Newbie Question about limb thickness taper

[Nesbo]

Hello all,
I am new to the forum and new to bow building.  I have tillered a Gary Davis bow blank with success and that is currently the only bow under my belt.

My question is how to get your limb thickness taper.  I see in TBB I and from Gary Davis' Rattlestick that the method is drawing a line using the back as a guide.  How does that taper the limb?  Or do you start at a thickness, say 1/2", and work the stave down to that mark where the entire limb is 1/2" thick then taper by tillering?  I just need a starting pont because now that I have a taste for it I want to start from a stave.

Thank you for your time.

[Elktracker]

Try doing it like gordon shows here on the first page http://www.primitivearcher.com/smf/index.php/topic,4815.0.html , looks like a great method! I usually try to just eye ball it the best I can because most of the staves I work have allot of crown to them and are sapling size.

Welcome to PA! you will really enjoy it! This is one of the hobbies I didnt lose interest in after the first few weeks as I do with most of my interests

Josh

[PEARL DRUMS]

Im an eyeballer myself.

[mikekeswick]

Get the width of the stave worked out first. This gives you flat edges to the stave with it still too thick. Try drawing a series of parallel lines on the stave sides start with say 3/4 , 5/8 , and 1/2 lines using the back as a guide like you mention. Then divide the limb length into sections of equal length, say 6 inches. Then you can join the dots between 'boxes' to get an accurate taper.
Hard to describe in words but it works great when you figure it out. One of the keys to making good bows is getting the tiller spot on as early as possible.

[Pat B]

Once you get your back profile just remove wood from the belly until you get the bend and draw weight you want. I know this is simplistic but it is the way I've always done it. Each piece of wood is different so there is no set taper for a desired weight.

[johnston]

What Pat said and...it is important to keep the thickness even from side to side. Eyeball
constantly for humps and dips then work them out as early as you can. This adds to the
bow's longevity and eases good tiller.

Lane

[Buckeye Guy]

Welcome to the great addiction !
Worrying about taper is more of a manufactured bow problem !
We just start removing every thing that is not the bow that We see in the individual stick we are working on!
( eyeball it )
Some of us have better eyes than others !
Keep it simple
Keep it fun!
Guy

[adb]

Pat B is right... there are no cook book recipes, or short cuts. However, remember... even tapers, make even bends.
Your limb thickness taper is determined by your tiller. It is also determined by your profile taper. Eg., a pyramid bow, with fades starting around 2" and tapering evenly to 1/2" tips, will end up with an almost even limb thickness from fade to tip. Another Eg., a stiff handled flat bow may end up being around 1" thick at the fades, and tapering to a 1/2" or less at the tips. Thickness taper really depends on design.

[Pappy]

I get them to about 5/8 thick and then floor tiller until the limbs are bending even,never really tapper with a rule,that would be hard to do unless you are doing a board bow where the back is perfectly flat. I let the tillering set the amount of tapper.  and by the way I learned from Gary many years ago.
   Pappy

[Del the cat]

I start off by eye, but a set of vernier calipers makes it easy to check.
I mark every 6" along the limb and then measure the thickness with the calipers (in mm as it's convenient).
You can take the reading at each end and the subtract one from the other and work out each step in between
You can pic up a mechanical vernier cheap these days because everyone wants the fancy digital ones.
I generally find it works out about 1.5mm every 6".
A vernier is also good for helping you to eyeball it, you lock the vernier at say the the thickest point and slide it down the limb whilst holding up to the light, you can see the gap between limb and vernier opening up evenly as you slide along.
The old fashioned external calipers are handy too used in a similar manner, but held against a ruler to give you the measurement (not so accurate).
If you don't know the tools I'm refering to just google vernier calipers and external calipers.
I only work to say the nearest 0.5mm to get the taper pretty even, the real work is done by eye on the tiller.
One way to work is to rasp down the lim at the 6" marks to the thickness you want and then join these areas up by rasping away the intervening areas. I've worked down quite thin laminations using this method.
Del