How to choose bow width

[txdm]

Here's a google sheet that calculates the width based on KS15s formula:

https://docs.google.com/spreadsheets/d/1YGOuEcokwRiWDs7oGAn7y-Q56rM9f60iA9TI3cBk3hc/edit?usp=sharing

Give me a definitive guide to specific gravities of wood species and I'll see if we can make a dropdown so you don't have to look that up.

[sleek]

Just for the record, Tim Baker presented a chart of widths for a 50 pound bow made from maybe a dozen different woods in The Traditional Bowyers' Bible Vol. I.

To my knowledge, that had never been done before. Though it seems some of you are doing it again.

It's good general starting points, but what I am trying to do is make a formula that tells you exactly the dimensions a bow needs to be for a given draw weight. I'd post it here but I don't want to post something I'm not done proving yet.

[Jim Davis]

As others have said, there is a lot of variation within a wood species. The best that can be done is to find an average of performance predictions. Baker's list does that. It's a starting place for the listed woods. Nothing more specific would be any more accurate.

The Forest Products Laboratories tested thousands of pieces of wood to reach their average of mechanical characteristics.

[sleek]

As others have said, there is a lot of variation within a wood species. The best that can be done is to find an average of performance predictions. Baker's list does that. It's a starting place for the listed woods. Nothing more specific would be any more accurate.

The Forest Products Laboratories tested thousands of pieces of wood to reach their average of mechanical characteristics.

Well, like I said Jim, I have to prove it before I can claim it. However There is merit to what these guys are talking about.

[RyanY]

Here's a google sheet that calculates the width based on KS15s formula:

https://docs.google.com/spreadsheets/d/1YGOuEcokwRiWDs7oGAn7y-Q56rM9f60iA9TI3cBk3hc/edit?usp=sharing

Give me a definitive guide to specific gravities of wood species and I'll see if we can make a dropdown so you don't have to look that up.

This must be for a specific style of bow like a pyramid bow. That width seems overestimated in my experience with similar density woods.

[Marc St Louis]

I think that bow width is really up to what you want from the bow.  Osage will work well at 1.25" width but it will also work well at 2" of width.  It's the same with all other common bow-woods.  The suggested width for the different bow-woods in the Bowyers Bible are merely guide lines.  All of them will work at narrower widths than suggested even at higher draw weights as long as you compensate with length

[George Tsoukalas]

Tim Baker did a nice chapter with a chart as a starting point.

As was mentioned above when I find limbs getting too thin then I begin to narrow them to bring the tiller home.

Jawge

[mmattockx]

It's good general starting points, but what I am trying to do is make a formula that tells you exactly the dimensions a bow needs to be for a given draw weight.

You can't do that without measuring the modulus of elasticity for the actual piece of wood you are using for the bow. If you measure the MoE then you certainly can do a pretty accurate calculation of the bow dimensions.


Mark

[Mo_coon-catcher]

I like the weight I want to determine my baseline width, then I shift that width narrower if I want to make the bow longer for the same draw length, or make the limbs wider if I want to make a shorter bow for the draw length. The extreme ends I’ve done are a 50# at 27” hedeby style longbow only 7/8” wide and about 70” between nocks and bending through the handle  and on the other end of the spectrum a flip tipped paddle bow pulling 60# at 27” with 2.5” wide limbs and 46” between the nocks. Both took about 1/2” set with the paddle bow still holding 1” reflex.

Kyle

[Badger]

   Any formula you used for width would have to include a lot of information that bow makers don't usually have access to. I don't think a formula would get anyone any closer than the common rules of thumb we all use.