Bison Horn Composite Bow Adventure

[swamp monkey]

It was a sickness with only one cure.  I had to try one.    So I began gathering materials for a bison horn composite bow.
Materials: 
•   Osage orange core
•   Four bison horns (12+ inches long ea.)
•   Deer leg sinew for backing bows
•   bow string crafted from deer back sinew
•   hide glue  (yeah I bought this batch.  The batch I tried to cook got me banned from the kitchen)
Tools:
•   Drawknife
•   Spokeshave
•   Cabinet scraper
•   Candle wax warmer for hide glue (works great and my wife knew what I was using it to do!)
•   Clamps, lots of clamps
•   Large boiling pot and tongs
•   Welding gloves
•   Hardwood scrap pieces for clamping use
•   Naphtha thinner
•   Small paint brush
•   Clamping rack
•   Hack saw blade for roughing up surfaces
Resources:
Jim Hamm’s bows arrows and quivers of the Native Americans.  His chapter on making a bison horn composite bow is dog eared. I contacted “Indianguy “on the PA community online, and he gave a lot of good advice.    His best statement was “you’ll figure it out.”  Experience really was the best teacher.  For the sinew processing and string making I consulted “Jackcrafty’s” posts in the build along section of the PA webiste.   See for yourself how well I used what they taught me.

[swamp monkey]

In the Beginning:
I began my adventure by learning how to process sinew.  I worked deer tendons from backstrap and legs into sinew fibers.  It was brainless work but it took time and effort.  I had a good collection of deer leg tendons and got some additional supplies from “Patches”.  Many thanks Patches – that was a lot of work on you and a kind gesture.  In between sinew sessions, I made the economic wheels turn with each internet purchase of bison horn. 
I crafted a rack for bending and clamping work from a ripped two by four.   

Core of the matter:
I began to craft my Osage core.  Before I got too far into it I began to wonder if one method would be better than another.  So I decided to craft two cores.  One I did by chasing a growth ring on a 36” stave and tillered to 25# at 22”.  This one had a bend off to one side that I took out with heat.  For the other core I used an Osage piece that was wavy and far from flat.  I carved and sanded out a flat 36” piece that I would not tiller until it was backed with sinew. 
Yes, I was making two bows.  I considered it an experiment for comparison.

[ssgtchad]

Work has just stopped inmy neck of tbe woods.

[swamp monkey]

OK I lied:
I was really making three bows.  I had NEVER backed a bow.  Ever.   I had a 42” long Osage bow that I backed first.  No belly laminates.   I wanted to ensure I got my process down before I got cranking with the composite bows. 

The stave image below shows the two staves I worked with.  The one on the left yielded two of the bows.  The portion on the right side became this sinew backed experiment bow. 

So In line with my second approach I worked the stave flat with even thickness, degreased with naphtha thinner (aggressive degreaser), let it set for a while and then began painting hide glue on the back and applying hide glue, soaked  sinew.   I am glad I practiced.  There is an art to applying sinew in a manner that looks good.  I know this because mine did not look like the sinew backed bows you see on PA, but I am learning. 
My daughter wanted a Cheyenne style bow, so this youth model was tillered to suit her.  This bow was graced with a sinew string made from deer backstrap sinew, and pulled 29# at 21”.    I named it “Prairie Wind” and she was elated.   

[swamp monkey]

here the bow is at low brace and a bad pic at 21" draw.  I need to photograph the bow at full brace height and get a better full draw pic.

[swamp monkey]

Horning in:
The pieces cut from the bison horn are called scales by the experts, so that is what I call them.  Cutting bison horn scales smells a lot like burnt hair.  Be mindful of family members if your band saw is in the garage or basement.  The resulting sawdust from the cutting was oddly decorative.  It was a contrast to the wood dust I was used to seeing.   Horn cuts easily with a metal cutting blade.  I used only the outside curve of the bison horn for my scales.  To get them flat I needed to bend them, but before I did that I cleaned them up a bit with the bench sander.  I was shooting for 1/8” thickness, so  I took them to 1/4” thick so I had plenty of dimension to work with.  Thick scales are harder to bend and take longer to heat.  Dressing them up really improved the process. 
I used the largest pot I could find and boiled them for about 20 minutes.  It took longer to get the pot to a boil than the actual boiling.  Tongs and welding gloves made this process painless – literally.   Steam from the pot was hot.   I had all of my clamps ready to go.   I had to work fast and fumbling around with a clamp costs time.  Clamping a scale flat and straight takes quick effort but it pays off.  A couple of scales had to be boiled again and reclamped. 
After cooling I laid out a template for the belly on each scale.  I traced the template with a pencil and sanded the scale to near final width and thickness.  When satisfied I roughed up the glue surfaces of the wood and horn and proceeded with degreasing.
This was new work for me.  The first one was the hardest and the rest went a lot better.  I would suggest having enough clamp blocks to prevent marring of your stock and to distribute clamp pressure more evenly.  Also have enough clamping racks for the number of scales you have to work.

[swamp monkey]

A union made in heaven:
My wife permitted use of her candle warmer for the hide glue and that must have been just the right medicine!  This part went great.  The warmer kept the hide glue liquid instead of a gelatinous goo.  I painted a thin layer of glue on the wood core belly and the bison horn as primer.  Then I applied a second layer and put them in place for clamping. The whole effort took only a few minutes.  I left this clamped up for about a week though.  I wanted it good and dry.  I saved the hide glue by placing it in the freezer so it could be used for sinew backing at a later time. 

[swamp monkey]

Back to backing:
With one bow backing event under my belt I went for a second.  I kept my bundles separate so I could tell how many legs’ worth of sinew I consumed.   This short bow utilized one leg tendon per layer.  After the joints and ends were wrapped I had made of use of just over two leg’s worth of sinew invested in a two layer sinew backing.

[bubby]

very cool stuf swamp monkey, don't make us wait too long

[Joec123able]

This is awesome

[swamp monkey]

Time to Tiller:
I tillered the stave that I decrowned first.  I had a stiff limb and a one that bent more in the mid-section.  I scraped thin layers of horn off the stiff side but with little affect.  After studying on this for a while I applied a layer of sinew to the weaker limb.  Things got better.  One additional layer and a light scraping of the horn belly got things right where they needed to be.  I have no idea what the core would have pulled before the belly lamination.

[swamp monkey]

Now we all wait:

Sorry fellas, I have to wait on some things to dry and can't get on this again until the weekend.  When I report back I will have some brace shots and full draw pics. 

[Onebowonder]

Watching this theread with both eyes!   

When I'm a big grown up bowyer I want to be good enough to do one of these type of bows!!!

OneBow

[ssgtchad]

Watching this theread with both eyes!   

When I'm a big grown up bowyer I want to be good enough to do one of these type of bows!!!

OneBow

Me too

[Newindian]

I was wondering how this was done very resenty