Dimensions of a mini bow to figure out if mystery wood will work for a bow

[Nasr]

I have been advised a few times and read on a post here and there that when trying to figure out if a mystery wood would work for a bow a good approach is to make a mini bow. I am currently trying to build a mini bow but i honestly dont know where to begin. I am currently not in the US and have a few species of trees that i can try but as i am limited with tools and time i really cant spend too much time trying all these species of woods. So my plan hopefully is make a quick kids bow and see if it works but....

1. If i make it a kids bow what would be a good overall length? I havent made much kids bows and the ones i have were just rushed so that my kids can have something to shoot with.

2. How would i even scale up from that is there some kind of formula? For example if i make it 15-20 lbs how would i take that weight along with the dimensions and determine whether it would make a decent not too big 50-55 lbs bow. My goal isnt just to make a bow that is at a weight i like but make a decent bow that will last me a while.

3. I know there is a different method in which I can take a slat of the wood in question and do a bend test however that requires tools i dont have and cant get at the moment. I am very limited to an axe rasp some sandpaper and a scraper. Honestly not limited at all when it comes to building bows but i have gotten comfortable with my power tools and miss them dearly. I really dont know how good you have it till you lose it lol or in my case away from it for a while.

ideally i would like to make a 64-66 ntn bow with not too wide limbs maybe 2inches or less. I know i cant be picky here cause ultimatly its down to whether the wood can handle that or not but i thought i would put this information here just in case it will help with answering my question.

[Eric Krewson]

The safe formula for adult bow making it to make the bow twice the shooters draw length +10". For kid bows it depends on how big the kids are, I made ther little guys a 36" bow, when they out grow the bow add about 10 " to the bow for 8 year olds and another 10" for 10-12 year olds.

I made and gave away a number of kids bows, for safety reasons I always backed these bows with bamboo to make sure they would't break and hurt the child.

[Nasr]

how would you then take that kids bow to determine whether it would make a good adult bow. Are we just saying that a successful kids bow will definitely make a good adult bow just by the mere fact that it works as a kids bow? just trying to make sure i understand.

[Eric Krewson]

I missed the part about you looking for a design that would be used as a kids bow that would be the same as shortened adult bow.

The kids bow and the adult bow won't have a similar design as far as width and length goes. Most of my kids bows would be an inch wide with a 3" handle section at the most. Because I use osage, all of my adult bows are 1 1/4" wide and 64" long for up to a 28" draw and have a 4" handle section, I may go to 66" long for a 29" draw and to 68" or more for a 30" draw. I had a number of bows that failed for the guys with a 30"+ draw so I stuck to making bows for the 28" draws and less because I replaced broken bows, it set me back a week or so to replace a bow.

One guy broke two of my bamboo backed osage bows, I made him a replacement for the first broken bow and refunded his money on the second one.  I found out later after more broken bamboo backed bows showed up that I had gotten a run of bad bamboo from Frank's, it looked good but wouldn't hold up.

You may find like I did that a kid's bow is the most difficult of any bow to make, when you get down to a bow in the 15# range you don't have hardly any
wood thickness left in the limbs and one too many swipes with your scraper will make the bow hinge, you have to have the tiller spot on to pull it off.

I think you need more reference material to study designs; I made up my own design which performs well for me and the people who own one of my bows. Some designs are fit for white woods, others work well for osage and yew.

Because you are using mystery wood to make your bows, make them wide, flat bellied and long.

People get hung up on trying to gain a few extra feet per second out of their bows, which is good because we all learn a little more from their efforts. I go for smooth drawing, stable and long lasting with very little set.

These bows span my 26 years of bow making before old age and injuries shut me down, the static with a little set has been shot so many times over a ten year period that if I guessed the number of arrows that had been though it would sound like a lie. The top bow is bamboo backed, I had it stored too close to the ceiling in my shop and the summer heat cause the bamboo to crack and the handle to pop loose, I am in the process of adding a new handle to the bow, I had already fixed the minor cracks in the bamboo 

 

[Nasr]

Beautiful bows you got there.

I think i might not have been clear on my intentions my sole reason for making a kids bow was to test whether or not this mystery wood would be a good bow wood to make adult bows.

Just to give my background which i should have done in my original post.


I am not a new bowyer and have made many bows although i wouldnt say i am a good one lol.

My knowledge however is limited to woods that are common in the bowyer community in the US. I am currently travelling and need to satisfy the bowyer's itch and just wanted to know a good way to tell whether a unknown wood speicies would work. I remember being told that a good way was to make a mini bow.
i am guessing now that by the virtue of it working as a kids bow it should work as an adult bow. Just probably need to make it overbuilt and remove some mass as i get to the end. 

[TimBo]

I have often thought about making a test mini bow, but have never done it, so take this with a grain of salt.  However, I would just make one 18-20" long, scale the proportions as best you can, and evaluate set once it is finished.  If it is not a suitable bow wood, you should be able to tell easily since it will likely break or take lots of set.  If neither is the case, you can make a full-sized one with a conservative design knowing that it won't be a waste of time, and experiment further from there.  Don't get hung up on making a kid's bow, which as Eric points out is a different set of problems.  If you have the Bowyer's Bible books, there are a couple of pictures of mini bows in there somewhere. 

[Nasr]

That sounds like a great idea TimBo. I think I will lower the weight as well maybe to 5-10lbs as well.

[TimBo]

Traditional Bowyer's Bible vol. 4 has a couple of pictures on p. 139.  Good luck!

[Nasr]

Traditional Bowyer's Bible vol. 4 has a couple of pictures on p. 139.  Good luck!

Thank you for that!

[Terrier]

Where are you going to get the wood?  Board staves?   

Are you going to cut something down and split it out?  Fruit and nut tree wood almost always works well.

If you’re going to cut something and split it out, you should be able to determine if it’s decent wood, just by how it splits.  Then rough out your bow with, say, 1 7/8” limbs at around 67-68” to floor tiller dimensions.  Floor tillering should give you an idea of what you’re working with, then let it dry for a month (if you have that long.).  If things are going well at that point, rough out a few more and adjust the dimensions based on your past experience, just to have spares.  You don't want to have it go south and have to wait another month for something to dry...   After a month of drying, you should be able to tiller it. 

*This is Jim Hamm’s technique for a quick(ish)-drying time that I have found to work quite well. 

[Terrier]

BTW, What's the flora like where you are?  Do they have "Tree of Heaven*" ?  Those things seem to be everywhere... Asian invasive in the States.  They pop up all over.  AKA, "Chinese Stink Wood", although, it's the young plants that stink.  I was surprised to find that the large tree I cut for staves to try out didn't stink at all!  They can grow to 80' and be 12-14 inches in diameter, and finding a straight one isn't too hard.  The one I cut was within the woods, about 12 feet in from the field, and was straight and clean as a post for 8-10 feet and 8" in diameter.

It's purported to make a pretty decent bow, and I have a stave all shaped up and drying for a flat bow that I'm going to tiller in 4-6 weeks.  It splits easier and cleaner than American Elm, but once it dries, it has about the same density rating as American Elm, and also Hackberry, in the low 50's.  2" wide at the fades, and you're in bidness!

*I wouldn't make it my first choice, if it's even available where you are, in lieu of a better wood you might find.

[Nasr]

No tree of heaven isnt available here. I did try tree of heaven back in the states and was also confused why it was called stink tree when there was no stink to it. The tree i had was also large diameter and i still have a bunch of it back in the states. I dont really like it tbh i tried making a bow from it and just seemed brittle to me. As for the wood i currently have it has interlocking grain and it seems to be decent in tension strength but i dont know yet as i am still roughing out some staves to floor tiller. I plan on force drying these as it seems to take heat well without splitting which might be because of the interlocking grain. It reminds me of ASH maybe little heavier i would say maple but i dont have much experience with maple. I would like to get some updates on that Tree of Heaven bow once you are done with it. I tried to search online for successful bows form it online but didnt find much.