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Angocoellum Mirrored Sighting Device

Angocoellum Mirrored Sighting Device
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Very soon after finishing my previous project I realized a need for this device.

What was happening was the front (and only) sight on the rifle was a bit lower than where my head is when firing the rifle so when I looked at it there was a subtle angle between where I was looking and where the actual barrel was pointing. At extreme short range this was not much of a problem but if I moved about 15-20 feet back (still quite short given the range of the rifle) I would have to aim the rifle about 8 inches lower than where I wanted my projectile to hit. (In my video on the other project I shoot at a section of palm tree with spraypaint. I hit the center with no issues but I had to point the sight at the bottom of the outside circle to hit the center)

Obviously I needed to do something about this since moving forward or backwards would affect the aim and while this is fine for archery, a rifle ought to be more consistent.

What I decided to do was to bounce my line of sight off of two mirrors so that in the end, I had, in effect, a horizontal line from the sight to my eye instead of the angled one.

This is all good and well but there's still the issue of looks . . .I couldn't simply slap a couple of mirrors on and call it quits so after getting the basics designed I made sure to do a couple of things to keep with the steampunk theme.

If you like this please rate and comment! If not, please let me know what you think I ought to do differently so that I can improve in future endeavors!''

Come with me now and I will show you how I made this and how you can use it to develop your own!
 
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Step 1Background and Theory

Background and Theory
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Before we jump right in I felt that some of you may benefit from some theory regarding mirrors since we'll be dealing so closely with them. If this is all old news to you then just skip this step.

Everyone knows what a mirror is and how it works and indeed it's common knowledge when it comes to a single flat pane of reflective glass. . .but when working with two mirrors and needing precision, a bit of physics will help immensely with design.

Our eyes work by receiving light and transmitting the information to our brains which interpret it. duh! The cool thing is that we can bounce this light off of certain types of surfaces and shiny or reflective ones work the best (again duh).

With flat mirrors perpendicular to a light source, the light reacts in an intuitive way: if comes in, bounces off the reflective surface and exits all in a straight line. At an angle, the light comes in and bounces out slightly differently, rather than exiting the way it came in it exits at an opposing angle (much like a ball bouncing on a flat court if we had no gravity). The convenient thing is that if we draw a line perpendicular to the mirror coming out of the point of impact (sounds cooler in my opinion) we can measure the angle between our line and the light's line. this angle is the same for the incoming and outgoing light! (see diagram). What's even better is, you can have light coming in and exiting at an infinite number of angles and following this rule all simultaneously.

This is why we're able to perceive objects as if they reside within the mirror.

The last convenient property we'll take advantage of is the fact that the reduction in intensity due to passing through the glass of the mirror and the imperfections of the reflective substrate is negligible. So we can bounce that light around as much as we want until the cows come home without worrying about dimming it.

So without further ado hop on over to the next step where we'll be using these properties to angle and place two mirrors.

*NOTE* the images for this step were lifted off of google since I lost my drawings and didn't have the heart to re-do them . . .
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23 comments
Feb 11, 2011. 12:27 PMbadideasrus says:
i love it. very functional. however i spy a problem. unless you mark one of the mirrors, probably the bottom one for looks, you will be able to twist the point of aim all over those mirrors. say if you pointed your gun just a little to the left or right, your sight will still show up, but it won't be centered, and will shoot off. same is for up and down. what i would do is take the bottom mirror and paint a black ~v~ (like an rear iron sight) shape at the height of the front sight. this way, you can line up the horizontal and vertical axises. (if you plan to do this, when finding the height to paint, take into acount the angle of the mirror. see picture.)

a more adventerous (and somewhat unrelated) idea is to mount the bottom mirror on an adjustable frame, so that you could turn a screw and lift the mirror higher. this would give you elevation control, and allow you to aim further.
Jun 19, 2010. 8:24 PMjason the red says:
id totally use this... if i wasn't making a minigun accuracy's not that important when youre spraying a wave of metal..
Apr 18, 2010. 7:21 PMnaruto the ninja13 says:
does this really work?
Sep 15, 2009. 5:47 PMurbanprimate says:
Once again, an awesome build! I never would've thought to make a periscope for a rifle. Kudos on a novel and artistic solution.
Apr 28, 2009. 1:16 AMArticas says:
i wouldn't use it .. i cherish my lego to much (it my only outlet of crativity ...and anger)
Apr 19, 2009. 1:10 PMKazeem says:
Ingenious use of lego... And i have so much of that kind of lego technic. I'm going to have to get spray-painting my lego :P
Apr 10, 2009. 6:17 AMArticas says:
OMFG you Used lego in it Who da thunk it
Feb 7, 2009. 4:38 PMbounty1012 says:
Very nice we need some more steampunk things on instructables.
Feb 5, 2009. 1:35 AMMattrox says:
Your skill amazes me.
Jan 18, 2009. 9:18 PMFenris The bbw says:
It needs a fake axel or something.
Jan 19, 2009. 10:05 PMFenris The bbw says:
The gears don't seem to actually be connected to the mirror in any meaningful way. I think the gears should extend onto the axel the mirror pivots on.
Jan 11, 2009. 5:34 PMshooby says:
uh yeah...excellent use of lego here. Paint is convincing
Jan 10, 2009. 1:48 AMgmjhowe says:
Keep it coming! great mod to your project. Im looking forward to your next one.

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Author:Kaelessin
I am a recent recipient of a BS in Computer Science. Currently working for an eDiscovery company as a web repository technician (hosting, searching and helping attorneys to process their electronic da...
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