J
Joseph Gwinn
Guest
As mentioned in a S.E.D. posting in the "Re: Digital Microscope purchase"
thread on 23 June 2019, I recently purchased a well used Model 570 StereoStar
Zoom. As it turned out, this unit had been dropped, cracking the housings
where the erecting mirror boxes (one per eye) live. I purchased on eBay a
for-parts-only model 570 body to get those housings, and was able to assemble
a perfectly good model 570, plus a spare set of optical components. Missing
are some knobs and screws.
By the way, one cleans the optics with 91% Isopropyl Alcohol from the
drugstore, using cotton balls and/or Q-tips. Do not use any kind of paper, or
anything sold for eyeglass lenses. Old 100% cotton teeshirts, washed and
dried (use no antistatic stuff), are also used. And note that the mirrors are
coated with pure aluminum on the front surface - very easily scratched.
Remove fog, but particles here and there are harmless.
It is very useful to be able to attach things to the Accessory Port (the ~
1-7/8" diameter threaded port in the nose of the body), but plain adapters
(no lens) et al never come up, so I decided to make one. It´s just a
thread, and with the right kind of lathe, one can make any thread, standard
or not.
Now, I never found any details on this thread - AO Proprietary, and they´re
not talking, or still exist.
So, time to measure. Long story, but it turns out to be a mashup of
then-standard American threads. (Metric - what´s that?) The purpose of this
posting is to publish the details of this thread, so others can also make or
have made screw-in accessories.
The thread form is a standard American Unified 60-degree V shape. It is _not_
55-degree Whitworth (widely used for microscope objectives.)
There are 36 threads per inch (tpi), regardless of diameter. It is _not_ the
Metric 0.75mm pitch used for optical filters et al; this is equivalent to
33.87 tpi threads, and so closely resembles 36 tpi threads, but they will not
mate. Nor can one tell them apart by eyeball, unless one has a thread gage.
The nominal diameter is 1.875" (47.625 mm), not 48 millimeters.
The above emphasis on the non-metric thread details is because the modern
stereo microscope accessory thread is M48x0.75. This is often wrongly called
two inch, which is close (to this and a few other kinds), but a M48x0.75
external thread will not screw into an AO Stereo Microscope accessory port.
The thread length is 0.125" and there must be a shoulder (where the
diameter increases abruptly from 1.875 to 2" in diameter) against which the
adapter will bottom, to prevent screwing the adapter in too far and damaging
the optics within.
I have machined such an adapter, and the threads mate perfectly. In the
newer, cleaner body, the adapter turns freely but is a snug fit. On the older
body, the fit is slightly loose, but is still secure.
For the record, I measured the Pitch Diameter (PD) of the newly machined
adapter thread using the three-wire method and micrometers. The measured PD
is 1.874". This will be useful to anyone machining the thread, to tell when
they´ve cut deep enough, but not too deep.
This adapter is now used to mount a 56-LED ring light, which works better
than the original oblique illuminator. AmScope WR63HWR on Amazon, $26 or so.
Don´t buy the 144-LED unit - there is a negative review that tells
why.
Joe Gwinn
thread on 23 June 2019, I recently purchased a well used Model 570 StereoStar
Zoom. As it turned out, this unit had been dropped, cracking the housings
where the erecting mirror boxes (one per eye) live. I purchased on eBay a
for-parts-only model 570 body to get those housings, and was able to assemble
a perfectly good model 570, plus a spare set of optical components. Missing
are some knobs and screws.
By the way, one cleans the optics with 91% Isopropyl Alcohol from the
drugstore, using cotton balls and/or Q-tips. Do not use any kind of paper, or
anything sold for eyeglass lenses. Old 100% cotton teeshirts, washed and
dried (use no antistatic stuff), are also used. And note that the mirrors are
coated with pure aluminum on the front surface - very easily scratched.
Remove fog, but particles here and there are harmless.
It is very useful to be able to attach things to the Accessory Port (the ~
1-7/8" diameter threaded port in the nose of the body), but plain adapters
(no lens) et al never come up, so I decided to make one. It´s just a
thread, and with the right kind of lathe, one can make any thread, standard
or not.
Now, I never found any details on this thread - AO Proprietary, and they´re
not talking, or still exist.
So, time to measure. Long story, but it turns out to be a mashup of
then-standard American threads. (Metric - what´s that?) The purpose of this
posting is to publish the details of this thread, so others can also make or
have made screw-in accessories.
The thread form is a standard American Unified 60-degree V shape. It is _not_
55-degree Whitworth (widely used for microscope objectives.)
There are 36 threads per inch (tpi), regardless of diameter. It is _not_ the
Metric 0.75mm pitch used for optical filters et al; this is equivalent to
33.87 tpi threads, and so closely resembles 36 tpi threads, but they will not
mate. Nor can one tell them apart by eyeball, unless one has a thread gage.
The nominal diameter is 1.875" (47.625 mm), not 48 millimeters.
The above emphasis on the non-metric thread details is because the modern
stereo microscope accessory thread is M48x0.75. This is often wrongly called
two inch, which is close (to this and a few other kinds), but a M48x0.75
external thread will not screw into an AO Stereo Microscope accessory port.
The thread length is 0.125" and there must be a shoulder (where the
diameter increases abruptly from 1.875 to 2" in diameter) against which the
adapter will bottom, to prevent screwing the adapter in too far and damaging
the optics within.
I have machined such an adapter, and the threads mate perfectly. In the
newer, cleaner body, the adapter turns freely but is a snug fit. On the older
body, the fit is slightly loose, but is still secure.
For the record, I measured the Pitch Diameter (PD) of the newly machined
adapter thread using the three-wire method and micrometers. The measured PD
is 1.874". This will be useful to anyone machining the thread, to tell when
they´ve cut deep enough, but not too deep.
This adapter is now used to mount a 56-LED ring light, which works better
than the original oblique illuminator. AmScope WR63HWR on Amazon, $26 or so.
Don´t buy the 144-LED unit - there is a negative review that tells
why.
Joe Gwinn
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