You get to answer your own question here. I agree that Dave's drawing isn't too clear on the dimensioning of the rebated top rail dimensions.
The apex of the runners (plastic or metal) sit 6mm above the horizontal on the rebated rail and the top of the end board.where the frame top bar sits. So thats runner 6mm + top bar thickness 9mm = 15mm. OK, so that's that dimension sorted, but hasn't answered your question yet.
If your frame lug rests on the 30mm flat, giving you 8mm bee space between the frame side and the box side wall it poses two problems.
1. How will you be able to get the hook of your J-type hive tool between the top of the rebate/end wall and the lower surface of the lug?
2. Having worked out that it would be impossible as soon as you built it without rails, how much more impossible one the bees managed to propolise that lug to the rail?
So you have now worked out your own answer? The rail gives you jacking space and bee space where they will scuttle out of the way of your hive tool as you jack up the lug to remove the frame. The apex of the triangular runner gives a point contact on the lower surface of the top bar and bee space either side of it, giving minimum opportunity for getting glued up. You won't believe me when you are prising frames out of a busy hive, but consider how much worse it could be if you didn't use runners at all.
The critical dimensions are all determined by the frame sizes (which you will find on Dave Cushman's site), bee space and either 1 or 2mm clearance for the ends of the frame top bars.
Bearing in mind that the difference between a standard deep and a super is the depth, see this drawing. Looking at the diagram top-right, I see no reason why the dimensions should not allow the bottom of the top rail rebate and the top of the end wall should not be flush. Likewise the bottom rail and the end wall bottom. Just maintain proper bee space. The bottom rail is splayed/beveled so as not to retain rain.
Happy building. Make sure you understand all the dimensions before accepting them as gospel. Just remember that bee space is 7.5mm +/- 1.5mm. That explains my anomaly with 8mm between frame sides and box sides. 1mm clearance on the ends of each lug means that space could vary between 7mm and 9mm with a bit of float on the frame taken into consideration.
I hope this has been of help to you. If you were to make a Nuc with 12mm ply, then the width of the rebates in the end rails would need to be increased accordingly.
Hombre, thanks for the very informative reply. Infact, I got a reply by email from David himself. I will need 6mm runners. I've assemble the hive over a dozen times already!! Virtually on computer I have all the dimensions on a CAD, so I can get a good 3D view of how everything will sit. Frames and all.
would it be possible to get a copy of the plans on cad?
i use sketchup and vectorworks mostly but would be able to import from cad.
could maybe send you you back an animated hive parts thing that i plan to do soon in exchange?
Thanks for the file you have sort of beaten me too it with the sketchup model!
i have looked at the model and am a bit confused, should the top of the super not have a recess? or have you doe it like this to put metal rails on that will then create the recess. i have sent you back a file with the part in question highlighted.
As you are building national hives (bottom bee space, I suggest that you assemble a couple of frames, use runners and set them so's the top of the frames are flush with the top of the hive, likewise with the supers, this obviates the necessity for accurate measurement.
A picture paints a thousand words.
sorry just looking at my post its not that clear what i meant ! i was concerned with the space under the ends of the frames but looking at the drawings again i can see that when the runners are in place that would allow the end of the frames to overhang.
John i like your tip about frames being flush on the top with the box makes sense now
I was looking at some brood boxes the other day, and was wondered if the construction process of the runners could be simplified, for the home builder.
In the shed I have some white plastic "mini-trunking", of the kind used for cabling.
By trimming off the sides of the trunking itself, and the edges of the lid, [the extruded bits that hold the lid in place], you would end up with two flat pieces with parallel sides, depending on how well you can cut, of course.
These could then be pinned in place, probably with frame pins.
The only snag that I can foresee could be if the bees cannot get a foothold on the plastic.
If you have a quantity of the trunking and can cut straight, then it may be cheaper than using plastic runners, but at the risk of producing odd-kit with a possibility of things not matching well in a few years time.
Plastic runners are available from Thornes, and probably elsewhere, a lot cheaper than the metal ones.
The argument that they can't be flamed is void as you would be in exactly the same position if you were using quality polyhive boxes and plastic runners.
If you are overy concerned about the bees not being able to grip, give them a light rub with a fine abrasive sheet to take the surface polish off - err, the runners, not the bees - there are too many for that.
What i have always used for all my runners is and are we sitting comfortable,
wall tile edge bead yep thats right go to b and q and have a look at there ceramic tile section and look for the edge trims i use the plastic version but the steel / ali and stainless versions work just as well it has a profile of a P so the top part becomes the runner and the tail which is the part normaly covered over is stapled to ther inside face of the brood box