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Modeling 1/24 Losi Micro Crawler Extension

posted Apr 19, 2015, 9:48 PM by Neil Caulfield
Project Date: Fall 2014
View project here.

Fabricating custom components is a popular part of the RC hobby, whether it be done by the individual, or by a third party parts company. While there are structural and dimensional limitations to 3D printing, useful components can still be made right at home. 
I saw a popular modification for the "V" framed 1/24 scale Losi Micro Crawler, which has been discontinued, but replaced with a similar model that shares a lot of the same parts. (This newer version has a longer wheelbase, which improves certain handling characteristics.) The $20+ modification gave the crawler a truck like chassis,similar to the one in the new version of the crawler. The problem was that many of these kits did not include the axle extensions or shock towers/shorter shocks. 

I figured I could try and print an extended version of the "V" frame. I started doing a little research to try and get the dimensions and placement of holes on the chassis, but there was no information on this model. Nobody else had done (or at least posted) a chassis modification with a 3D printer yet. I traced the frame on paper, and used calipers to get a few references for length and height. From there, I was able to guess and check the placement of the bolt holes. Once I had a frame shape that shared the necessary characteristics with the old design, I was ready to print both the left and right plates. I attached the suspension/shocks and the central part of the chassis to both sides, and attached the tie rods. All that was left was to make a drive shaft extension.

The losi crawler uses a telescoping design that moves appropriately with the suspension system, and with an extra length between the transmission and the axles, this setup was going to be a problem. It was an easy problem to solve, I just printed a shaft extension that matched the ends of the other two components, and connected everything together. Since this is a low speed, low gear vehicle, I did not have to worry about torsion or sudden shock along the driveline. I initially tried using the outer shell of a BIC pen, but this did not extend/retract properly. 

Was this project worth saving $20? Probably not after all of the trial and error, but it was fun to make and improve a design. 

When I was done, I posted the design to Thingiverse to give other people the ability to upgrade their crawlers, and post improvements to the design if desired. The downloadable model can be viewed HERE.