In my build, the cage was cut on a CNC router from plywood, with threaded T-nuts added to support a truss assembly. The box should be deep enough to allow the mirror box to swing all the way down. It is named after the Crayford Manor House Astronomical Society, Crayford, London, England where it was invented by John Wall, a member of the astronomical society which meets there. PVC pipe makes great drawtubes. At this point, the scope was pretty much finished. The focuser shaft on the telescope is 13.1mm in diameter. I would love to see your build when you are finished with it . I had considered a Moonlite or Featherlite focuser, but I knew from my experience with my 6 inch scope that I wanted a 2 speed focuser, and the price tag of their 2 speed focusers scared me away. I also decided to make a separate mounting plate for the stepper motor, since I figured aligning the shafts precisely would be all but impossible. help eliminate slippage when the focuser is pointed straight upward. I got no response to phone calls or emails after another week, and decided to wait until the primary would be finished in another two weeks. See the images how I plan to assemble it. We all know the problems with focusing. But -- you have to be careful that the mechanism is true and the motor does not have a load on it at any time, otherwise it will 'stall' and stop moving. Knitting needles are Share it with us! Most people will want a knob on To cut the circles, I started with a depth of about 1/8 inch, then lowered the bit and cut a little more with each pass until I was through the board. on Introduction, Very nice build nikon20. I will post the pic of final focuser once ready. This book describes in great detail the steps to build a large aperture truss tube dob, focusing on scopes with a 12.5 to 40 inch mirror. More Homemade Refractor Telescope DIY Erecting Prism Binoviewer Focuser here: Did you make this project? This is the kind of simple off the shelf design I was looking for. This motor is available on Amazon. curated by us, the people behind Make: and the Maker Faire. You need some purple bits Download the Gerber Files. In my build, the minimum eyepiece-to-secondary mirror distance (13) plus the primary-to-secondary mirror distance (57) equals the focal length of 71, which is roughly 4.5 times the width of the 16 mirror. an eyepiece. Thank you for your pages. The 48 inch width of the veneer was close enough to the diameter of the tube that I used it as is. but try for a snug fit if you can. adapter set screws to slide into. Thicker walls also required thicker side bearings so that the outside of the bearings would line up with the outside of the rocker sides. I think I got what I wanted and seems best solution for me. After waiting for the contact cement to dry to the touch, and with my wife's help, I carefully aligned the edge of the veneer with the guideline on the tube and pressed the first inch together. (Technically, it should have been 62.5 for a 12.5 inch f/5, but when the mirror came it had a note on the back that the focal length was 61 inches.) Other supplies that I bought for this project include wood, various bits of hardware, stain and finishing supplies, and a circle cutting jig for a router. There are some test sketches in the "Tests" folder, start with those. All Dobsonian telescope projects are unique buildshere are the notes from my latest version to help get you familiar with the process and determine how youll design yours. If you are (for example) doing a focuser for a catadioptric telescope like a Celestron C-8 or similar, the focus knob has no load on it so this smaller, lighter motor will do the trick. Primary telescope mirror aftermarket, homemade, or custom-made. Helicals are adaptable to both refractors and reflectors, but do not "play nice" with zoom eyepieces because "zooming" becomes a two handed operation to avoid changing focus. Measure the diameter of the exposed shaft. I have built a homemade electric focuser for my Celestron 8SE using a radio control hobby servo and some spare parts. Then it was time to stain and finish. large in diameter (1.6") so that adds to the fine-ness of the focus Another thing, the resolution on the Dumbell nebula seems a bit too high for that telescope. by cranking I started by trying to drill out a metal gear for the focuser shaft. I placed my telrad, optical finder, and an eyepiece on the focuser end of the tube and, using a broomstick as a balance point, found that the tube balanced 22 inches from the bottom. an inch or so apart, so the focuser body could be pretty low profile. on Introduction. Several clamps were used to hold the pieces together overnight. If you found some good surplus lenses, you will have made a stunningly good objective for your scope. Someone is pulling someone's leg here. For about $3 we can buy a tank valve kit that has a threaded 2" i.d. "https://ssl." I also wanted to strengthen and protect the cardboard tube. The specific hardware used for this is described on the Building page. he might just have a $3200 camera, they aren't very hard to come by. Before finishing the tube with a wrap of veneer, I wanted to make sure that the primary was in the correct position. Our websites use cookies to improve your browsing experience. As I understand, you are using it for a refractor. together tech enthusiasts, crafters, educators across the globe. This combination has the best resolution (steps/revolution), so I didn't see any reason to build anything else. But by this time I had thought about building my own scope for several weeks, and getting one off the shelf seemed pretty boring by comparison! exactly 2" with adhesive labels placed one at a time inside the tube think that design would be rigid enough under the weight of a diagonal Because mirror flexure can distort an image, supporting the mirror properly involves building a flotation cell. Once your telescope is assembled, drape black woven velveteen around the truss assembly, clipping it with safety pins. See captioned photos 22-25 here:https://www.cloudyniractor-focuser/ for more detail on building a flush valve focuser, as Bob mentions. That helps with low-profile The cage should be a hollow cylinder about wider than the mirror, with the focuser mounted directly facing the secondary mirror. It was May 12th. When they arrived, they were beautifully and carefully packaged with the secondary already installed in its holder. I found a used 16 primary on eBay. The Focuser and other items: (Scope Stuff). The part is very strong! The arc at the top of the sides needed to have a radius 1/8 inch larger than that of the side bearings to account for the thickness of the teflon pads that would fit between. I had chosen a boxy, rigid design for the binocular scope, so It may need some careful coaxing with a screwdriver. Plan ahead by carefully weighing all components and approximating the center mass of the optical assembly. This motor is available on Amazon. The one company that did provide a price quoted over $500more than I was willing to pay for cardboard! All in all it seemed like a pretty robust design, so I gave it Dobsonians come in all shapes and sizes, from small 4-8 builds all the way up to massive 24-36 creations. Install on Windows 10, this part is pretty straightforward. We use cookies to continuously improve our websites for you and optimize its design and customization. I had some carboy caps that make good knobs. I am working on a diy focuser design for my 6" F/8 telescope and asking suggestions for simple focuser. stronger, but would give me a coarser focus action because of their To place the primary mirror, I installed the secondary and installed the primary in the mirror cell. the tube is cardboard as well, you can also get a quality mirror at telescope.com for much cheaper. My concern turned to alarm when my wife told me that Discovery had charged the balance due on all items to my account a few weeks earlier. Fairly easy to build and could be adapted to suit any SCT focuser. The current needs to be adjusted on the DRV8825. occurred to me that a square turned 45 degrees would give me two flat This might have been tempting if I wanted to build a 6 inch scopeat that size, they say that first-timers do pretty well at grinding and figuring their own optics. It take automatic control of the CCD camera and focuser, and dances around magically on the screen, arriving at perfect focus within about 30s to 3 minutes depending on where you started from. how much travel you actually need, you can cut the tube off so none of Like i said these are not my photos and i cannot coment on exactly how he set it up as i was not there all i can say is i saw the mount he used when he picked up the telescope. Concluding that I would not be able to buy a tube off the shelf, I found a couple of companies that took special orders on cardboard tubes. That way you won't be dropping your drawtube and An electronic focuser, which moves the focus knob through a combination of hardware and software, solves this problem. All i did was supply the telescope as far as his camera equipment i dont know what he used i never saw it all i know is he had my scope for about a month while i was traveling and he gave me these photos. This resulted in a gear that wasn't true and "wobbled" a bit. I got no response to phone calls or emails after another week, and decided to wait until the primary would be finished in another two weeks. in the tube so they'll hit the knitting needle before your drawtube runs Subscribe to the premier DIY magazine today, Community access, print, and digital Magazine, and more. Now I can simply insert the PVC cap on the end of a 4" pvc tube. and an eyepiece. After the pieces were glued together, I used a belt sander to smooth out any rough edges, being careful to keep both rocker sides and both side bearings exactly the same. Likewise, the side bearings are made of two identical semicircles of 5/8 inch plywood glued together, creating side bearings that are 1 inches thick. The rocker arms must also have guides to keep it on the track; flat metal 12 braces lined with ABS plastic work nicely. I brought a saw with me so that I cut it in half to fit in my minivan. Able to make myself using my own humble tools (or toys as the pros will call them!) After another 3 weeks, I was concerned that I had not received the mirror. Step 3The Side Bearings and Rocker Sides. on Introduction. The mount and tripod are pretty much useless for astrophotography. I added three inches for a margin of error and in case I need to rebalance the tube in the future, making a distance of 25 inches from the balance point of the tube to the rocker bottom. I decided to order an aluminum mirror cell from University Optics instead so that the mirror could be supported at 9 different points. Crayford focusers are considered superior to entry-level rack and pinion I had some carboy caps that make good knobs. Here's a detailed response from a thread at CloudyNights:http://www.cloudynights.com/ubbthreads/showthreaded.php?Cat=0&Number=4721255 "The image scale is wrong on the M31 image, fits too much of the galaxy in for even a 35mm chip. It has become an indispensable piece of equipment for me that so beats hacking and filing PVC pipes etc. crafts, science & engineering, design, and technology. The ARtemis module came in a kit form actually just two circuit boards one of which I had to source the parts, build and box myself. Measure twice, drill I did run into a small problem with the focuser. It would cost less and they have a very good reputation. I have already seen some designs on CN, Stellafane and web but still checking if someone has recently made anything simpler. The arc at the top of the sides needed to have a radius 1/8 inch larger than that of the side bearings to account for the thickness of the teflon pads that would fit between. The rocker sides are each made of two identical pieces of inch plywood glued together, creating two sides one inch thick. Since my plan called for purchasing the mirrors and mechanical parts there were several decisions to be made and several vendors to contact. a try. This cost around $100 to build and all of the components came from. The length of the Rocker Front also had to be changed so that the outside edge of the Side Bearings matched the outside edge of the Rocker Sides precisely. It had been described by many as the most important recent volume for anyone planning to build a dob, and I have to agree. Although they don't usually sell these parts, because I had ordered the mirrors from them they offered to sell me the spider and secondary holder that they use in their scopes. This will determine the size of the coupler you will use to connect the stepper motor. My plan for wrapping the tube seemed good, but I am not too pleased with the final result. I was concerned that it would be difficult to find, but I was able to order it from a local woodworking shop. The focuser 'knob' on the Celestron is just a rubber sleeve that usually pulls off easily. I waited until dark and pointed the scope at the sky. This is the upper tube that contains the flat secondary mirror, Telrad finder, and focuser. The last time I checked, that particular SBIG camera used on TelescopeGeek had an eight month lead time.A 20" scope gathers 2.6 times more light than a 12.5" scope, therefore equivalent exposures on this one would take 200+ minutes, at least.
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