The Evolution of the Tillering Gizmo, Lets Make One

[Eric Krewson]

Since I made my initial tillering gizmo there has been an input of ideas to make it work better from other bow makers. Consequently it has evolved into a differently made tool than my original design.

Here is how to make the latest version. I use a drill press, bandsaw and belt sander because I have them. This tool can be made out of any scrap wood, holes drilled by hand, out of square and work just fine.

I cut a large downed cedar looking for a bow stave. I may or may not have found a stave but I definitely found a bunch of beautifully grained gizmo material.

I start by cutting a piece of wood 1" square and 6" long. You can make the gizmo longer if you want to, length is not a critical issue

         

A little sanding to get rid of the saw marks.

         

Mark the center of the block length wise and center.

         

Drill a 5/16" hole on the center mark.

         

I use a 1/2" forstner bit to cut A 1/2' deep hole over the 5/16' hole I just cut. The forstner bit cuts a clean hole but any 1/2" bit will work just fine.

       

Next I mark the ends of the block with a 45 degree angle to shorten side opposite the pencil of the gizmo. This allows one to run the gizmo closer to the tips while tillering.

   

2013 update;
Here is and update for a slimmer shape for your gizmo that will go further up the limbs with out string interferance.

 
 


I tap a 5/16" nut into the 1/2" hole and seat it all the way down with a piece of dowel.

         

[Eric Krewson]

Too many pictures for one post so here is the rest of the story.


Screw a pencil into the nut(I put the pencil in a vise and screw the gizmo on it) and you are ready to tiller. I sand the pencil a little after I cut thread on it so it will screw in and out easily. It only took me 10 minutes to make this tool, start to finish.

With a little Tru-Oil this will be a beautiful little tool, it has a wonderful grain pattern.

Older version;

   

Newest version:
 

[OkKeith]

Eric,

I saw your gizzmo several years ago and have never been without one since. Great little tool. I bought a box of golf pencils to use with it 3 years ago and still have half the box left. This is the one tool I can throw when I screw a bow up and not worry about hurting it, me or someone else (hope you are not offended by that, sometimes ya gotta throw SOMETHING).

That cedar is good looking as well.

Thanks for your contribution to my bow building.

OkKeith

[razorback]

Eric. how does the taper on the pencil side increase the usable area. I made one with the taper on teh other side so it would get closer to the tips before running into the string. I also made one with holes equidistant from the center that I can insert dowels into to give me a centering tool for staves.

[bjansen]

Thanks for sharing that, I will be building one this weekend..Great advice!

[Eric Krewson]

I did a little photo editing. The pictures should be corect now. I actually cut my tapers going the wrong way in the first attempt and didn't notice it until I had already posted the pictures. I now have a 4" gizmo(by accident) and a 6" gizmo.

[Leo L.]

I'm having a hard time trying to figure out why length isn't an issue?  Wouldn't a gizmo that is too long, or too short give different readings?  Maybe I just don't understand how it's to be used...

[Eric Krewson]

A longer gizmo would ride higher on a bows belly and would be good while on the long string, shorter would be OK for fine tuning on the short string.

[broketooth]

i dont understand how it works

[Eric Krewson]

After you floor tiller your selfbow and go to the long string. Bend your bow slightly and lock the string with your tillering tree or stick. you back the pencil off and run the gizmo up and down the limb to find where the limb is bending the most.

Adjust your pencil to be just off the limb at the deepest bend,

 

Run your gizmo up and down the limb and it will mark where you need to scrape off wood to get an even bend in your limb.

 

It won't tell you where to remove wood to get the fades moving so you have to eyeball that area.

[Jack Denbow]

Thanks Eric. I have been wanting to make one I guess now is the time. I have a nice piece of curly maple to use. Thanks again.
Jack

[Pluck Yew]

Mr. Krewson, I'll bet if I cleaned my garage I could find another 5/16" nut...    

Shawn...

[Eastern Hunter 14701]

Neet little tool. Thanks for sharing  

[Shaun]

Great tool! I often use mine (plain piece of pine with a friction fit hole and pencil). Nice tutorial Eric and lovely piece of cedar you used. I may even break down and make a pretty one with the 5/16 nut improvement.

[Steve Kendrot]

I too made one of these based on the first iteration. After using it, I thought of tapering the ends as well. I made my first several bows last year and after tillering the first one without it and coming up 30 pounds under weight because I let a hinge develop, the gizmo was the key to success with my later attempts. If you are just starting out, don't make another move until you make one of these things!

[Jack Denbow]

I made a pretty one. I cut the angled ends back 1/8" from the end so as to not leave a sharp edge that would get banged up. Now I need to go put it to work. Thanks again Eric for giving me the motivation I needed to finally get around to making one.
Jack

 

[Eric Krewson]

What did you stain your maple with Jack? Looks like Aqufortis. I have a flintlock almost done and plan to use aqufortis on the stock when I stain it.

[Jack Denbow]

Eric I used Aqufortis like you suspected. I used a heat gun to "activate" it. I think you mentioned it a couple of years ago on a thread. I made some panels to mount some horns on and they really look nice using the curly maple. Thanks again.
Jack

[razorback]

Man, i hope your bows look as good as that gizmo. if you take that much pride in your tools I bet anything made with them will be just as good or better.

[buckhuck]

Thanks for posting Eric.  I am going to have to make one of these.