Just as a quick follow-up to this thread, I ordered the Yonico bit set. It arrived within a week which is pretty good.
I tried the bits for the first time the other evening, just with a few offcuts to make a mock-up of the joint, and so I could get the set-up right. Apologies for the lack of pictures, I forgot to take any!
First, I put the groove bit in my OF1400 (in my router table) and discovered that, with the bearing mounted above the cutter (with the router inverted) the shaft wasn't long enough to reach through the table & to the height I needed, so I had to disassemble the bit, & reassemble it with the bearing going onto the shaft first. This allowed me to set the cutter high enough to cut the grooves in a few pieces.
The bit is 1/4" (6.35mm), but the resultant groove was nearer 7mm. When I checked, the cutter wasn't completely 'flat', and had a slight wobble to it that caused it to cut a wider groove. I put this down to my reassembly of it (I didn't try it beforehand).
Next, I put the tenon bit in, and set the height as near as I could by eye. I made a sled to carry the rails securely, and ran a piece of scrap. The resultant tenon was less than 6mm thick. I checked this bit, and it also had a 'wobble' on both cutters. I hadn't altered anything on it, so knew this time that it wasn't me!
Yonico supply a couple of extra spacers (thin washers) so you can adjust the gap between the cutters. I fitted one, but it was still loose in the groove, and ended up fitting both. This resulted in a nice tight (but not too tight) joint, albeit with a slightly wider groove than I wanted.
The panels are going to be 6mm MR MDF, and whilst they don't want to be a tight fit, I don't want them loose enough that they can move. I'm in two minds at the moment whether to try to reduce the wobble in the bits to get a narrower groove, or just leave everything as is & go with it. I'm just worried that if I do try to alter it I might make the situation worse...
In general, the bits seem OK, but I've only run a couple of feet of poplar through them so have no idea yet how well they'll keep their edge. When I run all the final stock (which will hopefully be this weekend) I'll try to remember to take some pictures...
