I've made many of these bows and may offer up some suggestions, the first bow like this I posted here won me bow of the month and I have helped several people make them successfully.
The bison horn can withstand an extreme amount of compression just like their cousins the Asian waterbuffalo which is the favorite material of the Asian and European horn bow makers.
You did a pretty good job making this bow but it seems you went about it the hard way!
I have found after making about two dozen of these bows that boiling or heating the horn is unnecessary. You should start by making the bow completely finished and tillered to about half the poundage you want the finished bow to be...for example if you want a 50# finished bow make your bow 25#. The horn and sinew will double the weight in most of the bows.
I always make the belly as flat as possible but if it is not perfect that's okay as long as it is close.
Cut your horn strips and flatten them to an even thickness on a belt sander, take your time and thin them until each section of horn is flexible.
I then glue the pieces to the belly of the bow which has been scored with cross hatch patterns, I usually start with the longest piece of my horn section and put it in the middle part of the bow, each piece is then clamped down with "C" clamps as many as you can get on the section of horn. I continue the process until the entire belly is covered with horn.
After clamped up the glue needs to set for 3 days until it has set enough to remove the clamps.
At this point I take a file and round off the sides of the horns on the edges of the bow and take hide glue and make sure any gaps are filled that might not have got enough glue.
I then sand and score the back of the bow and sinew back it.
I then let the bow cure for about 10 days before stringing it. I do not pull it but let the string settle and check the tiller, Usually it will be close to spot on at brace height if you have taken the time to make your horn pieces even thickness. If the bow is out of tiller you can lightly scrape the horn belly to bring tiller to where it needs to be. I then wrap each horn joint (butt joint) with reinforced sinew wrappings.
This will take several days to cure good enough to string the bow, I usually wait two more weeks before stringing and shooting, the bows take a while to reach their potential and get better the more you shoot it.
The Sinew backed bison horn bow pictured below is seventy pounds and cast an arrow a tad bit over 200 yards, it is the best one I have made performance wise and now lives overseas!
Bows like this are not documented with a physical specimen surviving that I'm aware of but have been written about by early explorers.
Good job and thanks for taking the time to post this thread.
Eric
