Limb cross sections

[coaster500]

From reading and searches I've seen all three of these used.

I've built a few bows but still greener than green.

Two Questions......

[Bevan R.]

Type 3 is for when you have a wood (or backing) that is better in tension than the back is in compression. Hickory is a prime example.
Or most woods backed with bamboo.

[Dauntless]

I think you have it backwards Bevan.  If the back is wider than the belly it will overpower it unless the compression strength of the wood is higher than the tension strength.  A tension strong wood can have a thinner or rounded back for better performance.

Coaster, rounded bellies are a little easier to tiller and more pleasing to the eye. The rectangular cross section works fine for most woods, juste make sure the corners are well rounded to avoid popping a splinter.  By the way your examples #2 and #3 are essentially the same thing : narrower bellies compared to the back.

[blackhawk]

Type 3 is for when you have a wood (or backing) that is better in tension than the back is in compression. Hickory is a prime example.
Or most woods backed with bamboo.

Wrong...its the exact opposite. His drawing is a reverse trapezoid and that is for tension weak and compression strong woods.

If it was drawn n labeled the other way around then that's a trapped back favoring wood strong in tension and weaker in compression.

And coaster you forgot a round english D belly cross section.

[Bevan R.]

Yes, sorry. Got my back and belly mixed up. SORRY

[blackhawk]

Now between #1 and #2..well that has caused much debate over many years amongst many a great bowyers and each has its own place. If you have a stave that has higher sides than the middle( a term called riding the rails) then a crowned or radiused belly (#2 drawing)is desired to keep the thickness even and to help keep the stress off the sides. Also if you have a stave with some questionable areas on the edges #2 will help reduce the stress off that edge and force it down more in the center of the belly. #1 is beneficial at spreading the stresses over the belly better than #2,but if your side to side thickness is off then your compression line will deviate from one side to another. By doing #2 it keeps that compresion line down dead center. Much more can be said of all these things and each person seems to have there own stubborn opinion about. My opinion is they all have there place and should be used in according to the certain piece of wood you have.

[Lone500]

wow blackhawk the thanks for sharing. the nuances of bowmaking. good thread

[coaster500]

Thank you...

I'm kind of a loose cannon or a rasp, file nut so I seem to end up kind of naturally at #2....  I really like feeling my way around a knot or two

[Dauntless]

Pair up that rasp with a sharp cabinet scraper and you have all you need for shaping and tillering.  Rasp for wood removal, scrape off the tool marks.

[George Tsoukalas]

Just make a bow. If you use hand tools you will end up with a slightly rounded belly because that is how hand tools are the most efficient.Jawge