USING THE TILLERING GIZMO
After floor tillering your bow, bend the bow slightly on your tillering tree or tillering stick using the long string. Retract the pencil in the Gizmo and run the wood block up the bow’s belly and find the widest gap. Screw the pencil in the block to a point it is almost touching the bow’s belly at the point where you found the widest gap. I change the angle the pencil has been sharpened to a very short angle and sand the tip of the pencil flat for the best results in marking the limb. This lets you work very slight bends.
Initially I set my gizmo pencil about 1/8” off the limb for the first few corrections. This course setting will mark only the stiffest spots. If you set the pencil too closely for your first few passes it will mark the whole limb.
Run the Gizmo up the belly making sure it is centered on the limb. The
pencil will mark non bending areas that need wood removed. Always check the entire limb with the gizmo every time you use it and scrape wood from all the stiff spots at the same time, not one stiff spot at a time. Start on the long string, continue at brace and up to about 20” of draw. You do need to have a way to hold your bow string while you mark the limbs with the Gizmo.
I often set my gizmo for one limb and use this setting on the opposite limb as well. This way you will end up with two closely matched limbs.
I have holes in my tillering tree and insert a 3” piece of dowel in one of the holes to hold the string with the limbs slightly bent while I mark the limbs with the gizmo.
Go slowly, no more than ten scrapes on the marked areas of the limb, flex the limb 30 times and recheck. I have found it usually takes 5 or more check, scrape and check sessions to get a stiff spot moving so be patient. You can get the limb bending perfectly this way. You will still have to eyeball bending in the fades but the rest of the limb will be perfectly tillered. Hinges will be a thing of the past.
Make a few passes with the gizmo on your limb and the areas that need attention will be perfectly obvious. You can fine tune the tillering by closing the gap between the pencil and limb to almost nothing. At this point I like to use a cheap orbital sander to remove both wood and any tool marks that are left. With course sand paper, the sander will leave tiny swirls in the wood so I like 220 grit for my final tillering work with the sander and follow with a light hand sanding.
The gizmo doesn’t work in the fade out area of the riser so you will have to eyeball the bend in this area or put a flat board across the back of the bow in your tillering tree and watch the gap between the back of the bow and the board to see where the limb is bending.
Tillering that once took me hours to get close takes me about 45 minutes with the Gizmo and the end result is close to perfect.
Remember the key thing to remember for proper tillering is using a scraper or sand paper and work slowly, only scrape off your pencil marks, flex the bow and recheck. I often make a zig-zag pencil mark from one side of the limb to the other over the gizmo’s pencil mark to make sure I remove equally from one edge of the limb to the other.
If you ever get the urge to grab a course rasp or use a belt sander to speed things up even more, take a coffee break and come back when these thoughts have passed.
Topic: The Evolution of the Tillering Gizmo, Lets Make One (Read 4088 times)
