Author Topic: Updated Gizmo instructions with pictures.  (Read 1547 times)

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Offline Eric Krewson

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Updated Gizmo instructions with pictures.
« on: September 03, 2017, 06:31:11 am »
Photobucket zapped my how to on making and using a gizmo. Here is an updated version with pictures;

Mods, you could replace my Trad Gang version in the how to section with this version.

Making and using a tillering gizmo;

Easy to make, a "1X6" piece of softwood, drill a 5/16' hole in the center and a 1/2" hole about halfway through the wood on top of the 5/16" hole.





Tap a 5/16" nut in the 1/2" hole;



I cut the excess wood off the block to this shape so the tool will go further up the limb with out string interference.



Screw a golf pencil in the nut and you are good to go.

A blunt pencil work best.

Here are the instructions I send out with the tool;

After floor tillering your bow, bend the bow slightly on your tillering tree or tillering stick, I start at about 3” of bend 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 sharp angle the pencil has been sharpened to a blunt angle for the best results in marking the limb. This lets you work very slight bends.



 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.  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 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 slow, no more than ten scrapes on the marked areas of the limb, flex the limb 30 times and recheck. My bow limbs tend to be slightly round belly so the Gizmo only marks the top of the crown on the limbs belly. I scrape the marked area as well as the rest of the limb side to side to keep things even. 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.

I adjust the gizmo one time on the long string and set it to the deepest bend on the weakest limb. I use this setting for both limbs. If you continually adjust the gizmo you will chase weak spots up and down your limb. One adjustment and hold this adjustment until you have removed enough wood to the point that can run the gizmo up both limbs without making a mark. As you increase draw length readjust the gizmo.

 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 sandpaper, the sander will leave tiny swirls in the wood so I like 220 grit for my final tillering work 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 proper tillering is using a scraper or sand paper. 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.
 

Offline Pat B

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Re: Updated Gizmo instructions with pictures.
« Reply #1 on: September 03, 2017, 07:17:32 am »
Thanks Eric. I think this will be a big help for lots of folks.   :OK
Make the most of all that comes and the least of all that goes!    Pat Brennan  Brevard, NC

Offline PaulN/KS

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Re: Updated Gizmo instructions with pictures.
« Reply #2 on: September 03, 2017, 08:05:40 am »
Thanks for the re-post Eric.   :OK
The photo bucket "info massacre" really made a mess of things eh..?

Offline Knoll

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Re: Updated Gizmo instructions with pictures.
« Reply #3 on: September 03, 2017, 09:10:24 am »
Thanks, Eric, for taking time to do this.

As a very minor mod, I have been subbing a t-nut for the hex nut.

This tool is ideally suited for arc-of-circle tillered bows. Is there a process you've adopted for more elliptical-shaped tillers?
... alone in distant woods or fields, in unpretending sproutlands or pastures tracked by rabbits, even in a bleak and, to most, cheerless day .... .  I suppose that this value, in my case, is equivalent to what others get by churchgoing & prayer.  Hank Thoreau, 1857

Offline Badger

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Re: Updated Gizmo instructions with pictures.
« Reply #4 on: September 03, 2017, 09:21:50 am »


This tool is ideally suited for arc-of-circle tillered bows. Is there a process you've adopted for more elliptical-shaped tillers?
[/quote]

   When I first started using the gizmo I had the same issue, I also complained the bows had handshock. Several ways around this. You can use the gizmo say out to about 24" and then finish your tiller by eye or you can just start gradually moving the gizmo out further from the handle in the last several inches of draw. I have found that if I use the gizmo at brace height it pretty close to gives me the tiller I want at full draw with only a little extra scraping to refine it. It really reduces the time in tillering, kind of feels like cheating.

  I will very often sit down in a chair with a braced bow in my lap and start marking it with the gizmo, I scrape off the pencil marks plus a few strokes, draw the bow several times and then do it again. Every few minutes I will get up and put it back on the tree to check weight and see how it is doing.

Offline Pat B

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Re: Updated Gizmo instructions with pictures.
« Reply #5 on: September 03, 2017, 09:39:03 am »
I also use the Gizmo to help adjust twists by running it down either side of the belly. it will show you where each side is bending and where it is not bending.
Make the most of all that comes and the least of all that goes!    Pat Brennan  Brevard, NC

Offline xin

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Re: Updated Gizmo instructions with pictures.
« Reply #6 on: September 03, 2017, 10:28:41 am »
Thanks for posting the tutorial on the gizmo.  I've been meaning to make one of the things by trial and error for years and have never gotten around to it.  Now I have no excuse with your very explicit instructions.  Thanks again.

Offline Morgan

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Re: Updated Gizmo instructions with pictures.
« Reply #7 on: October 02, 2017, 05:58:14 pm »
I've been Hoping for a new post on this!! Does this only work on stiff handled bows? Or will it work on D bows as well? Also if you have a pretty wonkey that  has some jumps and dips will it work, or is it better suited for straight staves?

Offline Knoll

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Re: Updated Gizmo instructions with pictures.
« Reply #8 on: October 02, 2017, 07:10:59 pm »
I also use the Gizmo to help adjust twists by running it down either side of the belly. it will show you where each side is bending and where it is not bending.

Hmmmm ... sounds like good idea. Thanks!
... alone in distant woods or fields, in unpretending sproutlands or pastures tracked by rabbits, even in a bleak and, to most, cheerless day .... .  I suppose that this value, in my case, is equivalent to what others get by churchgoing & prayer.  Hank Thoreau, 1857

Offline Eric Krewson

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Re: Updated Gizmo instructions with pictures.
« Reply #9 on: October 03, 2017, 04:59:40 am »
It works on any bow that has a flat limb configuration. It wouldn't work on one with a lot of roller coaster dips and humps in the limb.

Offline Badger

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Re: Updated Gizmo instructions with pictures.
« Reply #10 on: October 03, 2017, 05:43:04 am »
  It works great on lam bows, really valuable for getting a bow bending evenly early on. I have been using one more and more the last few years.

Offline RAU

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Re: Updated Gizmo instructions with pictures.
« Reply #11 on: October 03, 2017, 06:09:40 am »
I just built 1 and used for the first time and it is a great tool. I can't magine a more foolproof method to tiller a straight limbed bow!

Offline Badger

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Re: Updated Gizmo instructions with pictures.
« Reply #12 on: October 03, 2017, 07:12:55 am »
  About the last 6" of draw or so I start using it on sections of the limb and comparing it to sections on the other limb. I like mine a bit elliptical and it does help me with fine tuning. I have always lacked the fine artist eye that can pick up on micro imperfections, this works great for that.

Offline Stick Bender

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Re: Updated Gizmo instructions with pictures.
« Reply #13 on: October 03, 2017, 08:57:04 am »
I have been using the Gizmo only to brace height and then switch to regular type tillering Im to afraid of taking set pulling & holding the bow any farther then that a few secounds at a time but has been working good for me like that !
If you fear failure you will never Try !

Offline NonBacked

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Re: Updated Gizmo instructions with pictures.
« Reply #14 on: October 03, 2017, 09:01:20 am »
Here’s another tip for “fine tuning” that I use to compensate for my inability to recognize perfect limb symmetry (I really envy those guys with daVinci vision). In the last few inches of tillering, I switch to a Gizmo that’s only 2” long. It will indicate minute thickness differences along the limbs, and ensure a smoother curve. Eric mentioned in a post on a previous thread, and Steve reiterated, set the pencil depth on the “weaker” limb, and use that setting for both limbs to help balance the bends and working loads.