18bikes News
Tool of the Week 8!
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This exciting edition of Tool of the Week features our head tube machining fixture. When we build a frame with a conventional 1 1/8" headtube we like to make sure it's up to the task. We do this by using a slightly thicker walled tube, then mount it in the lathe and remove some of the material to save weight.
We don't want to simply reduce the wall thickness all the way round, so we mount the headtube eccentrically and only remove material from the front, leaving the thicker wall where the top tube and down tube are attached. We also want to leave some extra material at the top and bottom of the headtube to reinforce the area the headset presses into.
We could do this by mounting the headtube in a 4-jaw chuck, centring it, then adjusting the chuck for the correct amount of offset. This can take a bit of time, so we made a little fixture that holds the headtube at the correct offset. This means we can put a headtube in the fixture then mount it in the lathe and know we have the correct offset. We then remove 0.6mm of material from the front of the headtube, leaving 10-20mm at each end (this can be fine tuned depending on the application)
The reinforcing rings left at the top and bottom also frame our headbadge really nicely so the front of the bike looks just as good as the rest
Published Friday 26 August 2011
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