Introduction: Homemade Tripod Wedge for SCT Telescope
I have owned a 4 inch telescope for over 30 years. I was never happy with the little tripod legs that came with it. I wanted something I could change with latitudes of various places.
Off to the garage to see what I had on hand..
I looked at all the things I thought that would make a great tripod wedge combination and found I did not really have anything that would work.
The next step was to see what was available on the internet. Has someone else made this before and if so how did they do it? I did not find anything there. Then I researched how other telescope manufacturers were making their SCT wedges work. It dawned on me that I did not have to make the tripod. I could buy a home depot tripod in the store and convert that to my needs. The tripod would fold out and in, be transportable, weather resistant, and did not cost much.
I had my project idea started - time to design
Step 1: Step 1: Design It in 3D
Now that it was narrowed down to what I wanted to make and what I could afford to buy, the next step was to design it around my telescope's dimensions. This is where I used Autocad Inventor to design my model. If it could make it work in Inventor it would work in real life. As with anything new you create there will be minor little changes you did not think of as you design it. This is where I made changes to the drawings as I updated the build. It has to work or it will become just a nice piece of whatever standing in a corner.
The slider arms are a good example of this updating process. I could not find on the internet the right size I needed to carry the weight of the telescope when it pivoted on the base. So I made my own. The star knobs I picked up at Harbor Freight are for a 3/8" bolt. The directions show you how I did all of the construction. If you follow the prints you should be able to duplicate exactly what I am showing you in the first photographs. A good knowledge of reading prints is helpful here.
- Wedge updated sheet 1.pdf
- Wedge updated sheet 2.pdf
- Wedge updated sheet 3.pdf
- Wedge updated sheet 4.pdf
- Wedge updated sheet kit.pdf
Step 2: Step 2 Materials Needed
What you will need is the following:
- A good Tripod that can carry the weight
- Enough 3/4" wood, (use the plans to figure out how much you will need)
- (7) T- nuts 3/8" (mine had little holes in them) I ended up epoxy these in once I was happy with the functions.
- (7) Star handles 3/8" with the threads all the way through
- (4) Nylon balls that are 3/8". (These are so there is no friction on the base when you slide the telescope around)
- (4) bars 1/2" x 20" x 3/16" from a hardware store. I ended up screwing mine into the wood and epoxied the ends together. Sanding them on a 2" sander to make the profile. Like a knife scale sanded knife handle
- Some drywall screws (length depends on your taste)
- A Bandsaw
- Drill press
- Router table
- Scroll saw or Jig saw (for those inside cuts)
- Screw gun with a tapered drill bit for drywall screws
- 2 ton 2 part epoxy and yellow wood glue
- Finish how you want
This is where it will come in handy to have some knowledge of woodworking.
· When drilling metal it helps to punch the center of the hole with a punch to guide the bit in. Drill slowly and you wont over heat the bit. (use this method for the metal sliding bar)
· You may have to oversize your holes so the star knob bolt passes through without any binding. You can use a bigger size bit or a round rasp.
· After you assemble the two bars to the wood ends. Make sure that the screw you use is flush to the metal. You only have to screw in one side. The nylon nut and bolt will hold the piece in place when you are ready to epoxy them together. Use a 2 part epoxy. Once the epoxy had dried sand it down to the profile shape (mentioned in the note 6 above)
· Use sharp bits when drilling in wood. Using a waste board underneath the piece of wood being drilled helps keep the hole clean.
· A router stand is helpful to round the edges and radius the sides. This is not necessary but more for a pleasing look. I used a 3/8 round over bit on mine.
· It is always best practice to drill all of your holes then router or round over your edges.
· You may have to use a vice when end drilling in the wood that goes on the back of the telescope base for the T-nuts. I used a forstner bit.
· When you lay out your pieces try to watch your grain pattern. The longer pieces should go the length of the grain pattern in the wood. On plywood this does not matter at all.
Step 3: Step 2. Assembly
Time to find out how well you did on your cuts.
After you have all of the parts cut out, drilled, and sanded. You should test fit each part to make sure it fits flush with the next piece it is suppose to attach too. Make sure the sliders have enough room to allow the 3/8 bolts to pass through. Make sure your T-nuts are secure and do not bind anywhere or interfere when a star knob is screwed in. Depending on how good you cut your parts out you may need a spacer washer here and there. Dry fit everything before finishing or gluing anything together.
These are the steps I would take to assemble the pieces. (use the pictures and plans for reference)
1. Put together the piece (12) to the tripod first. Your tripod may need to be a custom fit. Start from the bottom and work your way up. I ended up screwing my base into the tripod to the wood from the bottom of the aluminum tripod. The center will get a T-nut
2. Decide how many nylon balls you want to use. and half drill these out. Just insert them so they spin in the holes.
3. Assemble the arms (7)(11) to the the next part (1) with the drywall screws, but don't glue them in. Make sure both arms line up after you screw them in. You also want to make sure you over sized your holes to work with the star knobs so they spin freely. (like in the picture). Counter sink the drywall screw holes
4. Put together the side plate (9)(10) to part (4) that the telescope will attach too. Dry fit the two wood plates like you did the sides from the previous step. Use the drywall screws and don't glue it to the wood. Counter sink the holes
5. Screw in part (5) to the bottom of part (4). Counter sink the holes. Drill out for the 2 T-nuts on the ends so that they are flush with the sides of part (4). use the plans for reference
6. Assemble the sliding arms like I spoke about in the directions and the previous page, or refer to the prints.
7. Once you have built two of these, dry fit them with the star knobs, and T-nuts to the sides of the arms (7) (11).
8. Make sure all your T-nuts work and there is no binding when you screw a star knob in. You want the arms to slide loose when you turn the knobs. But, you want it rigid tight when you tighten them up.
9. Take the part (4) that is assembled and screw it to the sliding arms (8) screwing in with the star knobs toward the top and the star knobs in the middle of (7)(11)
10. It will be up to you to decide what is the best way to attach your telescope to the wood plate that pivots (4). I just used a small screw in the bottom of my SCT and screwed one in there. My telescope fits in the slot on the top and gravity holds it in place. You will have to figure out what works best for you here. I am just showing you how to make your own tripod wedge with a store bought tripod. Some SCT scopes have electronic plug in like mine did. That is where I sized my hole in the center of part (4) so I could plug in my DA and RA slow mo controller.
11. Once you are happy with how it works, take everything apart and finish, glue up and re-assemble in the steps I laid out for you.
Step 4: Step 3. Using Your Tripod
Now show it off to your friends.
Now that you have completed your wedge tripod it is time to take it into the field and adjust the slider arm and the telescope for true north. There are many google articles explaining how to do this type of Polar alignment. The adjustment on this wedge should get you the angle you want in your location. An article on how to do this is here. Some tripods be can flimsy and shaky depending on how much you spend. The construction tripod is built to last. That is what I chose it. I used wood and metal because these telescopes can carry some weight. Having the telescope over the center of the bolt on the tripod makes it very easy to pivot when turning and looking for new things to view in the heavens.
I took care of the balance of the telescope to make sure this works for the telescope I own. I think it might fit an 8 inch. I don't know. But it works really great for my 4 inch SCT. I can shoot some really spectacular photographs with this setup. As anyone will tell you a rock steady stand is essential in shooting clear steady photographs or for viewing.
You can if you want add little chains like I did on mine to keep the tripod from spreading out too far. I really enjoyed making this and hope you enjoy making one and showing it off at your next star party.
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