Reticle Cross Hairs - How to make?
Matthew Sherman
I goofed up the crosshairs in my finder eyepiece. What can you replace it
with, and where do you get it?
Also, what tool do you use to turn the rings inside the eyepiece (field
stop?) so I don't screw up again?
Thanks!
Matthew Sherman
NGC ME!
JMc
hairs. Be careful when milking her though ;-)
Edmund Scientific sells glass reticles with the cross hairs engraved and
these can be mounded in front of your field stop. If it's just a finder
scope, you could also take a clean disc of plastic and scribe your own
cross hair reticle with a sharp pin.
The tool used to remove the rings is called a lens spanner wrench. It
costs about $90, so unless you really need to own one, try two nails
driven trough a piece of hardwood. Bend them to the proper spacing, and
file the tips to fit the slots in the ring.
Jim McSheehy
eclipse
Speaking from unfortunate experience:
You can use the finest of cat hair/fur. If black is available use that, if
not, you can colour a hair with marker. All cat hairs are not created
equal so collect a bunch (use care, cat owners will understand) and choose
the finest ones using a magnifier.
Internal rings can be rotated/unscrewed by abusing fine point tweezers.
The hairs can be glued with crazy glue and trimmed with a razor blade or
surgical scissors..
If at first you don't succeed, try again. The results can be quite
satisfying and much cheaper than replacement of equipment.
Clear Skies,
Richard Jordan
Matthew Sherman wrote in message ...
flabbergasted
hair so my crosshairs are actually finer than the originals and I can
sight through the hairs on bright stars. I've used individual strands
from 22AWG stranded hook-up wire too but the hair trick works better-
it's even more fun if snatch 'em off of unsuspecting folks!
Fine-jawed needlenose pliers will do in a pinch for getting rings out
but you could probably find some snap-ring pliers that will work a bit
better.
Good luck and Happy Hollidays!
Bill
On Fri, 22 Dec 2000 14:58:00 GMT, "Matthew Sherman" <mid...@gte.net>
wrote:
Michael A. Covington
> with, and where do you get it?
I've been thinking that one possibility might be to take some lamp cord or
other stranded wire and pick apart the individual strands of copper wire. I
need to do one of these myself.
> Also, what tool do you use to turn the rings inside the eyepiece (field
> stop?) so I don't screw up again?
A gadget called an optical spanner wrench, available (not cheaply) from
www.edmundoptics.com among other places.
Rockett Crawford
Actually from trial and error, I found that human hair is
much better than wire strands. Wire stands look like
huge pipes when placed at the focus of an eyepiece.
The way I mounted the two human hairs was to
take 5 minute epoxy and glue one end of the hair
on one edge and later pull the hair taut across at
the focus and glue the other side, holding it until
the expoxy hardens. Then cut the excess part of
the hair off.
Repeat for the other axis.
Rockett
"Michael A. Covington" wrote:
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Michael A. Covington
> much better than wire strands. Wire stands look like
> huge pipes when placed at the focus of an eyepiece.
OK, I'll try that. Babies and blondes have the thinnest hair... my own hair
is very thick.
btwir...@my-deja.com
Matthew,
I've used very fine fiber glass strands that our Survey Repair
Department uses for cross-hair repairs in old instruments. Superglue, X-
acto knife and your done. You can make a custom retaining ring spanner
with a thin flat piece of steel cut the width of the retaining ring.
Take the steel and use a dremel tool with a grinding disk to cut the
teeth and remove any metal that would otherwise be in the way.
Brian
Sent via Deja.com
http://www.deja.com/
Mike Simmons
>
> I hear that Black Widow spider silk is the preferred material for cross
> hairs. Be careful when milking her though ;-)
I knew an astronomer (now retired) who used to do this. He'd just hold
the black widow in his open hand and tilt it over until she'd "fall"
off. She'd produce a strand of silk to lower herself on. I never tried
it, though -- and I don't intend to. :-)
Mike Simmons
dbro...@eldec.com
floss are much finer than human hair or the smallest copper wire. Tease
out a single fiber, lay it across the ring with something laying on it
at each end to provide a little tension, and apply a minute dab of
superglue at each end. Give it a few minutes to set, then _gently_
trim the excess length.
Dave Brodeur
Seattle
In article <YZJ06.79$ti7....@paloalto-snr1.gtei.net>,
"Matthew Sherman" <mid...@gte.net> wrote:
Steve
I made my own by pulling very fine glass fibers from a pasteur pipet
using a bunsen burner. A thin glass rod would probably have done just as
well as a starting point. If you haven't pulled glass before, the trick is
heat the glass until it starts to flow, remove it from the flame and *then*
pull. By experimenting with the amount of time you let the glass flow and
the speed and length of the "pull" you can make fibers of almost any desired
thickness. I attached them to the field stop of a 26mm Celestron plossel
using super glue. Getting them to meet at right angles was a bit more of a
challenge but a template I drew on my computer helped. I hope this helps.
Clear skies,
Steve
Bob Botts
"Michael A. Covington" wrote:
A friend used cat hair, (which is very fine by comparison), but, complained that
it was very sensitive to humidity and would sag very noticeably.
Cheers... Bob
--
Complex problems have simple, easy to understand, wrong answers.
Stephen Tonkin
>Hi all,
>
>I goofed up the crosshairs in my finder eyepiece. What can you replace it
>with, and where do you get it?
Depends how thick you want it. I use my daughter's (very fine, blonde)
hair for relatively thick webs. For fine webs I make use of one of the
irritating properties of hot-melt glue -- its tendency to string into
fine filaments.
I believe that dental floss can be separated into strands of varying
appropriate thickness.
>
>Also, what tool do you use to turn the rings inside the eyepiece (field
>stop?) so I don't screw up again?
You *should* use a peg spanner. I use a screwdriver or a pair of snipe-
nose pliers.
Noctis Gaudia Carpe,
Stephen
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Stephen Tonkin
>Getting them to meet at right angles was a bit more of a
>challenge but a template I drew on my computer helped.
The simple solution (which I use on my finders) is not to have them
cross at right angles. I use three webs which are orientated as below
(use a fixed-width font to view):
\ /
\ /
\/
/\
_____/__\_____
/ \
/ \
/ \
Centre the object in the middle triangle; never gets occulted by the
webs.
William H. Foley, Sr.
This is not the time of year for it, but spider web is very good for
reticles. I have read that the Black Widow's web is best for the
purpose, but have not tried that, I don't want to take the chance.
I used to use glue or model cement, pulled quickly across the reticle
holder, for this, but the Testor's would not hold up well. I suspect
that contact cement would fare better, I think it would be less brittle.
Of course, Edmund Scientific sells reticles, but I am not sure if you
could adapt theirs to your use, of if you would want to spend that much.
Bill.
Dan McKenna
Black widow is what was recommended if memory serves.
clear and steady
Dan
Steve
Nice idea. Thanks
Clear skies
Steve
Stephen Tonkin wrote:
> <snip>
Mike Hanlon
Mike
--
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Essex, UK
http://www.btinternet.com/~mike.hanlon
"Matthew Sherman" <mid...@gte.net> wrote in message
news:YZJ06.79$ti7....@paloalto-snr1.gtei.net...
Rod
During WWII, I believe the web of the Black Widow spider was used because it
has one of the finest filaments. I wouldn't encourage it's use though.
Clear skies,
Rod
Mike Hanlon wrote in message <920ti2$ndh$1...@uranium.btinternet.com>...
Larry Brown
it is best to take advice from those who have actually done it and not from
those who have "heard somewhere." IMHO, this is true for everything in this
particular hobby.
I have used glue stretched across a diaphragm into a thread, which
worked, and fine hair from my cat, which worked much better. What is really
miserable are the glass reticles that Edmund and others sell. The problem is
that the glass surface is also in the focal plane, and any dust or scratches
show up really well. Sometimes you see more dust than cross hairs.
Many people find that they enjoy a product more if they have made it
themselves. Good luck and have fun with it.
L Brown
Mike Simmons
>
> The story of Black Widow spider web is probably apocryphal.
Black Widow spider web used to be used quite a bit. Accordingly to one
astronomer I worked with who did it regularly, it's not as difficult or
dangerous to get as is commonly assumed. I don't know if anyone is
doing it anymore, though.
Mike Simmons
JMc
Here is an interesting reference about spider silk:
http://www.designinsite.dk/htmsider/m0609.htm
As far as the Black Widow is concerned, during W.W.II, several spider
farms were set up to supply Black Widow silk for military applications.
Even with all our organic chemistry and textile engineering, the fibers
we make in laboratories are crude by comparison.
Jim McSheehy
William H. Foley, Sr.
I remember an article long ago in S&T magazine about Black Widow web
being preferred for reticles. It was a serious article. I believe that
they were used in some of the large observatory telescopes.
Bill
k...@infocom.com
from the coccon of the Brown spider. I recently had the crosshairs
replaced in an older transit by RP Parrish at
http://www.antiquesurveying.com/. RP uses very fine fibre glass
strands (.0002" thick) as fibre glass will not sag. According to RP,
crosshairs should be transparent.
Ken
On Fri, 22 Dec 2000 14:58:00 GMT, "Matthew Sherman" <mid...@gte.net>
wrote:
>Hi all,
k...@infocom.com
older surveying instruments.
Ken
Dave Novoselsky
believe the Yerkes scope originally had these type of 'spider' reticles for
the eps. I recall seeing examples either up there or at the display that
was at the Adler Planetarium in Chicago. Dave
"William H. Foley, Sr." <bif...@attglobal.net> wrote in message
news:3A456EB6...@attglobal.net...
Mark Gingrich
> The story of Black Widow spider web is probably apocryphal. ...
The following is from Roger Sinnott's article "Crosshairs from Spider
Web," _Sky and Telescope_, January 1987, p. 97:
In a back room of a Philadelphia firm where surveyors'
theodolites and transits are repaired, black widow spiders
live out their lives in pampered luxury. Controlled mating
keeps their population to about three or four healthy adults
(there is not as much need for them now as formerly). But
every five years or so, when the quality of the webs they
spin begins to suffer, a trip is made to Arizona in search of
wild black widows to improve the breed.
According to Chip Smith, general manager of North American
Survey Supply Co., 2070 Markim Rd., Philadelphia, Pa. 19116,
the web of this poisonous spider is the strongest and thinnest
material known for making crosshairs. ...
Sinnott also cites an article from _Optics News_, November 1986, p. 4,
that suggests techniques for harvesting spider webs, the good news
being, "any nonpoisonous arachnid will do."
In addition to crosshairs, astronomers have long used spider silk for
the indexing threads on their filar micrometers, a fact pointed out
by such renowned double-star observers as Paul Couteau (_Observing
Visual Double Stars_, p. 49) and Robert Aitken (_The Binary Stars_,
p. 42). And Sproul Observatory's Wulff Heintz touts their superior
optical properties: "Because of their low scatter of light, spider-web
wires of homogeneous thickness, if available, are preferred to quartz
or similar materials." (From "Double Stars," a chapter in _Astronomy:
A Handbook_, G.D. Roth, editor, p. 478.)
--
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
Mark Gingrich gri...@rahul.net San Leandro, California
Eugene Griessel
>My old surveying books say that crosshairs are made from the strands
>from the coccon of the Brown spider. I recently had the crosshairs
>replaced in an older transit by RP Parrish at
>http://www.antiquesurveying.com/. RP uses very fine fibre glass
>strands (.0002" thick) as fibre glass will not sag. According to RP,
>crosshairs should be transparent.
From "Plane and Geodetic surveying" by Clark:
"Replacing cross-hairs: Suitable webs should be selected from a
spider's cocoon, failing which, if a spider can be found , procure a
V-shaped piece of wire and and get the spider on one end of the
prongs. On shaking him off he will spin a web which is to be wound on
the fork so that the separate strands are not too close. Immerse the
web to be mounted in warm water for a few minutes then gently remove
the surplus water with a colour brush. Stretch the web across the
ring, using small weight to ensure tightness, and by means of a pin
adjust it to lie exactly in the notches. Fix it by applying a drop of
shellac on one end, and when this has hardened see that the web
remains taut before similarly fixing the other. If spider webs cannot
be procured floss silk is a convenient substitute."
Eugene L Griessel eug...@dynagen.co.za
Personal Page - www.dynagen.co.za/eugene
SAAF Crashboat Page - www.dynagen.co.za/eugene/eug3.htm
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Snakes - www.web.netactive.co.za/~sean
John Simmons
There's alawys the ubiquitous "RCH".
:-)
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Dan McKenna
k...@infocom.com wrote:
> My old surveying books say that crosshairs are made from the strands
> from the coccon of the Brown spider. I recently had the crosshairs
> replaced in an older transit by RP Parrish at
> http://www.antiquesurveying.com/. RP uses very fine fibre glass
> strands (.0002" thick) as fibre glass will not sag. According to RP,
> crosshairs should be transparent.
>
> Ken
I wonder if you could illuminate the fibreglass cross hair
by shining an led down the end of the fibre. I guess that to
get enough light down a .0002"( 5 micron) fibre you might use a focused pen
laser.
or maybe not.
Clear and steady
Dan