I’ve been watching 3D printing from the sidelines for a few years. Frankly, most of the output has left me underwhelmed: tacky keychains printed at super low resolution, desktop hobby printers which take too much effort to achieve acceptable results, cosplay enthusiasts who spend hours priming and sanding parts to hide printing artifacts, and low strength parts unsuitable for serious real world use. In short: meh.
However... I had a couple of design ideas recently which looked like they might be good candidates for SLS printing (what’s that?
). Now that I’ve received my first parts from an online printing service
, my initial impressions are that the parts look great and came out as well as I could have hoped. Time will tell if they are strong enough to withstand the abuse I plan to inflict upon them but I’m cautiously optimistic. The best part is the realization that if I break a custom part while I’m on the road for three years, I can update the design and order a replacement. I can at least pretend to be less apprehensive about losing access to my workshop.
The custom CA3 hood above was my second print order. I designed this in Fusion 360. Love that Loft tool. My goal was to hide the octopus of connectors in the back of the CA3 and provide some waterproofing as I anticipate the bike will see a lot of rain. I also needed a place to mount the Feniex Apollo
unit I’ve been using as a daytime running light. I made the enclosure big enough to fit the Grin GPS Analogger
as it prefers a short run for the data connection to the CA3. The other cables are routed through a 2” (50mm) polycarbonate tube attached to the front derailleur frame tube. The crank clearance is just a few millimeters so I was relieved that my measurements were spot on.
The small brim over the screen was supposed to reduce glare and improve daytime visibility but road testing cardboard prototypes revealed that it would need to be much longer to be effective and I just didn’t like the way that looked.
I have a newfound appreciation for people who design plastic parts for a living. The SLS printing process practically eliminates design constraints inherent in other manufacturing methods: no need to worry about undercuts, supports or minimum draft angles. It’s pretty idiot proof
beginner-friendly. Draw the shape you want, upload to Shapeways and open your wallet. US$103 for this part… so not exactly cheap.
My first print order was a little simpler. This is the new motor assembly for the trailer tilting mechanism. It’s about half the weight of the previous linear actuator and fits inside the trailer boom tube to protect it from dust, water and crash damage.
The two gray pieces and the white end cap are 3D printed. I designed these in SketchUp because I’m much more proficient with it but it’s not really the right tool for the job. I spent as much time cleaning up unwanted geometry as I did actually drawing the part. Some fillets would have been nice but I made everything chunky enough and the walls of the tube help hold the part in place.
In the end, they printed just fine. The dimensional accuracy was spot on. I designed pockets for captive stainless steel nuts and they fit nice and snug. The inner diameter fits the motor perfectly and the outer diameter slides into the carbon tubes with just a little play. The gray pieces will be subjected to significant torque so I had those printed in their stronger “professional plastic” option at about twice the cost of the standard stuff. Total cost for these 3 pieces with tax, shipping and a “priority fee” to get it in 2 weeks instead of 4 weeks: US$97. The second order arrived in exactly 7 days without paying rush fees so the 4 week turnaround estimate on the first order may have been due to my bad timing right before Christmas.
Final thoughts? While I’m still not interested in acquiring a hobby 3D printer, some of the hype is justified. This will make a valuable addition to my bag of tricks.
PS: Love ebikes and 3D printing? Check out Tom Stanton on YouTube
. Mad lad is printing drivetrain components with PLA.