Flat vs. Round Belly

[TheUnatural]

I am currently planning out a bow right now (sinew-backed Juniper) that is going to have a set-back handle area, as well as some slight recurve on the tips. I have been reading as much as I can about similar bows, but I have come to a bit of a problem.  I have seen some information regarding the belly x-section that has been contradictory, i.e. flat vs. round. The only bow I have seen that was similar in materials and shape (SB'ed Juniper with recurve) had a round belly (to help prevent splintering, chrysalling, etc). But I was just reading vol. 3 of TTB, and Jim Hamm stated that bows with this kind of curvature require a flat belly (to handle the compression). Does anyone here have any idea about the route I should take? Unfortunately, I really can't experiment with the two designs (lack of resources and time). Any help would be appreciated.

[John Scifres]

A well-built round belly bow may compress more and follow the string a bit more but will have less mass at the tips so it will still be an efficient bow.

A flat belly bow may follow the string less and can be very efficient but it loses something in the aesthetic.

In the end, you can make a beautiful, great shooting bow either way.  But don't expect your first one of any style to be great.  You will have to put resources into it to have a good result.  In other words, your first or fifth or tenth may not meet your expectations no matter what style you choose.

[mwosborn]

I recently finished a sinew backed erc.  I went with a rounded belly.  I had read that the compression of erc was good and could handle the rounded belly. It turned out to be a really nice shooting bow.  I can send you pics if you want.

[TheUnatural]

Originally posted by mwosborn:
I recently finished a sinew backed erc.  I went with a rounded belly.  I had read that the compression of erc was good and could handle the rounded belly. It turned out to be a really nice shooting bow.  I can send you pics if you want.

Please do. Did you put any curves in your bow? And how much heartwood did you manage to get in the belly?

[Bowjunkie]

I make all of my bows with a rounded belly. Flat flatbows just ain't done yet  

[Bob at Work]

can you post pics of the erc?

[mwosborn]

Here are a couple pics - thought I posted some here a while back, but can't find the post!

UN - I did not put any curves in it.  The sinew has kept it dead straight with no set.  Been shooting it for a couple of months now.  I really like the way it shoots and will definitely make some more from erc!  I am sure you could curve the tips some - although I have never tried to bend erc.  I did not use heat on this one at all as the stave it came from was nice and straight.

 
 IMG_1963  by  mwosborn1 , on Flickr

 
 IMG_1964  by  mwosborn1 , on Flickr

 
 IMG_1962  by  mwosborn1 , on Flickr

 
 IMG_1961  by  mwosborn1 , on Flickr

[Bowjunkie]

mwosborn, that's nice. What are the specs on her? Length, width, draw weight, etc?

[TheUnatural]

That big knot in the last pic doesn't affect the bow at all?

[takefive]

Beautiful bow    

[Igor]

the post of the ERC by thenatural.....


 http://tradgang.com/noncgi/ultimatebb.php?ubb=get_topic;f=125;t=009755;p=1#000000

[PEARL DRUMS]

I keep low compression woods flat with slightly rounded edges and high compression woods getting rounded off. The highest point does the most work, it only makes sense to me.

[mwosborn]

The knot doesn't seem to bother anything.  I just followed the grain around it.  This was about as knot free erc that I could find.  

Looks like Igor found the other post - it has the specs if your interested.

[Roy from Pa]

Very nice bow.

[mwosborn]

Thanks Roy - slowly learning!  

[LittleBen]

Very nice ERC. I like th elook of mixed sapwod and heartwood. I will have to try one like that with nearly all sapwood.

Regarding the flat belly vs round, I agree it's not that big of a deal, obviously the absolute most efficient design is a flat belly, with that said, if you prefer the look of a rounded belly, I say go for it. No one shoots trad bows for the smoking unbeliuevable speed and performance ... what is a couple FPS really.

I keep all mine for the most part flat for two reasons, one I think it's harder to get a perfectly even and smooth looking round belly, I like the mix of old and new you get with a wood bow having a flat profile like the fancy factory bows.

[TheUnatural]

Yeah, that's a great looking bow! Thank you for the pics, hope mine turns out half as nice. Well, I guess I can at least hope mine doesn't snap in half from the strain of the design.

[burnt]

Use to make round belly bows but like John I found the limbs took on more set than I liked. Lately I make flat belly bows that slowly transition into a round profile towards the tips starting somewhere in the midlimb.  That being said ERC looks really nice with a round belly.  Highlights the wood more.

[Pat B]

I agree with what Pearlie said. radiused belly for compression strong woods and flat belly for everything else.
 Very nice looking bow, mwosborn. Sinew backed ERC is on my list.