Reverse Engineering a Motorcycle Foot Peg – Part 5

Part 5: Final Result

Welcome back to our reverse engineering series. As a reminder, the goal of this project was to re-create a functioning foot peg for a BMW motorcycle. The original peg was broken, and the new design was meant to fit and function better than some generic, off-the-shelf replacement. So far, we’ve covered:

You know what they say, all good things must come to an end… so today, we wrap up our awesome series with the final product!

We used the Markforged Metal X printer to print the main body of the foot peg, and the Markforged Mark Two was used for the top footrest. We also used standard hardware components to join the two printed parts together.

Foot Peg Body

We started by testing out the design before we printed the entire model, we decided to print out the body using the composite printer. This wouldn’t be robust enough to actually use on a motorcycle, but it would give us a clearer picture into how the design would come out when printing with the Metal X.

Test 3D Print of Foot Peg in Composite Material

When evaluating the print, we can tell that the overall size and shape came out great. We were excited to see this start to come to life. However, once we took a closer look at the part, a few major issues became apparent. First, the holes where the foot peg attaches to the motorcycle where slightly deformed! If you zoom in close enough, you might be able to see this in the picture above. This is one of the most important parts to the entire build. There were also some areas with a rough surface finish due to the support material. The build direction and some other design considerations were the root cause of these issues. We are certainly glad to learn these things before we got to the real print. That’s what you call rapid prototyping inside of rapid prototyping!

Foot peg printed with Markforged Metal X

With the original design in mind, we were able to re-orient the print to ensure the most important holes were parallel with the build plate. This made these holes come out pristine! Look closely to see how the surface finish of the top of the peg and the holes came out.

Footrest

Comparing the original foot pad to the 3D printed prototype

Now let’s talk about the footrest. This piece was printed out of the composite plastic and was meant to fit snugly into the foot peg. The design came out nearly perfect and was missing only the hardware.  We used brass inserts that were press fit into the design after the printing process. These brass inserts can be purchased easily from McMaster Carr, you just need to have the right size chosen. Matching screws could also be purchased and before you know it…you have your final kit!

Final kit of the foot peg and foot pad assembly showing internal details

Final Product: Our 3D Printed Foot Peg!!

Quick comparison in size and shape between the original foot peg that was broken, and the new 3D printed version created using SolidWorks and Markforged printers

There are some noticeable differences between the two parts, but remember, perfection wasn’t the goal! We needed a working foot peg that fit on the motorcycle and felt good for the rider. Mission accomplished! Thanks so much for following along and coming on this ride with me (figuratively of course, though now with my 3D printed foot peg, I could go for a literal ride)!

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