Extruded angle bar & flat bar Cartesian - instead of - round bar design

I'm look at is enclosing my Darwin with a shell.
Which could provide,

- the opportunity for design to have a significantly bigger influence on the final form.
- Safety
The option of a heated chamber to reduce shrinkage

To attach a shell I have looked at clips but we ideally need flat surfaces to create a strong connection.

I came up with a couple of options to attach flats to the current design, replacing the side diagonals with flat bar, or attaching flats directly to the corner brackets. But I think it could be simpler to just design a new support frame.

I am thinking about using 20mm extruded aluminum angle bar, gauge approx 3mm. I'll also be testing to see if the frame will be strong enough without diagonal supports.

The current design is great because it has tolerance for bars which have not been precisely cut. Any ideas on how to design a similar tolerance using angle bar?

In the current Darwin design, at least 4 of the 12 bars used for the edges of the cube are also used as guides for moving parts. Replacing them with angle bar might be tricky.


> The current design is great because it has tolerance for bars which have
> not been precisely cut. Any ideas on how to design a similar tolerance
> using angle bar?

The first thing that comes to mind is:
- cut all the angle bars a bit short to allow gaps at the corners
- use oblong or loose-fitting holes to attach the angle bars to the corner brackets
- square up and tighten frame
- drill and mount panels in situ, using them to keep the frame square

Re-design the clips to suit the existing frame and be RP-able so the basic Darwin can make the parts to allow the enclosure to be added therefore keeping the entry costs to RepRapping low. Steel is about as cheap as you get verse strength and is universally available Aluminum extrusions are much more expensive and not so universally obtainable.

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Ian
[www.bitsfrombytes.com]

For mounting the PCBs on my Darwin, I picked up a bag of nylon P-clips at the hardware store. Like this:



I ended up using 1/2" ones which were slightly too small but workable.

Something similar could be used to attach panels to the existing frame. The picture I have in my head is acrylic panels mounted on the frame, with plastic corner protectors covering the gaps at the edges.

Why not simpley build a freestanding box just big enough for your Darwin to fit in snugly? If your goal is an enclosure for industrial design, safety and temp control I see no reason to attach the box to the machine. Just a thought.