Created some mid span supports as well: https://www.thingiverse.com/thing:3040712
Almost done printing, going to build this one soon!
Looks pretty fancy
What you’ve done here looks good.
How much flex is there in your frame? If you throw this in the back of a car and drive for a couple of hours, will the frame still be square, or will it have slightly shifted? If you pick this up, how careful do you have to be when moving it so that you don’t put it out-of-square?
Not sure how to quantify it, but it feels extremely sturdy. Of course, most of the time it will be either on a flat table or mounted on a flat piece of spoilboard. Should it ever get out of shape in the upward (Z) direction, you’ll notice it when you put it on a flat surface. If this happens it can probably be fixed by loosening and re-tightening the 16 bolts in the corners.
I don’t think the aluminium extrusions will bend easily. There are even stronger 4040 extrusions, which don’t have holes running through the 4 corners. I have some of these as well, but they are really really heavy, so decided not to use them. Trying to keep this “mobile” after all, and it’s already quite heavy with the current frame and a bit difficult to handle because of the dimensions.
As far as XY out-of-square (skew / parallelogram), I’m unable to flex it at all. We’re using large corner brackets (4 bolts each instead of 2) which seem to hold it into place very well.
> a bit difficult to handle because of the dimensions
How big is your frame - 3’x4’?
My first MPCNC has outside dimensions of roughly 2’x2’. I wanted it to be portable so I could through it in the back seat of my car. I’m using a 2’x2’ piece of 3/4" plywood as the base with 2’x4’s underneath the outside edges to try to prevent the plywood from bending/twisting.
The outer dimensions of the frame are 930x720mm, so that’s about 3’1" x 2’4".