Print of Main Frame Centre

The main frame centre has now finished printing, and it’s come out nicely. I had one failed print, where because I didn’t have any glue to put on the print bed, the corners warped to the extent that it would have been impossible to actually attach anything to the bottom:

Warped edge on left
Warped edge on left – you can see the shadow underneath

So I added lots of pritt stick (the recommended way to make prints stick better) to the bed, raised the bed temperature from 60 to 75deg, and tried again.

It came out perfectly:

Perfect print of main body
Perfect print of main body

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Base Parametric Design for the Frame Centre

Ok I’ve started modeling the CAD file for the main centre of the frame, which will contain the electronics and hold the arms in place.

The first step is to create a base sketch that maintains the shape that I want. One thing I do want to ensure is that the motors are all equidistant; that they form a square. This, while not strictly necessary, means that the quad will react in the exact same way in both directions.

Because I’d rather have a longer and thinner frame than a big fat one, I’ve decided to have a rectangular space for the components in the middle and have a separate space on each end for the attachment of the arms:

A quick sketch of what I mean
A quick sketch of what I mean

In the CAD software (Autodesk Fusion 360, which is essentially the same as Inventor but cloud-based), I have opted to make extensive use of ‘parameters’, akin to variables/constants in code: I can set dimensions to ‘centre_width’ or ‘fitting_depth’ etc.
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Test Print of Attachment

I’ve done a test print of just the attachment between the arm and the frame, to check that everything lines up and fits properly; it works beautifully.

Looks a bit ugly but that's because I haven't cleaned it up - it's actually a beautiful print
Looks a bit ugly but that’s because I haven’t cleaned it up (the lines are from where the support material was) – it’s actually a beautiful print.

There are a couple of small problems that this has revealed with the design. First, the screw won’t physically fit underneath the attachment for the bottom mounting, let alone a screwdriver: something that I overlooked. The same will be true for the left and right sides when it is part of the bigger design for the frame.
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