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Old 10-08-2013, 09:01 PM
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Join Date: May 2012
Location: Downtown LA, CA
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Made some progress in my machining classes and started getting into CNC. Decided to try my hand at making a set of triple trees. The plastic scrap I had lying around was material that had been donated so it already had holes and markings in it.

Half-scale narrowglide triple tree: Drew up the model in Solidworks and generated code for it. Ported it to a desktop CNC mill and cut it out of the plastic.

Perfected the code in half-scale and tried porting it to our full-size CNC mill, a 20+ year-old POS. Found out the machines interpret coordinates differently, and had to rewrite the program completely.

Instructor asked me to mill the upper side of the triple tree, and had to write a new, shorter program that altered the tool paths. Had to clamp the rear half of the tree (as mounted on the bike) while the front half was machined, relocate the clamps to the front, and have the program finish machining the rear. Crashed the machine once or twice while I altered the toolpaths to move around the clamps. All in all was a bitch but I got it done. Curved cut on the top surface and randomly placed holes were already on the stock to begin with:

Satisfied that I "could" make triple trees if I wanted, I decided to forgo cutting a set out of aluminum. The only kind of trees I would actually want to make are 3-degree narrow trees similar to WCC units, but our mill does not have 4-axis capability so it would be extremely difficult to work out.

I decided instead to make a part I didn't already have on the bike; my rear caliper bracket. Modeled the bracket again in Solidworks and cut a prototype out of plastic:

Since I didn't want the bracket to be cut out of an entire block of aluminum, I made a fixture plate and bolted the aluminum stock to it. The mill would cut the piece of stock and slightly into the fixture plate, and I could unbolt the bracket afterward. Was having problems with the toolchanger so I had to do the entire program with a 1/4" cutter. Also had to slow the program down considerably since I was no longer cutting the soft plastic. Program ran well but discovered my coordinate origin was slightly off, shifting my bolt holes and axle hole center:

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