to shrink, or not to shrink, that is the aggravation

A project log for Minamil 3dp: another minimal CNC mill

A very compact, very inexpensive, very DIYable, very precise little CNC mill. This one uses 3d printed parts.

paul-mcclayPaul McClay 09/26/2023 at 02:070 Comments

This is just a rant so I can stop thinking about it.

So I made another frame last year. The one on the left:

I made it a little big considering uncertainty about how big it needed to be.

Earlier this year, it looked like some of the packaging ideas were working and I got fired up about redoing pretty much everything less haphazardly and taking it to MRRF. Including shrinking the footprint to match shrinking uncertainty about how big it needs to be.

To start with, I cut the mounting tabs from the bottom of the X+Y stack and switched to screws up from below into the interior of the tabless bottom part. That reduced the lower bound on footprint. And also slightly confounded my first draft build doc.

But such a laundry list of things to (aspire to) do before the show, and finite time, and other life. And other aspirations on said laundry list -- mostly accomplishing or improving integrations of function into the frame and redoing the extra-janky first whack at the folding enclosure -- were bigger step changes than "see! it's a little smaller than that other one you won't ever see".

So, reluctantly, I abandoned the idea of making a new frame. That was hard to swallow because most of everything else I wanted to do would be made to fit the frame and everything made to fit the oversize frame was a nagging reminder that instead of shrinking the frame I was sinking more sunk cost into the oversize frame that I still hoped to shrink "later".

Later is now.

Cutting the simple excess while allowing for thicker hinges shaves the square from 191 mm sides to 182 mm. Not very exciting. So I've spent yet another chunk of time pouring over sketches and CAD looking at things that make the footprint bigger than the basic square dimension of the X+Y axes and what I can shuffle to debigger them. Getting down to 175 mm wouldn't be too hard. 170 mm if I do something different with the rather thick X motor connector that I've just spent time neatly securing at the back of the X+Y stack. 

So I could shrink the footprint by 21 mm each side. Less than an inch but a little over 10% or a little over 20% area. That serves the objective of minimizing the footprint i.e. maximizing the brag. And I don't think any hard constraints prevent shrinking other stuff in the box to match. But then that's time spent to build a new frame, plus time to more significantly re-arrange (vs. incrementally improve) all the sunk cost other stuff in the frame.

To do, or to not do? To decide before sinking yet more time in the other integrated stuff. Aaaargh.

Ok. I'm going to not. But keep plugging with the frame in hand, with all it's surplus bigness.

BuT iT cOuLd Be SmAlLeR!

But it's not. Again. Sigh.