From @gpagnozzi s build thread…
I figured that I could weigh in. I figured probably better in my own thread though.
Given that engineering choices are all about trade-offs, I do see some patterns there. Many of these patterns I’ve kind of broken with my build choices, but that’s of course completely on me. As compared to other build styles, you’re far more likely to choose a 2 part structure to hold pulleys and idlers. This is quite evident in the LowRider, as well as the ZenXY builds (both of them) and what I saw for the older MPCNC, though not the Primo. I see this as a decision that is generally to eliminate a need for 3D printed support pieces, while providing double ended support for axles. On the whole, given that my printer has always been weak at bridging, and that I despise supports (and trying to separate them from the printed pieces) this appeals to me.
You also will sometimes do things that it takes me a while to recognize that are to decrease unique parts, both printed and otherwise. I get this from a kit point of view, it makes so much more sense to have all of the xxx sized bolts the same length where possible, and eliminates packing errors. This is the design decision that I’m most likely to change up with my builds, by changing materials, or sizes.
And of course, you make some design decisions based on hardware that’s easy for you to source, or that you will have on hand from other projects. Most of it is also pretty easy for me to source as well, with some funky stuff around Metric/Imperial that are regional issues.
Rather than patterns, I see evolutions in your designs. Some things, like the bridging tricks in the screw holes have been around for a while, and since they’re good ideas, don’t change much anymore. Some things get simplified as unnecessary parts get removed. For example, the belt locks on the LowRider using zip ties and the little rounded inserts became the lock piece on the Primo, which became that folded lock in the ZenXY, and then became the clipped piece locks that you use here. Each one is a step towards a more simple, compact lock that still has adequate strength for the belt tension, but becomes a little smaller and more compact.
For the low unique printed part count, as it applies to this project in particular. The low model count is nice, and from the standpoint of making replacement parts, it’s pretty cool. Using the same motor mount 5 times in particular is great, and the repeated Z axis has some nice advantages.
The mirrored Y trucks took a bit of thinking on to make sure that I did things like put the rails on the correct level, and I did mess up my CAD a little there, because I spaced it for the motor sticking up to be on the lower level, though it’s the other way around. I guess I let that one variable slip, but since it also put my side plates at 600mm (So I could fit 2 on a 2’ by 4’ plywood sheet) it’s probably for the best that I didn’t make it that little bit taller.
Overall though I didn’t really see any real downsides to the repeated parts. There are some provisions (like for the X and Y belt chunks for the optical stops) that are underutilized, (My X stop belt chunk is held in with hot glue, because I didn’t put it in before assembly)
I still see your designs as being a cut above for ease of building, but then having built a few of your machines (All of the current ones, I believe), I can make some intuitive leaps in how things are likely to work, and that makes it easier and more straightforward.