Quote:
Originally Posted by Andrew Lawrence
Precision for chain isn't difficult to do, since you just need a multiple of the pitch, which is in eighths and easily measurable with a tape measure or ruler. It doesn't take precision fabrication to get C-C distance with hand measurements and an electric drill (something I've done for the past 4 years as a student on 256).
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Although the topic of the thread implies it, I feel I should clarify that you should
not fabricate parts for a chain run using this method for anything but #35 chain. And even for #35 chain I would not suggest suggest using a tape measure for your C-C distance. And I definitely would not make the statement that precision in a chain system is easily achievable with the methods you suggest. What you're suggesting is somewhat worrying, using a ruler and hand drill is not a terribly accurate way of positioning holes. It may be true that #35 chain doesn't need extremely accurate C-C distance, but only in the aspect that it can handle significant slack compared to belts of #25 chain. The point is that the tolerance for positioning the holes is a heavily lopsided bilateral tolerance and not a unilateral tolerance. This is extremely important, if you're using a ruler or something similar to position your holes and attempting an exact C-C distance I wouldn't be surprised if half the time the holes are just a hair too far apart. If you are going to drill your holes based off of ruler or tape measure measurements I suggest accounting for the error in the measurement and drilling of the holes and aiming for slightly less than the exact C-C distance.
-Adrian