Bow wood strength and calculations for quartered wood

[Eric Krewson]

You guys are over-analyzing this bow making stuff. When you tiller a bow it doesn't matter if there are places in the limb where more early wood shows.  If the limb bends correctly the visible wood configuration on the belly is of no concern.

When I first started making bows I read somewhere that one needed to feather the grains evenly down the limb on a bows belly to make a proper bow. Messed up several bows trying to achieve this effect before I realized the author didn't know much about bow making and the irregular grain configuration of osage.

I have made several quarter sawn bamboo backed bows and dozens of plain sawed bamboo backed bows, both performed the same.

[adb]

That's fine for belly wood, but not for backings.

[WhitefeatherFout]

Thanks for replies fellas.  E. Krewson, I came to the same conclusion with the boo backed Osage I have done.  I wasn't sure if I was messing something up or missing something in design, hence the original question.  If you came to the conclusion that there is no performance difference in the two than that's good enough for me.  I guess I need to start asking why or how people came to a certain preference when I talk with them and keep a little survey just for curiosities sake.

[Marc St Louis]

There advantages and disadvantages to both.  Wood is actually slightly stiffer on the quarter-sawn plane.  Bows made from quarter-sawn boards in the core can develop problems when making high string tension bows with low string angle at brace.  The problem, and this is one I have noticed with Osage in particular, is lateral stability.  With such bows you have to have string tracking pretty well perfect or else the bow wants to self-destruct, sideways.

In the early days of the RD BBO, bows were made out of Osage boards that had been cut from wood that was pretty well unsuitable for selfbows.  This made for slats that had considerable ring runoff along their entire length.  Not much of a problem once backed with Bamboo except that as you made your bow you would get quite a lot of "steps" from the early-wood being scraped down faster than the late-wood.  I don't know if this affected performance, most likely didn't, but it sure was a pain for appearance especially if the early-wood ring was thick enough.  You don't get this "problem" with quarter-sawn boards.  The ideal would be to have perfect flat-sawn boards for the core but who wants to cut perfectly good Osage like that into boards?

[mikekeswick]

You guys are over-analyzing this bow making stuff. When you tiller a bow it doesn't matter if there are places in the limb where more early wood shows.  If the limb bends correctly the visible wood configuration on the belly is of no concern.


Your statement uses the word 'if' what I was trying to say is that 'if' isn't a certainty with flat sawn boards with soft earlywood. It may bend right to begin with but ultimately that earlywood has made a small 'hinge'. It's not over thinking IMO.

When I first started making bows I read somewhere that one needed to feather the grains evenly down the limb on a bows belly to make a proper bow. Messed up several bows trying to achieve this effect before I realized the author didn't know much about bow making and the irregular grain configuration of osage.

Yes but this really isn't the same thing 

I have made several quarter sawn bamboo backed bows and dozens of plain sawed bamboo backed bows, both performed the same.

I bet they didn't! I bet they performed in the same ballpark!

[WhitefeatherFout]

The "step down" issue is certainly an issue both cosmetically and in my opinion performance.  The way I look at it, the bow is only going to be as strong as it's weakes point, being one of theses dips or valleys in a step down.  The higher wood may just be adding more mass without doing much work.  I've learned a few tricks to avoid this effect.  I use a rasp to do a good deal of my rough tillering, stepping down aggressiveness if the tools as I proceed.  Then move to a scraper to start smoothing things up.  This is where I really pay attention to avoid the washboarding using very minute scrapes or in some cases very long smooth strokes, whatever the wood wants.  At the first sign of washboarding I go to sandpaper and then switch back and forth between scrapers and paper to get desired tiller and smoothness.  Maybe not the easiest or quickest way but it does force me to be more patient.  I'm not hardwired for patience so I have to force myself into that state of mind!

[BrokenArrow]

I made my first 2 bows from quartersawn wood and the fist was unbreakable the second lifted slightly. I shot them at 60 to 65 pounds and they seemed to shoot slow. I then backed them with 1/8th hickory strips and the weights went to between 65-70 pounds. My next test is to shoot my 68 pound quartersawn hickory backed hickory bow against my newly made 65 pound flatsawn hickory bow with hickory backing and see the fps comparision...then I have an answer to quartersawn versus flatsawn hickory. Will have in 2 weeks. The flatsawn is 180 fps and quartersawn available soon:o

[bow101]

I have only built board bows from 1/4 sawn wood.   Some on here have used rift and flat sawn.  I will have to try the other saw cuts to make an honest opinion on what works better.  Maybe I can tiller a bow better using rift or flat sawn material..     I hope you can make out the chart.