what are these 'frame hinges' called?

[The Night Tripper]

... and where might I get hold of some of them (cheap, if possible)?

I think they are used as some sort of shipping frames.

Thanks Jon N

[polygonum]

Volvo dealers?

They certainly used something similar for distributing spare parts - but they were always returned for re-use, so getting them for keeps might be another matter.

[Andy Burns]

Collar Euro Hinges?

[The Night Tripper]

Thanks Andy, that looks good ... and led me to 'pallet hinges', or 'pallet collar hinges', which looks even better:

Cheers Jon n

[The Night Tripper]

PS: FWIW I have several of these 'pallet frames' which I have used successfully for stacked raised beds in the garden. I am trying to 'design' (ie. in my head) something similar for stackable frames for compost heaps. The designs which use cutouts at the ends of wooden slats are IMO badly flawed.

Cheers Jon N