请求翻译：望远镜的支撑斜杆

最开始是在剑桥天文爱好者指南上看到的，后来在北馆FTP上找到Sky&Telescope原文，可惜pdf有限制不能复制到谷歌翻译里面，我英文水平又还不够，请问哪位同好能帮忙翻译一下？不用一字一句，大概说说是怎么做的就行，我看看自己能不能做一个。

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我给你OCR了一下
As a rule of thumb, the longer the tube of your telescope, the more
pronounced the improvement a Hargreaves strut wiH provide. Never-
theless; the stability of the author's Celestron C 74 Schmidt-Cassegrain
improved dramaticaHy after one of these simple widgets was retrofitted,
has less stiffness per unit weight than a
hollow tube. The ends of the tube slide
into a mating pair of injection-molded
plastic universal joints (McMaster-Carr
catalog number 60625K96, $12.05 each)
and are held in place with setscrews.
  One universal joint is attached to a
stamped metal conduit hanger via a 5/8-
inch-long, 1/2-inch-outside-diameter alu-
minum tubular standoff (McMaster-Carr
catalog number 92510A343, $1.14 each,
specify #10 screw size bore when order-
ing). Tap the standoff's bore with a l/4-20
tap and secure it to the conduit hanger
with a l/4-20 machine screw. Clamp the
conduit hanger firmly around the mount-
ing's declination axle simply by tighten-
ing a bolt. With a portable instrument,
you'll probably want to replace the con-
duit hanger's slotted-head bolt and mat-
ing hex nut with a thumbscrew and
knurled knob for easier assembly and
disassembly. A 1/2-inch conduit hanger (in
galvanized steel, McMaster-Carr catalog
number 3006T11, $2.92 for a package of
10; in stainless steel, catalog num-
ber 3006T41, $11.27 for a package
of 10) will fit the counterweight
shaft ofVixeds Great Polaris (GP)
and Great Polaris Deluxe (GP-
DX) mountings as well as their
Chinese equivalents, Celestrods
CG-4 and CG-5. To avoid mar-
ring the shaft's rather soft electro-
plated finish, it's advisable to line
the interior of the conduit hanger
with a thin layer of felt. Alterna-
tively, you might consider modi-
fying a standard shaft collar or
even turning one from scratch on
a lathe.
  Now to connect the other end
of the strut to the telescope. Natu-
rally, most amateurs would balk at
the prospect of drilling a hole in
Even instruments with relatively
short tubes can benefit from having
a Hargreaves strut. Here the author's
well-equipped Celestron C14
Schmidt-Cassegrain rides with re-
markable sturdiness atop his Los-
mandy G-ll mount.
the tube of their telescope in order to at-
tach the second universal joint. Fortu-
nately, spare felt-lined clamping rings to
fit the tubes of all the popular Japanese
and Chinese telescopes are available from
Hands On Optics (Damascus, Maryland)
and Sky Instruments (Vancouver, British
Columbia, Canada). These rings have a
handy flat mounting; boss complete with
an integral y4-20 threaded stud that was
originally intended to attach 35-millime-
ter cameras for piggyback photography.
This feature makes attaching a universal
joint a breeze. Simply screw a second
tapped standoff over the threaded stud,
then slide the universal joint over the
standoff.
Once you have oriented the second
universal joint so that it pivots along the
axis defined by the telescope's tube, se-
cure it to the ring's mounting boss by
tightening a setscrew bearing against the
托一inch bolt. Now the ring is aligned ra-
dially so that the universal joint is per-
pendicular to the bottom surface of the
telescope's tube, then tightened behind
the objective-lens cell. Finally, lightly ten-
sion the strut by sliding the conduit
hanger or shaft collar toward the bottom
of the counterweight shaft and clamping
it in place. Alternatively, you can apply
compression by sliding the conduit
hanger toward the telescope tube.
Exceptions and Alternatives
If your mounting's counterweight shaft
doesdt rotate when its declination axle is
turned, adding a Harg;reaves strut be-
comes a bit more complicated. Rather
than simply clamping the bottom end of
the strut to the counterweight shaft,
you'll have to use a collar lined with a
nylon or bronze sleeve bearing so that it
can rotate freely as the telescope is
moved in declination. This collar should
be sandwiched between a pair of thrust
washers and shaft collars that can be
locked in position once the proper ten-
sion has been achieved.
Retrofitting a Hargreaves strut to a
Newtonian reflector with a rotating tube
presents a few complications. The ring
that supports the universal joint will
have to be loosened and retensioned
(along with the usual pair of mounting
rings) whenever you rotate the tube.
Otherwise, the installation and operation
of a Hargreaves strut will be no different
~2001 Sky Publishing Corp. All rights reserved
than for a telescope with a non-
rotating; tube.
   As a rule of thumb, the longer
the tube of your telescope, the
more pronounced the improve-
ment a Hargreaves strut will pro-
vide. Nevertheless, the stability of
the author's Losmandy G-ll
mount, which carries the heavy
payload of a 14-inch Schmidt-
Cassegrain festooned with a
video camera, sliding counter-
weight sets, an auxiliary 80-mm
f/5 finder, and a 90-mm f/ll
guidescope, improved dramati-
cally after one of these simple
widgets was retrofitted. In my
case a $50 investment paid very
rich dividends - it stopped me
from spending a small fortune on
a larger mounting!   
THOMAS A. DOBBINS is a noted ob-
server and instrument maker. A con-
tributing editor for Sky & Telescope,
Dobbins /s also one of the authors of
the newly released book Video As-
tronomy, reviewed in the July issue.

第一页
telescope techniques
The
Hargreaves
Strut
Give your telescope a new and
improved level of stability without
the expense of a new mount
BY Thomas  A Dobbins
HE LIGHT- AND MEDIUM-DUTY                Above:The author's Celestron CP-102 refrac-
German equatorial mountings
manufactured
Vixen and their
in Japan by
Chinese clones
dominate today's marketplace. Sadly,
they're often severely overtaxed by the in-
struments that many amateurs call upon
them to carry. The long overhang of the
tubes of many refractors and Newtoni-
ans makes such a combination very sus-
ceptible to flexure and vibration.
   To cure the annoying shakes of an un-
dersize German equatorial mounting (or
to further improve the stability of a well-
proportioned one), generations of ama-
teurs have installed a brace between the
upper end of the telescope tube and the
declination axle or counterweight shaft of
its mounting. The brace forms the hy-
potenuse of a triangle. Since a triangle is
tor is attached to a CG-5 mount. The Har-
greaves strut, which joins the objective end of
the telescope with the mount's counterweight
shaft, greatly improves the stability of the
setup. The strut assembly is made from off-
the-shelf components. All photos by the au-
thor unless otherwise specified.
Right: Since hinged tube mounting rings are
sold by the pair, you may want to use the sec-
ond ring (arrowed) to fabricate a sliding tube
counterweight to counterbalance accessories
like cameras and heavy eyepieces.The exam-
ple shown here was made from 3/4-inch alu-
minum square bar, a length of 3/8_inch_diam_
eter stainless-steel rod. and a short length of
2-inch-diameter stainless-steel round bar.
an inherently rigid structure, improved
stiffness and vibration damping invariably
114    September 2001  I Sky & Telescope
~2001 Sky Publishing Corp. All rights reserved
Rounding Up the Pieces
A Hargreaves strut suitable for most am-
ateur telescopes can be assembled in less
than an hour using inexpensive, off-the-
shelf components available from several
sources,including the McMaster-Carr Sup-
ply Company. You can peruse this firm's
huge catalog online at www.mcmaster
.com. It's a treasure-trove of hard-to-find
parts, tools, machining stock, and fasten-
ers for the amateur telescope maker.
     The strut itself is nothing more than a
length of i/2-illch diameter aluminum
tubing with a lA6-inch wall thickness (Mc-
Master-Carr catalog number 89965K54,
$11.96 for a 6-foot length). Resist the
temptation to use a solid rod here - it

kevin_kou 发表于 2013-2-11 23:32

                               
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第一页
telescope techniques
The

O(∩_∩)O谢谢

scorpio_tiger 发表于 2013-2-12 21:19

                               
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O(∩_∩)O谢谢

别客气,我就简单校对了一下,可能还有点错误.