Build Along ( building by mass)

[Badger]

Mark, go up about 4 posts, and I commented on the mass of your bow, going to try what you said about pushing the bow sideways abit and trying to train it. Looks like th ebow you are working on should be between 27 and 30 oz but I am a little concerned about how narrow it is, Steve

[Rich Saffold]

MarKinEngland, My last one that length was just over 1 1/4" wide, and usually I like them around 73" for just over an inch otherwise the tapers are just to constant, and sometimes the bamboo amplifies this effect.

Rich

[mamba]

Thanks enjoy watching you work.Be careful with those didjits(fingers).Learned a few things with this build along.

[Justin Snyder]

New question Steve.  I'm building a bendy handle bow that is stiffer in the handle, what do you calculate for the handle. 0" or 2-3" I have dropped my target weight down because it was way to high for the width and physical weight.  Justin

[Badger]

Justin, If it is bendy handle but just slightly stiffer 2 or 3 would be a good number, I always use the word semi because it means 1/2. so if the center 10" is slightly flexing I use half that figure and call it 5". Stiff. This is pretty subjective when it comes to estimating stiff handle area but it will still keep you in the ball park. I have actually built about 12 bows in January, some short some long, r/d, 1 recurve, and a few stave bows. Maybe if the weather is good I will get some photos this weekend and go over the mass on them. I actually use mass on every bow I build. Contrary to popular belief my bows have considerably more mass than they use to have. Whole trick is just making the mass work and keeping it in the right palces. Looking at some of the old primitive relics from different cultures I believe formly that our ancestors had a firm grip on mass placement in their bows. They usually had favortite woods and styles they had become very familiar with so demensions would remain pretty consistent. In our bow building journey we tend to have pet projects that change over time, sometimes they are just evolving and sometimes we change direction all together, currently my pet project is limiting set a bow takes, trying to keep it as near to zero as possible from starting profiles. The type of bows I build are more prone to set simply because I crowd my tillers into short working areas as much as I can get away with. This is why for my mass is so important, I can't get away with underbuilding a bow. I used to rant about overbuilding. I was really pretty hap hazard for many years, a lot of them were underbuilt and a lot of them were overbuilt. I don't expect everybow to be a rocket launcher but I do like to feel confident that when I start a bow I know it will have a high level of performance when I am finished, regardless of the style of bow or wood I am using. ( another rant LOL)  Steve

[Justin Snyder]

Thanks, I might need to drop the draw weight a little more or get more bending going on in the middle.  I knew I was underbuilt on this one, but when I started seeing set I ran it through the mass and found out just how much.  Every bow is a learning experience though.  If I push the tiller and andjust the weight I think I can learn to use your mass calculator a little more efficiently. This bow has already proved it works.  Justin

[DanaM]

Question regarding reflex, on the form I use to induce a little bit of reflex most of it is
on the outer third of the limb and I usually end up with 1.5" to 2" of reflex measured at the tip
So on your spreadsheet I put that number in correct? With this amount of reflex I'm pretty confident I can
end up with 1" or less of string follow. But that is still up to 3" of set. i guess I'm lost as to how you tiller
to stop this from occuring?

[Justin Snyder]

OK Steve I'm right on track, I forgot the 1/2" of set it took while trying to be to heavy. 
Dana, if you keep it down to the weight the formula says the bow can handle, you should be able to keep 1" of reflex.  I punched in all the #'s and made sure it allowed me a couple of ounces to shave off during tillering.  My bow was way under the target weight so I kept reducing the draw weight on the formula until the mass was where it needed to be.  That was my new target weight. Justin

[Badger]

Dana, if you glue in 2" of reflex you want to keep 1" of reflex. One thing I have found out the last year is how important it is to keep the bow as near to it's original profile as possible. Usually on the type of bow you are describing the oter limbs are pretty stiff, If this is the case add 2' to your draw length on the spread sheet and it will allow for more mass in the working part of the limb. Don't be shy about keeping that inner limb wide, just keep the outer limb narrow. use the mass where the bow is bending most. In my eyes both the elb and the holmgarde are perfect examples of really well designed bows. have you got the current spreadsheet? Steve

[DanaM]

i have the one I posted in a early reply.

i just roughed out a maple stave, the goal is 67"NTN, 55#@27' 4' handle, 1.5" fades so I used 8"
I only have 1.75" width to work with so I kept it that wide for 15" then taper to 1/2" nocks
Once its flow tillered I will put it on form to heat in 1.5"-2" of reflex
your calculator comes in at  21 oz

But I think I should assign it 10" for the handle which changes it to 22.5 oz does this sound about right?

At present its at about 38oz so I have a long way to go

[Badger]

Jason, that sounds about right, I normaly only use the 8" figure when the bow is pyramid, your tiller will be more elyptical because of the paralell section of the limb. I think your projected mass looks pretty good for that.
    I am working on one right now just to see how the formula works on short bows, it was only designed to work down to 54". The one I am doing now is 50" long, stiff handle and fades with 1" reflex, ash backed ipe 35#@ 24". 6' handle and fade section and I deduct 10% for being a backed bow. the formula call for 7.5 oz, I went and checked my glue up and it is about 8.2 oz right now so should be pretty close. I will judge it's success by it's finished profile and it's performance. If it feels stout I may cut it down to 48" and draw down to 23". Steve

[DanaM]

Who's jason

So I keep most of the bend from the fades to where the limb begins to taper to the nocks?
This will result in a elliptical tiller correct. Think I will just call it 23oz and make that my target weight.
Wish I had a little more width but that is all this stave had so I will use it. If I have to I can drop the weight down to 50#
This bow is for a the gentleman that let me cut wood on his property and he's never shot a selfbow so if its
overbuilt some that probably a good thing.

[Badger]

Dana, once you start getting it bending you will know right away if you have enough width or not. The mass will clue you in real quick. if it is too narrow the bow will be too light when it starts bending. Steve

[DanaM]

Thanks Steve, As was said earlier I think your mass theory has the potential to accelerate the learning curve.

I'm going to apply to the next several bows I make and see where it leads me.

[DanaM]

Ok i've got one limb barely bending when I lean on it and I'm down to 33oz from 38 oz
so I lost 5oz if I lose the same on the other limb that will put me at 28oz, so I will still have 5oz to play with in tillering
and shaping the handle. I actually think I'm getting this