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Stellafane ATM: Grits, Polish & Pitch

For hand grinding, the coarse grit sequence of 40, 60, 80, 120, 220 is typical (start at the grit size appropriate for your mirror diameter as given in the section above). Silicon Carbide is used almost exclusively. Fine grit sequences vary more, and are often adjusted based on …


Joy of Mirror Making: Fine Grinding - BBAstroDesigns

The goals of fine grinding are to prepare the curved mirror face so that it is ready for polishing and figuring and make any adjustments of the focal length. Previously in rough grinding we deepened the center of the mirror's face either by grinding …


GRINDING – Astro Khan Telescope Making

You start fine grinding once you are done with rough grinding, reached the required sagitta and the desired focal length of your mirror. In fine grinding, finer abrasives are used, i.e. above #400. I use M301, M303 and M305 for fine grinding.


Fast Mirror Grinding & Polishing - The ATMs Workshop

The mirror ended up with a very smooth, zone free, nearly spherical figure ready for final figuring. Figure 1: Polishing pads applied to a 9 inch grinding tool. Another local ATM has also tried the polishing pads with abrasive and CeO. His own 17.5" mirror took about nine hours to polish out completely.


Grind and Polish a Dobsonian/Newtonian Telescope Mirror ...

Now, you'll use the normal stroke as in fine grinding and polishing agent to get the surface of your mirror super smooth. It's best to do these sessions in at least 1ish hour increments - the polish works better after 10-15 min of warming up from the first strokes and the pitch really conforms best after a bit of friction.


Mirror Finish - Norton Abrasives

The fine grade silicon carbide abrasive and nylon fibres in grade 2SF (soft & semi-conformable), or in grade 3SF(slightly harder & more durable) imparts a finer / brighter finish. By the end of this process, you should have a smooth, bright satin finish – taking the time to remove imperfections at this stage in mirror finishing will make your final polishing step quicker and …


FINE GRINDING THE MIRROR - sidewalkastronomers.us

FINE GRINDING THE MIRROR. After generating the mirror curve by rough grinding it remains for us to smooth it by fine grinding and polishing before finally correcting it to a parabola of revolution. Fine grinding is done in about the same way as the last wets of rough grinding, but with a series of finer and finer grits such as 100, 220, 320 ...


Mirror grinding - scope making

Draw a grid on the mirror surface with a permanent marker (<--picture) Add the usual half teaspoon of grit, sprinkle with water and grind for a couple of minutes, rotating tool and mirror often. Rinse the mirror and inspect the grid lines. If the …


How is the mirror polishing finish done on stainless steel ...

The mirror finish is achieved by mechanically treating the surface with a series of gradually refined abrasive materials. At this stage, the deep scratches must be removed because any surface defects on the final product are very noticeable. After this, the final process involves polishing the surface for 5-10 minutes to form a mirror-like ...


Grinding mirror using CNC router - ATM, Optics and DIY ...

I guess I will have to do fine grinding, but I won't have an appropriate grinding tool because I skipped rough grinding. Yep, your guess is correct. If you already have the tool piece..6" glass... best to just grind like most ATM'ers and have the fitting tool to take you through the rest of the mirror fab.


Build your own telescope part 1: The mirror – Thomas ...

Rough grinding. This step is about making one side of the glass concave. It will give your mirror its overall focal ratio. If you make the centre deep, you will end up with a fast telescope (e.g. F/D = 4) well suited for deep sky observations. On the opposite, a shallow mirror (e.g. F/D = 8) will be performing very well on planets and the moon.


Ed Grinds a Mirror -

The Great Old Grinder looked over my mirror after the first hour and pronounced that I was "pretty much average" in terms of rate and the quality of my work, which was fine by me. Two more people finished up during the second hour, but I wasn't so nervous anymore.


Mirror Grinding Machine | Hackaday

Grinding and polishing your own mirrors is a long, arduous process. Instead of lapping the blank by hand, Laurie Hall built this mirror grinding machine from scratch.


Fine and Intermediate Grinding of Your Mirror | Guy's Math ...

Grinding, Grit, Mirror. 3. Grinding (intermediate and fine): Once you have reached your goal for the sagitta, and inspected it, then it's time to move on to the next smaller grit size and to a more conventional grinding technique. First of all, throw away all of the used newspaper, rinse out the water bucket, wipe off and put away the grit ...


How to Grind a Telescope Mirror in 10 Easy Steps – Starry Nova

Grind the back flat. Try and prevent astigmatism. After having the ground and face of the mirror flat through the 220, you are good to begin rough grinding the curve into the mirror. Do some fine grinding. Proceed and trying getting a sphere. After getting your final abrasive, you can now perform polishing.


How to Make Your Own Telescope Mirror - Instructables

After your finished with fine grinding the mirror you will need to make yet another tool. This tool is called a pitch lap. It is made the same way as the penny tool you made to do the fine grinding except instead of pennies you will use "Pitch". [Fig 6] Here is a photo that shows the tool being pressed against the warmed pitch.


Joy of Mirror Making: Rough Grinding - BBAstroDesigns

31 Grinding the curve into the mirror face can be done by one of the following approaches: …


TELESCOPE MIRROR MAKING HOW TO: Fine Grinding - YouTube

In this video I am showing you how to make a DIY telescope mirror! This is the second part in the series, showing fine grinding in a step by step tutorial.


Grinding Mirror Fine

Grinding the back flat is just the first step in preventing astigmatism. The next step is the proper mirror support. Fine grind and polish the mirror face up. A thin mirror bends over the edge of the tool if it's worked on top, so the problem reduces to supporting the mirror from its underside.


FINE GRINDING THE MIRROR - sidewalkastronomers.us

If the tool is much smaller than the mirror blank, the fine grinding and polishing should be done with the tool on top. It is a good idea to use lukewarm water during the last wets of fine grinding, and also during polishing. Cold water may shrink the mirror face allowing us …


Thin Telescope Mirror Grinding Advice

Grinding thin telescope mirror blanks: Thin glass mirror making techniques differ only slightly from "standard" mirror making practices. Keep these principals in mind when grinding and polishing your thin mirror blank, and you'll be fine.