looking at your pictures again, it looks like the non-drive side outer walls are bent a little. is this the case? is this because you didn't bore out the wood to disperse more of the crimping force?

i'm thinking about going more of this route:
http://farm6.staticflickr.com/5346/9...67d5ecc4_c.jpg

Here's another version:
https://flic.kr/p/cmHqTL