Selfbow Caul

[Osagetree]

I have really never used a caul, probably because I never took time to make one. I just eyeball the rough cut stave and hold it in position after heating & until it cools. None of my bows are as near perfect as other people making selfbows.

I see & hear all the time; .125 positive tiller, 1/8 of center string line, tillered for 3 under, etc. etc.

That stuff has always been a bit too deep for me and I figured the primitives never had the luxury of micrometers, chalk lines, tape measures, etc. etc. Oh sure, they probably had some of their own types of measure,,, tip of pinky to tip of thumb =equals= long enough,,,, stuff like that!

I see primitives slowly warming a shapened bow at a fires side using the soft earth under his foot to provide leverage to manipulate the bow wood to a more suitable profile.

I guess that the primitive bowyer seen things sort of the way I and others may... If a bow is made by one's self, such bow has the speed and authority to gain adaquate penetration, the maker/shooter can find the bow and the man flinging arrows to a confident accuracy,,, well then the process comes full circle.

I am neither a authority on primitive skills nor can I always spell properly.     I hope no one takes this ranting of mine to heart. Everyone has an opinion and at times I wish I was as precise as others making and posting selfbows.

My patience and time run short and I don't always try and improve myself when given the opportunity. I guess the above was my attempt to justify my lack of concern for a better performing selfbow.

Seeing a recent post by Dano mentioning Gary Davis; it reminded me of this caul process. The cual has hounded my temptations since I saw Gary Davis at a trad show a few years back. He had a bunch of rough shapened osage selfbows for sale and they all looked really good as far as the preshape and the reflex in each bow. At the time I did not know who he was and but he explained on my comment to him about each selfbow looking so much the same. Gary proceeded to be informative and showed me his caul forms. He had the the cauls marked and shaped to certain demensions for different lengths, etc.

I have seen cauls here on the Tradgang and some have a simple slope from middle to the tips,,, really very gracefull and simple shapes.

If my memory serves me correclty Mr. Davis's cauls were more flat until about mid-limb, then they had a precribed and measured curve to match the lenght of the bow being formed.

Seems to me, either process or caul shape provides the same performance effect on the end result.

Is there an advantage to either shape of caul? What do you use when preforming your osage or other selfbow woods?

[Pat B]

Joe, I use a caul for two reasons these days. To remove side to side bends allowing the string to track properly and to add reflex to increase performance and lesson string follow. I too don't consider positive tiller or other "glass bow" terminology when making wood bows. I'm trying to get away from the "Fiberglass Mentality" when I make wood bows. They are two different methods of achieving a similar goal; building a bow.
  My goal is to make a bow as simply as possible and still have it be an effective hunting weapon.

[bluegill]

Joe,
I started building selfbows in 1995 and would just try to build the best bow I could with the wood I had. I never had any inclination to build a caul until I went to Mojam in 2005. There I met Gary Davis and was able to get my hands by bows made by Tim Ott and Mickey Lotz, I was impressed to say the least.

I started using a caul/heat gun soon after. While I can’t say that all the performance gains I have seen are due to the caul, as I also started using faceted tillering and a little heat tempering at about the same time. However, I can say that by getting my string to line up in the center of the handle my bows are a lot easier to shoot consistently.  

I typically heat in about 2 1/2” of backset and after final tillering the bow profile is flat.  Even though the beginning profiles are similar there are enough nuances in every stave that the bows still remain individuals and not cookie cutter copies.

Sean

[Dano]

As recall Gary Davis' caul is pretty simple, he measures up the end of the caul in 1/2" increments and from tip to midlimb in 1" increments, then draws a line from increment to increments, which gives you a nice gentle slope. Here's a picture of what I'm talking about.

 

[Pat B]

I use 2 different cauls for reflexing and straightening and for recurving.
 
 

[Osagetree]

Okay,,, thanks for the pics.

Now saying I was to make me a caul,,, what would be the best way to find the arch best suited for bows in the 58" to 72" range. I mean how would I guage the curve on a 2" X 12" board, draw it on to cut out? I the an easy way to mark and cut this curve or does one use a template?

[Walt Francis]

Here is a picture of the caul I made/use:

 

I used the same method as Dano for laying it out.  This form is adjustable from 48 to 72 inches.  I had an older model that was fixed for a 64" bow, but had problems getting the amount of reflex I wanted on shorter bows and too much reflex on longer bows.  The blocks sitting on top fit into the open area created when the form is extended/lengthened and leaves the area by the handle flat when using it on longer bows, but it has worked great on bows up to 72”.

[Dano]

Now that is a dandy caul Walt, I'm gonna have to copy that one, if ya don't mind buddy.

[Walt Francis]

Here is how I build my non-adjustable forms:
Use a piece of butcher paper a 2-4” inches longer then ½ the length of your projected bow start at one end mark every 2” along the horizontal and ½” along the vertical axis then connected the lines like Dano’s did in his post (I tried using 1” inch increments for the horizontal axis but 2” increments smoothed out the reflex more to my liking, experiment until you get one that is visually appealing to you).  After laying it out use spray contact adhesive and glue the paper to a ¼” piece of masonite or similar composite wood sheeting, not plywood.  Next, rough cut the profile with a jigsaw or bandsaw, LEAVING THE LINE.  Now take some flexible 12” sanding strips (, I use 36-60 grit but any grit works.) and sand to the line making sure everything flows evenly.  When it is ready, screw the masonite to one end of your stock wood and trace the its profile, then turn it over and repeat the process at the other end.  Again, cut out the profile on the stock material using a jigsaw or bandsaw, LEAVING THE LINE.  Finally, take a router  with a flush cut trim bit, adjusted to ride on the masonite, and trim off the excess on one half the form, followed by trimming the other end (after repositioning the masonite template in the same screws used previously).

Standard 2 X material will work, it is what I used on my first few forms, but has will usually warp after being heated several times.  I got tired of replacing warped forms every five or six bows so I made the adjustable form in the post above using LVL and it is still good as new after a dozen bows.  

I know, these directions are lacking, but it is hunting season and don’t have the time to put together a build along at this time; maybe this winter I will do one for the adjustable form.  If you need some clarifications let me know.

[Walt Francis]

 Dano,

Go ahead, you could even take a lot of pictures and post a build along so I don't have to later his winter.  

[Dano]

What else ya gonna do this winter Walt?    

[Tom Leemans]

As they say in the Guiness commercials Walt... Brilliant!

[Osagetree]

Walt,

Thanks for the pics and the explination. And thanks to the rest of ya too!

That is a really good idea with the adjustable long lasting design.

[dutchwarbow]

Walt, that's one excelent caul! Might give it a try once I get back to selfbows  

Nick