The Triplefold frames were a good idea in some respects, but there were drawbacks. As there was only space in the nuc for the three folded panels, there was no provision for feeding. As we are dealing with small colonies of bees that have been selected or filtered to have a greater proportion of young nurse bees, as can be achieved using the Marburg Swarm Box, it was thought that there may not be enough bees foraging or that if there were they could be better employed "at home" saving their flying energy. I also think that by providing food the lower amount of forager flying will result in less drifting between nucs.
There was no provision for comb drawing within the nuc.
The brood cell count was inadequate for testing the freshly mated queens.
My first solution was to make some mating nucs that would take a Triplefold frame, a 1/3rd width frame and a 1/3rd width frame feeder.
It then occurred to me that five 1/3rd width frames have a total width that was the same as a half width frame (I also had many of these already in use).
It was a simple step to produce a design that would accept 5 x 1/3rd width frames along the box or 3 x 1/2 width frames across the box.
A frame that was hinged only in the centre was much simpler to make and stronger (because there were fewer joints to fail or move) and could still be used in a full sized box over winter.
The wooden parts that bear the hinges are shaped as in the drawing at left.
The drawing below shows a Cell Space incorporated into one half of the frame, this is optional and I have some "with" and some "without" this feature.
This design has short lugs (19 mm) with small pads to provide correct spacing when used in a full sized box.
To get started with this system I filled a National brood box with eleven of these frames fitted with foundation and used it to house a swarm, I fed this swarm copiously with syrup to ensure rapid drawing of the comb. Two of the central frames were taken out before they were fully drawn, shaken free of bees and used in mating nucs to store a couple of "old" queens that I had removed from other colonies (bees from those colonies were shaken in with their respective queens and closed up for three days). The rest were allowed to be fully drawn and later a small batch of new queens were grafted and the sealed cells placed in mating nucs. After the new queen is mated I like to let her lay up the nuc. I then can assess her quality and can go on to let that brood emerge if I want to have more detailed information. This means that I have more nucs in operation than is strictly necessary, but they are self maintaining and can still be used for several batches per season.
At the end of the mating season The frames can be utilised in 5 frame nucs or full sized boxes, which makes use of any brood, pollen or stores that are in them (I use flour to unite the bees that are on them with the "receiving" colony). I have a number of both bifold and triplefold frames scattered among all of my colonies, that way I always have the ability to make a mating nuc "at the drop of a hat".
Before using them I coat the brass hinges and the faces they are fitted on, with petroleum jelly to make removal of any propolis easy and prevent a build up that would stop the frames folding out into the straight position.