Time for another project!

Hey everyone!  wanted to do a post and update on the latest project I’ve been working on!  I’m creating a shift knob for my car (manual transmission) that is custom molded to my grip!  You might ask yourself “but how does this involve 3d printing?”.  My answer for you is “trust me, it does :P”.  In order to get the custom shift knob, here’s the process I am currently going through:

1.) Mold the general shape out of PlayDough
2.) Grip the PlayDough the way I normally would my shifter
3.) 3d scan the PlayDough knob
4.) 3d print the stl generated by the scan
5.) test for fit
6.) make a silicone mold from the 3d printed knob
7.) cast the mold in resin so the resulting knob is a cool color and solid plastic
8.) sand the resin cast starting at 120 grit sandpaper and working my way up to 400 grit
9.) apply 2 coats of polyurethane to make the shifter glossy!
10.) my shifter uses a M12x1.25 thread, so drill a hole in the bottom of the shifter and tap that hold with the correct threads.
11.) screw shift knob onto shaft in car and enjoy!

Steps 1-5 went off without a hitch, and the print came out perfectly and fit my hand like a glove!  I learned real quick from other projects, though, that I’m allergic to resin…. it makes my face swell really badly :(.  So I enlisted the help of a good friend for steps 6 and 7.

After I had finished sanding, the surface was very smooth, but it wasn’t as shiny as I would have wanted, so another friend suggested step 9, and it turned out incredible (see below pic)

I still have to complete steps 10 and 11, so stay tuned for more updates and more pics!

John (aka The Mad Printer)

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