I really need some "mass principle" help

[bownarra]

The length of the bow doens't matter one jot. You simply need to mtach the tiller profile to the bow design. Remeber the 80" pecan (?) bow is TTB. Same as all the elbs I make they are shocky if you get the tiller wrong. In a longer bow that generally means npot having enough bend mid to outer limb and or too much bend near the handle.
If I said to you do a pyramid bow and a parallel limb bow have the same tiller? Do you know what I mean? This is what Ryan mentioned above if the tiller shape doesn't match the limbs width taper you will never make an 'optimal' bow. Get the TBB 3 it explains 'tiller logic'. This principle alone will allow you to get closer to high performance more so than obsessing on the physical weight. The mass principle is something to apply AFTER you have tiller logic dialled. A well tillered bow with correct profiles will shoot much faster than the speeds you are getting.
Your moisture content is also high, elm is best around 8 -9%. Also think how heavy water is
Your long and wide elm bow will be way over physical weight by the sounds of it. A long bend through the handle elm bow should be 1 1/4" wide max through the center section with no fades.

[Selfbowman]

sometimes if the bow is too long,, you have to cut it shorter and re tiller to get the mass down,,and keep the weight up,,

YES!

[RyanY]

But there are references of bows of specific length at specific weights. Yes, cutting it down can keep draw weight up but the expected mass will also continue to go down for that design. I think Don is wondering how it’s possible that his bows are so much more massive than Steve’s mass principle results and if it’s even possible to make bows of those stats.

[Don W]

I have made some progress and discoveries. I know a little more than I did. And that's the goal, right? First, I think I was not interpreting the chart correctly. If I compare it to the list in the next chapter of the bows tested (page 110), the numbers relate closer to the left hand column. I took my HHB bow and tried to recurve it. That broke the tip, so I had to shorten it 6". At that point I didn't have much to loose. Doing all work on the sides i managed to get a bow that is 6" shorter, 1pd lighter and 10fps faster at the same draw. That's with a boat load of mistakes along the way. I also took one of the oak board bows. Tore into it, narrowed it as I watched the weight, and speed. The speed obviously decreased, but at a slower rate than the weight. It's not done yet i ran out of time. After shortening it, it's now a 45# bow shooting 140fps with a 400gr arrow. Weight is in between the two numbers on the chart, but it's also got a longer handle and fades. That's so much better than it was. I think the moral of the story is don't take the chart quite so literally. Just let it be a guide.

[bradsmith2010]

you making progress,,

[Selfbowman]

Yes one of my best pyramid bows came in at 28 oz. But most of the mass is in the handle and fades to mid limb. The he expected at mass demonstrations d not affect the speed that much. Overbuilt maybe but no ones beat it yet. So no the charts aren’t everything. Arvin

[PatM]

The principle is maybe a bit  outdated.  Not long after it came out it was already being revised. 

 I don't bother weighing bows for mass.  It doesn't seem like a number to chase.

[Digital Caveman]

If it worked then it should work as well now.  I think better systems could be had, but I don't think most of us would be able to appreciate the difference, much less incorporate it into our work.

[bradsmith2010]

also I do believe if the bow is designed for a short draw, stellar arrow speed can be achieved,, the longer draw can give you an advantage, but the shorter draw can have great cast,,as well,, even with hunting weight arrows,, stellar being being open to interpretation

[Don W]

The principle is maybe a bit  outdated.  Not long after it came out it was already being revised. 

 I don't bother weighing bows for mass.  It doesn't seem like a number to chase.

That's fine if you already know how to build efficient bows. It's definitely a learning tool for us who need it

[bradsmith2010]

  If I have a bow thats shooting like a dog, I will check it to see if I have overbuilt it,, but if its shooting really well, I might check the mass weight just for fun,, its usually in the ball park,,
   if you make a bow with tried and true design, it will probably shoot well, for example like 66 inches long 1 1/2 wide, ,27 28 draw,, it will shoot nice,,and probably be close on the chart,,

[RyanY]

The principle remains true qualitatively in that we want the lightest mass cross section without taking set and that mass distribution/movement allows varying degrees of flexibility in terms of how much we have to push for low mass.

[PatM]

The principle is maybe a bit  outdated.  Not long after it came out it was already being revised. 

 I don't bother weighing bows for mass.  It doesn't seem like a number to chase.

That's fine if you already know how to build efficient bows. It's definitely a learning tool for us who need it

 It might make you jump too far to the extreme though.   Steve builds bows in  large quantities and tends to not shoot them for too long before moving on to the next one.  He also wants them to remain brand new and fresh.  That leaves no margin for error and may be why the pendulum has swung back to at least slightly overbuilt bows.
 
 It's more of a learning tool for after you have considerable experience.

[Don W]

The principle is maybe a bit  outdated.  Not long after it came out it was already being revised. 

 I don't bother weighing bows for mass.  It doesn't seem like a number to chase.

That's fine if you already know how to build efficient bows. It's definitely a learning tool for us who need it

 It might make you jump too far to the extreme though.   Steve builds bows in  large quantities and tends to not shoot them for too long before moving on to the next one.  He also wants them to remain brand new and fresh.  That leaves no margin for error and may be why the pendulum has swung back to at least slightly overbuilt bows.
 
 It's more of a learning tool for after you have considerable experience.

It sounds like you don't think it's the best avenue to pursue. With 10-12 bows under my belt that shoot ok and a desire to get better performance, what would be your recommendation? After all that's the ultimate goal here is just continue to get better.

[scp]

Speed matters. You need to shoot for around 100 plus your bow's draw weight in FPS using a 500 grain arrow. That's not easy for beginners. Once there, it's up to you what you want from your bows. You can go after appearance, style, efficiency, world records, or whatever that matters to you. For me, physical exercise itself in making bows, without making too much dust, is what matters most, because of my sedentary lifestyle. Still I consider a bow a failure if it does not have enough speed in it. Good luck.