How to Make Mirror Cell Parts for a Renegade Telescope Using a CNC Router
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- Опубліковано 16 лип 2024
- Gordon Waite shows how to make a "keeper ring" for a mirror cell on a 12.5" Renegade Telescope. Starting with the CAD drawing, Gordon shows how the part is designed and then prepped for CNC cutting. He also demonstrates how the CNC control software works, and shows the CNC router actually cutting the part. Finally, Waite installs the piece in the mirror cell, showing the various features of the spherical bearing support system.
- Наука та технологія
Genius! It's a huge pleasure watching your work. Cheers David
+david duffy Thanks, David! Glad you enjoyed everything.
Really neat design!!
l0ckcr4ck3r Thanks so much. The spherical bearings really make life a lot easier.
Great project!
honorio sergio Thanks, much appreciated!
Gordon, if you tear off a corner on a piece of printer paper you can use t he paper as a feeler gage between the bit and your work piece. The paper is general 0.004" of an inch. Makes finding your Z height fairly easy.
First time watching this video. I was going to suggest the same. To build off of what Driver said, slide the paper back and forth, stepping your bit down slowly to feel for it to grab. That's your reference point.
thank you for educating us. i learned a new thing today. so nice of you to take your time and helping and encouraging complete strangers. sir can you make a video on Foucault testing measurements and how to plot and read the results using softwares
Nagarajan K I've been thinking about making a video on testing. I'll try to free up some time on my next mirror and document the process for a video. Thanks! -Gordon
GordonWaite Dear Mr.Gordon i have posted another request on spherometer . i have a 0.001mm graduated dial gauge with maximum 1mm measurement. what could be the ideal diameter of the sphereometer between the ball bearings.
GordonWaite Thanks for accepting my request
Very nice work!
nirvanix88 Thank you! Have to give a lot of credit to the software and CNC machine... once you know what you need to do, and how you want it to look, the CNC is pretty much perfection every time. It's great, too, to be able to think up some custom feature and be able to get odd and difficult pieces done so quickly.
GordonWaite Yes the CNC lathe is a wonderful toy! But my comment was directed towards the design and fabrication of the whole cell. That is brilliant. The Renegade is a gorgeous scope, although I thought they originally had a smaller (like a ring) upper cage? Someday I hope to give you a jingle about a 20 f/3!
nirvanix88 Thanks, you are very kind! The upper cage has always been had the wooden liner as standard. We've experimented a lot with the thickness, and have now settled on a 1/8" aircraft-grade plywood for the liner. It's very light and very stiff, and quite easy to fabricate. The mirror cell was a tougher design. I've made a lot of different ones before getting to this one. The first ones I did were hard to make accurately. But with the CNC-cut template, it's now easy to get them spot-on. I'm still playing with the "keeper" plastic, though. I'm experimenting with adding an outside set of pieces just to make sure everything is perfectly placed. The spherical bearings are so good that the pieces can move around a lot unless they are gently constrained. Usually the design just snaps into position when the mirror is put on it, but once in a while something gets slightly out of bounds. It's easy to re-align with a quick little shake, but I will get rid of the effect entirely with the outer limiters, I believe. The 20" f/3 is really a joy to use. Every place I set it up, people think it's a 16" because it is so short and the bottom is so compact. It's actually easier to set up than my old 8" f/8! I'm working on a 20" f/3.3 now, as some folks think the f/3 is actually a little too short! That 66" focal length lets me use a slightly smaller secondary, which makes the UTA a shade lighter, and reduces the diffraction a bit and improves the contrast a little. Thanks again for you generous comments! -Gordon
GordonWaite You're welcome. Looking forward to more videos.
Nice learning.. 👍
I have a small question to ask,
If you could take out a moment and help me understand the utility of the three rod end bearings that have nothing mounted in their holes.
Gordon, thank you so much for sharing your experience with all of us! I am in the process of building a light weight hexapod with 14.7" x 0.8" mirror and will most likely use your awesome mirror cell design. Could you please recommend the total thickenss of the plywood rings for such cell for my mirror? I also have a CNC and designing my scope with FreeCAD. It has a great feature, where key parameters like mirror size and FL can be entered into the spreadsheet inside of FreeCAD and everything else can be computed from there. Just an alternative to LUA.
The thickness of the cell isn't really critical. If you don't want protection, make the cell short to save weight and material and fab time. If you want protection from the cell, make it at least 6" tall, if not taller.
In a classic dobsonian, the collimation bolts are at the mid point of the bars that connect the triangles (where you currently have the 3 rod ends meting each other). But in your design, if all the collimation bolts are racked up and contacting the mirriror, then are the triangles doing any support at all? Forgive my ignorance, only tryign to learn from your design. Thanks
Great work. There are rules of thumb out there, but you have real world input so... In your experience, how thick does a mirror need to be to not require multi-point suspension?
Too thick if it’s bigger than around 8”.
Thank you for the great video!
The cell looks very heavy but as you lifted it I thought it must be made of plastic :D
May I ask what it´s really made of?
Ukuhlehleh Thanks for your kind comments on the video. The black outer ring is made from laminated baltic birch plywood that is cut on the CNC machine. It is made in layers, and threaded couplers are glued in between the layers. All of the spherical bearings are stainless steel. The triangles are all baltic birch plywood. The little tips that the mirror sits on are nylon. For a 12.5" mirror, the mirror cell itself probablyonly weighs a pound and a half or maybe two pounds. Plus the tops of the triangles sit only about 1.5" above the floor of the housing. Pretty low and pretty light at this size. For a 20", the stainless parts get a little bigger and a little heavier, but it's still very light compared to a cell that has a square tube welded steel frame.
Baltic bitch triangles instead of aluminum. Genius.
Zero with a brass plate + crocodile clip, battery and bulb, choose the thickness of the brass plate so its easy to just add that depth after the plate is removed.
Yes. Since the video, I purchased the company's zero plate. Works like a charm, and much easier!