How did you modify the adapter to get it to achieve infinity focus?
I am facing the same issue with mine, and am looking at using a metal lathe that has enough precision to remove the slight excess metal. The rim and the mount are going to require just a very marginal amount of material removal to achieve infinity focus while preserving the overall structure of the mount.
if you have a better way, I would love to hear it.
Trimming it on a lathe is the preferred way, obviously, but in my case, seeing that I had to remove only approx. .1mm (.004"), I decided instead to simply sand the two halves of the adapter to the desired thickness. If you have access to a lathe, I'd suggest you do it that way, but as I recently lost access to the lathe I'd been using, I decided to give this approach a shot. Worst case, I'd be out the $110 I paid for the adapter and would have to start over with another one...
Using a thick piece of glass to insure a flat work surface, I used spray adhesive to attach several small pieces of emery cloth (ranging from medium to extra fine) and a piece of 1000-grit sandpaper, and then made several circular passes over each grade with each half, being careful to rotate them slightly every few passes and using as even an amount of pressure as I could manage so the excess material was removed equally. (You can gauge how equally you're applying pressure by watching how equally the black finish is removed from each side; if one side is becoming shiny aluminum at a quicker rate than the other, then you're applying pressure unequally.)
I worked slowly and used a pair of digital calipers to measure the thickness of each piece in several places after each pass to be certain that I didn't remove too much material or get out of square. (In fact, the two pieces, as delivered, are slightly skewed -- i.e., thicker on one side than the other -- I believe, to compensate for the upward pressure applied by the ball-and-spring used for the detents. Alternatively, they are not machined to very tight tolerances, but since the skew on each piece was matched to the other piece, I believe this was done intentionally. Anyway, because I removed the ball-and-spring -- I find the detents to be annoying and not useful -- I removed the skew by sanding those sides a bit more (by sanding with one side on the paper and the other side over the glass) and ultimately made both pieces "square.")
Because making the halves thinner also makes the dovetail portion less wide, you have to carefully adjust the tightness of the dovetail clamp that holds the assembly together to minimize any play in the mechanism. Fortunately, I found there was enough play in the holes and rebates for the clamp's two mounting screws that it was only necessary to use a small screwdriver to lever them into the correct position while carefully tightening the screws. Although it took a few attempts, I was able to dial-in enough resistance so the thumbscrew stop is no longer needed, but not so much that I can't still move the lens with the pressure from a single finger while holding the camera in my hand.
Oh, and because sanding the aluminum removed the black finish, I used a permanent marker to "paint" it black again because this was the easiest way to accomplish this without adding any significant thickness to the surfaces.
All in all, it took maybe two hours from start to finish, including making at least a dozen trials to verify that I'd not yet removed enough material. (And if you do somehow screw things up and make the adapter slightly too thin, this isn't the end of the world as it only means you can't flip the lever all the way to its stop to focus at infinity, but will now have to pull it back from there ever-so-slightly.)
I have been asked to write up this procedure and illustrate it with step-by-step photos by another blogger and had hoped to do so this weekend, but since I have just bought a CV15 lens, I've decided to wait until it arrives and see how it focuses first. If I can, I'd like to be able to use just one adapter between both lenses, so I don't want to do anything further to this one just yet...
Anyway, I know I've gone on at some length here -- my apologies if I oversimplified (or overcomplicated!) anything -- and I hope this answers your question.