Adjust the weight

When drawn straight 40lbs is to much.
For to slow down the drawweight you have to work only the bending sections.
I guess 3,5cm in thickness for the core and the horn would be enough to end up with an about 50lbs- bow. 2.5 layers of sinew would be suffucient.

Good luck, Michael

I took it down to 4mm wood and 4mm horn. Now it comes around easy at 20lb.

Now it has the first layer of sinew, 47 gram dry weight. After 36 hour the sinew feels rock solid.
I'm thinking about bracing it just to check what it become. The shrinking has not start yet.

It did not blow.
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30#@18"

Take patience! Wait some more weeks before bracing the bow.
You say, shrinking has not started yet - so the sinew has not cured till now.

Here we are in a dark spot. All know that wait for the sinew, but how many know why?
How many have try?
How many know if there is a difference or not?
I never do what told if they can't explain why.

Looking good redhorse ,I really like the horn handle.
I have been guilty of not waiting for the sinew to shrink before.Once the sinew tore and lifted ,when I braced a bow too soon .I guess the hide glue wasn't strong enough yet . :(
The other reason ,that I know for waiting for the sinew to cure is,If you string it before it's cured,the tiller will reflect more of the horn and core.But if you wait the tiller will include the sinew more.

"waiting for the sinew to cure"
I have wonder what that means, cure. What happens with the sinew?
The handle was better then I thought it would be. I will do that more times. I have a lot scrap horn from sides :)

Redhorse,

please don?t brace the bow now!

Horn, sinew and the clue are consisting of proteins, they are polymeres, curing means polymerisation. It takes time, polymersisation don?t care for your impatience! Curing means much more than to become dry.

Michael

"polymerization" if I remember from school it's molecules that build strings.
Does water open it? Is there some kind of reports and data on this?

Last year a participant of one of my bow- classes. who is a medical scientist with focus on human and animal proteins explained the "curing" of the traditional glues and what happens during the "drying".
It is polymerisation. At first the molecules build strings, when this is done, a backing is dry, but the more important thing happens now: the strings build crosslinks, this takes time according to moisture and temperature.
He told me the old bowyers knew very well what is to do, so rely upon their time- table.
He has begun some more detailed research for me some month ago, I?ll post his results.

I was never satisfied when I saw a sinew- backing drying within 10- 14 days, but the old ones told me let it dry some month. So I begun to ask around what the "curing" really means.

Michael

Good, we need to know what is happening.
But for this bow it does not matter anymore. The wood give up. Not the sinew, not the horn but the core did delaminate. Next will have thinner core.

Sorry for this, thats always a sad moment :(

Can you give some photos from the failing point? Would be helpfull for others.

Redhorse; Wow! I guess we now know that this elm is not sturdy enough for a core. Everyone who thinks that the core is just a frame on which to hang sinew and horn have a good look. -j-

If not Elm, what then? I have Ash, Rowan, Juniper, Maple and Oak.
My thought was that the core was to thick and did have to much weight.

Hello Redhorse,36 hours it's a very small time to dry the sinew.I don'think it's a good idea to bend an hornbow until it's completely finished and dried.Consider that the elastic modulus(stiffness) of sinew will increase with drying:the neutral plane moves toward the back as the sinew dries and becomes stiffer.If the sinew is still wet (or if you put a layer too thin or both things) the neutral plane will be too much toward the belly,putting the wood underneath sinew under too much tension.Even when dried sinew is less "stiff" than horn(and a lot softer than wood)but it can be strained more:this is why it's better to increase reflex during sinewing. Maybe it's this the reason of the failure;anyway 4mm of thicness for the core it's better.
Bye
Francesco

I buy that neutral plane but this bow did explode when the sinew was more dry then first shooting.
Elm as backing on two wood bows don't explode. And sinew backed elm bows don't blow.
Should not the core be able of bending full draw without horn or sinew? As a test before glue? And after the horn are glued on?
Has anybody made any tests?
If I have a sinew backed bow and thin the belly down and glue on horn, what happens?
A core is done in some hour, sinew is easy to put on. But replace the horn is worse :( it's so hard to get.
And, if a bow hold from beginning it should hold later, but a bow that are not tested, do we know what happens later?
Did this bow blow because Elm is not usable as core (JF) or because sinew was not fully cure (AF) or just bad piece of wood?
I'm not a control freak but I like to know every part in what I do, what ever it is. Mostly folks don't know when asked, I found that in almost everything.
People just do because it was done so :) modern society.

Redhorse,

it?s easy to say: this broken bow is history, just an experience.

I draw every core till 2/3 of the desired drawlength, when the glueing of the core and the horn is done(at least 1 week!), I draw again at 2/3 of the desired drawlength very slowly and carefully checking for glueing and other failures, tiller, twists.....and drawweight. Every layer of sinew adds 5-8lbs to the drawweight(depending on the design).

Maybe elm is for any reason not suitable as a core- wood for hornbows, I?ve never heard that elm has been used in hornbows. I guess elm is a great wood for long, wide flat- bows. That?s how our ancestors have used it.

So take your ash, but the best is mountain- maple, due to its great flexibilty and gluing- capablities.

Cause I?m always sucking for juniper, we could make a deal: I give you mountain- maple for your core and you give me a juniper- stave?

Michael

What dimensions on the Juniper do you want?

Sorry but I don't understand what means "I buy that neutral plane":neutral plane is a line that divides the part that is stretched(back) from the part that is compressed(belly),it moves towards the stiffer material.
Bye
Francesco

As you wrote, the sinew moves the neutral plane. But I guess that it will always be in the core. Some wood over and some under. And Elm handle both ways well.
I do still believe that the core was to thick for the arc.