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Shift Knob + Destuction Test
10-08-2013, 07:29 PM (This post was last modified: 10-11-2013 08:22 PM by harlen.)
Post: #1
Shift Knob + Destuction Test
Printed this knob to see how the threads would come out, and they turned out great! There was a bit of support between the threads, but it wasn't hard to clean up. After I printed it, I wanted to see how structurally sound it would be so I did some load testing on it.

Slicer Settings:
0.25mm Nozzle
1.0mm Thickness
0.125mm Layer Height
20% Fill

Part Geometry:
2" Diameter Sphere
2.25" Overall Height
M12x1.25x25mm Thread

2007 Honda Fit
~600lbs on the left rear corner

[Image: 20131003_081245.jpg]

[Image: 20131003_081417.jpg]

Load Testing on threads:
[Image: 20131008_183858.jpg]
Slight over 100lbs of weights trying to pull a bolt out of the threads, wanted to put more, but I couldn't find the rest of the weights.

So plan B...
Tried a few times to get it to stay, but it wouldn't. This is the best one of the 3 tries.

Plan C...

Loading the knob as a whole:

I basically didn't have anything that's heavy besides a car, so that's what I used, and apparently that's still not enough to break this thing!


Finally failed the threads!

I put the knob in a mechanical press and used c-clamps as the load on the lever arm.

Weight of lever arm on one end = 2lbs-1oz
[Image: 20131011_093431.jpg]

Force output from the lever arm + gearing on the inside of the press = 27lb-12oz
[Image: 20131010_172234.jpg]

Weight of each clamp = 8lbs

Video of process:

2.0625 lbs of input = 27.75lbs of output
Force multiplier through the lever arm and gearing = 13.45

15 clamps @ 8lbs each to fail the threads = 120lbs

120lb x 13.45 = 1614lbs!
Round it down a little bit since the clamps aren't on the end of the lever arm, but that is still quite impressive!

1500+lbs to fail 23mm of 1mm thick threads @ M12x1.25 diameter and pitch.

I will upload the .stl file for this knob on Monday for those that are interested.

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10-11-2013, 08:32 PM
Post: #2
RE: Shift Knob + Destuction Test
Updated the 1st post with more awesomeness!
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