Here is a backplate I recently tuned out. It is from a SRAM Red (2011? 2010? Whatever?) 11-28 Cassette. I ended up getting the older version of the SRAM cassette instead of the 2012 version because: a) 11-28 was hard to find for 2012 b) I wanted 11-28 since most of the ultra events can have painful climbs around 180mi into it c) I found a new one on the cheap, it was worth the $150US cost savings from a 2012 version d) I like climbing a lot, especially the stupid steep stuff. The goal was a little weight loss - which did happen, but nothing substantial to write home about - and to open up the backplate in hopes that the echo-chamber of the cassette would be a little quieter. I won't know of this effect until it is installed and ridden.
Method: remove backplate (described earlier in the thread by the Végàn, Eric), then I made a pattern to follow based off of a SRAM XX cassette's largest cog, printed that pattern out, made it a stencil, outlined onto the backplate the pattern I wanted cut, then started cutting using a few tools (carbide cutter and occasional cut off blades). For the cutting portion I used a series of bolts and large washers to hold the backplate steady, parallel and off the working table. I then sandblasted the backplate to clean it up a little bit.
Could I have done a better job? Yes, definitely.
Am I a professional rotary tool master? No, not at all.
Am I ok with the results? Yes, definitely.
Could you do a better job than I did? Probably.
I am still debating whether I want to polish it or not. At the moment I have a "dremel" polishing kit heading towards me, and this may be a good area for practice/technique before I start polishing other smaller parts. But if I drop this cassette into an ultra-sonic cleaner with some degreaser in the tank, would the polish get removed? Might as well find out.
The pattern I used is attached as a JPG file. Apparently I can't attach PDFs on this forum?
|| Other projects in the works.