A devisating Truth of Sinew Backed bows.

greenchicken
Registered User
greenchicken
Registered User
Joined: June 22nd, 2005, 5:13 am

May 15th, 2006, 1:11 am #1

I recently re-posted a complete build-along for sinew backing. That reminded of that bow that never was completed. The end weight, at the time, was too strong for me but in the many months since I have built up to it.

I took it out back and shot a dozen arrows. Very happy. Took it back to the shop and did a sanding to remove all the tool marks, cut some horn for nocks, and got the rattle snake skin ready. Tonight I was to make up a batch of hide glue and finish this bow up. Already started dreaming on the Jim Hamm NA quiver/bow case design.

Before starting this I decided to shoot it a little more just to be sure the tiller was perfect. I shoot about 50 arrows and then looked at the bow. My heart sunk.



I swear the tiller was almost perfect when I started shooting. I have heard that sinew need to be 'worked in; but I never imagined this much.

The bows weight is perfect but ONCE AGAIN I will have to drop below my desired weight to fix a hinge.

How utterly depressing!
Quote
Like
Share

Guest
Guest

May 15th, 2006, 1:28 am #2

Yeah that sucks. Sinew bows need to be well cured and very well shot in before final tiller. They can be touchy beasts.
Quote
Share

thebarbariansam
Registered User
thebarbariansam
Registered User
Joined: March 1st, 2006, 2:30 pm

May 15th, 2006, 2:41 am #3

wait why do you have to drop the weight? couldn't you correct the tiller by adding more sinew?
-SamMy fellow americans in these troubled times of uncertainty we need a new leader, one capable of dealing with, wars, managing resources, and global warming and drastic climate change thats why I would like to Nominate Otzi FOR PRESIDENT
If its tourist season, how come we cant shoot them?
Quote
Like
Share

badger5149
Registered User
badger5149
Registered User
Joined: June 3rd, 2005, 1:13 am

May 15th, 2006, 2:47 am #4

just shoot it like it is if it shoots good, adjust yor nock point a little and enjoy it. steve
Quote
Like
Share

badger5149
Registered User
badger5149
Registered User
Joined: June 3rd, 2005, 1:13 am

May 15th, 2006, 3:09 am #5

Phil, you can also make adjustments by simply bending and working a sinewed bow over your knee, use a little care wnen you do this but it works. steve
Quote
Like
Share

greenchicken
Registered User
greenchicken
Registered User
Joined: June 22nd, 2005, 5:13 am

May 15th, 2006, 3:32 am #6

Thanks for all the advise. I will try your suggestion of a little forced bending Steve and I may do a little more tillering on the stiff limb (near handle - as suggested by TB whom I sent pictures to).

Not sure if I am up for more sinning, but it is a good idea.

I hate to admit it but even though I love the way it is shooting right now my need I can bear to leave it like this. It must shoot good and look good otherwise I consider it a failure.
Quote
Like
Share

badger5149
Registered User
badger5149
Registered User
Joined: June 3rd, 2005, 1:13 am

May 15th, 2006, 3:45 am #7

Phil, most guys that shoot short sinew bows will brace the bow, put it over here knee adjust the braced tiller then go have fun, next time you shoot it will change again, you might end up just tillering it death. Steve
Quote
Like
Share

Simo Hankaniemi
Registered User
Simo Hankaniemi
Registered User
Joined: June 16th, 2005, 3:10 pm

May 15th, 2006, 8:17 am #8

Yes, sinewed bows are difficult to tiller. The last one I made for myself was about 70 pounds when young. Then I had to tiller her more, and more... She is now 50 pounds and about five years old. Now I enjoy shooting with her and the tiller is perfect. I would not like to do any forced bending to get the tiller even.
Quote
Like
Share

Marc St Louis
Registered User
Marc St Louis
Registered User
Joined: April 14th, 2004, 9:08 am

May 16th, 2006, 10:57 am #9

Adding more sinew will only make matters worse. Sinewed bows need to be used frequently or the tiller goes off. I would do as Steve suggests, although I would just place the strong limbs tip on the ground and apply pressure, like floor tillering.
Marc
Quote
Like
Share

Guest
Guest

May 16th, 2006, 1:23 pm #10

It seems to be more of a factor where the R.H. is pretty variable. Interesting that for the most part, sinewed bows were only common where the climate was dry.
Quote
Share

Joined: February 18th, 2010, 10:59 pm

October 25th, 2010, 5:25 pm #11

I know this topic is older than Al Greenspan probably, but I was wondering what preventions one can use to avoid tiller change. From what various posters have stated:

-Not curing well can change tiller
-Humidity can change tiller
-Not shooting often can change tiller
-Not shooting it in really well can change tiller

I am going to sinew a pyramid bow, and hope that the pyramid taper of sinew would, like in any other material would result in an even bend. But for one limb being stronger I am a little weary. I have only sinew backed two other bows, one which did get a screwed up tiller. The other one was perfect. Both of them I did not tiller afterward. The first one I did not tiller after just because it was one of my earlier bows, I was kinda just psyched out that I made GLUE more than the bow itself! I have seen a video on youtube where a Korean bowyer sinews a bow. The method he uses is to just put a small strip down the center on the bow, I guess as that it the most likely area for a tension failure.
Quote
Like
Share