I just didn't want you to think I was whining or complaining about them.
I'm most definitely not doing that.
I do like your design and as I said, I have utterly no intention of removing or altering them.
As others on the forum have done already, and for the same reasons, I had been contemplating adding diagonal braces to the framework for some time anyway.
Even with the front center bar in place, the frame flexes noticeably as the printing head performs rapid starts and stops.
This is most evident during the violent reversals of "infill" operations.
Slowing the print action way down definitely helps, and when doing that the framework seems more stable.
But doesn't that defeat one of the main features that is promoted for these printers- speed?
The problem is that these are large box sections and like any box section, it is quite easy to deflect them into trapezoids.
Even a modest brace across diagonal corners will dramatically reduce or eliminate that effect.
The original melamine corners and tees are actually beneficial in this regard despite their other flaws, and I can appreciate why FT made them that way.
They in effect do triangulate the box sections quite a bit.
When moving to the smaller aluminum corners and tee plates such as many people (including me) have installed, a lot of that effect is lost.
Then when you also remove a structural framing member, it creates a very large open box section profile.
This is emphatically not the fault of your brackets!
It is just a mechanical reality of the modifications taken in combination.
It is a system.
I take your point that the remaining boxed members should negate most of the effects of these deflections, particularly because the X carriage is referenced to a point roughly 75% up the vertical sides.
But, the Z platform isn't. It is suspended on tiny metal rods that can bend.
You can very easily deflect it side-to-side, front-to-rear, and out of level. Try it, you'll see.
So, if the framework which is supposed to be square and rigid isn't, its deflections can be induced into the Z platform as well, and probably worse because of resonances and other effects.
An aside, but relevant to the current subject-
I built a large garage at home a couple of years ago using steel framing.
I am talking about framing that is comprised of 1/4" x 14" x 8" steel I-beam sections.
When erected, but before adding diagonal braces and shear walls, I could easily shake the entire 24'x40' structure with my bare hands because it consisted of an assembly of box sections. It was almost frightening.
OK, granted I weigh 200 pounds, but I am no gorilla either.
After adding 1/2" tensioned diagonal rods to the walls and roof sections, it became rock solid
With the shear walls and roof sheeting added it will now withstand earthquakes and high winds.
Super rigid and strong.Triangulation is your friend.
That is in effect exactly what "massive ft-stein" did with the side panels and what some modest diagonal braces will do.
The top needs them as well, but of course we have to be careful not to limit access for the filament to the print head.
The base is extremely rigid already due to the base plate.