TELESCOPE MIRROR MAKING HOW TO PART 1: Rough Grinding
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- čas přidán 29. 08. 2024
- Welcome to my channel - in this video, we will begin to make a telescope mirror from scratch! I'll be showing you the basics of telescope mirror grinding!Here I begin to rough grind the mirror! We will end up with a finished mirror after grinding that we can use to see objects in space with!
Bro I'm 37 and a geek. I love this stuff.
Wow - This is a terrific video, you explain the process perfectly for a beginner (me) Thank You & Keep up the great work!
thank you for the excellent video! i can tell that you have a passion for sharing knowledge and your good at it. You should be proud of yourself. Thank You!
Except spherical mirrors don't provide the proper angle of reflection.
Just to be clear...Are you creating a Spherical mirror or a Parabolic Mirror? Thsnks.
Spherical mirrors are way easier and cheaper to make. Any cheaper telescope will have spherical mirrors. But, if the f number is larger, or Numerical Aperture smaller, this really doesn't matter. It's like the difference between a Chevy and a Porsche. Depends whether you have lots of budget or just want to get from point A to B
To the best of my knowledge, you need to spin cast to yield a parabolic shape. Which, is what you want… if you are going to spend you time and money to do something, well… anyway.
Excellent narration and very knowledgable.
I don't understand how you got the right shape...
Naturally. If you ground it like it is shown in the video it will naturally create a concave mirror and convex tool.
Because a sphere is made of a bunch of circles. For this to work, you have to be very diligent in keeping even. The more gradual the material removal, the easier that is. It won't be perfect when you do it by hand like this, to make it perfect you have to make a machine to automate the process. The point here is that you can make a good enough mirror to get started for way easier and cheaper than a super fancy telescope. You totally can automate the lapping process, but you can also imagine how much work that would be, and a beginner needs easier quicker reward for his efforts, so he's motivated to push on
This is a very informative video! Thank you!
Discovering dobsonian scopes brought me to mirror making...
If you are putting a flat tool, on a flat blank how do you get concave shape?
Are you applying even pressure evenly across the tool?
Is it the characteristics of "the strokes" that do it?
Thanks Logan.
Subscribed.
My understanding so far is that it's the characteristic of the strokes and the relative size of the tool Vs blank, but since he says the tool may be as big as the blank I think that means the push and pull means that more pressure is placed on the edges of the tool than the centre in that case but perhaps the grind is unstable so that any deviation is amplified because the tool edged will be proud from the perspective of the mirror surface as it begins to curve.
In other words, the blank sags a little when pulled halfway off the tool. Mine had a handle on the blank. I just walked around. Pushed and pulled it. Wash it off, wet it, point toward Sun. You can see the focal length change.
An even simpler explanation - The tool is always grinding away at the centre, since the strokes used are always catching more than half the blank at once. The edges don't get cumulatively ground as much as the centre - that is, there is always an outer sector of the blank which is NOT in contact with the tool. The central area is always in contact on every stroke. Doing this, you are guaranteed that the centre will be deeper and will end up with a dished shape. As you go from the centre to the edge of the blank, the amount of cumulative grinding decreases smoothly. The uniformity of the dish (i.e. the variability of the height around the edge relative to the centre) depends on rotating the blank regularly and evenly.
Tanks from Iceland. Good video
Thanks!
great vid !
Hello from France texereau's addict ;)
Hah nice! What a good book!
This is great! Would a curved tool help? A 3D printed blank could come with the necessary curve, with tiles epoxied over the top. I do a lot of 3D printing and robotics and I am wondering how 3D printing could help. Maybe a simple grinding and polishing machine would be useful, tho cave man work does have a certain appeal.
For a good mirror, tolerances are close to quarter wavelength, unachievable by 3D printer… and for the tiles glued in it, you don’t really need any pre curve in the tool.
how many hours of grinding? might do well to use 3d printing and arduino or something to machanize and automate the grinding process- then apply to 30 inch glass plate
How come you created the arc from a sphere? A parabola is the correct shape to properly focus light. Your cad software should be able to do that easily. There is a phenomena known as spherical aberration that is caused by using a spherical mirror.
Looks like a used electric pottery wheel would make the job a lot faster and easier.
Logan... A very skilled young mirror maker has that name. He made very thin 18" mirrors. Same one?
Liked and Subscribed. Thanks for making this tutorial :)
Thanks Pinak!
Awesome dear best wishes definitely going to try
manoj india
Thank Manoj!
Nice work! 8" f/7..... planet killer I take it?
Why didnt you use your drill based grinding machine for this mirror?
Could you please tell me where you got the plastic template to measure the rough curve? Is there somewhere to find this to print out?
This was so interesting Logan! Keep up the awesome work. : )
Thanks!
This is awesome dude
Yeah, I would love to do this. All I'm missing is the glass. You can't get it anywhere.
Discovery world for the kit.
Hii Logan, thank you for sharing this beneficial process. I have a question.
Would you please tell that is the tool in flat shape or in the parabolic shape?
I will waiting for your reply 😊
Hi, thanks for watching! The tool starts out flat!
@@AustralianAstronomy does the tool get curved itself while griding? What if the mirror gets convexed 😅?
Cool beans man
Your going places brother
Is the tool flat?
Logan where can the glass for the mirror be purchased? I live in Brisbane. I've watched all your videos and you've done an excellent job.
Hi John,
My route would be to ask your local astronomy club esp. if they have a telescope making section, you'll likely find people who could sell you a blank, if not you could ask around on facebook or similar platform in astronomy groups. Cheers!
Thank you very much for the information Logan.
Maybe you can share this info there if anyone you know is interested.
Is there any thing special to these glass mirrors? Can you order them anywhere?
The only thing is is they have to be stress free so well annealed, for good measure I'd go through an astronomy mirror retailer. Cheers!
Do you apply the reflective surface at a later stage? Cause your base is just a peice of transparent glass right?
Yup. You send it in to a business that has a chamber that vaporizes aluminium which then deposits onto the glass making it a mirror.
@@UpcomingJedi ohhhh okay. You don't have the name and info of this business by any chance?
I'd have a lot more confidence that this is going to work if your work area wasn't such a mess. But I'll watch the remaining videos to see how this comes out.
Where do you source your billets I can't seem to find anything
How long did this take you to grind down eventually?
Can anyone please tell me . Where i can buy mirror for grinding
Cloudynights, or gotgrit
Go bigger!
It's flat tool , and what is the size of tool
Can you do with home tools?
Yeah, you make the tool with regular plaster like his.
Gee, I think I'll grow my own rubber and make some tires. Really, it's good you know how to do this and enjoy it, but this ain't for me.