Published by Tristan on 02 Nov 2009 at 10:46 am
Using the lathe to measure fork rake
I had a pair of forks which I wanted to measure the fork rake to see if they’re a suitable replacement for another fork. Accurately measuring fork rake is hard without a frame builders fixture but using the lathe I managed to do a good job.
First I mounted the steerer tube in the 3 jaw chuck with a quick release axle held in place between the fork’s dropouts….
…Then use a vernier to measure from the bed of the lathe to the top of the axle. The axle needs to be perfectly horizontal to ensure accuracy – this is easy to do by measuring both sides of the axle and making sure they’re the same….
…Then rotate the lathe chuck 180 degrees and measure again….
…and with a bit of simple math we know the fork rake is 42.1mm
A vernier height gauge would have made things easier and would be useful to have with my granite surface plate – I’ll put one on the shopping list.
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