Always double check your work

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Jul 8, 2009
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I'm converting Bruder Cross-country Jeeps to RC for Christmas presents this year, three of them plus the prototype - gotta make sure it works you know.. Part of this conversion involves modifying the existing wheels to be compatible with the N20 gearmotors that I'm using to get 4 wheel drive. I made a drilling jig to allow me to easily drill the required holes in the correct locations. This jig is used to drill the 4 mounting holes required by the hubs that I have for the N20 gearmotors. When I designed the jig I measured the outside to outside dimension of the holes on the hub, this measured 19mm. No problem, I laid out a 19mm circle on my model and put four 3.5mm holes at the appropriate locations on that circle. This 19mm was really convenient because that also happened to be the apparent bolt circle diameter that Bruder used for the 8 fake lug nuts. I just lined up my jig so that I was putting my holes where 4 of the fake lug nuts are located. I printed out the drilling jig, it took about 4 tries before I was happy with the fit of the jig and the way the holes lined up with the fake lug nuts. I then proceeded to drill all 4 holes in all 4 wheels - in the wrong spot.

I was able to save the wheels, but much aggravation could have been avoided if I had compared the actual hub to the drilling jig. Before drilling the holes instead of after, when I was trying to figure out what went wrong.

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Tim Wescott

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Jun 3, 2018
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Measure twice, cut once -- but which measurement should you use?

It's a special feeling when you go and make a tool, do a bunch of work, and then find out the tool is wrong. It's not good special, but it is special.

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