5/16/96 copyright Alan Shinn
All of my brass stock, except for the focus block, comes from the hobby
section of my local hardware store. The material for the focus block is
a rectangular rod 3/16 x3/8" x 3ft that I found at a scrap metal yard,
you can find a bolt or something to saw it out from.
Lets start with the main plate (two mirror image pieces). Buy 1" x
12" x 1/64" brass at the hobby section of the hardware store.
Pound both sides against an anvil with a large ball peen or planishing
hammer (I have a 2" dia. hardened steel ball) of about 4" of
this sheet until it looks like you made the sheet from some lump of brass
(or start with a lump if you have the time). The sheet should be fairly
flat (no curl) when you are done. keeping in mind which sides will be out,
mark the outlines and cut two pieces with tin snips (a little over size).
Clamp them together and drill 1 of the 1/16" rivet holes through both
pieces. Rivet together temporarily with 1/16" aluminum tubing. Now
drill the other 1/16" rivet hole through both pieces and again rivet
together. Where the 4-40 bracket hole goes, drill another 1/16 hole and
rivet. Now, file and smooth the outline to size. ( the following , bracketted
text is soon to be modified to a better procedure({Drill the .04"
lens hole undersized (.03") as it will stretch in a later operation.}
Drill out the rivet where the 4-40 hole goes with the 4-40 tap drill and
while clamped together near the hole, tap through. Gently drill off the
other two rivet heads and separate the two sheets, being careful not to
bend them. finish smoothing the edges with fine sandpaper.
The four screws are made from .115" brass rod (this is for 4-40 thread).
I have been making 4-40 screws but I recently found a 4-32 tap and die
set that will probably make screws that look closer to the originals, but
I haven't tried them yet.( I have now tried them and they are good--looks
more authentic) I thread the rods first, using my electric hand drill on
slow speed and a threading die. Then pound the thumb screw end with a ball
peen hammer . I find that anealing the end helps quite a lot though it
does prevent the cracking that appears in the original. For the short screws,
I thread (tap) a piece of tubing to use as a handle. File and sand as needed
for a pleasing shape. The little ball handle for the subject pin is made
from 1/8" rod ( or use the same .115" stock) with an electric
hand drill and some jewelers files. The subject pin and ball are either
pressed together or soldered.
The focus block is sawed out from stock and filed to size and shape. the
radius is filed with a round file. Then drilled and tapped.
The bracket is made from 1/16" x 1/4" rod stock. I cut it oversize,
bend and then cut to size. Drill the two holes and tap one of them.
Thread the focus screw through the bracket about an inch. put the smooth
end of the screw into the non tapped hole in the focus block, be sure to
get the orientation correct.
Now, peen the end of the screw such that it is riveted onto the focus
block but still free to turn.
It is time to discuss the lens. Antoni Van Leeuwenhoek made many, many
microscopes, all with different focal lengths, depending on the subject
to be examined. I have settled on a 2 mm dia. ball for my replica. I have
found a source for ground and polished balls (you can get them from Edmund
Scientific) However, you can make your own (only slightly inferior) ball
lens with some glass and a propane torch. WEAR EYE PROTECTION for the next
three steps!! Break a jar and find the two longest shards. Fuse them together
in the flame until you have fairly large melted zone.
Remove from the flame and quickly pull apart, forming a thread of glass several inches long and about .01 or.02" in dia. (it probably won't be round, that's O.K.)
Break off the thread and save it (wear eye protection, pieces zing around when you break it) Now, slowly feed the thread into a small flame forming a ball as the glass melts keep rotating the thread by twirling between your fingers. Continue until the desired size is reached. Work over a protected surface (like wet news paper) as sometimes the little ball drops off and can burn the table top (makes significant others mad)
you now have a (almost) perfect sphere with a little handle attached.
Make several, you will need one to use as a tool.
(the following paragraph is soon to be modified to a better procedure)
Now to finish. Place the least pleasing of the balls seated into the (undersized)
1mm hole in one of the main plate parts and place the other plate over
it (also seated) place the works on the end grain of a piece of wood and
using another end grain piece of wood as a buffer, strike with a hammer
such as to dent the sheets of metal to form seats for the ball. If the
ball shatters use another until both sheets are nicely dimpled. Now size
the hole to 1mm. File the outer side of the sheets (see sketch) so that
an object can be brought close to the ball.
Finally, place the lens into it's pocket, between the two sheets and rivet the two sheets together. Insert the focus screw and the subject pin into the focus block.
Attach the bracket to the main plate with the short screw.
NOW stick something (like a hair root or a very thin shaving of cork)
onto the subject pin with some beeswax and look at it through the microscope.
With this lens, you will probably have the most luck looking towards a
small light source like a 60 watt bulb at 5 feet --experiment to find the
best source for you. (My fused lenses seem to have too much astigmatism
to use with large light sources. Happy scoping.
By the way, you might want to start out with these lenses and crude snipped
up bits of soda cans with punched holes and adjust things by squishing
wax, instead of building the whole works. You can be doing microscopy in
less than an hour that way instead of spending all day (or more) making
the brass replica.
If all this is too much, you can buy a completed microscope from me. Perhaps
even parts (like ground and polished ball lenses)
alshinn@mindspring.com
Alan Shinn
2429 McGee
Berkeley, CA 94703
(510)-548-2048
Much of this information (dimensions and descriptions) was derived from
Brian Ford's book " The Leeuwenhoek Legacy" and Gerard Turner's
book " Collecting Microscopes"
Here are the drawings for the parts
