[Update added bow pics] Having set issues during the tillering process

[Loa]

Hello,

Although I make relatively "light" bows (25#-40#), I find that they take a significant set during the final stages of the tillering process.

As I make the bows from an ash billet, most of my staves have a healthy reflex once they're roughed out. Yet they all lose that reflex, and even gain a inch or two of set once tillering is done.

Bow type: self bows, ash, with either pyramidal, meaere heath, or mollegabet design. Bow length: 72" ntn for my 31 inch draw, and 64" ntn for my wife's 26" draw.

During tillering:
-I never pull them harder than the desired weight
-I work on them only when they're between 9%-11% in moisture
-Every time I pull an inch further, I draw it repeatedly to that new distance at least 10 times before going further.

Am I missing something?

Thanks

Loa

P.S. Back to the forum after a long break: a new born girl will do that to your hobby time!  :-)

[okie64]

Sounds like you are using good tillering techniques. Set happens, especially with ash. Ash is strong in tension but not in compression. I've built a few ash bows and they took more set than I was happy with so I quit using it. Try some osage and you will be amazed.

[mwirwicki]

I second Okie's comment.  I would also say to quit using the ash.  Although some are getting good results by heat treating it.  Do you have access to osage?  What other wood species can you get?

[PEARL DRUMS]

Width was never mentioned? I wouldnt build an ash bow under 2.5" wide for your long draw, even at 72" long. Still, Matt and Jamey are right. Set happens especially with ash. If your ash bows are holding strong and not chrysaling, you done good in my book. I get my whitewood fixes with hackberry, elm and hickory.

[Loa]

Hello,

I make all my bows wide (my pyramidal and meare heath are 2.5, the mollegabet is 3), as I like the look, and I can live with the loss of cast. Also, I'm quite afraid of making tips that are 1/4" wide: mine are 5/8 to 3/4  and I'm constantly afraid that they'll break on me!  :-)

The very first bow I made (2 years ago) is still going strong with no signs of chrysaling, and I've never had any of my bows breaking. I just don't like the look of that set!  :-)

As for the wood: white ash is very cheap and easy to find around here (Quebec), but I could also get my hands on some hickory or even ironwood billets. Much more expensive and hard to get. There is no osage for hundreds of miles, sadly. Importing it from the states would be ridiculously costly.

Anyone willing to send me some?     :D  

Loa

[Living_waters]

Just a quick listen your tillering process it sounds good. Ash is a finicky wood that is prone to taking some set. If your bows are light draw at 72" long and are as wide as you say then they are pretty thin I assume. There is a happy medium with a compression weak wood, if it is too thin then there is no internal integrity to return the wood (if I am saying that right). A correctly built self bow is half broke from the start. I have built a similar bow 72 NTN 2 3/8 wide 40#@29" with almost 1" tips an american flat bow. Took massive set but after 3 years it was still a safe and dependable shooter.
Local woods you might try your hand at are beech (getting ready to cut some american beech in a few weeks) birch and maple, those three are similar and are not prone to the cast robbing set. The iron wood you are speaking of is probably blue beech my neighbor makes some really nice bows from it and says he almost prefers it over osage.

[George Tsoukalas]

It's a matter of practice. 2 or so in of set is acceptable. So if you start with 2 in of reflex and loose it you have 2 in of set. Having a science background...I have to ask how you determined your mc was 9-11%. I actually prefer 8-10% as determined by a moisture meter. Anything over 10% is too high. My first instinct is that your wood is wetter than you think.    Jawge

[George Tsoukalas]

I use  a moisture meter  right down to stringing for the first time and if I get a reading above 10% I stop and let it dry next to some heat. For hickory I prefer it closer to 8% and even 6% is ok. Osage likes around 8%. Have fun. Jawge

[burnt]

I would tend to believe its first a common problem with ash to take set and second the moisture. If you are not already, rough out the bow and then let it sit for two weeks to a month. After this time it should be dry enough. Could try a different style like indian flatbow with even limb width out to half limb length and then tappering to 1/2 inch.

[Steven Russell]

Just a few thoughts.

In what portion of the limb is the set occurring?  Are you possibly concentrating the bend of the limbs in too small of a section, thus causing set?

It would help if you could post a picture of some of your bows at full draw and unbraced.

--Steve

[Loa]

Hello,

Thanks for the added replies. I'm guessing that the set is somewhere between 2 and 3 inches. It's not so bad when unbraced, but considering that it had a decent reflex before, it's just a shame to lose it all.

@Living_Waters: translations of names of wood can be very tricky, especially if you add the fact that there are a lot of different birches, and beeches, etc...

@George: I use a moisture meter for lumber, and try to poke it a few places and make an average. Sadly, once I'm close to finishing, I can't really poke the limbs anymore. How low can I go with white ash?

@Burnt: the problem with letting them sit is that my workshop has very low humidity in the winter: high teens or low twenties. It's too dangerous as the wood will go too low.

@Steven: I'll try to get some pics, which is hard as I'm 6'1" with a 74" bow, and it's freezing outside right now! But I always tiller from the flares to roughly 6 inches away from the tip. (Except for the mollegabet, of course.)

Thanks

Loa

[Loa]

Hello,

Here are some images of freshly finished bows. They have not even been fired yet. The first 3 bows came from an ash billet I split myself, and all had about 2 inches of reflex after being roughed out and dried to 10%.

First up: meare heath inspired design (64" ntn, 30#@28", 2" at flares up to mid-limb, 7/8" at nock)

Fully braced:
   

10 minutes after being unbraced:
   

------------------------------------
Second bow: meare heath inspired design (72" ntn, 40#@28", tillered to 32", 2.25" at flares up to mid-limb, 7/8" at nock).

Important note: the roughed out bow's top limb had a significant wave (up and down, not side to side), that is now less noticeable. The end result, when braced, is not the optimal curve because of this wave: there's a spot that doesn't seem to curve, but in a sense it is, as it was reflexed before. (Is that decision correct?)

Fully braced:
   

10 minutes after being unbraced:
   

----------------------------------
Third bow: Mollegabet inspired style (72" ntn, 35#@28", tillered to 32", 2.25" wide).

Note: I was planning on making this bow 3" wide, but I discovered a worm hole when roughing it out. Regardless of that modification: mollegabets require a lot more work than pyramidal type bows! damn!

Fully braced:
   

10 minutes after being unbraced:
   

--------------------------------
Fourth bow: This is my very first bow, now 2 years old. It has been shot thousands of times. Specs: straightforward pyramidal design: 72ntn, 35#@28", tillered to 32", 2.5" at flares down to 7/8" at nocks.

Fully braced:
   

10 minutes after being unbraced:

   


There you go. Thanks for any help!

Loa

[Nim-rod]

My first ash bow took a bit over 3" of set but at 60# it's still fast. The next ash bow I made I flipped the tips  some and it holds about 1" of total set and looks a little "gull winged" when unstrung which I kinda like. Ash is a fine wood in my opinion as it is pretty easy to work and grows really straight. It takes a bend nicely and so putting in static recurves restores any cast that may be lost due to set. Mine are still looking good and shooting strong and fast so I wouldn't worry too much if that's all you can get.

[PEARL DRUMS]

Your tiller isnt the culprit. Honestly your side profiles dont look too bad for a selfbow of ash.

[George Tsoukalas]

I'd go now lower than 8% with ash. Jawge