A microtome is a device for slicing very thin cross-sections of stuff, in order to view them under a microscope.  Commercial ones are available, but they cost upwards of $50.  There is a classic DIY solution, but it involves a piece of old technology — a wooden spool for thread.  Outside of antique stores, those aren’t common.  Plastic ones tend to be hollow, meaning there’s no guide surface for the razor blade; and the razor is likely to shave the plastic instead of slide across it.  Gluing a washer to the plastic spool would address both of those problems.  But there is very little gluing surface on the end of a hollow plastic spool.



Lacking a wooden spool, I cut a cube off the end of some scrap 2×2 and bored a slightly-oversize hole through it.  Using Gorilla Glue, I attached a flanged nut and a flat washer to opposite ends of the hole.  Before the glue set, I used the bolt to center and clamp them over the hole.  Gorilla Glue expands 30% as it sets.  To avoid permanently gluing the bolt into the body, I carefully removed it after a few minutes.  You can see glue in the threads adjacent to the bolt, in the image at right.  A few minutes with a wire brush cleaned the bolt threads.






Lastly, I flattened and polished the washer on a lapping plate.  The edge of the washer-hole was rough, and glue had expanded out of the hole and onto the surface.

The nut & bolt are 1/4 x 20.  One complete turn is 1/20″.  So a quarter-turn should be 0.0125″ thin.  That, and a fresh razor blade, should make slices thin-enough for a microscope.

MMS Eclipse watching party

Although poorly attended (only one full and one future member) everyone had a great time observing the 98% solar Eclipse.

Using the official MMS pinhole card:





Too bad the eclipse image is so poor, what a minute – whats that on the building next door?


Openings between the leaves of trees are acting as pin hole cameras and giving hundreds of images of the eclipse, we felt a little silly looking at the tiny ones the card was making for the first half hour :-)

You can also see some on the leaf in the foreground (I’m writing this on an old netbook so I can’t tell how the pictures are coming out, so I didn’t clip or tweak them)

And just so you don’t think its some other effect, here’s a shot at the max we witnessed, notice the arc is at the top instead of the side:

I’m still not sure why we had such a poor turnout, after all its only a 36 hour drive to San Francisco!