[mochalatte]

Thought I would share my weekend project. I have a pair of Yakima King Cobra bike carriers that I used on my old CR-V that I want to use on my ID.4 until I can get a hitch receiver installed. I bought the cross bars from VW parts, but needed adaptors to mount the Yakimas to them. I got a 3D printer during the pandemic and learned how to use FreeCAD and decided to put those skills to the test:

Everything printed in PETG. The good news is that none of the 3D printed parts have to bear much stress, so even if a part fails, nothing should fall off the car. But everything feels really solid, so I don't expect any problems.

 

[JimmyVW]

some honest feedback: As a (former) mechanical engineer, i'm slightly frowning at thin front section, vs the large gap in the back.
Screwing down the back section that far (until the whole cap is closed), will create a fairly strong pull force on that thin front half section and i'm expecting it will actually over-stretch it.
meaning that the material permanently deforms and sooner or later will fail there.

Think that personally i would have kept the back gap considerably smaller, to prevent the material to overstretch.

 

[mochalatte]

Think that personally i would have kept the back gap considerably smaller, to prevent the material to overstretch.

Yeah, I was thinking the same thing actually when I installed them last night. In the design I replicated the gap size of the Yakima adaptors for the CR-V cylindrical crossbars, but once I saw that deformation I thought the gap could have been smaller. Easy enough to revise the design and print again.

 

[JimmyVW]

Yeah, I was thinking the same thing actually when I installed them last night. In the design I replicated the gap size of the Yakima adaptors for the CR-V cylindrical crossbars, but once I saw that deformation I thought the gap could have been smaller. Easy enough to revise the design and print again.

yeah or just don't screw it down as tightly. 5nm is probably already more than enough.
had a second look and think that the weak point will actually be just behind that T-section insert, as it will prevent the strech backwards.

 

[ChristophW]

At first I wasn't so sure about the orange color, but it (almost) matches the orange parts you have on the bike carriers. Great project!

 

[gtwhitegold]

An alternative to reprinting the mounts could be to get some plastic washers and insert them in the center gap? This is just a thought. I'm not a engineer.

 

[7S POWER]

An alternative to reprinting the mounts could be to get some plastic washers and insert them in the center gap? This is just a thought. I'm not a engineer.

Very good solution. Or a rectangular spacer in the shape of the gap. This will help to spread out the load.

7S POWER

 

[mochalatte]

Had my first occasion to use my bike carriers today. Worked like a charm--nice and solid.

Drove about 50 miles at about 55 mph getting 2.8 mi/kWh, which is to be expected with all that air drag up there. Normally I would have probably been at about 3.5-3.6 on a drive like that without the bikes on top.