selfbow layout tips?

[walkabout]

working on a selfbow, and was wondering if there are any tips for laying out the dimensions on a stave that has lots of curves. im trying to get a pyramid limb shape, but laying out a straight line on a curved stave is nearly impossible. i know measuring from the center grain line will help, however since this design is pyramid i dont know how to equally divide the taper along the length. any help will be appreciated.

[Pat B]

This is a tool I found out about and it works great for finding a center line on snaky or uneven staves. Works on straight ones too. If you have Eric's gizmo you can add two dowels to it to make this. for real snaky or wider staves mark with one side forward then the other side forward and average the two to get your mark.
 
 
 

Once you get your center line get your limb widths by marking from the center line(3/4" for a 1 1/2" width)towards the edge. I usually mark down the limb every 6" along the center line from the middle of the stave to the tips and put my width marks at 6" intervals.
 

[walkabout]

very ingenius tool and method, ill have to make myself one. i have figured out the paralel width design (2" wide tapering to 1/2" tips past midlimb) but am having trouble with a pyramid layout on a snaky stave. i though maybe someone would know how much the limb would taper maybe every 6 inches or so on the pyramid design.

[Osagetree]

Infreak'n genious!    

   Yourself, Eric and many, many others that are on here that take the time to assist the layman are in my opinion a superb example of the kindness, unselfishness, giving people and personalities that live on way beyond their time here on earth.    

 

[Pat B]

You could draw it out straight on papers , duplicate the layout marks that are on the bow and get measurements that you can put back on the snaky stave. It might help to make 2" or 4" intervals (instead of 6") down the stave to get more precise measurements for the pyramid design.

[scrub-buster]

This is my method.  It takes a little while to do it.

1.  Every 4" down the length of the stave, I will measure the width with a flexible ruler.  I use the metric side and mark the center  If it is 44 milimeters wide, I make a mark at 22.  Once that is done, I use the ruler to connect the marks and make a center line down the stave

2.  Next, I tape several sheets of paper together that is equal to the length of the bow.  I make a center line and mark every 4" just like I did on the bow.  I lay out the dimensions on the paper, then transfer the width measurements to the stave.  It is like having a blueprint to read off of.  

This is not the fastest method, but it works for me.

[Osagetree]

Sorry Walkabout, that kinda math is too much for my primitive brain!

MY TRY    

A mark every 6"... Say for the sake of math, a 30" limb = 5 marks on its lenght...

2" wide at fade to the tip draw two straight lines. At each 6" mark subtract 3/16 of an inch from each side of the 2" limb width marks... Connect the dots and end up with just under 1/2" tips.    

I realy suck at math   :confused:

[walkabout]

actually osage your idea helped alot, i worked it out on a calculator with some tweaking and its very close. with this i should be able to get the profile right.thanks a bunch!

[Don Armstrong]

What Osagetree said. You guys are great. Don

[John Cooper]

Just remember: half of x/4" is x/8", half of x/8" is x/16".  If you're dealing with a bow that's 1 3/8" (11/8") wide, you can count off a half of an inch plus 3/16" (11/16") to either side of the center line.  Does that make sense?

As for getting the taper correct, here's an example of how I'd do it.

for a bow with 1 3/8" fade, there's 11/16" on either side of the center line.  Make a mark 11/16" on both sides.  You'll probably want 3/8" tips, so mark 3/16" on either side of the center of the tips.  Here's the tricky part: find out how many 16ths are between 11 and 3 and divide the length of the limb by that number.  There are eight 16ths.  Say your limb is 30" long.  Divide that by 8 and you get 3.75.  Every 3 3/4", make a mark on your limb.

On your first mark after the fade, count 10/16ths" to either side of the line, next mark 9/16ths" to either side of the line etc. til you get to the tips.

This is a lot more complicated to write than to just show you, but I hope I made sense.

~John

[Art B]

Try laying your limb off in equal incerments. Simpliest way on a snaky limb that I can think of is laying/taping a string (starting at the limb's fades) down the middle of the limb to get your correct length and then removing and folding in 1/2's /1/4's 1/8's and marking each bend. Then lay/tape the string back down to the center of the limb and tranfer the marks to the limb. This would give you exact incerments.

Laying out the pryamid design would be just as simple. Divide the difference between the fade's width measurement and the tip's width's measurement and mark this at mid-limb (half the string's length). Break down the differences for the other remaining incerments the same way. If in doubt, revert back to that folding string trick again. Hope that helps. ART

[walkabout]

all great ideas, thanks guys. i have this page bookmarked now for future reference when i need it.

[Pat B]

Joe, that is the embryo of your bow in the pics. My centering tool came in quite handy with that stave!
  I enjoy doing this stuff so much that I want to see others enjoy it as much.
  I come by this naturally. Art B(and others) has taught me about bow building and especially about cane and shoot arrow building over quite a few years now and I want to share what was shared with me.
  Art, I saw a pic of you and Little John at ATAR. Charlie Jefferson took them. You guys never change. Hope you both are doing well...and the rest of the gang as well.

[Art B]

Still limping along Pat, and getting older of course. We sure miss you guys at ATAR. ART

[Pat B]

Yeah, I miss going to ATAR and seeing all you guys too Art. Maybe next year.
  Talk about being old, I turn 60 on July 28. Hard for me to grasp that for sure!

[Adam Keiper]

Just trace the grain to establish your centerline.  Then break the limb widths down every 2" along the stave and make "tick" marks on either side of the centerline.  (Maybe use 1" divisions on really snakey sections.)  Then simply connect the dots to get your limb profile.  

One question on that tool, which I've seen pop up now and then...  In order for it to establish a centerline along the grain, wouldn't the outer edges of the stave also have to be pre-established (traced) and cut perfectly to the grain?  Even assuming the edges were cut perfectly with the grain, given wood variances, wouldn't the resulting centerline be less accurate than tracing the actual grain?  It seems to me like it would actually require alot more work than just penciling a single centerline.  What secret am I missing?    

[Art B]

I'll hit the big "60" myself next year Pat. Hey, look at it like this, once you turn 60 the younger generation thinks you look more distingushed and the older generation thinks you're more desirable           . ART

[DVSHUNTER]

adam, I was wondering that myself. I always just follow the grain that runs vertical for my center line, then I make a mark here and here. On at the tips n one at the fades and something somewhere around mid limb. From there, I just wing it and draw what I want the limb to look like. I'm still new to this,, but it works for me. I try to keep things simple as possible when it comes to layout. If someone was going for the perfect layout on a snaky stave I would tellem to follow the grain for a center line and then make the other marks to get it perfect. I laid out a black locust stave today and went 1¾in. At the fades then 28in. limbs with ½in. tips. Then I came from the tip towards the handle 12in. And made  a 1½in. mark and connected it by hand.

[Pat B]

Adam, I don't think this gadget will follow the ring exactly but it will give you a general center line. I mark with it canted to the right and also to the left so it actually gives you two lines to average out it a single "center" line. So far it has worked for me. I guess we'll see!  d;^)

[DVSHUNTER]

I don't see why it wouldn't work as long as the log was split and not cut. A cut log could allow for vertical grain breaks.