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ATM: Multiple Small Scope Projects


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The "Nanodob", a (very) small Dobsonian :-)

I am aware that this little telescope will look completely funny and out of place against those 20" - 30" Dobsonians or RC-s with computer control that you will receive in this Cloudy nights contest. But, it is very easy to make , and the total cost is a mere 20$. The construction of this telescope started out when I ordered a 60 mm F7 spherical mirror from Surplushed out of pure curiosity.. It costs only 6$.

This is the tiny mirror mounted on a fully collimable mirror cell. The cell is made out of small s****s of wood, cut out with a hole saw. The remote control is included for scale.

The small mirror is glued to the "cell" with aquarium silicone, toothpicks used as spacers until the silicone cures. The mirror does have some sleeks and scratches, but the figure is practically perfect :)

Here is the tube, painted and drying. It is a piece of 75 mm PVC drain tube, with a short piece of 32 mm PVC tube epoxied at the side.
This shall be the drawtube focuser.

As the secondary mirror, I cut a piece of 14 mm wide front surface mirror that I have found in a broken scanner. The secondary holder is a piece  permanent marker pen housing cut at 45 deg.. It is also cut in half on the front side, and a piece of hacksaw blade epoxied inside. This serves as a 2 vane spider

The finderscope is made out of a Tasco 0.96" 3x department store Barlow lens tube. The objective is a 25 mm achromat, and the finderscope eyepiece is a homemade 19 mm Plossl made out of a Surplushed kit. The brass part contains the 19 mm Plossl, and can be focused.
The finderscope brackets are leftovers from a vintage Edmund 4.5" F10 telescope that received a larger finder. The dew shield on the finder is a part of an old vacuum cleaner :) In the telescope focuser, you can see a 15 mm kellner eyepiece.


The mount is a single arm Dobsonian. I used the particle board leftovers from speaker cutouts that I had in the junk bin in the garage. The tube is mounted on a piece of DIN fuse rail via 2 cable wraps. Also, there are felt pads that glide on the boards for smooth movement of the scope

Telescope compared to a CD. It IS tiny :)

The most "serious" observing session this tiny telescope had was the public observation of the Venus transit. I realized that its small size and low height would be perfect to employ it as a projection scope for those who are still not tall enough to reach the eyepiece on the 4.5" F10 with Baader solar filter

The kids simply adored this telescope :)

At the moment, this 60 mm Dob is on a permanent loan to 10 year old Marko, who uses it regularly to observe the Moon, large open clusters and the Jovian moon dance.... The scope easily sustains 90x power with a 5 mm Ortho eyepiece

 

A 11x80 "Ballantine's" finderscope

 

My latest scope that I am building is a 16" F4.8 Dobsonian with a homemade mirror. While the mirror is sent to be aluminized, I started to build other parts for this scope, among them a mighty 11x80 finder. The 80/400 objective lens, 2"  focuser, diagonal, reticule, and  eyepiece kit were ordered at Surplushed. And I had to find a tube to assemble the scope. A Ballantine's bottle can was found, and upon further inspection I realized that the objective lens fits perfectly inside the can, and even the length is just right :) The 2" plastic reflector focuser base was sanded flat, so It can be mounted to the flat end of the tube. The eyepiece is a 36 mm 5 element Superplossl , focused on a vintage military reticule made in 1945. It is very lightweight, and everyone that saw it so far had a really good laugh :)

The "Dobsonian Equatorial" mount

After an unsuccessful attempt in building a EQ mount for the vintage and superb Edmund 4.5" F10 optical tube out of a automobile steering column, washing machine parts etc, I decided to try a different approach. The steering column mount was prone to vibration, although it was given a fancy name "The Subaru-Maytag telescope" :-) (by Adolph Kurt)


"Subaru -Maytag telescope"

 

The inspiration for this was a wood  mount described in Richard Berry-s book, and a modified design that I found on a Belgium site. I used simple friction bearings that are commonly used on every Dobsonian, and made the mount in a form of a German Equatorial. Material of construction is 19 mm particleboard, a steel tube for the counterweight shaft. The counterweight is a old automobile braking drum

Early stage of construction

And, this is how the finished mount looks like. It is by far superior than the old mount. I am thinking about adding a RA drive to it, a small stepper motor should drive a nylon threaded rod that would drive the RA bearing.

8" F6 computer aided Dobsonian


 

The 8" is lightweight, portable and has enough light gathering power to keep a observer busy for a lifetime. The optics and focuser are bought ready made, and the rest of the telescope is constructed from whatever I could find in the garage workshop. Here is the material list :

1. Spider
Vanes holder is a plastic hexagonal 1/2" female to 3/4" male adapter. Spider vanes are hacksaw blades, fastened to the holder with 3.5x16 mm screws. Secondary holder is a piece of PVC 40 mm sink extension, spring between the 2 is taken out of an old VCR.
One M6x60 screw as center screw, and 3 M5x40 screws for collimation.

2 Finderscope
Canadian army binoculars objective, glued to a piece of 50 mm aluminum tubing that used to be a pole for a large sun umbrella
Drawtube focuser was made from a piece of the drawtube that was cut from a 80mm F5 refractor.
Eyepiece is a 20 mm Kellner, with 2 hairs found on my sisters hairbrush as crosshairs
Mounted on a metal "L", which is bent from a piece of lightning conductor.

OTA:
250 mm diameter 1 meter long PVC sewer pipe... cut in 2 sections, separated and held together with 4 metal broomsticks.
The clamps to hold the broomsticks are made from perforated metal usually used to hang ceiling constructions...
Altitude bearings : 200 mm PVC sewer pipe plugs riding on pieces of carpet
Handle on OTA is taken from a welding mask. Counterweight system is a threaded rod and a Meade SCT counterweight

Mirror cell:
2 plywood disks, with springs mounted under DIN fuse rails , springs taken out of a motorcycle clutch, 3 M6 threaded rods for collimation. Mirror rests on plastic sponge pieces taken from a lid of a bed scanner. Side mirror holders and holders for the threaded rods made from 25 mm wide 3 mm thick lightning conductor

Mount: laminated wood tabletop
Bearings : 3 ball bearings riding on a metal plate , metal plate was cut from an old foldable table which had a broken leg.
Leveling : 3 C clamps, cut in half

Eyepiece rack: piece of MDF, cut at 45 deg, usually used to connect parts of kitchen furniture
They can hold three 2" and five 1.25" eyepieces
Setting circles: printed on paper and glued, pointers are furniture magnets
A small bubble level from the hardware store
Handle on mount is made from leftover wood and a piece of the broomstick that connects the upper and lower OTA part

And a yellow rubber keychain :-)

The "special features" of this telescope :

Front side collimation. You can easily collimate the primary mirror while observing trough the focuser.

The 3 threaded rods visible in the picture move the primary mirror.

The OTA can easily be shortened to gain more in focus for a binoviewer or camera. Just loosen the bolts that hold the broomsticks connecting the tube sections, and voila :-)

The telescope is equipped with protractors that enable pointing the telescope to an object via alt az coordinates calculated by a computer.


The altitude protractor


The azimuth protractor. The pointer is magnetic, so it can be easily adjusted if you did not aim the "0" mark perfectly North.


To operate correctly, the scope should be leveled. A small 2 way bubble level is permanently mounted to the base, and the leveling feet are half of carpenters C clamps bolted to the bottom

Most practical and most reliable is the vintage HP 1000CX  DOS palmtop computer, running the " Dob_pc" freeware


To achieve smooth motion in azimuth, the bearing is made out of a steel plate , 3 ball bearings riding on it. Note the ball bearings mounted in the triangle corners.


Mirror cell bottom. 3 rubber feet enable resting the tube on the ground vertically without damaging anything. This is quite handy while loading or setting up the scope. 3 counter bolts to counter the cell once it is collimated.

 

A couple of pictures taken in the early stage of construction

Another view at the telescope

This telescope enabled me to observe some not so usual objects, especially for a telescope this size. Like Pluto, and the G1 globular cluster in Andromeda. And a whole bunch of NGC-s that I would never, or hardly found without the help of the coordinates.

Homemade large tripod


tripod with 25x100 binoculars mounted

This tripod will easily hold your giant binoculars, your 150 mm refractor or even a lighter 250 mm Newtonian OTA! Buying such a tripod (if you can find one that is this tall) will easily cost you more than 400 €. If homemade, it costs under 100 €.
 

After our astronomy club purchased the large 25x100 binocular, it was immediately clear that we will require a solid, large tripod to hold it. Commercial solutions were either not adequate, or way too expensive. So I decided to give it a try with making a tripod at home in the garage :)

 

Materials needed:

40 x 40 mm hardwood 9 pieces, 1 meter long per piece
3" male-male pipe connector (nipple) 1
steel square profile 40x30 or 40x40 30 cm in length
flat steel, 3x30 mm (lightning conductor for ex.) 2 meters in length
4x25 mm wood screws 24
M10 threaded rod 1 meter
M10 wing nuts 9
M10 end nuts 3
M10 oversized washers 6
chain 1.5 meters
rubber feet 20 mm diameter 3
end caps 30x40 or 40x40 (depending on profile used) 3

Tripod head

 

We start with cutting the square steel to pieces 70 mm long. The squares are then welded to the hexagonal pipe fitting,
at 120 degrees apart.
20 mm of the edge of the square, drill 10 mm holes, for the M10 bolts. These will hold the legs of the tripod. Paint with primer, then color of choice. At the end, insert the finishing plastic caps. Picture below shows finished tripod head, with legs already attached.

The leg clamps

A little more metalworking is on the way. We need a minimum of 3, or for better stability, 6 leg clamps. They are basically a flat piece bent to a U shape, and a M10 nut welded over the hole. If you will use this tripod to hold your binoculars, 3 clamps are OK, but if you want to put a larger , EQ mounted telescope, 6 clamps are necessary. Also, paint with primer and color of choice.

Preparing the bolts:

Out of the M10 threaded rod, we need to cut three pieces 140 mm long, and 6 (or 3 if 3 clamps) 30 mm pieces. The 30 mm pieces are welded on M10 wing nuts,  but of course, if you can find such bolts ready made in your hardware store, you can skip this.

Now, some woodworking :)

Each leg assembly is made out of 3 wood pieces, 2 upper part, and 1 lower part.

On 6 wood pieces, drill a 10 mm hole, 20 mm from the edges, and make a 45 deg cut 30 mm from the other end (sketch to the left)

On three pieces, cut a "spike" , 70 x 20 mm.

Round the corners, either with a router, or sandpaper. Paint with whether proof varnish

Assembling the tripod

I found that the easiest way to do this is if you hang the tripod head on the ceiling. Mount the upper wood pairs with bolts and washers. Put the middle wood piece between the 2, and tighten the wing nuts on the tripod head. This will hold the pieces in place until you mark the holes and attach the leg clamps

Glue a coin on the wood under the M10 wing bolt, this will distribute the pressure evenly and the bolt will not damage the wood. Attach the rubber feet with a woodscrew to the end of the "spiked" leg.

To prevent the legs spreading out under weight, attach 3 hooks to the inside of the tripod (picture above)
Spread the tripod legs to 30-40 degrees, and measure the chain length needed. Cut 3 equal pieces, and attach the ends to the hooks. Bend the hooks fully closed, so that the chain is securely attached.

And, that's it :) Depending what you want to mount on your new tripod, you will either want to make an alt azimuth head for your binoculars, or attach a adapter plate for mounting your EQ head.

Binocular alt azimuth mount

 Tripod folded

This is the tripod and 25x100 in action. The observer is 180 cm tall, and the tripod is still not fully stretched! On this particular night, the binocular hunted down an impressive list of more than 150 objects. The complete observing report can be found here


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