Best way to pocket rectangular tubing for weight saving

Technical CAD
#1

Our team recently purchased an OMIO X8 Router and a WCP Tube Jig.

We would like to pocket some of the rectangular tubing on our robot to save some weight. However, we are unsure of the most efficient way to model these pockets in Inventor. We are pretty unexperienced when it comes to Inventor, but can do basic part design. We already have the main parts modeled in Inventor, we just want to add the pockets to the model.

Would anyone mind sharing the process they use when modeling pockets in parts, especially rectangular tubing?

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#2

If you Google image search “frc 233” there are quite a few photos of robots they have built with different styles of pocketing in tubing. The most efficient way is to draw the shape once on the tube and then cut extrude it. Then linear pattern that feature along the length of the tube.

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#3

In general we try to use thinner tubing instead of lightening. If we do have to lighten tubes we default to an isogrid style pattern. It helps that there’s an OnShape featurescript for it.

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#4

How does one go about using the featurescript? I have never used OnShape.

#5

The “correct” way to pocket for weight savings is to use thinner tubes.

If you are going to pocket your tubes for Reasons, just have the students draw something up that looks cool and is made of triangles. Isogrid is a good example. Don’t worry about getting into more specific specs. At some point, you will find out that one of the pockets is in an inconvenient place and you can’t mount something to the tube in that place anymore. Oh well. Make your peace with that moment now.

Once you’ve got the pocketing year out of your system - I like to put a 0.5" pitch grid of 5/32 holes on every tube on the robot. It takes about a quarter as long as pockets (a tenth as long after counting design hours), and lets us have an obvious place to mount literally anything later on with easy known spacing.
We also have a very small team, with a very limited group of CAD capabilities, if you don’t need to optimize as hard for design time then it is easier to justify pockets.

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#6

Our team went through the same transition of pocketing 1/8” tubing for a couple years to just drilling patterns in 1/16” tubing. I think the students have found it really helpful if they need to modify or move around mechanisms on the robot since the holes are in known locations.

One caveat I will point out is that pocketed 1/8” will often hold up better to impacts. On our team there have been a small number of 1/16” parts that crumpled over time and had to be replaced.

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