Stefano's Deflection Gauge...

UPDATE- December 31st, 2005 - Recently, I had stumbled across an interesting thread on RCU in the Pattern forum.  There, to my surprise, was "stek79" discussing his adaptation of MY adaptation of someone else's (who knows whose?) Deflection gauge.

His first explanation of his invention -

"Hello Bob,
   here is a brief description of what I modified, and why.

As you know, I started with your idea, that is using a protractor to precisely measure control throws.
At the beginning, when I saw this setup, I really liked the idea! But I was not sure how to construct a god joint for the pin. To be honest, I didn't understand how you build yours, since my english is not so good... (if you want, remove that last sentence ;-) . 

As you noted, it is crucial for the tool precision that the pivot point will be as friction free as possible. So I thought about it, but I din't came up with a solution...

Later, inspired by RCU discussion with Mike East and Troy Newman (among the others), I had the idea: if I make the protractor bigger, finer readings could be done! So I searched the Net looking for some big protractor... and guess what? 

I found a little image of a protractor... so the idea was born: we can use a printed protractor, instead of a plastic one! This is more easily scaled to be big enough, and also will be much lighter! Being lazy, instead of designing a new one by myself, I searched the Net again, and I found a good Word file with a protractor in it: I enlarged it and printed it. What I got is what you see in the pictures: it has a radius of about 5 inches. In order to have something solid, I glued it to a 3mm depron sheet. Also, for precise pattern throw measurements, a smaller protractor could be printed. For example, only +20 - - 20 degrees should be enough: it will become even lighter this way.

The other improvement, perhaps the most important, is the pivot one. While searching the Net looking for a printable protractor, I found an astronomic site (http://www.fis.unipr.it/~albino/documenti/azimutali.html - Bob, it is in Italian) that explains how to measure stars position using azimutal coordinates. Guess how they can be measured? With a protractor... and the site also suggested how to build one: they suggested to use a cotton wire and a little weight instead of our pin... simple, easy and with almost zero friction? In fact, you will see that the weight keeps oscillating with very small damping.

The other parts are pretty easy to build: I've used a clothes peg because I don't own clamps... I have to buy some! Remember this is the very first device (I've just finished it!)...

This is the basic idea. Summarizing, the advantages are:

1 - it is LIGHT: mine weighs 16gr, but can be made extensively lighter, using clamps and a narrower protractor

2 - it is PRECISE: since cotton wire is pretty thin, a sub-degree precision can be reached.

There are many improvement I'm thinking about, which are:

1 - my protractor is crooked, due to the fact that depron is very flexible...
2 - you will notice a little tube on the pivot point. This is done in order to prevent the wire from touching the protractor.
3 - the protractor: the one I found has only degrees printed, but we can be more precise: also .5 deg or even less can be measured, since the cotton wire is very thin.
4 - parallax error...

Bob, that's all I think! Are you going to put that one on your site? If so, feel free to adjust any part with a better english :) Also, it would be very good if someone with a CAD could design a better protractor, with sub degrees indicators and with a vectorial draw, so that it can be scaled without resolution problems... I can't use CADs, too bad!

It would be good to come up with a better and better tool, if you have ideas, let's keep sharing!"

He sent some pics, and I found a LARGE protractor that was downloaded, so made my own version of HIS version, and boys and girls, it is COOL.

Haven't ever SEEN or USED one this repeatable, easy-to-use, cheap to make, and accurate.  Using thread, you can extrapolate to .25 degree with ease.  Using my 1/16" wire pointer, about .5 degrees.

Interestingly enough, I've found that my 30% Yak has .25 degrees per "beep" of electronic trim, with Trim Rate set at "3" in my JR 10X.  This gauge/meter is accurate and sensitive enough to permit you to SEE clearly one beep of ATV, also!  Enjoy!

From Stefano - after his "Second Version" --

"Hello Bob!

I made my second throw meter! SUPER FINE readings are possible with the
protractor image you find!

I made some little improvements:

- cutted the protractor in order to read +/- 21 deg
- still used 3mm depron, but glued with epoxy: the result is that it is
perfect plane!
- used a single (and smaller) piece of ply, in order to fix the wire and
the peg
- used a smaller diameter tube to guide the wire
- reduced weight: a small round shim has been used

The results are that is is even lighter (now it weighs 12 gr, but the
most heavy part is the peg... this should be changed) and much more
precise! "

The complete setup using thread as the "pointer"	The "Pivot" and attachment point to the clothespin.	In use, you can observe the thread angle.	You can see how fine the resolution is of this protractor!
Here's mine, I wanted more measuring ability, so left more of the protractor in place.