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Today the final m6 cap screws arrived for me to assemble my milled and turned chain guide. The back plate consists of 3mm aluminium sheet which has had actuated slots cut in it as so that the ISCG 05 tabs can be used as attachments points. The 'guide' itself is made of a low grade plastic which is easy to machine yet strong enough for the job. The guide then attaches to the plate via a m5 cap screw and nyloc nut. To ensure the 'guide' can move there is a aluminium inserted which also acts as a washer at one side, this ensures strength and allows for a little play in the system!
http://drive.google.com/open?id=0B1TpIvuu8ru2ZlFKYTVfbXpUWm8
https://drive.google.com/open?id=0B1TpIvuu8ru2MUtlWmJPVFdwejQ
https://drive.google.com/open?id=0B1TpIvuu8ru2VVhTXzF1eG5tTlE
https://drive.google.com/open?id=0B1TpIvuu8ru2NU5McUlZTTlxNjA
Weighing it at 41g it is lighter than guides which cost £60+.......OK it took about 10h from designing to completion and about £5 in cap screws! Aluminium sheet would have cost about £10 and the plastic under a pound.....so cheaper than most guides as well!
Good effort.
Ugliness is fine if you can live with it but your design is fairly flawed with it's sharp trouser/leg catching edges, backplate and non recessed guide mount bolt. stiffness and rotational retention of the plastic guide looks to be poor too. Tolerance of the actual plastic guide looks too tight or is that intentional so it will wear in to fit?
It would have made more sense to design a simpler and lighter less adjustable guide if it's only going to be used with the one bike/crank/chainring set-up.
OneupComponents guide looks very good value for money in comparison.
The tolerance of the plastic guide is fine and it doesn't rub the chain even at the limits of the cassette.
The idea behind the adjust ability was partly so it can be used on different bikes and also so that any tolerance issues with the position of the guide can be changed and experimented with. Plus it meant spending and afternoon making a jig as so the arctuated slots could be cut.
The one up design is pretty smart......I think 35g is a weight which is definitely do able as the plastic guide has a large area which is structurally useless and could save a couple of grams, then there is the matter of the cap head screws which are all slightly too long so they could be cut down.
for a home-made guide I am pretty chuffed with it....I'm glad you like it!