This is my second BFM build, did two 800mm wide Titan 48s last spring. The DR´s are for sure more complex, but I must say, a lot more interesting and enjoyable build
Those of you who hesitate to build them, just do it:) With my Titans I went very much CNC, watercutted all the plywood panels, just cutted the angled edges on a tablesaw. Since we used arauco, the panels twisted a lot from the water:P but it was no problem to straigthen them out, the cabs are very square
'But on the DR´s I felt that it would be to much work for not as much gain to do a full CNC-job, even more so taking in account that the construction probably wouldnt straighten out it self the same way as the Titans did.
So I went the middleroad, CNCed moulds for all parts that arent just square panels, or gets trimmed against the cab itself. This have definitly saved me time, havent had to measure so much, or convert to mm, I did that easily in Autocad
And all curved surfaces are routered against the aluminium moulds:) I´ll take a few pictures today.Sadly my landlord just moved his nice big professional tablesaw to a different workshop, the same day i started my build.. So I´ve used a circularsaw with a sled, a jigsaw and my router, and has worked out great:)
Today we are gonna put on the first curved panels, thats gonna be fun
We didnt find any nice 6mm, 3 ply pine plywood, so gonna go with 2 layers of 3mm, laminated together, couldmoulding in boatbuilding terms. That should be atleast as strong, or even stronger.But, now I run in to a "problem", the backhalves, and the compression horn "chamber" sides are to be made out of 1/8" 3mm plywood, I was thinking to use the pine I have here also, but now I´ve seen in the new plans that Bill says the 3mm ply must be either Birch or Poplar. That makes me wonder, is that because of the superior strength/stifness of the Birch compared to Pine, or mostly because its much easier to bend it without cracking the Birch? I may very well be wrong, but isnt Poplar a lot weaker then Birch, or even Pine?
I remember using poplar plywood to make floorboards on a lightweight race-yacht we built at a boatyard I worked years ago, and it didnt feel very strong, more like balsa then pine almost.
So, would there be an issue if I make the backhalves and HF chamber sides from 3mm pine? I did a testpiece yesterday, no problems at all to bend the backhalves with the pine, from flat sheet to full bend directly, no cracking noises or anything, and gets really nice and stiff when its held in place with one hand. I could laminate the HF chamber sides to get them stiffer, not so much bend in those, if that doesnt create any other negatives, the chamber would be slightly smaller of course, so the outside skins still match. But there are many stiffeners on the inside of that skin, so may be enough with one layer of 3mm, as per the plans, even if using pine.
Still gonna need to buy more plywood for the HF chamber, one sheet will be just enough for the backhalves and the woofer chamber sides. But it would be nice to not have to buy birch, mostly because birch is around 3 times more expensive then pine, and a lot harder to come by here in Gothenburg/Sweden, partly because the grossers who sell it are only open when me and my partner are at work, and its a bit of a drive to get it
So, whats the verdict, can I go with pine, or do I need to bite the financial apple and take the hassle of going to town to buy one sheet of BB?
I´ll upload some pictures of our progress so far later today
even if they are timecomsuming, been at them for 2 weeks now, a few hours each day, but soon its just the finishing and such left 
