July 5, 2019
Description
This is a printable mold for creating silicone donuts (or gummies or o-rings or w/e) to keep a Kryptonite New York from rattling around and making a ton of noise while riding. These donuts are designed to fit the lock model with a 16mm diameter shackle, though they may work on other sizes as well.
I'm using a method for fabricating these parts that I put together while playing around with designing my own soft robots. If you'd like to learn more about those bots or building a cheap vacuum chamber for yourself or combining 3d printing and casting, you should check out the book I wrote.
I cast these with Smooth-On EcoFlex 00-50 and they've been holding strong for a week, but they'll probably last longer if you use a harder, tougher silicone.
This project requires:
To make your own:
Print out the parts in PLA (other materials may work, but I haven't tested them for cure inhibition with the silicones I use). Set your wall thickness to >1mm making sure it is at least 3* the diameter of your nozzle. Use an infill of 20% or higher.
Clean up the print and give it a light spray with Mann Ease-Release (or any other mold release that's compatible with silicone castings).
Assemble the mold halves with M5 nuts and bolts. Clamp the halves together until you are not able to see any light leaking through the seams when you look down into the sprue.
Mix together your silicone (the process requires ~20g of silicone -- some for filling the mold and a little extra to make sure there's enough volume to mix everything properly). Measure everything out with a digital scale, wear gloves, and use a new cup and tongue depressor for each batch you mix.
Degas your silicone.
Pour into your mold. This sprue is fairly small, so I found it was easiest to slowly pour the material in using a thin stream until the sprue became occluded. After this, I put the mold into the vac chamber and lowered the pressure until bubbles pushed up through the sprue. I refilled the sprue and repeated a few times until no more bubbles came up out of the sprue.
Allow the silicone to cure (~4hours at STP for the EcoFlex I'm using).
Remove the bolts and pry the mold apart.
Use a pair of nail scissors to snip off the sprue/vent material and any flashing.
Once you've cast two donuts, you can slip them over the ends of your U-Lock. They should get compressed between the plastic cover/aluminum mount and the lock body.
License:
Creative Commons - Attribution - Non-Commercial - Share Alike
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