I have just made 64 top bars for my two Warre Hives (8 frames per box). I used two 2 x 4’s for the top bars by cutting 5mm off of each edge to ‘square’ the stock (although not completely square) and then I ripped the length at 24mm, width at 10mm, and cut 319mm in length. I have seen frame sizes range anywhere from 335 to 324mm, but since my lumber was at 19mm thick, the rebates set at 1cm x 1cm, it seems that 319mm is the best suited for my boxes.
I also used a router and made center slots into the top bar to allow for foundation if I wish.
My research concluded that the Delon style frame was the easiest way to make a frame for the Warre box. I even broke down and bought a cheap rod bender. As it turns out, I had not done my research on pricing. I thought 1/8″ steel rod wouldn’t be that much money, but I was wrong. Each rod will have to be at least 20+190+319+190+20mm (bent at 90 degree angles). At 2.00USD a rod, making 64 rods is just way too much money. A lesson to be learned by an alternative noob beekeeper. My suggestion is to stick with wood.
I have decided to follow the Denis tradition and use 90mm side bars (Porte Rayon). Based on his pictures, this allows for the bees to build comb that will not stick to the sides.
I am fastening the side bars to the top bar using a simple jig. Just take your Warre hive box, place a place a 120mm piece of wood on each side for the side bars to rest on, then put the top bars in place. Make sure they are square and plumb. I then use a 18 gauge pneumatic brad nailer/stapler and place two nails into the side bars from the top bar. Since 18 gauge is quite small, I then take out the frame and place another nail into the side bar and angle it towards the top bar. Time will tell if this is strong enough, but my logic is the side bars are really place holders; the comb itself will reinforce the frame.
So instead I have opted for the Denis style frame. It seems that Denis (a professional beekeeper in France using the Warre style hive) figured out that he could use the same dimensions as his top bar, but keep the length at a mere 90mm which allowed the bees to build comb that would not stick to the sides of the hive.