I asked this question yesterday on rec.photo.equipment.large-format, but haven't gotten a lot of responses (a couple private emails). Since this forum is so much more active, I though I'd give it a try here as well.
I have one of the older Arca Swiss A/B models that was the predecessor to the current F Line. The model I have has a 4x5 rear standard, a tapered bellows and a 6x9 front standard (similar to the current F Line Field model). Much to my dismay, I discovered last night that the front standard of my camera is not compatible with current Arca Swiss 6x9 lensboards. It's close, but the new boards are about a millimeter larger in both the x and y dimensions. If that was the only issue, it could be fixed in a jiffy with a file or benchtop sander. But, the new boards are also thicker in the middle (~1/8") with a ~1/16" lip around the perimeter to form a light trap. I'm concerned that this mechanical light trap may also prevent the new boards from fitting my camera. I can't know for sure unless I trim 1/2mm off the outside of the board all the way around first. Given the price of a new Arca board, I am reluctant to do so only to find out it still won't fit. The older boards are completely flat (~1/16" thick) and rely on a foam light seal in the front standard to be light tight.
So, anybody else shooting with an older Arca with a 6x9 front standard? If so, have you been able to modify the new boards to fit. Or better yet, do you know of a source for the older style 6x9 Arca boards?
If I can't find anything, I may just have a batch made up. I drew up the design last night in a CAD package. It only took a couple minutes (it's just a flat piece of aluminum with radius corners and a round hole in the middle). I also priced what it would cost to get some made. Once you get past the initial set-up fees, the piece price is very reasonable. Any machinists out there have any comments on what finish to put on these boards. Originally, I was thinking bead-blasted and black anodized. The service I'm considering using doesn't offer bead-blasting. As I'd prefer a matte black finish, powder coating is another option (the one original Arca board I have is painted flat back on the back and textured silver/gray on the front). Any comments on how durable powder coating is compared to anodizing for this application?