6:47 PM

Spacer Design

Having some fun making some custom spacers for myself.  I’ve used a cheap carbon 10mm spacer as a benchmark.  At 10mm with a 1 1/8 ID the spacer comes out to 5.5 grams.  The goal is to come up with a design that’s as strong but lighter and made out of 6061 aluminum.
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My first concept is a butted design.  The walls in the center of the spacer would be thinned out just enough to have a strong enough wall that wont deflect or cave in.  Edges are all smoothly filleted to alleviate stress concentrations.  The program’s calculator predicted a mass of 4.85 grams for the piece in aluminum.  Also, a design like this can be popped out super quickly on a lathe.
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The second concept is a rifled design.  The idea here is that the rifling acts as columns and transfers all of the forces from top to bottom.  This to me seems like the stronger option but it takes a bit more time to manufacture.  The surprising and disappointing thing about this design is the weight.  at 9.44 grams It seems that the columns take up a lot of mass and Its difficult to adjust anything else any more than I did without compromising the strength. 
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The last design is from KCNC and its arguably the best concept.  Here the spacer is hollowed out in the middle.  I suspect this design to be very strong vertically.  It also comes out to be the lightest design.  The only caveat here is that it’ll likely take the longest to manufacture. 
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So simply being carbon fiber doesn’t make something light or strong.  The design and geometry plays a huge role.  There are more elaborate designs out there that claim better strength to weight too.  There are also stronger yet less dense materials out there too.   Hopefully I’ll have some time to make a set of each of the three I mentioned to verify the strength and weight.