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Topic: a screw hinge to adjust angle? (Read 675 times) previous topic - next topic

prismspecs

Here is my setup: It's based on another laser mirror project in which there are a number of mirrors (6 here) spinning on a CD set on a CD motor. Each mirror is angled slightly more than the next so that the laser pointed at it will reflect at 6 different points along the vertical axis. Here is a picture or two to show you what I mean:




So I'm wondering if there is something I can get at a hardware store that will make this an easier process than painstakingly hot gluing and testing. If you were to look at it from the side it would simply look like this

wizdum

If you mount them on a bracket with a hinge, you can stick a machine screw through the hinge or bracket, with a nut on the back to adjust height.
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Retroplayer

The one thing to keep in mind is that spinning the mirrors will provide a force on them so whatever method you choose should securely hold the mirrors.

A modification to what wizdum suggests would be two machine screws (one affixed to the base and one affixed to the mirror) and to use a standoff in between them to adjust.This way there is always a (mostly) solid connection between the mirror and the base. There will ultimately be some wiggle at the hinge and this is going to show up in your dot on the wall.

Perhaps anothe idea yet would be to fix the tops of all of the mirrors together and to slide the bottoms in and out instead. Pretty much the same concept using a threaded rod with the mirrors affixed to standoff nuts. This would probably end up with less wiggling.

And finally, a spring in there of some sort to pre-load the mirrors (pushing them outward against the screw) would also help with either method.

retrolefty

#3
Mar 05, 2013, 01:00 am Last Edit: Mar 05, 2013, 01:02 am by retrolefty Reason: 1
Be aware the using rear surface mirrors in applications like this is inferior to using front surface mirrors, due to refraction of the beam as the light passes into and out of the glass. But it is more affordable.  ;)

Lefty

KeithRB

You might find a cheap compass with a screw adjustment at a office supply store. And mount it somehow.

PeterH

Glue each mirror to an angle bracket which is then glued to the base? You can bend the bracket to adjust the angle. I assume that once everything is set you'll have some scheme for securing the mirrors solidly in place and then balancing the assembly.
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CrossRoads

I think you can get by with a small "turnbuckle".

http://www.fastenal.com/web/search/product/_/Navigation?searchterm=&sortby=webrank&sortdir=descending&searchmode=&pageno=1&refine=~|categoryl1:"601922 Lifting and Rigging"|~ ~|categoryl2:"601938 Rigging Hooks and Attachments"|~ ~|categoryl3:"601952 Turnbuckles"|~

Don't know if they can be found small enough for your mirrors. Might be overkill if you only need to adjust for one angle.

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prismspecs

Thanks for the advice, all.
I think I'll try the angle brackets first, that makes sense even though it's not quite as convenient as being able to adjust with a screw.
When I went to the hardware store just now for some advice the guy insisted that what I was looking for was "straight out of James Bond" so I might try another store next time ;-)

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