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aostling
09-11-2007, 02:57 AM
I bought this on eBay for $27 (including shipping). This is the auction photo, since it hasn't arrived yet. I'll be using it in a fixture to measure thermal expansion of materials. It reads 0.0001" without a vernier, so seems like a lot of precision for the money.

http://i168.photobucket.com/albums/u183/aostling/mikehead.jpg

IOWOLF
09-11-2007, 07:03 AM
Wow, Now you just need a use for it.

Your Old Dog
09-11-2007, 08:04 AM
I ebay'd mine for something like $20.00. Then the guy tried to beat me out of the shipping fee. Mine was everybit as nice as that one but it would have seen no use in my crude shop.

Evan
09-11-2007, 08:11 AM
Why are you measuring the thermal expansion of materials, if I may ask? Have you invented unobtanium or similar which has not yet been characterized? Also, it seems to me that for measuring such small differences a non contact optical method such as interferometry would be more suitable.

There are also other optical methods that will work. Optical systems are a particular interest of mine. You might find this interesting:

http://vts.bc.ca/metalshop/laser/flattest.htm

aostling
09-11-2007, 12:53 PM
Why are you measuring the thermal expansion of materials, if I may ask? Have you invented unobtanium or similar which has not yet been characterized?

Evan,

Not exactly, but I do need to know the C.T.E. of some organics, like bamboo, wood, etc., not typically published.

Also, I intend to use this micrometer head as an actuator, used in experiments in lieu of an actual material undergoing thermal expansion. I'll have to be careful doing this, as I'm sure the micrometer head was not designed as a "jack" subjected to axial loading.

On another topic: I'm inspired by your turning lens barrels from black plastic pipe. One of these days I'd like to make a pair of periscopic binoculars, like those used to look over the edge of trenches during WWI. With the arms swung out these greatly increase the baseline, increasing the stereoscopic effect in direct proportion to the separation. I used to do stereo photography, and became mesmerized by hyperstereo views of distant scenes (the Grand Canyon, cityscapes, etc.).

Peter N
09-11-2007, 01:07 PM
I'll have to be careful doing this, as I'm sure the micrometer head was not designed as a "jack" subjected to axial loading.


It'll be fine.
I've been using some of those adjustable Vernier spanners for years and they still grip on rusty old nuts...

Peter

Evan
09-11-2007, 10:59 PM
I have made other optical instruments with black plastic pipe. There are many fittings that can be easily modified to different purposes.


I used to do stereo photography,...

A favorite of mine too. Here is a crossed eye stereogram of the frame for the spiral staircase I built.

http://vts.bc.ca/pics2/frame1.jpg

aostling
09-12-2007, 01:47 AM
A favorite of mine too. Here is a crossed eye stereogram of the frame for the spiral staircase I built.


Evan,

Now that is what I call a staircase!

I can instantly fuse parallel images too, so feel free to post 'em anytime.

dp
09-12-2007, 02:14 AM
I have made other optical instruments with black plastic pipe. There are many fittings that can be easily modified to different purposes.



A favorite of mine too. Here is a crossed eye stereogram of the frame for the spiral staircase I built.



That's right at the limit of what I can parallel stare at comfortably. With crossed eyes it pops right in. How did you shoot that?

Evan
09-12-2007, 04:37 AM
I shot that hand held with a separation just slightly greater than usual interocular separation. The key is to use the same point of aim for both shots, not just move the camera over a few inches. Crossed eye is usually a lot easier for most people. Parallel generally requires that the center of the two images be no further apart than the viewers interocular distance. Since I have no control over the absolute display size each person is using parallel isn't a good idea. I might try some anaglyphs though. Get out the red/green glasses.

aostling
09-12-2007, 05:14 AM
Parallel generally requires that the center of the two images be no further apart than the viewers interocular distance. Since I have no control over the absolute display size each person is using parallel isn't a good idea.

Could a script be devised which would sense the display size, and scale posted parallel stereo images to 60-65mm between homologous points?

Evan
09-12-2007, 05:45 AM
Not possible. Information regarding physical size of the display isn't available to the system. It has never been a part of the "Plug 'n Play" specification for the data transfered to the computer on request.

This is all that my laptop knows about it's own screen and that is more than many computers.

http://vts.bc.ca/pics2/dispinfo.jpg

IOWOLF
09-12-2007, 07:19 AM
OK when do we get the blue and red cheap glasses?

Evan
09-12-2007, 11:39 AM
I got mine with the Sports Illustrated 3D Swimsuit Issue a few years back. They work extremely well. Those things could put someone's eye out (not the glasses). :D

Evan
09-12-2007, 12:39 PM
Here's another.

http://vts.bc.ca/pics2/stereo2.jpg

And here is an anaglyph of the same scene. I have altered the parallax to make the standing piece seem to stick out of the screen a couple of inches.

(red on right eye)

http://vts.bc.ca/pics2/anaglyph1.jpg

aostling
09-12-2007, 01:04 PM
And here is an anaglyph of the same scene. I have altered the parallax to make the standing piece seem to stick out of the screen a couple of inches.


I dug into my photo drawer and found red and blue filters. But the blue filter transmits too much red for these to work on your anaglyph.

How are you making these? An anaglyph option in some photo editing software?

Evan
09-12-2007, 02:32 PM
I use Paint Shop Pro and combine the images as 2 colorized layers and then multiply one by the other.

Evan
09-12-2007, 02:39 PM
Let's try red/green.

http://vts.bc.ca/pics2/anaglyph2.jpg

aostling
09-12-2007, 05:51 PM
Let's try red/green.


That doesn't work either. My green photo filter is just not dark enough to block out the red.

But no matter -- I don't think anaglyphs are very impressive, compared to a separated stereo pair. I realize you posted it for the benefit of those who can't view stereoscopically otherwise.