So I decided to go with yet another hotend for my 3D printer, since I'd munched the previous one by crashing it into the build plate. It still worked after a fashion, but required (very) regular attention.
I looked around, selected what looked like a really well regarded unit (E3D V6) which turned out to be reasonably priced too. Clicked 'buy' on the website and waited.
A couple weeks go by, and the package arrives - well heck, the fitting for the bowden tube is going to be lower than the deck of the current (kludgey) groove mount so if (when) I need to pull the tube, I'd have to disassemble the carriage. Not acceptable. Time to think...
I started by looking around at how groove mount hotends are typically mounted, and it became obvious that I'd have a much larger project on my hands if I didn't invent something. Excellent - I actually enjoy figuring stuff out.
This was a pretty simple build - starting with 0.125x1.25" aluminum bar stock, I cut out a couple of coupons that were about 0.75" wide. I clamped them in a vise, then drilled out to 0.5" at the center. That gave a bit of clearance for the 12mm shaft of the groove mount. After trimming off the corners with a hacksaw, I slotted down the center of the ends to about the depth I wanted. At that point, I center punched the ends of the slots and drilled for an M3 screw, since that's what I had laying around. After the overall outline was finished, I cut them in half.
I found that using a fine bastard file to do roughing is truly tedious - I noticed that big roughing file in the drawer and the trimming and thinning went way faster. Note that there's a bevel on half of the parts; these are to provide the clamping necessary to keep the hotend from wobbling. I used around 220 grit sandpaper to do final finish.
There you have it - the proof of concept parts came out well enough that I don't need to go any further. Enjoy.