Thanks - I'll investigate Bigheads. And oddly Simon, I was just thinking of those things you mention. The reason I'd discounted is that they push down with little teeth into the wood, which would be fine but wouldn't allow one to pull back/tension against it. But I'd kinda thought that if you put a few small wood screws around the edge into the surround, then they might hold nicely.
...aha... the bigheads are indeed similar and they too could be screwed rather than bonded. Very lovely things. In this instance, I'll try the other things first as I think they may be easier to get hold of, if I can get in a large enough thread.
.....
looking at the threaded cross dowels aka barrel nuts aka what you get in an ikea flatpack for assembling most of their stock, the barrel nut might do less disturbance in the beam than faffing screwing into the top. I have good side access and they would also self drain?
...aha... the bigheads are indeed similar and they too could be screwed rather than bonded. Very lovely things. In this instance, I'll try the other things first as I think they may be easier to get hold of, if I can get in a large enough thread.
.....
looking at the threaded cross dowels aka barrel nuts aka what you get in an ikea flatpack for assembling most of their stock, the barrel nut might do less disturbance in the beam than faffing screwing into the top. I have good side access and they would also self drain?