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Fixed post grinding complete

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#1 Stargazer

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Posted 21 August 2019 - 08:21 PM

Hi all,

 

   After the failure of my first "porcelain" tile tool, I ended up getting glass tile mats

with 1x1  squares.epoxied these to my original 15" F-5 pitch lap base and went at it.

 

Took a bit of manual labour with 80 grit to get them set close enough to the curve of

the glass so the tool would spin properly on the glass but once it did things went well.

 

worked with 80 grit and maybe 3/4" overhang and 30 pounds of weight on top of the

tool to deepen curve  then I switched to 120 grit to smooth things out, ground

there till I was sure tool and glass where close to mated as possible then I moved the 

tool out to 1-1/2" overhang and ground with 120 for 1 hour, once everything was working

good and pit size was the same I switched to 220,with 15 lbs weight on tool ground for

about 1/2 hour then moved the tool out to a 2" overhang and ground for 45 minutes more,

RoC was 183.

 

Switched to 320 with 10 lbs on tool and ground for 1 hour, did marky test after 45 minutes

and confirmed the surfaces of both the glass and the tool were mated,

 

Next was the 25 M with no added weight and did 1 hours with this, tested for pit, tested RoC

to be 182.5.

 

did 9u next for 50 minutes then had a big bo bo "scratches" tried for 20 minutes to grind them

out with the 9u but even though it help, decided it was probably 2 hours work to fix this bo bo

so I instead went back to 12M ,after 40 minutes with the 12M the scratches were gone so off

to 5M this time

5m went real good, 40 minutes worth, no pits and sharpie test confirmed real good mating of

tool and glass. I was so impressed that I decide to go the one step further and did some 30

minutes with the

 3M, all end up great, never so much as saw a sleek and the pits are all even

in size, best of all the RoC is currently 181"., not bad for a 180 RoC target eh.

 

Polishing is next, will keep ya posted.

the 20" glass was F-5.125 and I was changing focal length to an F 4.5.

 

Thanks


Edited by Stargazer, 21 August 2019 - 09:05 PM.

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#2 Pinbout

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Posted 21 August 2019 - 08:27 PM

I like pennies 


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#3 Stargazer

Stargazer

    Vostok 1

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  • Loc: NewBrunswick, Canada

Posted 21 August 2019 - 09:07 PM

Sorry Danny, I hit wrong button before I was even finished typing,had to do an edit 


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