Wedge/Tripod Mods, Specs, & Designs
Subject: LX50/200 Tripod/Wedge Problem Solutions --part 1 of 2 
From: Dave Sage <dsage inforamp.net>
I have always considered this modification trivial but I have noticed in the past, owners of a wedge mounted LX200 struggling
with the LX tripod during dis-assembly and transport, so I'll pass it along.
The way the tripod is shipped (at least as far as I could figure out) if you put an equatorial wedge on the tripod, the whole
assembly is very loose or threatens to fall apart when you release the tripod leg spreader. With the purchase of a longer piece
of threaded rod you can eliminate this problem. Sorry I dont' have the length of the rod in front of me, but if you assemble
the pieces as described below using the original rod you can figure out how much longer the new rod needs to be (it's only
a few inches) to make it work. You won't need the C-clip or need to make a slot in the new rod, just use a plain old piece
of rod.
Starting at the top of the rod, if you assemble the pieces as stacked below the whole thing will stay together:
- The big hand nut (sometimes has a compass in it)
- The Wedge itself with or without the 2 or 3 small screws in the slots that are supposed to fasten it to the wedge.
- An optional piece of very thin mylar or tough plastic, circular and cut to the diameter of the tripod top with a hole in
the center for the rod to go through.
- The tripod
- One nut
- A second nut tightened very tight against the first (locked together)
- The spreader bar
- The second bug hand wheel used to tighten the spreader.
- The acorn nut on the end of the rod (for personal safety from sharp threads)
Now, because of the double nut arrangement, the tripod and the wedge have been isolated from each other and you are free to
release the spreader and the wedge will remain securly clamped to the tripod by the big had nut at the top. Or, conversly the
wedge can be loosened (for RA adjustments) without having to loosen the legs of the tripod. The thin plastic washer allows
the top hand nut to be very tight while allowing enough slip for RA adjustment (with the RA adjuster or by hand).
I dunno - maybe this is ridiculously simple and maybe I missed something (or was missing some parts in the original shippment)
but the whole thing was a sloppy mess from the factory and was a pain to adjust.
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Subject: Subject: LX50/200 Tripod/Wedge Problem Solutions --part 2 of 2
From: Mark Taylor <mctaylormindspring.com>
I'm not really sure what each of you are seeing based on your descriptions, but it *sounds* like Ralph may have the same problem
I had with my standard wedge when I first opened it. I had to disassemble and re-build the "pre-assembled" portion
of it, because it was done improperly at the factory.
Note, I have an LX200, but I think they use the same wedge.
The problem: The heavy-duty aluminum rod/bar which:
- (a) keeps the walls of the wedge spaced
- (b) provides a solid "brace" through which the long latitude screw runs
...was in the WRONG place on the wedge body!!
If I hadn't noticed this, and installed the tilt-plate in the only "logical" place that it would fit, I would have
put *both* sets of tilt-plate bolts through the curved latitude scale to anchor it in. But any significant force (such as the
weight of a scope!), would cause the plate to slip along the curve. I think that is what I heard Ralph describe that he is
fighting.
The fix: The rod came installed between the holes at the *top* of the wedge's "triangle" (from a side view); rather
than being in the holes at the *bottom corner* (where it is a 90 degree angle). The top holes are supposed to be for the pivot-point
of the tilt-plate; *only* the lower bolts of the tilt-plate should go into the curved latitude-scale track. So I had to get
a phillips head screwdriver, and move the rod down to the lower corner holes where it belonged.
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- Bill Kelly wrote:
>I doubt the 7" MAK is much, if at all, heavier than my 10" LX50 and suspect
>possible misassembly of the wedge. I'm not sure if all LX50 wedges are the
>same, the following describes mine. I have 3 bolts on each side of the wedge,
>one on each side for the pivot point, and two on each side along the lattitude
>scale. Of the two along the lattitude scale, one has a screw on the inside of
>the wedge for fine tuning the declination angle, and once set all can be
>snugged up. I find no need to excessively tighten any of the 6 bolts to
>securely hold the wedge and scope securely.
Ralph, I have 5 bolts on my wedge, on each side I have 1 Bolt at the pivot point that uses a plastic triangle with a washer,
and 1 Bolt at the latitude scale. Facing the right side, I have a single declination fine adjustment that has a smaller
hex bolt
and a hex adjustment. It seems that when the four bolts slip, they can drive down the single fine adjustment toward 0 degrees.
I wonder whether I got the wrong wedge or whether this is a new design.
Subject: Tripod Leg Refinishing/Protecting --part 1 of 2
From: Bill Beeman <bbeemanbeemangroup.com>
Michael Wyatt wrote:
>Has anyone painted the LX200 tripod legs (silver parts) with a clear paint
>to help reduce rust problems? If so, what were your results and what
>paint did you use.
I went the hard paste wax route with mine. The Krylon (or other spray coating will fail where the clamps bite down, and will
wear from the rubbing when sliding the legs in and out. Also heard that rubbing the rusted area with crumpled up aluminium
foil will restore the finish.
My tripod has seen enough exposure that I do see some rust discoloration of the original screws in the OTA (I have not yet
replaced them with stainless hardware), but the legs look perfect. You will have to renew the wax occasionally, but it only
takes a few minutes.
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Subject: Tripod Leg Refinishing/Protecting --part 2 of 2
From: Michael Dziak <crowsnestobservatoryyahoo.com>
I work with different types of finish materials for application to metal in my automotive accessory business. In my experience,
painting any chromed finished parts with clear finish has some undesirable after effects that tend to create problems other
than the rust prevention.
The nature of chrome is a ultra smooth, highly polished surface that makes an applied material, clear or otherwise, difficult
to bind with. The finish will need to be scuffed in order to create recessed areas for the applied material to bind. This will
create a dull appearance. The clear material will eventually degrade from exposure to A and B bands of the suns ultra violet
rays (if regularly exposed to sunlight) which will cause the clear appearance to "fog" and eventually degrade at
the molecular level. Some finishes boast an ultra violet blocker, but still will slowly degrade with time. Some of the clear
finishes such as Polyeurathane are made to resist yellowing and cracking.
If your tripod is moved frequently, you may find that the finish will easily chip away from the chrome, which it will expose
to oxidation, again.
I recommend you consider obtaining a quality automotive grade polyurethane gloss made for chrome and stainless steel which
will effectively prevent rust from eating the chrome away from the base metal it is applied to. It is easily applied with a
clean terry cloth much like wax and will clean any shallow surface rust away, restoring the chrome finish. Thats why on old
car bumpers, you can find the chrome bubbling, and chipping off the base metal. Quality finish glosses and sealants contain
an anti-oxidant and will prevent ultra violet degradation of the finish. In my business, I am careful not to use rubbing compounds
or abrasive metal cleaners, that scratch and swirl the finish, and require frequent buffing to keep its luster.
I have used a product made by Derrick Steel International called Ultimate Gloss on the chromed legs of my LX200 classic and
previously, the tripod of the LX2120 10" I owned for 10 years. I apologize for the shameless plug, but I do sell it through
my automotive accessories studio to a lot of car and especially semi-truck drivers for their chrome, stainless steel tanks
and aluminum trim. One application lasts 1-1/2 to 2 years!
If you would want more information, please contact me at my business e-mail address at: <signsatdmwt.net>
If the legs of your tripod are badly rusted, it will be necessary to sand off the rust with steel wool and wash the surface
with a wax and grease remover obtained from a local automotive parts / paint distributor. Then a quality urethane finish of
your choice can be applied. With this severe of a rust problem, refinishing it with a commercial grade urethane truck bed liner
material, that can be brushed or sprayed on, will provide years of durability to the tripod finish. The advantage is that this
material is designed to be very resistant to marking, chipping and cracking with heavy use and provides an attractive "pebbled"
anti reflective black finish.
Subject: How to Detach Tripod Head from Legs
From: Dennis Williams <drwicu812comcast.net>
Joachim Plocinski wrote:
> I have a LX200 field tripod and I'm wondering how to detach the tripod
> head from the legs without ruining the reassembly possibility.
> I see that the legs are attached with threaded
> pins and are tightened with a nut. I was hoping that you
> only had to screw out the pins like a screw, but since it's only a nut
> I don't know how to get the threaded pin out.
> Can I just drag the pins out, or are they threaded into the legs?
Nothing hard about this once you know how it is made. The threaded pin you mention is a long set screw, the nut is an acorn
nut that main purpose is to be pretty.
- Take a wrench and unscrew the acorn nuts. They may seem a little tight because they have a thread lock goo (glue) to keep
them from coming off.
- Find an Allen wrench to fit and back out the set screws...done.
Note 1:
Once a nut is removed you can see that the screw does not screw into the leg, it screws into the tripod head. The legs have
through holes (clearance holes) for the set screw to go through. The screw acts as the hinge for the legs to pivot on. You'll
see it.
Note 2:
The legs appear to have way too much slop between the castings, but that is to allow the legs to move around sideways and ever
which direction in the truck of your car without breaking. Remember that when the scope is attached, the tripod is solid, the
leg spreader takes out the slop......leave the design along, it works well!
PLEASE NOTE THIS:
The tripod head and the leg tops are cast aluminum and are easily broken if put in a bind.......SOOOO......When putting the
acorn nuts back on the screws, DO NOT tighten them against the legs. Just tighten until they touch the legs. Remember they
are mainly there for show, and to keep from skinning your knuckles on the set screw ends.
Subject: Tripod -- Reducing Height by Shortening Legs --part 1 of 4
From: John Hilliard <j_hilliard848bellsouth.net> Date:
March 2005
----- Original Message -----
> I am considering reducing the height of my giant field tripod and I
> am a little concerned about heating the tubes and tapping the tops
> off to facilitate cutting the tubes to the desired length. Does
> anyone have experience with this process and have any advice to offer?
> Also, is there a more preferable height?
We reduced the tripod's height by shortening the legs. Start by heating the upper castings with a household propane torch
and twisting them off the tubes. I cannot remember if there was any discoloration of the black castings or not...there was
non on the chrome tubes. If there was any discoloration on the castings, we touched it up with a black Magic Marker, and it
was never noticed again. We had a machinist friend cut the leg tubes and shorten the lower spreader links...I would have made
a mess.
Click on this link: <http://www.bbcl03736.pwp.blueyonder.co.uk/tripodmod.htm>
These are the instructions we used and everything worked just fine. Be sure to clean all the old epoxy off the tubes and
castings before reconstructing the tripod, and make sure all the little screws inside the tubes that hold everything together
are screwed in tightly before reassembly. These screws have nothing to do with the shortening of the tripod, but they still
rattle when one falls out later on. Life is so much better with the tripod 8" shorter.
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Subject: Tripod -- Reducing Height by Shortening Legs --part 2
From: <graywolf49aol.com>
I reduced the height on my LX200 tripod and was glad did. It makes life a lot better. I use a plain propane torch for about
$12 and heated the caps only. They are put on with a type of resin glue. Rap the tube with an old towel and place it in a vice,
be sure you do not clap down hard. Use a rubber mallet and tap the top end off. You will have to apply the evenly around the
cap. By the way, Be sure to remove the top platform first and take apart each leg. Keep the flame way from the chrome or it
will turn blue on you. The rods in the center will be to long so you will have to oder a new set from Pertersons. The address
is: <http://www.petersonengineering.com> Look for the shrink kit. All of the instructions will be there. You will find
that the legs are not even. Take them to any machine shop and have them cut.
Contact Meade they will have the rubber bottoms in stock. I just replace mine about two months ago. To remove the bottom
end caps you will have to remove them the same way as the top. Use a heat source and heat them up evenly and tap them off.
You maybe able to contact Meade and see if the will sell you replacement tubes. Meade does not like to mess with small orders
so if you need anything else order everything at one time. One more thing if the tubes are bent I would replace the lock screws.
More than likely they are bent as well.
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Subject: Tripod -- Reducing Height by Shortening Legs --part 3
From: George Cushing <pinyachtayahoo.com>
Aluminum melts at around 1100F. and probably doesn't expand much after 500F. So you have a little room for error. Welding
suppliers can sell you crayons that have different melting temps so you can better judge the heat you've attained. Unless you
have a commercial pizza oven handy you'll have to use a torch to heat the tops. I don't think a heat gun can deliver the BTUs
as aluminum conducts the heat away so well. To hammer off the tops without banging them up find a piece of iron pipe that fits
over the chrome tube but not the cylindrical end of the top. Wearing gloves use the iron pipe as a slide hammer to knock the
top off. For refitting the tops can go in the oven as they will now fit! The tubes can be cut to length with a plumber's pipe
cutter. This will also leave the new tube end slightly rounded making refit easier.
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Subject: Tripod -- Reducing Height by Shortening Legs --part 4 of 4
From: Randy Marsden <jmarsdensan.rr.com>
Rather than use a torch, I used a heat gun like those used to strip paint or shrink heat-shrink tubing. I used two band wrenches
to grab the foot and the tubing to allow me to twist the foot while holding the tube stationary. Once the bond was broken,
it was easy to slide to foot off.
I cut the tube with an angle grinder with a thin wheel for grinding stainless steel. Then I touched up the edges with a Dremel
tool before reassembly. I slid the foot back on after running a small bead of medium strength Loctite about two inches below
where the top of the foot. Once the Loctite set, I drilled a new hole and used a rivet tool to put in a new rivet for security.
The whole process took an hour or so to do all three legs.
Subject: Tripod Threaded Rod Component Order
From: John Hilliard <j_hilliard848bellsouth.net>
The washer fits between the spreader bar and the tightening handle on the end of the threaded rod. Starting from the bottom
you would have the handle or knob, the washer, then the spreader bar...the ribs on the spreader should be on the underside.
The rod feeds up through the tripod head and the c-clip fits into the groove cut in the threaded rod to keep the whole assembly
from dropping back through when it is unscrewed from the telescope.
One suggestion...when setting up the scope, pull/jerk the spreader up against the tripod legs to properly spread the tripod
legs. This will allow a straight in approach of the threaded rod into the scope and makes tightening of the rod/spreader bar
against the legs of the tripod more even and secure.
Subject: Meade Standard Wedge Modifications --part 1 of 2
From: Kevin Dougherty <PLEIADE0aol.com>
Just finished putting up a website focused on LX200 / Astronomy. There is a section complete with pictures of the Standard
Wedge modifications I've made.
Feedback is appreciated, as this is a first round. I'll be sending a few versions of this mail out since I suspect a lot of
us just scan the message headings, so please forgive the duplications.
<http://members.aol.com/pleiade0/astro/> Press
the 'Wedge Modifications' Button
Note: should open a new window over this one.
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Subject: Meade Standard Wedge Modifications --part 2 of 2
From: Len Benschop <ldbenschopsympatico.ca> Date: May 2002
I have just updated my website with images and a description of my modifications to reduce flexure and vibration in the Celestron
Standard C8 Wedge. The Celestron and Meade standard wedges are very prone to flexure and vibration, even with only an 8"
scope mounted.
<http://www.astrosurf.com/benschop/WedgeMods.htm>
The project went very well. Prior to the mods the wedge vibrated badly. The setup is now VERY stable, with no detectable flexure
or vibration. It now seems to be as stable as even the Ultima Wedge.
Oak is excellent at dampening the vibrations and adds significant rigidity. I will be using this wedge with my Ultima 2000
and CB245 camera for imaging.
Subject: Meade Standard Wedge Stabilizer
From: Kevin Dougherty
I just finished some new modifications on the standard wedge focusing on a new stabilizer design. See the website below for
further description and pictures.
<http://members.aol.com/pleiade0/astro/> Note: should
open a new window over this one.
Subject: Mettler Wedge--Alternative to Meade & Milburn
Website for the Mettler wedge. Also
see SuperWedge page, click here.
There are several new wedges being made by members of the Mapug list, see
Ulti-Wedge by Randy Marsden
Superior Wedge by Mitty Observatory
Subject: Meade Superwedge vs. Milburn Wedge
See SuperWedge page, click here.
Subject: Best Wedge for LX200???
See SuperWedge page, click here.
Subject: Base Mounting Bolt Pattern (classic & GPS) URL
From: Michael Cook's page shows LX200 base mounting bolt specs. Distance along two to the sides of the triangle made by
the three holes is 6.75" and the third side (base of the triangle) is 6.5". Thus the three holes are not exactly 120° apart.
See drawing below drawn based on these dimensions:
Subject: Mounting with Center Bolt on Wedge
From: Doc G, Date: Sept 2005
I have advised using the center bolt for some years now. The center bolt goes directly into the cone structure that holds
the bearings for the fork. The three side bolts hold the remainder of the casting. All of the flexing in the base is in the
central cone and the bearings. The forks are definitely not a flexure point. Nor are they a problem when it comes to stiffness
They are well designed castings and very strong and stiff.
In the mid-1990s I made some measurements of the frequency of oscillation, the masses of the system and even calculated the
compliance of the cone and bearings. It is clear that these have not changed much over the intervening decade. However the
addition of the bolt in the center does definitely strengthen and stiffen the bearing cone. It was an excellent design change
that Meade made with the newest scopes. (particularly the RCX and large GPS scopes)
Subject: Maintaining Permanent Polar Alignment
From: Michael Hart and Ric Ecker
- >I'll give you a simple procedure to fix the alignment on your scope so
- > you get repeatability each time you remove the scope so when Its put back
- > on the wedge it will always be in alignment and you won't need to polar
- > align. Get the scope polar align than drill and ream two tapered pins to
- > the wedge penetrating into the base of the LX200 near the hold down
- > bolts where you can get some material to drill into. When you attach the
- > scope tighten the top screw then drive the pins through the wedge into
- > the base, now you have a registered fit and repeatability.
Ric has described what I believe is a significant method to easily maintain polar alignment on a permanently mounted scope.
The method Ric describes is very simple to do and effectively eliminates the need to tweak polar alignment on a permanently
mounted wedge when the scope is removed and reinstalled. I have used this rather effective modification for a couple of years
on my permanently mounted Superwedge.
I use taper pins on my Superwedge in EXACTLY the way Ric describes and have obtained exactly the results Ric mentions for
over two years. My scope has been on and off for many reasons without the need to redo polar alignment.
I recall using #4 X 1" or 1-1/2" taper pins and a 7/32" or 15/64" reamer (I don't recall which). I imagine
a drill bit could work. I attached the scope and drilled into the base just as Ric describes. Then, the small end of the taper
pin was inserted into the wedge and hammered in for a tight fit in the scope base (slight spreading of the metal). The taper
pins were purchased at a full line hardware store for about $1.00 each.
Addendum: The taper pins were verified as #4 X 1" and 15/64" final bore. White paint was used on the scope base
round protrusion before placing the scope on the wedge allowing the paint to mark the location to drill the wedge. Final drilling
was through the wedge into the scope base. The final bore was a bit off-center due to the stiffening ridges on the wedge that
forced the reaming out a bit.
Subject: Maintaining Polar Alignment Using a Tripod
From: Doc G
I have, with my 10" LX, a similar problem of reacquiring polar alignment with setting-up on a tripod from night to night.
Set up the telescope on a wedge and on the tripod. Put it in your imaging location. Then mark the tripod leg positions very
carefully. I have driven small wooden posts into the ground and drilled a hole in them for the pointed parts of the legs.
Keep the tripod setup all together and locked up. The next time you set up the tripod and scope you can just set it in place
on the marked location. You will be very pleased with how close you are to your previous alignment. It takes two people to
carry the setup or you can use a tripod carrier to do it alone. It is amazing how close you get to the same alignment. I know
many use this tactic. They store the setup in a garage and simply pull it out onto a driveway to set it up. If you have the
proper location this will work well.
Another tactic is to leave the tripod and wedge setup. Take the scope off of the wedge and put it back in the normal way.
You will be very very close to the original alignment when you do this. We have taken the scope off of a permanent pier and
put it back on the wedge with no new alignment required at all.
Subject: Wedge and Tripod Mods
From: David Olmstead <daviddavidolmstead.com>
I have been spending my free time this winter modifying my 10" LX200, it's wedge and tripod. My main interest is imaging and
I was not pleased with the wobbles and vibrations that were inherent in the stock product. So I went nuts! My father in law
is an almost retired machinist with his own shop and some free time and lots of energy. I drew up some plans and away we went!
I started with the wedge. Numerous cross bracing was added in places that I thought might help and I think it has. The mechanical
aspect of the wedge still needs to be addressed, however, and I would like to do something like Chris Heapy did with his wedge
but that will have to fall into phase 2 or 3 somewhere down the road.
I scratched my head for a while and came up with this design that would tie the wedge and tripod together but still provide
a means of adjusting the azimuth. I attached Ebony Star laminate to the head of the tripod and used Magic Gliders (typically
used for furniture) on the mating surface of the wedge to provide a smoother motion. As you can see from the photos a large
ring was machined with holes for eyepieces. This ring is attached to the tripod by means of large machined split clamps. A
vertical truss of sorts is bolted to the ring and rises to meet the bottom of the wedge. Both the vertical piece and the wedge
have matching plates with a radius which conforms to the sweep of the wedge as it travels through its limits around it's pivot
point at the head of the tripod. These two plates also have a mating surface of laminate and teflon gliders. The gliders are
recessed into one plate. This union is clamped to the desired amount via handle bolts.
I had everything sandblasted and then I painted it black. Lot's of trips to the hardware store for stainless bolts! As you
can tell by looking at this whole thing, it weighs a bunch. The next project is to fabricate a fixture which will be attached
to a heavy duty two wheeler. The fixture will mate with the tripod and wedge, which I will leave assembled, allowing easier
transport to my trailer.
I hope this is of interest to the group. It has been a lot of work but I am very pleased with the results so far. The mount
is extremely stout and ties everything together so there is virtually no movement. Oh, I drilled some holes in the fork arms
of the scope and put some backing plates in to help reduce vibrations there as well. Indeed the weakest link now is at the
bearings, as Doc has concluded. You can see the photos at:
<http://davidolmstead.com/astro/> Currently a list of links
to individual jpg photos.
Note: should open a new browser window over this one.
Subject: Leveling-- Wedge or Mounting plate? or is it Necessary --part 1 of 2
From: Ken Milburn <ken.milburnverizon.net> Date: Dec 2001
----- Original Message -----
From: Dave Schanz
> When I go to mount the wedge to the mounting plate of
> the pier and I am faced with a multipart conundrum.
> When I level the top mounting plate of the pier and then mount the wedge and
> hand tighten everything down, the bubble on the wedge is better than a half
> bubble off and a carpenter's level placed on the wedge (across the risers
> cast into the bottom plate) is even worse.
>
> When I level the mounting plate to make the wedge level according to the
> wedge's bubble level, the top mounting plate is out of level and the
> carpenter's level says the wedge is out of level using it in the same
> locations as before.
>
> So, what to use to determine level? The top plate, the wedge
> according to the bubble level, or the wedge according to a carpenter's level?
Hi Dave, you know what...I would level the head plate on the pier then forget about it. Having a dead on level base is not
a requirement for a good alignment anyway. The level reference plane is part of the computer's algorithm for the programmed
alignment procedure but that is about all it is good for. With a permanent pier, you will no doubt want to fine tune the alignment
using the drift method. In theory, a level base is not even in the equasion for drift aligning.
However, as a practical matter, being reasonably close to level with the pier or a tripod is still a good idea because you
want the Latitude and AZ adjustments to be independent of each other. If the mount is significantly out of level, a change
is AZ will also change the latitude and vice versa.
In the end, all that matters is that the polar axis is pointing at the pole. It does not matter how it got that way. A few
tenths of a degree disagreement between the pier head and the wedge level and/or and independent measurement are not worth
worring about.
---------------------------------------------------------------------------
Subject: Leveling-- Wedge or Mounting plate? or is it Necessary --part 2 of 2
From: Randy Marsden <jmarsdensan.rr.com> Date: Oct 2002
The bubble level on the wedge (or on the scope) is not very accurate as you have discovered. When I was designing my own wedge,
I did a fair amount of research into the use of wedges for polar alignment both on the web and by talking and emailing to wedge
users. The more I learned and the more calculations I did, the more I became convinced that one major reason that people have
difficulty with polar alignment is that they do not accurately level the wedge base before doing the alignment. This creates
cross-coupling between the altitude and azimuth adjustment. To compenstate for this many users employ a succesive approximation
approach by partially correcting one axis and then the partially correcting the other, slowly converging on an acceptable degree
of polar alignment. This slow process can be complicated by imperfect orthogonality between the azimuth rotation axis and the
altitude rotation axis or by a shift in the axis when the wedge is tightened.
So, when I designed my wedge, I tried to make sure that the axes would not shift unless I deliberately made them move and
that the adjustment axes were as orthogonal as reasonably possible. On the base of the wedge, I mounted a very sensitive bullseye
bubble level. When I set up the wedge/tripod combination, it takes five to ten minutes to get the bubble centered. But it is
worth the extra effort. When I do drift alignment, I make one altitude adjustment, then one azimuth adjustment. When I return
to check the altitude adjustment, it has not needed any further tuning.
If you are using a CCD camera, then I recommend using the camera to detect drift. By zooming in on a star using the camera
software and then centering the cursor over it, you will be able to detect drift much more quickly than using your eye at the
eyepiece. When the seeing is good, I can finish my drift alignment in 20-30 minutes. This is less than half of the time that
my fellow astronomers say that they require. When I am finished my drift rate is less than 2 arcseconds in five minutes (not
including PEC error). Then I do PEC training. Then I am ready to image.
You can find high sensitivity machinists bullseye levels at machine shop suppliers or from McMaster-Carr. I use their part
number 2308A4 which is about 30 times more sensitive than the level used on the Meade wedge (or most other wedges). Before
you mount a level like this on your wedge, have a friend with a machine shop mill a flat onto the top surface that is parallel
to the base; otherwise you will not be levelling the plane on which the wedge rotates.
Subject: Wedge Adjustments on a Permanent Pier --part 1 of 3
From: Dennis Persyk <dpersykworldnet.att.net>
----- Original Message -----From: Mark Whorton <whortoncoe.tsuniv.edu>
I'm in the planning stage for a pier and wedge to be permanently mounted in an observatory. It seems to me that as an alternative
to the Superwedge style designs, a pier with a fixed end plate angled for the proper latitude coupled through four bolts to
the telescope attach plate would allow for polar alignment (see an Maurice Gavin's example at:
<http://www.astroman.fsnet.co.uk/pier.htm> It
seems to me that if it is going to stay in one spot with a close initial alignment to North and the proper latitude, adjusting
the four interface screws is all that is needed and is much simpler than the complex/machined wedges. The only problem I see
is that the four screws are the load path and would need to be extra large for stiffness.
----- End of Original Message -----
I've had an LX90 mounted AltAz, on a homemade wooden wedge, and finally on a Miburn wedge. I now have an AP1200QMD GEM upon
which I mount a plethora of scopes from my friends. I speak from experience of many hours spent in drift aligning and iterative
aligning. My interest is imaging, as must be yours, else why spoil the ease and stability of the AltAz mount?
The system to which your link referred has no means for independently adjusting the RA and Dec axes - there will always be
some coupling. There is no direct means for RA (azimuthal) adjustment. This is the most serious downfall.
The AP1200QMD affords Dec and RA adjustment of 5 arc seconds per degree of adjustment knob twist. The Milburn wedge was about
5 times coarser in adjustment, but still fine enough. My base is level to a couple of arc minutes (as measured by a Starrett
machinist's level) so there is very coupling between the two axes. Drift aligning is still a slow process for me.
In sum, you are correct in assuming that once aligned, it will hold, assuming the pier is adequately set in the soil. I contend
that you will not be able to get it closer than a few arc seconds or tens of arc seconds drift in Dec per minute. If that is
good enough for your needs, the approach is sound.
-------------------------------------------------------------
Subject: Wedge Adjustments on a Permanent Pier --part 2
From: John Mahony <jmmahonyhotmail.com>
I don't understand your complaints here. If you adjust the two top nuts, you get adjustment in altitude. If you adjust the
two side nuts, you get adjustment in the perpendicular direction. Technically, for large adjustments, this would be a long
a line of Dec perpendicular to altitude at north (i.e., the meridian), or in other word, along the 90*-270* hour angle line,
rather than continuously parallel to the horizon as with Az, but since the corrections are small, this difference is insignificant.
As far as how fine the motion is, even though the bolts will be large and hence have a rather coarse thread, the adjustment
is over a large radius, so, for example, if the threads are 10 TPI and the bolts are at the corners of a 1 foot square, a full
turn will amount to 1/120 radians, or about 1/2 degree, which works out to 5" per degree of rotation, the same as your
AP.
----------------------------------------------------------------
Subject: Wedge Adjustments on a Permanent Pier --part 3 of 3
From: Doc G
You are quite right John. In fact, when the tilting plate is perpendicular to the polar axis (that is almost perpendicular
in the first place as with this design) you get very clean adjustment of the final setting of the scope RA axis to the polar
axis. It is the AltAz adjustments which interact. The East/West and North/South adjustments do not interact. Thus this is an
excellent way to mount the scope.
Subject: Wedge Measurements for Pier Height Determination
From: Rod Cook <Cookrodgurulink.com> Date: Nov 2001
John Teel wrote:
> Would someone with a 12" LX200 on a wedge mind taking a measurement of the
> vertical distance from the tripod/pier base to the center of the declination
> axis? I will be using a Milburn Deluxe wedge (still waiting) but I'm sure a
> Meade Superwedge is about the same. I'm trying to determine how high my pier
> has to be in relation to my observatory north wall in order to have a clear
> shot of Polaris. If you could measure this I would really appreciate it.
For a latitude of 32N, the verticle measurement will be around 23-9/16". This is the vertical distance from the bottom
of the Meade Superwedge to the declination axis when the axis is horizontal. I would say this value is + or - 1/8".
For the record, I have the following table:
Latitude åN Vertical Distance
20 19-9/32"
25 21-1/8"
30 22-7/8"
35 24-9/16"
40 26-1/8"
45 27-9/16"
50 28-7/8"
55 30-1/16"
Subject: Wedge to Tripod/Pier Bearing --part 1 of 2
From: Timothy Long <Timlong-family.com>
I tried the trick with a CD between the wedge and tripod. I also tried 2 CDs with a lubricant between them. It worked quite
well but the CDs ultimately crack under the weight. The material that CDs are made from (Macrolon) is quite soft (to allow
it to be pressed like a record) so its not really up to the stresses involved. Butter tubs, on the other hand, are near indestructible!
Someone on the LX200 group at Yahoo suggested this to me. I find it works rather well and it doesn't crack like the CDs.
-------------------------------------
Subject: Wedge to Tripod/Pier Bearing --part 2 of 2
From: Cliff Peterson <cpetersonweber.edu>
For both my pier and my tripod I built a bearing surface so adjustments would be easier. With almost all of the other methods,
(CDs, various plastics , etc.) I always found they tend to "stick" and then jump further than you intended when making
the lateral adjustment. I solved this quite simply by building a "bearing" much like a thrust bearing for that area
of contact.
I started with 1/8" thickness of aluminum plate. marked the center where I would eventually drill to allow the bolt to
pass through when mounting the wedge. Depending on which wedge I was using ( the Milburn was the easiest) I then scribed two
concentric circles, far enough out from the center, to be at the outer area of the tripod head, Every 20 degrees I scribed
a line from the center out across the concentric circles. At each intersection of the scribed line and the concentric circles
I drilled a hole. From the local bearing shop I bought loose balls for bearings that were slightly larger in diameter than
the plate was thick so the ball top and bottom surfaces stuck both above and below the plate. The holes that I drilled were
slightly larger than the ball size. This made 36 ball bearing surfaces to support the wedge above the tripod head (or mounting
plate on the pier) this plate was placed over the tripod head, balls inserted and then the wedge placed on top. You can tighten
down the stuff securely so no rocking or play exists and you can still smoothly adjust things in the lateral directions because
you have created a "thrust" bearing below the wedge that is allowing smooth movement without any sticking.
Subject: Use Central Bolt to Attached Base to Wedge?
From: Frank Sperl @ Mitty Observatory Machine Shop <astrocfl.rr.com> Date: Dec 2003
John Mahony wrote:
> The wedges I've seen (mainly the standard) are not designed
> to allow the use of a center bolt, although I see no reason this
> can't be done. Frank Sperl (Superior Wedge) mentioned that his larger
> wedges are now being made with a center hole, so that a center
> bolt can be used with the 14".
Since Wedges are a near and dear topic to me I offer this. According to the Machinist Handbook the aggregate load capability
of the three 3/8-16 bolts are roughly 1230 lb. and the Center bolt on the 14" adds another roughly 760 lb. capability.
Roughly because your mileage may vary according to the condition of the internal threads of the scope base etc. I would also
highly recommend using a standard size washer under the head of the bolts used to attach the scope.
My name is Frank Sperl, I am the designer and builder of the Evolution Wedge (CNC Machined) and formerly Superior Wedge (Handmade),
I also actively correct the deficiencies found in the Meade Superwedge.
With that out of the way in a proper disclaimer - I always use stainless steel socket head cap screws in any wedge going
back to a client, along with the appropriate nylon and stainless steel washer. Washers are important in distribution of the
load
over an area. Without the washer your contact point on the wedge casting or billet plate is small. I only use the outer bolts
in scopes up to and including the 12" LX200GPS or Classic. On the 14" it is my understanding from various sources
that the center conical area of the base has been beefed up and Meade places specific importance on using the center bolt
along
with the outer bolts to secure the scope. It gives you a 8 to 1 ratio on load under ideal conditions.
Like John said read the question. Since I'm on a roll I would also use quality bolts to secure the wedge to the tripod. Keep
in mind that the center bolt with the large rosette knob and compass is used primarily to tighten the spreader and as a pivot
point for Azimuth rotation. Although it is a rather poor pivot point in that it lacks rotational precision. For more you can
visit my web site:
<http://home.cfl.rr.com/mitty/Evolution_Wedge.htm>
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