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Best Way to Grind Down TDE after Finish Figuring?

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#1 msheald

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Posted 11 April 2021 - 06:39 AM

Hello! After much thought (and work!), I think I will forgo correcting the 1mm TDE on my 10" mirror.

 

    Rather than masking it off, I thought I might grind it down after I finish figuring the mirror.

 

    I've read a couple of posts about folks who do this after figuring. What is the best way to accomplish this?

 

    Is there another alternative? For example, is there a black paint that would adhere to the aluminized surface after aluminizing? Best regards.

 

Mike



#2 Steve Dodds

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Posted 11 April 2021 - 10:22 AM

I use these  https://www.harborfr...ocks-36799.html


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#3 Pinbout

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Posted 11 April 2021 - 11:46 AM

I like a rounded edge instead of chamfered 

https://youtu.be/lGMLJNVXV2c


Edited by Pinbout, 11 April 2021 - 09:26 PM.


#4 msheald

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Posted 11 April 2021 - 01:11 PM

Hello! Thank you for your comments.

 

    Is there a concern about glass grit from grinding down the edge to scratch the finished mirror's figure? That was my major concern with grinding out a small TDE after completing figuring. Best regards.

 

Mike



#5 mark cowan

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Posted 11 April 2021 - 02:42 PM

No concerns there, just do it under running water and keep the abrasive tool away from the face.

An alternative to what's mentioned is to get a large piece of flat glass and use abrasive on it with the mirror face down, stroking will remove the edge evenly all around and leave a flat ground edge.

But like Danny I prefer a rounded bevel on the finished edge generally.



#6 Mirzam

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Posted 11 April 2021 - 03:10 PM

I made a turn table with a small lazy susan bearing to help in blacking out a thin turned edge on an 8” mirror. Black enamel adhered well to the already coated surface and the whole operation only took a few minutes.  This would be very simple to do for a 1mm TDE on a 10” mirror.

 

The longest part of the job was centering the mirror perfectly on the rotating platform. Then using a beanbag or some other support to rest your hand holding the brush, slowly rotate the mirror and carefully apply paint.  Best not to drink a 16 oz coffee immediately beforehand. 
 

JimC



#7 Pinbout

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Posted 11 April 2021 - 04:51 PM

I made a turn table with a small lazy susan bearing to help in blacking out a thin turned edge on an 8” mirror. Black enamel adhered well to the already coated surface and the whole operation only took a few minutes.  This would be very simple to do for a 1mm TDE on a 10” mirror.

 

The longest part of the job was centering the mirror perfectly on the rotating platform. Then using a beanbag or some other support to rest your hand holding the brush, slowly rotate the mirror and carefully apply paint.  Best not to drink a 16 oz coffee immediately beforehand. 
 

JimC

A cake decorating stand... spin it by hand while painting out the tde.


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#8 msheald

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Posted 11 April 2021 - 07:47 PM

I thought a rotary Dremel tool might work. That is how I put the bevel in originally and then freshened it up as needed.

 

    Using a hand tool with running water to wash away the grit sounds like a good way to protect the polished surface as well. Best regards

 

Mike



#9 MKV

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Posted 11 April 2021 - 08:45 PM

I thought a rotary Dremel tool might work. That is how I put the bevel in originally and then freshened it up as needed.

Ouch! 

 

To grind off a turned down edge, use a smooth ceramic floor tile as a lapping surface and paint on it a very thinly a slurry of lapping powder (3 to 5 millimicrons in particle size) and water, then invert the mirror, place it carefully on the wet powder, and slowly begin to move the mirror in a W fashion as you slowly rotate the mirror about it's axis.

 

This will quickly put a narrow "flat lip" on the edge of your mirror, removing the TDE. Afterwards, use a very fine diamond file and some water to put a small bevel on the edge to to prevent chipping.

 

Don't be aggressive and overdo it; the lip forms very quickly.

 

The lip can be 2-3 mm wide. depending on the extent of TDE. The 45-degree fine bevel can be as small as 1 to 1.5 mm. 

 

Anything rougher than the finest lapping powder will leave a jagged border on the polished surface. 

 

grinding off tde.jpg

 

PS But if Dremel tool works that's fine with me, as long as the polished surface is not damaged. 


Edited by MKV, 11 April 2021 - 10:12 PM.

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#10 Pinbout

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Posted 11 April 2021 - 09:28 PM

I thought a rotary Dremel tool might work. That is how I put the bevel in originally and then freshened it up as needed.

 

    Using a hand tool with running water to wash away the grit sounds like a good way to protect the polished surface as well. Best regards

 

Mike

With the diamond tools there is no grit grin.gif  Just the glass that’s removed 


Edited by Pinbout, 12 April 2021 - 07:03 AM.

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#11 msheald

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Posted 12 April 2021 - 06:27 AM

Thank you, all!

 

Mike




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