I'm on photography.SE too, but only saw this question just now by reference from here.
That is a crappy question. I just downvoted and voted to close it on Photograpy.SE. If it came back here, I'd probably do the same. Put another way, it doesn't belong anywhere, so it doesn't really matter where it gets closed.
The first problem with that question is that there is way too much hand waving. I couldn't get a reliable mental picture of what exactly this "shim" is, why, where, how you are using it, etc. That really should have been obvious.
A picture or maybe a diagram might have helped initially, but now that you posted what you did first, I just want to dispense with it as expediently as possible.
Even if you added a picture and a better explanation, I wouldn't vote to reopen. This site isn't a contest to see how crappy a question you can get away with. If you can't be bothered to think carefully enough about the context of those you want answers from, then express things clearly in terms relevant to them, we don't want you here. Go away. Shape up or ship out.
Allowing you to first post crap, then have you grudgingly fix just enough for the question to not be close-worthy noises up the site. It also teaches you and others that making a mess first works. Bad lesson. Better to ruthlessly close and make the asker feel thrown out, not just turned down.