beam in half or thirds you up with 6.25 or 4.167mm), so you may as well have picked exact compatibility with an existing system, anyway.
I wish people were less afraid to use "half an inch" as their base unit, if that's the size they want. It's as if they hear 'metric is superior' in grade school and think that means that real-world objects that happen to be designed around something other multiples of 10 of some metric unit are yucky and they'd better adjust it slightly so nobody notices, even if that means throwing out compatibility with a lot of existing stuff.
Okay rant over.
- tonyarkles 2y agoLol I'm laughing about the time I designed a circuit board with standard 0.1"/2.54mm headers but accidentally ordered 2.5mm headers. The small 2-4 pin headers went in just fine and then when I went to put the big 20 pin header in... no dice.
- TOGoS 2y agoYep! The slight difference is often acceptable over short distances[1]. It's only when scale up that it becomes a problem. [1] e.g. http://www.nuke24.net/docs/2019/JSTRCYMiniPVCompatibility.html http://www.nuke24.net/docs/2019/JSTRCYMiniPVCompatibility.ht...
- kragen 2y agoi have a vague memory that this was a cursed soviet standard, but i might be confabulating in my dotage
- zokier 2y agoIsn't that just same as 10cm base unit with 8 subdivisions though? Doesn't seem that odd to me. I mean 50/25/12.5/6.25/3.125 is a series that comes up all the time, it is not exactly uncommon to subdivide a power of ten by a power of two.
- TOGoS 2y agoYeah, the holes will match up with VESA hole patterns, I guess. But that's the only 100mm-based standard I can think of. I would have[1] chosen a size that matched with 2020 rails, or LEGO bricks, or Erector sets, or common lumber (1.5" is a multiple of erector set beams, so two in one if you go that route), or something. [1] have. 1/3-scale two-by-two (1.5" square lumber)-based gridbeam actually works out really nicely.