Cad part weight reduction

[petedog07]

Hi everyone, I’m just here to ask a question that’s always been on my mind looking at experienced teams’ robots and how they get this cadded out either quickly or if there’s a specific rule they follow. I’ve wanted to expand my team’s cadding skills with part design but currently, we just use octagons to save weight. I may not know what it’s called, I know it’s something with topology but if someone could help that would be great.

Example (111 robot cad)

[Andrew_L]

973 RAMP - Pocketing

[Torrance]

Yup. The RAMP video covers it pretty well. There’s a great Onshape script to make that process even faster.

Pocketing is a bit of an art, because frankly the plate is almost always plenty strong but you get diminishing returns trying to keep pocketing more and more aggressively. At a certain point you are better off going with a thinner plate (1/8" instead of 1/4") to make it literally half as heavy with 0 of the design/run-time.

[Eliot]

I was on 112 last year, but same program.

I guess I’ll use the 12 motor swerve addon I designed for an example.

We start with the plate without any lightening, then draw lines where we need there to be aluminum to support everything.

Then, we use the lightening feature from someone? not sure who tbh. Here’s the featurescript link: Onshape. It’s also linked in Getting Started | Onshape4FRC.

That was a lot faster than I thought it was to say that, but hopefully makes sense

[Andrew_Schreiber]

@Torrance

At a certain point you are better off going with a thinner plate (1/8" instead of 1/4")

Paging @JamesCH95

[petedog07]

Thanks everyone this really helps!

[JamesCH95]

Bearing plates are one of those cases where pocketing a thicker plate often makes the most sense.

• Thicker plates are stiffer in bending (generally) which helps prevent misalignment between gears and shafts.
• Thicker plates support pocketed alignment features and standoffs that improve rigidity and alignment in the final assembly.
• The flange undercut on bearings can be quite large. A 1/4in plate ensures maximum bearing area engagement where an 1/8in plate would not.

I really like the “Lighten” addon already mentioned. I draw lines between all critical load areas and fuss with the widths until it looks decent. You will want direct load-bearing elements between all gear, pulley, and sprocket pairs to maintain their center spacing and minimize the risk of those elements disengaging.

[gellnick]

In Solidworks I tend to draw lines in strategic places, use offsets, and then add in a random word if the plate is large enough. It’s like scrabble, but you get 3 points a letter, plus a x2 bonus if you integrate a letter with the edge. x3 points if you integrate a bearing hole successfully. x5 points if you can get it past the design review without anyone noticing :D.
@Gavatron77 is a master at this.