the effects of grain

[joukahainen]

Could someone explain to me the effects that the direction of grain has for the bow ?

In the picture attached, I have 3 pieces of wood in which the grain runs differently.

In the picture the upper part of the pieces of wood represents the back of the bow.

Now, my understanding is, that is considered best to have the back of bow like it is on fig.1. So that the grain runs from side to side, and so that the entire back is made of one grain of wood. (dont know if that is the correct term, please correct me if not)

My first bow was made from a piece that resembles more fig.2. It works well, has not broken or splintered, but it has about 3 inches of string follow. It shoots about 110-120 yards far with my selfmade-pine-arrows with steel points. It's about 40 lbs draw.
Now, i do not have experience shooting glass bows, or those carbon-fiber-whatever-thingys, nor do I even have experience shooting well-made wooden selfbows, so it's difficult for me to tell whether my bows shoot well or badly, since my comparison-group is so limited. My second ash-bow shoots about 120-130 meters which is like 130-140 yards or so.The grain on the bow2 is somewhere between fig1 and fig2.

Somewhere I read, that a well made 45 lbs selfbow should shoot about 200 yards, so I'm pretty far from that.

So, my question is; What is the difference and the effects between the types of wood-grain in these figures? Will some shoot faster/slower? Will some take set more easily than others? Break more easily? And most importantly WHY?

I would like to understand how the wood works, so please someone enlighten me

[attachment deleted by admin]

[david w.]

making a bow from a stave would be like fig. 1

i have made bows from all of those and they have worked fine. as long as the grain runs straight from end to end it should work well.  I will always back my board bows for insurance.

with your bow having set it could be do to your designs and/or you overstressed it from tillerring.

Could you tell us the dimensions of your bows?

im not that experienced so hopefully someone else will chime in

[joukahainen]

Yes, the bows are about 75 inches long, about 2 inches wide at widest point, have a stiff handle of about 7-8 inches, and are somewhat pyramid-shaped. I think that the set is due to me having been too violent on the floor-tillering phase, and in general in the beginning phases. The thing is, I would like to try to make a 70-80 lbs bow (these fourtypounders seem very easy to pull and slow when shooting + I'm a pretty big guy) but I would like to resolve some of the issues I have had with the previous ones before I begin with a new one.

Also another question just popped im my mind, is it true that white-ash is better when the growth-rings are thick, as in fast-growing? rather than thin, as in slow-growing? The reason I ask is because it would seem logical, (to me) that slow-growing would be more sturdy. But then again, I have a feeling that the ash with thicker growth rings is heavier and thus more dense? Any experience/knowledge on this anyone?

[JackCrafty]

There are engineering tables that show how wood responds to loads based on grain orientation.  Basically, staves #2 and #3 are going to be stiffer than stave#1....assuming the back/belly is the wider dimension.  Arrow makers know that grain orientation affects arrow spine as well.

"Stiffer" means less deformation under a certain load and less deflection before breaking.  In other words, staves #2 and #3 will take more set because they will be closer to breaking (when you reach your final draw length) than stave #1.

Clear as mud?

[joukahainen]

Okay, I think I understand now. That was well explained, thank you!

How much say in percentage then is this difference? Is it a lot ?

[JackCrafty]

I don't like looking at engineering data (brings back nasty college flashbacks) but the difference is not much.  Maybe 10-20% on average?  It also depends on the wood species, moisture content, etc.

[joukahainen]

Ok. Thanks a lot crafty jack ! that was very helpful

[radius]

any one of those grain patterns will do to make a bow.

1.  plain sawn...like the outside of a tree, just under the bark and cambium layer.

2.  quarter sawn (edge-ringed)...just like a plain sawn board turned on edge.

3.  rift sawn...this is the grain pattern between 1 and 2.  If you buy a plain sawn board, and look at the growth rings on the end, you will see rift grain at the edges, unless it is a narrow board from a very wide tree.

I have noticed that sometimes riftsawn board bows develop twist at the tips...

It could be that your bows took set from too-high a moisture content during tillering.

[Ryano]

There are engineering tables that show how wood responds to loads based on grain orientation.  Basically, staves #2 and #3 are going to be stiffer than stave#1....assuming the back/belly is the wider dimension.  Arrow makers know that grain orientation affects arrow spine as well.

"Stiffer" means less deformation under a certain load and less deflection before breaking.  In other words, staves #2 and #3 will take more set because they will be closer to breaking (when you reach your final draw length) than stave #1.

Clear as mud?

You mean 2 and 3 will take less set right? More set doesn't make sense. There's less early wood being put under pressure that way.

[JackCrafty]

Ryano, staves #2 and #3 will take more set (not less).  Not only from an engineering standpoint but from personal experience.

All wood samples being equal, and the wood fibers/rings are not severely violated, stave #1 will bend more than staves #2 and #3 (before breaking), right?  This is what I'm assuming.

I'm not sure what you mean by "early wood being put under pressure".  Do you mean shear stress?  I think the early wood is put under "pressure" no matter how you bend the wood?

Anyway, if stave #1 will bend more, this means the wood is not as stressed as in staves #2 and #3 for a given amount of bending.  If the wood in stave #1 is less stressed, it will take less set than staves #2 and #3.

[sailordad]

OUUUUCH!! 
 my hurt is starting to brain.


                                                            tim

[George Tsoukalas]

Plain or flat sawn, quarter sawn or edge grained and rift sawn or bias grain will all make you a bow. Really the type of cut  does not matter even for set. The key in reading grain is to look for straight grained stock. Look at the edge grain and the grain on the face. I allow 2 run ups or run outs per limb for a 50-55# bow. For such a bow no backing would be needed. Backings come into play when the grain isn't as good as I've described above. Get a hold of Trad Bowyer's Bible #2 for  more info on board bows. Also, check my site.  Questions welcomed.Jawge
http://mysite.verizon.net/georgeandjoni/archer.html

[joukahainen]

Jawge, your site is excellent I have browsed through it many times since I started this obsess...hobby!

You have a lot of experience building bows from white-ash. Tell me, is thick or thin grained ash better? I have here a board which has very thick growth-rings. They are about ½ cm thick, compared to the other board I used for my first bow, which had growth-ring-thickness of about 1-2 millimeters. So almost five times thicker.

If I make a bow out of this one, it will only have 2 growth-rings at the tips of the limb. If i violate one of them, it will mean that i violate 50% of the grain.
On the other bow, it has 8 of which 3 are running off limb. Which is better?

[George Tsoukalas]

Thanks, jouk. The thickness does not matter. What matters is the straightness of the grain. I look at the face and the edge of the board. I allow 2 run ups per limb for 50-55#. You really have to be prepared to walk away from the board you want. Jawge