Ken,
Your blade is almost identical to the blade I am thinking of making. I have a piece of 48" pipe, 1/2" wall, that I am going to use 1/4 section of to make the curved blade. I am thinking of a 6' wide center section with wings just like yours set at 30°. I am planning 30° of hydraulic angle. I plan on 8' to 8'6" overall width so I am legal towing it down the road. Also plan on adding grader cutting edges. I am using such heavy material because I want weight to remove hard pack. Also planning on mounting the blade 2.5' to 3' ahead of the Bobtach to make an overall longer effective wheelbase.
My question is, when angled does it have a tendendcy to turn the machine when plowing down a road?
It will turn the machine at times. I only plow my own commercial yard and I get to it before there is alot of semi packed snow to deal with. Our snow is usually dry and light as well. So 98% of the time it is no problem at all.
I also run tire chains on the rear wheels as the lane itself is crowned and I was have trouble with the wheels on the ditch side not getting enough traction to point me towards the top and the more I tried the more I slipped sideways into the ditch. But it did this even with the blade up.
I'm legal width if I angle the blade, but I seldom trailer it anywhere.
How wide of a bucket can you handle in your "hard packed" snow? I'd let that be your guide. Are you making a trip cutting edge, or a trip mowboard or neither? I would not want a plow without a trip system of some sort. Without it someday your going to bite the windshield imo.
My blade has 3 springs but the 773 can lay it down fairly easy still. (2 springs was almost useless)
I always figured if it was tough scaping I'd use my bucket. because I don't see those conditions often, I made my blade wider then the oem would recommend, but it works great for me. If i end up selling my old one I'll make a 10' out of a 8' blade.
I also have a 2" dia single acting rams to angle each direction, which has enough power, but the volume is so little to fill the cylinder that you must have some sort of flow restriction, or the blade just whacks from one side to the other as soon as you touch the button, unless you idle the engine first. I'd say a 1/8" hole max, or needle valves from somewhere like
www.surpluscenter.com
I think that is alot of weight for a blade with 1/4" buy the time you get it all together it will be heavy. It will scrape good, and I guess you can carry it a little it need be, as opposed to me leaning the loader on mine.
Also be sure to leave some side to side movement in your main pivot pin, (a self aligning bushing would be a good idea) so the blade corners can move up and down as the road twists around. Otherwise your blade cornerwill carry all the weight lifting the opposite side of the blade of the ground.
Ken