Showing posts with label Amateur astronomy DIY projects. Show all posts
Showing posts with label Amateur astronomy DIY projects. Show all posts

Friday, June 26, 2026

Easy to make light and wind screen

Light screen fully assembled and functional.
Most of us are having to contend with worsening light pollution at our homes or other observing sites, and not just the overall sky glow, but nearby lights. Since LEDs became cheap and widely available, people just have to have more and more lighting. Many still think it deters crime (it doesn't), so they add lights, always brighter and rarely properly shielded. I can count at least nine lights, sometimes more, that are consistently in my eyes in my front yard, where I have to observe (trees in back). I also have cars stopped at a nearby traffic light whose headlights point directly at me.

But you can fight back, as I noted in my article on building a "Redneck Observatory," with stuff you have around your house or garage, if you have one. One of the items I used was an old PVC pipe target stand I used to use for .22 target practice out at an unsupervised public range. I added a wood frame and a blanket. I'll use that light screen more often than setting frames up against my garbage cans because I observe more now on a grassy strip on my front lawn and it's sometimes messy to roll the cans across the grass. I decided to make a second one to block out the lights across the street and the headlights and lights 90 degrees around from there.

Some people say they do fine just using a hood over their head, and I do use a hoodie to reduce light trespass into my eye and eyepiece, but I find it's just not very satisfying to see all those lights glaring at me as soon as I raise the hood. I also don't like being lit up like daylight and unaware of what's around me. If that works for you, though, no need to bother with a screen. But I think there is a primodial desire for shelter from outside intrusions that makes the screens, or an observatory, much more satisfying. It's kind of like a snow fort for amateur astronomers!


Light screen

The completed frame (non-transportable version)
The light screen consists of a base of 1-1/2" PVC pipe in two upside down "T" configurations that holds a taller frame of 1x2 or 2x2 furring strips (or fancier wood if the spirit and wallet moves you; that's a piece of old baseboard molding in the picture). Over that you drape a cheap moving blanket and use plastic spring clamps to hold it to the frame. The height depends on where the lights are in relation to your eyepiece height and how much room you want to maneuver. This one stands 72" tall to block out lights from right across the street. Do some measurements at night to be sure you end up with what you need.

Why the moving blanket? You could use a tarp, but I'm in a residential neighborhood and poly tarps tend to be noisy with any kind of wind. Moving blankets are cheap, they block out all the light, they are relatively heavyweight so they don't flap aound much, and when they do, they are quiet. You can also use them as blankets when observing from a recliner or to pack around your telescope.

Schedule 40 PVC pipe is generally sold in the United States in 10' lengths. My car can only fit an 8' length, so I used the self-cutting molding station in the store to cut off two feet of it. You could also bring a hacksaw and cut it in the parking lot, but then you'd be spreading plastic sawdust all over. Pine furring strips or their equivalent are usually 8', so no problem there. 

You'll use four PVC "T" fittings to make the joints. These are friction fit together so you can take it apart as needed.

The process, in a nutshell, is to cut the PVC pipe, assemble it, cut the furring strips, and assemble the frame. The frame just sits in the pipe openings.


Wind screen

Set up as a windscreen with the blanket lower.
The light screen can do double duty as a wind screen if you substitute 2x2s for the 1x2s and stake the feet into the ground or weight them down with something, which would be necessary if you set up on pavement. The  blanket shown is a small 72x40" (actual 70x39").

Depending on whether you sit or stand, and how tall your setup is, you may also want to lower the height, as shown at left.

You can adjust the width of the PVC feet by cutting different lengths for the cross piece. 

Note that  you'll want the side facing us in the image at left to be on the windward side so the blanket is blown against the frame. You can use additional spring clips to hold the lower part of the blanket to the frame if necessary.

Be realistic about how strong a wind it will be able to handle, and build accordingly.

The feet staked into the ground

Staking down the four feet will help keep the screen in place with some wind. I wouldn't set it up in wind over about 15 mph so you don't risk it plowing over your telescope if it lets go. You be the judge. (Put the stakes all the way in. I didn't bother for this picture but it'll keep it anchored better.)

If you're on pavement, use weights instead, but they have to be more than about 10 lbs. per side to hold it in any kind of wind. Leaving space below the blanket at the bottom will help it from becoming a sail. You want the protection at the level of the scope tube.

Parts list

  • One 10" long 1-1/2" (inner diameter, it's marked on the pipe) Schedule 40 PVC pipe.
  • Four PVC 1-1/2" Ts (S-S-S) for pressure applications. Make sure all three openings are 1-1/2" and smooth inside, not threaded. Don't get cleanout Ts, the pipe won't go in straight in the middle connection. The cleanout Ts to avoid have a slight curve to the outer contour.
  • Three 8" long 1x2" furring strips (or 2x2" if  you want it to be sturdier to stand up to higher wind, at the expense of a bit heavier frame). Seems that the big box hardware store selection gets worse every year. Cull through the boards to find the least warped, twisted, split, and otherwise pathetic specimens you can find. Find a good lumber yard instead if you can. You can use treated or untreated wood. Treated will be more expensive and heavier. Unless you are leaving the screen out in the elements (not recommended) you really don't need treated.
  • Eight wood screws. Make sure they are long enough to join the two pieces of wood together firmly without protruding out the back side. 1-1/4" should work for 1x2s (which are really 3/4x3/4) and 1x2s to 2x2s (which are anywhere from 1-1/4" to 1-1/2", pressure-treated being somewhat smaller), as long as you put them through the 1x2 first.
  • Alternative to wood screws: Four 1/4-20 knobs and four 1/4-20 T-nuts (less than 3/4" long). This allows you to disassemble the frame for transportation.
  • Cheap moving blanket or other blanket. A smaller size, like this 70x39" blanket (actual measurement) won't cover the entire frame from top to ground, but you probably don't need to, and it's lighter and less bulky than a larger blanket. Really, any blanket or tarp will work, depending on what you want. You can size the frame to fit whatever blanket works for you.
  • Four steel nail-type stakes (such as these) or weights (bags of grass seed or soil work well on pavement).
  • Four to six plastic spring clamps for holding the blanket to the frame.

Tools

  • Wood saw of some kind
  • Hacksaw or wood saw to cut the PVC pipe (unless you have a suitable pipecutter for 1-1/2" pipe).
  • Electric drill, with a countersink bit that matches your wood screw size (size 6 or 8 should work) and an 11/16" bit for drilling the PVC pipe to accept typical steel nail peg stakes
  • Phillips screwdriver
  • Sandpaper
  • Paint if you want to paint the wood


Build it

You can adjust any measurement as you see fit, especially if you plan on transporting it in your car, but these are my suggested dimensions.

Cut the following pieces of PVC pipe:

  • (4 pieces) 16" each (these are the feet)
  • (2 pieces) 9" each (these are the lower uprights)
  • (2 pieces) 4" each (these are the upper uprights)
  • (1 piece) 24 to 30" as you desire (this is the crosspiece and will determine the width of the frame uprights). The frame in the images at the beginning of the article has a 24" PVC crosspiece, for reference.
All the pipe pieces cut and the 4 Ts
If you want the widest possible spread between uprights and you have to cut the pipe to fit it in your car on the way home from the store, cut a 30" piece off the 10' length in the store.  You can always shorten it, but that will allow  you to cut all the other pieces to the dimensions above for a total of 120". After each cut, use a small piece of sandpaper to clean the cut edges. Sweep or vacuum up all the plastic dust and bits. Wear a mask so you don't get plastic particles in your lungs.

Brace each foot piece in a vise, clamps, or wood, and carefully drill a hole just big enough for the stakes you are using through both walls of each end, about 3 inches from the ends. The stakes will go through these holes into the ground, if you use them.


The assembled pipe base
Assemble the pipe frame as shown in the image at right.

Now, decide how high you need the wood uprights to be. You will be putting the wood uprights into the open pipe holes. I cut two 8" pieces of 1x2 and slip them into the pipes first. This allows the uprights to be shorter and still give me the height I want.

A piece of 1x2 slipped into the upright pipe
Left: An 8" piece of 1x2 dropped into the upright pipe from above will compensate for making the wood upright 8" shorter and easier to transport.

Cut the wood uprights from 1x2s (or 2x2s for a heavier frame). Cut a wood crosspiece to span across the two uprights as a brace. Cut a crosspiece for the top of the wood frame, over which you will drape or attach the blanket. This will probably be wider than the pipe base because you want good coverage with the narrowest base that will be stable. I used leftover wide baseboard molding for my top crosspieces, but you can use a piece of 1x2. 

If you use 2x2s for the uprights you will probably have to shave the four corner edges down some on the lower 8" of the upright so they'll fit snugly into the pipes. The 1x2s should fit without modification.

2x2s shaved down to fit into the pipes
Left: I had to shave the ends of the 2x2 uprights down with an orbital sander so they would fit into the pipes. 

If you're making this more wind resistant, use 2x2s instead of the 1x2s for the uprights, but you can probably stick with 1x2s for the crosspieces. The lighter the frame is, the easier it is to set up, and the more likely you are to use it. The heavier it is, the more wind resistant. It's a tradeoff.

You can fasten the wood frame together with wood screws, two at each joint. However, to make it portable so you can take it to a darker site that maybe has an annoying light or two or is often windy, you can instead drill holes where the pieces connect, then insert knobs through the two pieces and fasten them with nuts or wingnuts. 1/4-20 threads should be fine.

Knobs instead of wood screws for easy disassembly
Left: Using knobs instead of wood screws to attached the frame crosspiece. I have the pieces labeled with painter's tape so I can reassemble it easily. The hole in the side of the upright was a mistake. It's easy for a bumbling woodworker like me to not to get the hole straight, so I had to redo it on the other face of the 2x2. 


Close up of the knob
Right: Close up of the knob attachment point. Use a flat washer on both sides, and a nut or wingnut on the back side. These are all 1/4-20 size threads.







Here is the finished frame for the transportable wind screen. You can drill additional sets of holes in the uprights for a variety of heights.

The completed frame

The pipe base broken down to fit in the car
To pack the screen in a car, you detach the center cross pipe in the base and the crosspiece or pieces of the wood frame. Consider the length of the uprights in this case so they fit comfortably in your car (maybe with ends in the passenger seat footwell, extending through the gap between front seats, and across the tops of the back seats). This is why I like the 8" pieces of wood inserted into the pipes first. That allows you to use shorter uprights.

Once you have everything cut, sand the wood so you don't get splinters and paint it if desired, mostly to smooth the surface further and protect it from dew and other moisture. Bare wood and the white PVC pipe will show up well at night, but if you use it as a wind screen in a really dark sky, you might want to sew or tape some white fabric or tape to parts of the blanket so no one walks into it in the dark. If you have a site that dark, I envy you!

My old light/wind screen.
Why not make the whole screen frame with PVC pipe? I used to have one I designed that used 3/4" pipe, shown at left, and it worked well for a while, but after some years the pipes were either too loose or too tight and setting it up and taking it down became a chore. My wife sewed the fabric with pockets to slip the pipes into and velcro tabs. The wind would often pop it apart and eventually broke a couple of pieces. So I recommend a hybrid PVC and wood frame. It's also lighter and cheaper. PVC pipe has gone up a lot in price.

Friday, December 13, 2024

Build an air travel table mount for a tabletop dobsonian

Mount and table on the workbench
A tabletop dobsonian is a great inexpensive but capable and portable telescope. The mount is a single arm hybrid dob base. The basic ones can be disassembled for air travel, and reassembled at the destination with a screwdriver, but you still have to have a suitable table at your destination to set it on.

However, the scope that I have, the Sky-Watcher Heritage GTi 150P (6-inch), has an electronic go-to mount that I would be very hesitant to try to take apart and reassemble. It's too big to fit in an average suitcase, but I wanted to take the telescope on a dark sky vacation via airline. What to do?

The optical tube assembly (OTA) can go in a 22-inch carry-on hard shell roller suitcase as long as it's well packed. The base that I built, consisting of a mount and table or tripod, would need to be disassembled to fit in a checked suitcase. I have a 26" roller suitcase that I used for this. 

The total weight of OTA, mount, and table is about 25 lbs.

The mount and table disassembled for air travel
While you may not want or need to build this entire table mount, I hope this will give you some ideas if you are putting together your own travel setup.






Why not a tripod?


Some people use a sturdy photo tripod for their travel scopes, such as the Innorel RT90C, a carbon fiber tripod that is often recommended for light travel scopes. I have a few problems with that, though. First, I don't like standing when observing, which would be the case if mounting my 6-inch Newtonian on one. It gets tiring very quickly if  you're out observing for several hours or more, and it's difficult to keep your eye steady at the eyepiece when standing. Second, I was concerned with the stability. Third, and you knew this was coming, a good, light tripod is not inexpensive, especially after buying a mount to put on it. 


Choosing the mount


Svbony SV225 mount
I decided I would buy a lightweight mount and build a custom table for it. I chose the Svbony SV225 alt-az mount. It's relatively inexpensive and sold without a tripod. It handles the 10 lb. weight of the 6-inch tube with accessories very well. The SV225 is just over 5 lbs, so it's the heaviest piece of the table mount, but still quite manageable for air travel. The motions are smooth and the slow motion controls partly make up for the tracking I'd be missing by not having the go-to mount.

I chose not to adapt my existing table for the mount because I wanted to save a bit of weight and would also need to raise the mount so that the mirror end of the tube would clear the table when pointed at the zenith. With a spacer block raising it thus, the eyepiece still sits 2-1/2 " lower than with the stock Virtuoso GTi go-to mount. Also, at 20" in diameter, my existing table would not fit in the suitcase. Case closed.


Building the table


Tabletop and spacer block
Instead, I built a new table out of 3/4" pine plywood in a triangle shape with the corners cut off, a pretty common design to save weight. For the center spacer block I used two pieces of 3/4" plywood and one piece of 1/4" plywood. This raises the mount just enough, 1-3/4", for the mirror end of the scope, including the adjustment screws, to clear the table at the zenith. The block is on the left in the image. The edges of the top pieces are rounded to provide clearance for the OTA. 

I inset 1/4-20 T-nuts into the top of the table, same as my previous tables. The legs have hanger bolts screwed into one end, so they just screw into the T-nuts from underneath. See my previous article on building a table for details. The paper azimuth circle is glued to the tabletop with contact cement and sprayed with a clear matte sealer.

Diagram showing the difference in width between using a triangle and a circle
Making the table triangular instead of round allows for a wider footprint for the three legs for greater stability, with a smaller width to fit in the suitcase. Instead of the corresponding circle's diameter, the width of the table is the measurement from the center of one side to the opposite corner, which is further decreased by nipping off the corners. So a triangle cut from a theoretical circle of a larger diameter can fit where that same circle wouldn't, if you follow me. Basically, you have three legs at the same distance as you would for the circle, but with a smaller width for packing (reduced by the width of the blue arrow in the diagram). I cut the triangle from a theoretical 20" circle. The width in green is 15-1/2", so I reduced it by the 4-1/2" in blue by making it a triangle with cutoff corners.

6" telescope on the table mount
The problem with a typical alt-az mount like the SV225 is that it must be mounted in the center of the table, which then puts the center of gravity of the scope well away from center and makes it easier to tip over, especially when the back of the scope is positioned over a side without a leg immediately behind it. This would be the same if it were mounted on a tripod. To account for this, I angled the legs a little more this time, about 15 degrees versus 10 degrees, to make a larger footprint and give it more stability. The legs are also a little longer to make up for the difference in height of the go-to mount versus the SV225. I made the legs out of 2x2 balusters, just like my other table. They screw into T-nuts hammered into holes in the tabletop 13-1/2" apart.  

While it is more stable, it's still not as stable as I would like. The solution is to add weight below the mount. Yet I wanted to keep it light for travel. I'll get to the that in a minute.

The hardest part of this project was figuring out how to cut the triangular tabletop out of a piece of plywood without first cutting a circle and wasting a lot of the wood. After wrestling with the geometry of it all, I finally figured it out and made the cuts. Whew, I don't like my brain to have to work that hard.

Complete setup with rock weight on lower eyepiece tray
Back to adding the weight for stability. Since I had my original 18" tabletop made from 1/2" plywood that had eyepiece holder holes already drilled into it, I decided it would make a great lower level rack for the table. Not only would it help stabilize the legs, but it would also provide a place to put a large rock (or bag of rocks, or some other "found" objects). Weight really does wonders for the stability of tripods, which is why they sell stone bags for them. Same for this arrangement. It would also give me a place to put eyepieces while observing, since the small amount of clearance of the OTA over the tabletop would not allow for storing eyepieces in holes there. It just fits in my 26" suitcase.

The next problem was how to attach this 18" circular eyepiece/weight rack to the three table legs below the main tabletop. I solved this by wrapping a cam buckle strap around the outside of the legs (the orange strap visible in the image above). The circular board sits nicely on the strap, leaving the eyepiece holes clear. Easy to set up and break down with no tools, screws, bolts or nuts.

Close up of the mount with azimuth circle and pointer
I don't use straight-through finders, so I have a right angle correct image (RACI) finder mounted on the OTA's dovetail bar. I've been adding azimuth circles to all of my scopes, so I added one to this table, too, printing an 8" outer diameter circle from Blocklayer.com. See my article on adding an azimuth circle for details. I use the same magnetic digital angle gauge for all of them. The azimuth pointer is a long strip about 1/2" wide cut from a piece of aluminum roof flashing. It had to reach from the rotating top part of the SV225 base down to the tabletop, while clearing the spacer block. I attached it to the SV225 with Velcro so it is movable when aligning the table mount in azimuth at the beginning of an observing session. The SV225 has altitude and azimuth scales (the black circle below the slow motion cable in the image), but they are very small and pretty much impossible to view while observing.

Tape measure showing eyepiece height
The legs are 14-1/4" long, cut from 2x2 treated deck balusters, with the ends cut at 15 degree angles. I used a cheap plastic protractor to mark the angles and a mitre box with bar clamps to cut them with a hand saw. This puts the table height at 14-5/8" and the max eyepiece height around 42". 

The whole table mount setup breaks down and fits with a bunch of other gear in a 26" suitcase. I do set the arm of the SV225 in the more compact position that it came shipped in, and that requires an Allen wrench that comes with the mount. I also need a small socket wrench with a 3/8" socket to remove the 3/8" center bolt holding the mount and spacer block to the table. It screws in from underneath. This is not something I would want to do every night, but for air travel to and from my destination it's fine. 

Finding a suitable chair


Stool with cushion and tennis balls on the feet
You really have to consider everything when traveling for astronomy. One of the biggest issues was not having a suitable observing chair. Regular folding chairs are too big and heavy for a suitcase. The place I was staying at didn't have any suitable chairs. I normally use a Denver style adjustable observing chair, but an adjustable chair isn't necessary for a scope this small and there's no way I would try to take one on a plane. So I found a small folding tripod chair with the sitting height that I wanted, and added a round stool cushion, fastened to the seat with sheet stays, as well as tennis balls to the legs so it wouldn't sink into soft ground. The stool is only 1.4 lbs. and folds up to into a 17" bag. It's going to be great for short sits while birding and hiking, too (minus the cushion and tennis balls).

This setup worked great on my trip to Arizona Sky Village, and my brother and I were really glad to have the 6-inch along!

Thursday, November 7, 2024

Bino Body Mount - build a travel mount for binocular astronomy

Using the Bino Body Mount while reclining
I recently took a dark sky vacation to Arizona. I wanted to bring my 15x70 Garrett Optical binoculars, but they are 5.5 lbs., and I can't hand hold that with any kind of steadiness. I had previously built a zero gravity chair mount, but I wouldn't have access to a zero gravity chair. 

I was pondering compact and, of course, inexpensive solutions, and came upon this post on Stargazers Lounge. The observer uses a mini-tripod with one leg removed, resting the other two legs on his shoulders. This seemed like a great idea, except you still have to keep your elbows raised, which introduces both unsteadiness and fatigue. 

The Bino Body Mount
Taking that idea a step further, I devised a very simple apparatus that I call the Bino Body Mount, which solves the problem of having to raise your arms by adding a 90 degree handle to each side of a basic wood frame. You don't have to buy a mini-tripod, just a cheap 1x2 furring strip (my go-to wood for this kind of thing), a binocular tripod adapter, a 1" 1/4-20 stud knob, two star knobs, two hanger bolts, a flat washer, two fender washers, two neoprene washers, four wood screws, and two tennis balls (well, three really because they come in 3-packs). See parts and tools list at the end.

The mount breaks down flat for packing by removing three knobs. It's very lightweight, and can be used standing or sitting in any type of chair. Your arms stay at your side to provide comfortable support when standing and rest on the arms of your chair when sitting. As you recline further back toward the zenith, the shoulder bars transfer more and more of the weight to your shoulders, resolving the problem of raising your arms and tiring quickly. The Bino Body Mount also improves the view and fatigue factor with any size binoculars because you don't have to hold them in front of your face with your arms raised. 

Using the Bino Body Mount while standing

For Comet C2023/A3 (Tsuchinshan-ATLAS), I sometimes used the mount standing because it was relatively low to the horizon and I really didn't need a chair. It worked great. I wouldn't recommend standing and looking anywhere near the zenith with binoculars, whether handheld, on a Bino Body Mount, or on a tripod. That's just painful and awkward.


Using the Bino Body Mount while sitting

For objects near the horizon, you can sit up and rest your arms on the chair arms. 

Note: That's a Bino Bandit around the eyepieces. It's a neoprene eyepiece light shield that I highly recommend despite it's relatively high cost because it works so well. 



You're not going to get rock steady views with this, but surprisingly close, and your arms and neck won't get tired. My brother and I spent many hours on our Arizona vacation using these, and they worked great with almost no fatigue. You will primarily see a jiggle from your heartbeat. You can look around anywhere in the sky that you could just handholding the binoculars. You can loosen the knobs to tilt the bino bar at whatever angle works best for you. You can adjust focus with one or both hands.

At this point, I am using the Bino Body Mount for all of my binocular astronomy observations, regardless of whether I'm traveling or not. It's simple, it's lightweight, it's compact, it's inexpensive, it's easy to build, and it works very well.

Club member's Bino Body Mount
Sep. 2025 update: I was out at one of my astronomy club's observing sites recently and spotted a Bino Body Mount made by a fellow club member. He made it without the knobs, but still very serviceable! Mounting a 20x80 Zhumell binocular. 



Mike and his Bino Body Mount
Here's reader Mike with one of the three Bino Body Mounts that he built. Slick! I like the turntable chair mount, too. This is great if you don't want to have to move your chair to look at a different part of the sky. My kind of astronomy! 
















Build it

Thread-to-eye measurement
The critical measurement is the distance from the tripod threads in between the barrels of your binoculars to the end of the eyecups, what I call the "thread-to-eye" measurement. The correct distance places the binocular eyepieces exactly where they would be if you were handholding them. This doesn't need to be super precise- within 1/2 or 1/4" is fine. You can tilt the bino bar when observing to make up for any slight error.

If you have multiple binoculars with different thread-to-eye distances, as is the case with my Meade roof prism binoculars, you just drill a pair of holes in the shoulder bars at the correct distances and you can easily reposition the bino bar as needed. Or you could just make two mounts!

See the parts and tools list at bottom of the post.

Step 1:
Measure and cut

Measure and cut a 1x2 furring strip into five pieces. You can make them whatever lengths that work for you, but I made the two shoulder bars 12" long, which accomodates most porro prism binoculars with an approximately 4" thread-to-eye distance. On a second Bino Body Mount, I cut the bars 13-1/2" long for my Meade roof prisms, since the measurement is about 6" for them. The bino bar (the crosspiece that holds the binoculars) is 11". The two handles are 12". One six or eight foot furring strip will be plenty and leaves some extra in case of "constructor error."

Step 2:
Bino bar

The bino bar
Drill a roughly 11/64" hole in the center of both ends of the bino bar (the 11" piece) and insert a 2" 1/4-20 hanger bolt into each, using the "two-nut" technique (thread two nuts on the end, tighten them together, then screw in by turning the upper nut, screw out by turning the lower nut). The threaded end of the hanger bolt should stick out far enough to accomodate the 5/8" width of a furring strip, another 1/8" for a neoprene washer, 1/16" for a flat washer, leaving about 1/4" for the knob to screw onto. So leave about one screw thread of the wood screw part showing and you should be fine. You can always adjust it.

Drill a 1/4" hole in the middle of the bino bar. This will hold the tripod adapter using the 1" stud knob and flat washer.

Step 3:
Shoulder bars

Various parts labeled
Drill a 1/4" hole in each shoulder bar where the bino bar crosspiece hanger bolts will be inserted. This should be the measurement above plus about 6 inches. So for a 4" thread-to-eye measurement, drill the hole about 10" from the end of the shoulder bar that will rest on your shoulder. Put a neoprene washer between the bino bar and the shoulder bar, then on the outside of the shoulder bar, a 1/4" flat or fender washer and the knob.  

Step 4:

Test the fit. People's bodies vary, so if the above calculation doesn't work, make an adjustment by drilling a hole a little closer or further from the end. This is the important part, so make sure you get it right and it's comfortable for you. Adding tennis balls will give you a little more distance, and putting a thicker pillow behind your head or wearing a hood will give you a little less. It doesn't have to be perfect, just close enough to work for you. 

Remember you can make minor adjustments by loosening the side knobs and changing the bino bar tilt slightly. I like to have the binoculars tilting slightly downward compared to the shoulder bars (see images above), except when observing near the zenith. In that case, I like to have the binoculars pretty much pointing straight out parallel with the shoulder bars, especially when observing in a chair that doesn't recline very far.

I recommend getting pre-cut tennis balls made for walkers. Much safer. But if you cut your own, cut an X or hole in two tennis balls and stick them on the ends of the shoulder bars so they fit snugly and won't fall off easily. This is harder than it sounds. Tennis balls are tough! I used a large folding knife to poke an initial hole, then cut the rest until it fit snugly on the end of the 1x2. See this video, or if  you have an electric carving knife, this video. I always wear heavy leather gloves when working with sharp things near my hands that could slip. 

Step 5:
Handle bars

Attach the handle bars on the outside of the shoulder bars about 7" from the ends that rest on your shoulders with two wood screws per side. You can also add tennis balls to the handle bars for the ultimate in opulence.

Step 5:
Finishing touches

With fender washers under the two side knobs, a flat washer under the bino mount knob, and neoprene washers on each end of the bino bar (to help keep it from slipping without having to overtighten the knobs), test it all and if no further adjustments are needed, sand and paint the wood pieces. 

Completed Bino Body Mount with 15x70s mounted



The final assembled Bino Body Mount (with my 15x70s mounted).






Front view of Bino Body Mount



Front view showing placement of the neoprene washers.




The Bino Body Mount disassembled

The pieces disassembled for packing in a suitcase. This mount has longer shoulder bars with two sets of holes to accomodate both my porro and roof prism binoculars. No tools required to assemble and disassemble. Just unscrew three knobs.







Two Bino Body Mounts!
What's better than one Bino Body Mount? Two Bino Body Mounts! One for me and one for my brother. I hope you enjoy yours!








[1/27/2025 update] Some tips on use:

  • Always carry the apparatus by holding the binoculars. That way, if you forgot to tighten something or it got loose, it's the mount that will hit something, not your binoculars.
  • Apropos the above, periodically check that the three knobs are tight.
  • Some tilting of the binoculars from side to side on the tripod adapter is desirable so that if you are looking off to the side a bit it will stay lined up better with your eyes. 
  • When observing near the horizon while sitting, I like to rest my palms on the side knobs with my fingers curled around the ends of the handle bars, tucking my elbows in for support

Parts list

1x2 furring strip (6 ft.)

Binocular tripod adapter (example)

1" 1/4-20 stud knob (most come in multi-packs- good for lots of projects)

Two 1/4-20 2" diameter threaded five-star knobs

Two 1/4-20 2" hanger bolts

Three 1/4" hole flat washers 

two 1/4" neoprene washers

Four 1-1/4" wood screws

Two tennis balls or pre-cut tennis balls


Tools:

Tape measure or ruler

Power drill with 1/4" and 11/64" (or close) drill bits, and phillips head bit (or screwdriver, or both)

Hand or power saw

Two 1/4" hex nuts and two 7/16" combination wrenches or pliers (to screw in the hanger bolts)

Sturdy pointed knife and heavy leather gloves to make holes/cuts in tennis balls if you don't buy them pre-cut

Sandpaper, tack cloth, paint, and paintbrush

Nice to have but not essential: 

    Mitre box (to make straight cuts)

    Clamps (to hold the wood for sawing and drilling)

Saturday, October 19, 2024

Add an azimuth circle to a your Dobsonian and ditch that straight-through finder

Close up of pointer on azimuth circle
A couple of years ago I added azimuth circles to the bases of my two Dobsonian telescopes, and recently added one to a go-to tabletop dob to replace the often unreliable go-to system. Coupled with a digital angle gauge, available in hardware stores or online for about $20-30, this allows me to dial in the altitude and azimuth coordinates for any object, creating a "push-to" system. I can literally find anything anywhere now without straining to look through a straight-through finder, as long as I can see it in my scope and it's included in my sky charting app. 

The main advantages are:

  • No neck strain looking through a straight-through finderscope or red-dot finder (this was the impetus for me)
  • Ability to find objects in areas of sky without a lot of bright stars for starhopping, or in light pollution
  • Quick and easily repeatable
  • No finicky and power-hungry electronics (the angle gauge takes two AA batteries that last a long time)
  • Inexpensive


What you need and how you use it


Screenshot from Sky Safari Pro 6
You will need an app to look up the alt-az coordinates for an object in real time. As the earth rotates, these coordinates constantly change, and are based on your location and time. As always, I recommend Sky Safari Pro (Android or iOS) as a great all-round app that will list the coordinates and show you the star field once you've gotten close to an object. Even the Basic version has the alt-az coordinates, but for a smaller database of objects.

In the Sky Safari Pro screenshot at left, I have selected galaxy NGC 7331, centered it, and the current azimuth (88.5) and altitude (62.4) are shown in the upper left. Make sure you center the object. If you don't, it will not show the correct alt-az coordinates. Then move your scope tube so the pointer on your azimuth circle is set on 88.5 and your digital angle gauge shows 62.4. Look in the eyepiece and, if you have properly leveled and aligned the scope, the object should be in there somewhere. If not, check the wider view in the RACI finderscope if you have one, find the object, and adjust the pointer as needed.


The following are the steps required to find an object with the azimuth circle/angle gauge method. Steps 1-6 are done at the beginning of each observing session. Step 7 is repeated for each object you want to observe.
  1. Set the telescope base so that the azimuth circle is roughly aligned with either the Sun or Moon during daylight, or any bright object at night.
  2. Level the scope. A cheap bubble level will do fine. I use an app. I made some plywood squares with tread tape on them for rough leveling and use composite shims for fine tuning.
  3. Put in a low power eyepiece and find a bright object that's easy to align on without a finderscope. Just sight along the tube at something not too high in the sky. Once centered in the eyepiece, adjust your RACI finderscope, if you have one, to match.
  4. Look up the alt-az coordinates of the object in Sky Safari or your preferred app. The altitude should match your digital angle gauge plus or minus the accuracy of the gauge. Make sure your gauge is sitting evenly on the top of the scope tube.
  5. Adjust the azimuth pointer to match the azimuth shown in the app. Don't wait too long, as this will be constantly changing.
  6. Look in the eyepiece and you should see the object, or at least the star field around or near the object. Identify the exact location within the field by comparing your view with the star chart.
  7. To move to another object, look up the new object's coordinates and move the scope until they show on the gauge and circle. You may have to adjust the azimuth pointer slightly for inherent inaccuracies if you are in a different part of the sky, but you will be close.
I added right angle correct image (RACI) finderscopes to my scopes to verify I dialed the coordinates in correctly, help identify dim objects among star patterns, or move around an area to look for other nearby objects. You can get by with just having one RACI finderscope and putting a shoe on each telescope, then moving the finderscope between scopes. I do that with a 6x30 finder for my 4.5 inch and 6 inch scopes. I prefer an 8x50 for my 10 inch, and it can handle the extra weight of the bigger finderscope better.

Get a digital angle gauge


This is the easy part. If you have a telescope with a metal tube, pretty much any digital angle gauge will have a magnetic base that will work well with it. If you don't have a metal tube, you can stick on a metal plate or design some other system to attach the angle gauge. You'll need to cover the display with transparent red tape or something to dim it down to acceptable levels.

Digital angle gauge with cover
I chose a Klein Digital Angle Gauge because it has white numbers on a black background, so minimal light, and all I needed to do was cover it with a tranparent red material. I used the plastic pack that the gauge came in as a holder for the red material, and duct taped in a scrap piece of red acrylic I had leftover from resizing a laptop shield and some craft foam. It slips over the gauge with a friction fit. Just make sure the red material doesn't blur the display making it unreadable. The Wixey is another popular digital angle gauge. You can try to find one without a backlight if you are just going to use a red flashlight to look at it.

Making and installing an azimuth circle


There are many variations on the azimuth circle because telescopes are different and observers are different. Check out the megathread Degree Circles on Cloudy Nights for ideas and pictures. The standard way is to make the azimuth pointer movable, usually using magnets. You can also make the circle movable, but that's usually more complicated. You decide how you want to do it, but here's what I did.

Azimuth circle installed on 10-inch
For my 10 inch, I cut a notch in the round bottom of the rocker box and glued a paper azimuth circle to the round ground board beneath that. The azimuth pointer rides on a magnetic strip in the notch so I can adjust it during initial alignment and make subsequent fine adjustments.




Azimuth circle installed on 4.5-inch
For my 4.5 inch, my design of the base did not lend itself to simply gluing on a paper circle and cutting a notch, so I cut a circle out of a 1/8" thick sheet of FPVC, which is a light, semi-flexible vinyl, using a craft knife. I made the cut slowly and wore leather gloves for protection. I had to go over the cut mark multiple times until it cut all the way through. Then I glued a printed paper azimuth circle to the FPVC circle and assembled it below the bearing material disk. I drilled a hole in the center through which the bearing bolt passes. Here's my post on Cloudy Nights about my 4.5 inch project, with additional pictures.



Azimuth circle installed on 6-inch
For the 6 inch, I couldn't separate the round bottom of the rocker box from the triangular ground board for fear of messing up the electronics, so I cut the FPVC into a ring shape, glued on the paper azimuth circle, then sliced the ring in two places and attached it to the ground board with some double sided foam tape.



Close up of azimuth circle showing cuts to fit it to the telescope base
The cuts are next to 55 degrees and 295 degrees so I could attach the ends of the pieces to the "ears" of the ground board that you can see sticking out slightly from below the azimuth circle. I used small pieces of double-sided foam tape. You only need to make two cuts, 120 degrees apart, so you can position the bigger ring piece and then the smaller one to complete the circle.



New table for tabletop telescope
The azimuth circle added 3/4" to the radius all the way around the base. I had to make a new, larger table for the scope because the circle now blocked the eyepiece holders. This new one is 20" in diameter. The original was 18". I took the opportunity to eliminate the unused 2" holes that I had on the old one and make four 1.25" holes on each side, so no matter where I am sitting, I have lots of places to store eyepieces. I also used 3/4" plywood. White paint makes it easy to see where you're putting stuff and makes it less likely someone will walk into it in the dark. See my post on making a table for a tabletop telescope .

Use the website blocklayer.com to design and print an azimuth circle that fits your telescope. Some people take it to a FedEx or another store that will print it for you. I tried that and they printed it slightly oversized, so I just printed it in several pages on my home printer and fit them together. That introduces a tiny bit of inaccuracy, but you're likely not going to get it perfect anyway. It'll still work fine.

The Blocklayer site has a huge number of templates of all types, and it's fun to browse. But for this project, I used Circle Divider templates. There is a green "Metric Version" indicator at the top, which is actually a button to change it to Metric from the default "Inch Version." Leave it showing Metric.

Due to the popularity of creating azimuth circles for telescopes, Blocklayer has added a template for this specifically: Protractor - Setting Circle. It does essentially the same thing as the Circle Divider template, and you could use that instead. It appears they have removed the option to set the scale counterclockwise, which you would need if you had a movable circle and a fixed pointer.

Screenshot from Blocklayer.com
You have many options, including having the numbers on the inside or outside of the scale, black-on-white or white-on-black, size and length of tick marks, numbering of every 10 or every 5 degrees, etc. Choose what you like, but think about readability from where you are observing and using a red light to see it. Change the "Diameter inches" setting to what will work for your scope, then hit "Calculate" or use the slider. The circle needs to fit on your lower ground board or fabricated circle or ring.


These are the settings I prefer:
  • Black print on white background
  • Tick lines (default)
  • Primary increments 10 degrees (default)
  • Number orientation = Radial -90 (so you can read the numbers correctly at the eyepiece)
  • Outer marks - note that if you choose Outer marks, the diameter you chose becomes the inner diameter, so you need to adjust the size so the outer diameter is the diameter you need (e.g., your ground board is 22 inches, and so you need a 22 inch outer diameter circle, or a tiny bit smaller). Font size, tick thickness, etc. will affect this, so check the info in the center of the circle on the Blocklayer page and adjust everything with the sliders until you have it the way you want it and your outer diameter is the correct size.

If you like my suggested settings and have the same scope, you can download the azimuth circle PDF that I used for my Sky Watcher Virtuoso GTi 150P here. If you need a 22 inch outer diameter azimuth circle, here is the one I created for my 10-inch Hardin Deep Space Hunter. The Cloudy Nights Degree Circle megathread has a bunch of other files created for different scopes.

Once you have the circle the way you want it in Blocklayer, select "diagrams to PDF" at the top, and in the page that comes up, select the paper size you will be printing on, put in the file name, and hit the "Trim" button. Full printing instructions are at the bottom of the Blocklayer page. Hit the "PDF 1" button in the lower right below the circle (to exclude printing the tape that otherwise would also print out). 

PDF print preview showing the azimuth circle printed over several pages
Your own computer's settings will determine how you print it once downloaded, but make sure you are printing at 100% and select "tile large pages" or a similar setting that will print the circle over several pages. If you have it commercially printed, make sure they print at 100%. If it doesn't come out right, just adjust in Blocklayer and try again. I like to print a little smaller than the diameter of the ground board so the edge doesn't peel up.

Once printed, check the fit against your FPVC circle or ring. If it's good, glue it carefully onto the circle or ring using contact cement, making sure you get complete coverage with no bubbles or bare spots. Then spray the paper with several coats of a fixative (I use Aleene's Acrylic Sealer - Matte Finish) outdoors because these often have really bad fumes, especially Aleene's. 

Once dry, mount the circle or ring between the ground board and the lower rocker box. For my 4.5 inch, I drilled a 1/4 inch hole to fit the 1/4-20 center bolt, and the circle sits underneath the azimuth bearing plate. Yours might be different. For the Sky Watcher Virtuoso GTi 150P (6 inch), I had to make two cuts to remove an arc 1/3 of the circumference because I couldn't separate the ground board and rocker box. I then reassembled it into a ring and attached it to the ground board with a few small pieces of double sided foam tape. I tried larger pieces of foam tape, but fitting them under the rocker box board was a mess because they would stick before I could get the pieces in position. Smaller foam tape pieces worked much better and it still holds well.

You'll need to make an azimuth pointer. I made mine from a scrap of thin aluminum flashing material I had from a roof job, but you can pretty much use anything. I attached a tiny rare earth magnet to it using duct tape. I couldn't find any glue that would hold permanently- duct tape to the rescue again! Then I took a piece of magnetic tape and attached that to the rocker box board, so that the pointer will move with the rocker box. The azimuth circle is fixed on the ground board and the pointer rotates with the scope. 

For the Sky Watcher Virtuoso GTi 150P, I switched to using a strip of Velcro instead of magnets, because I kept knocking the pointer when reaching for the azimuth bearing lock knob. You can use anything as long as the pointer can be moved over an arc of about 30 degrees. Any less and it will be harder to rough align the scope when you first set it down and still be able to put the pointer within range. Put the pointer where you'll see it easily from your normal observing position. 


Telescope with digital angle gauge and azimuth circle
The Sky Watcher Virtuoso GTi 150P with new azimuth circle and larger table. The digital angle gauge sits on the top front of the metal lower half of the tube.