Tillering Gizmo, Design Update(pics)

[Eric Krewson]

I ran into Daniel Willoughby at my last tournament. He had made one of my tillering gizmos with a design change that was much simpler to make and easier to adjust to use.
I made one like he recommended and found it to be a much better design than my initial idea.

All you have to do is drill a 5/16" hole through your 1"X1"X6" block. Drill a 1/2" hole in one side deep enough to hold a 5/16 nut. Tap a course thread nut into the 1/2" hole with a hammer. I didn't epoxy the nut into place because it was a tight fit. Screw a pencil into the nut and you are ready to tiller. A blunt pencil point works the best because it doesn't wear down quickly. If your pencil gets loose in the nut just cut about 1/2" off it and screw it back in the nut.  

Finished tillering gizmo

     

With the pencil screwed in and ready to tiller.

     

The ease of adjustment makes this tool work really well.

[Bible5]

That looks like an improvement I will try. It beets tapping the pencil to adjust it slightly.

[poekoelan]

How about a quick "how you use it" tutorial? I think I know, but I would be more sure if I heard it from one of you guys.

[Eric Krewson]

After I floor tiller a bow and go to my tillering tree(tillering stick if you don't have a tree) I start using the gizmo with the long string and very slight bend on the bow, like the picture below.

   

 I have holes in my tree to hold a 1/2" dowel to lock the string in place for different degrees of limb bending.

 

Even with a little limb bending the gizmo will tell you where to scrape. Run the tool up the belly of the limb with the pencil retracted to identify the place with the most bend. Adjust the pencil to within about 1/32" of the limb at the point where the limb bends the most. Run the tool up the belly and scrape where ever there is a pencil mark on the belly.

 

The ten scrape rule really applies here. Ten scrapes, flex the bow about 30 times to no more than what would be brace height and recheck the bend, mark and repeat. Be sure to leave the last foot or so of the limbs stiff because this area will bend a lot more when you go to the short string.

When you have reached the approximate amount of bend as brace height with an even gap down the limb with the gizmo you can go to the short string at normal brace. The neat thing about using the gizmo is hinges are non existent if you use it properly.

I use the gizmo at brace and fine tune the tiller as well as adjust bend to within about 6" from the tips. I leave about the last 6" of the limbs stiff.

After I string a bow I check for my target poundage. If I am hoping for 56# and I pull the bow on the scale and find it hits 56# at 18" I don't pull the bow more than 18" while flexing. I advance the draw length in my pegs while  checking the bend and removing wood to about 20", going back to the scale to make sure I don't pull the bow past target weight.  

The gizmo won't tell you a thing about bending in the fades so you still have to eyeball this area or place a flat board on the back of the bow in the tree and watch the gap between the board and the back of the bow while you flex the bow to see if you have movement.

[BryanB]

Thanks for the update.
I now have one more project to do.
I like your new design.
Bryan

[Blaine]

Eric,

Thanks for sharing.  That should help a lot.

[DeanD]

Great thinking, Eric.  Thanks for sharing these "inventions" of yours.  Have to agree with BryanB though...now I have a new project.

Dean

[Eric Krewson]

I made a bunch of the old style up out of cherry and osage planning to sell a few at tournaments in a combination with my osage pin knot scrapers. I cut the screws off flush with the block, left them in the holes and polished what was left. They look like they belong there as decoration. It took me so long to turn scrap osage stave ends into 1x1x6 blocks I could't throw them out because the design changed.

[wingnut]

Eric,

You dog!!  That's a great idea.  I'll be making one tomorrow.  Wish I'd had it before I made the DVD.

COOL!!!

Mike

[rocdoc]

 
Thanks Eric!  I'm glad I procrastinated making one after reading about your first design.  I don't ever buy first model year design cars either.      

Headin' out to my shop now to make one up!

[the Ferret]

Geesh what a great idea. Ever notice how the great simple ideas are the ones rarely thought of?

Nice one Eric?

BTW when are you going to make it to Mojam. You're invited you know!

[Eric Krewson]

I bought a camper this year Mickey, been making more distant shoots and events than ever before. Might make it to Mojam next year.

One thing I have found using the gizmo is you will remove more belly wood because you will find even the smallest place that needs scraping. Start with a little thicker bow blank so you can still hit poundage.

[BillJ]

Fabulous idea.  I'm going to make one today.

Question, though - I've posted pics of several of my board bows on a tillering stick, and been yelled at for using the stick.  Everybody said I needed to get rid of the stick and go with the pulley on a tillering tree method - all to avoid excessive set.

It looks to me like this method would require you to leave the bow pulled on the tree, just as when using a tillering stick.  Do you find that the better accuracy in scraping afforded by this tool outweighs the problem of additional set caused by holding the bow drawn for longer periods?

I know - that was wordy - hope my question is clear.

BillJ

[Eric Krewson]

I usually check one limb at a time when I get above brace height. Lock in the peg, check and mark a limb, go back to brace then back to the peg to check the other limb. I can check and mark limb in about 10 seconds. I haven't experienced anymore set using this method, probably less because I can end up with such an even bend in the limbs with no place being over stressed.

[tom sawyer]

Wow Eric, that is one excellent idea.  After spending the weekend running various lengths of straight edges along my bow bellies, I can really see the utility of having the thing do the marking for you.  I also have a suggestion, maybe you can make it so the length of the stick can be adjusted?  A longer edge evens out bend over a longer distance, whereas a shorter one gives you an idea of whats going on over a shorter span.

You really need to make it up to MOJAM next year, you would love it.

BillJ, I'll pass along what Gary Davis told me at MOJAM.  He's a tillering expert if there ever was one.  I started to use his tiller tree for early-stage tillering, and he asked me why I didn't use a tillering stick instead.  He said it is an internet-spread myth that a tilleirng stick has no place in the tillering process.  His contention was that at any point of bending prior to brace height, you won't harm the bow by using a tillering stick and letting it sit there in a bent position while you take measurements.  He said that a bow will remain braced for hours and not show any damage, so a tillering stick won't hurt either.  Of course, you don't want to leave it bent any longer than necessary to determine where to work next, but if you aren't pulling to a really high poundage on your tillering stick/long string then you won't be putting much stress even on a hingey spot.  I tried it, and found that I wasn't losing any of my reflex during those stages.  I only lost reflex when I put the bow on the tree and exercised it to a fairly long draw.  And then, I did really good since I had it bending smoothly thanks to multiple looks on the tillering stick.

[where wolf?]

Looks great Eric!  What is the overall length of the tool?  Does it matter what length it is?

Nate

[tom sawyer]

One more question Eric.  How do you look at what's happening near your fades?  These tools like yours and Dean's walkie talkie don't work well when they run up on the fade area.  Do you put a ruler on top of the bow to see if the near-fade areas are moving?

Nate, it does matter how long the tool is.  The longer it is, the more of a gap you see.  With a shorter tool though, you are averaging less of a stretch of limb.  For instance, I sometimes use a credit card and it can be a challenge to see the small amount of gap under it when the bow is only pulled to 4-6" of bend.  But you can see smaller areas where there are flat spots.

By the way, I was in Excelsior Springs last week.  I was visiting my mom in Richmond and we went there to eat at the barbeque place in the old train station.  I got the piggyback plate and ate off of it for about three meals.

[Matthew D]

Eric, has anyone given any feed back using it with flat bellied bows? I was thinking this might be something I could use...

[Eric Krewson]

Pappy was going to give it a try but I haven't heard what his results were. I used it on an almost flat belly bow the other day and it worked just fine.

[Matthew D]

sounds good.. might have to make me one and see how it goes...