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Ready to be tested

crashtestdummy

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After the dissapointment of having many scratches in my lovely polished mirror I've been back through 400 and 600 and have now done another 4 hours of polishing with little or no scratching!This weekend I will make the long journey from Portsmouth up the teeside to see John Nichol at his mirror making seminar and will have my mirror tested for the first time.

People who know me know that I'm the ultimate pessimist so you won't be too surprised when I say that I'm expecting a turned down edge and the curve to be slightly too shallow and slight zoning on one section.this is just from what I can see and feel through the lap but by Sunday afternoon I will know for sure.I've currently just broke the 100 hour mark so have a lot of time invested in this project with hopefully only a bit more polishing and figuring to go.if my.mirror ends up needing the curve deepening then there will be no annoyances,I will just crack on and get it done!yes I will be dissapointed but disappointment won't get the mirror finished!!

On an unrelated note-I went out and did a bit of messier hunting in the garden with the 15x70's.it's nice to get some stargazing done from time to time or I will end up losing my way arround the night sky!!!ticked off a few Inc m31,m11,m27,m13,m92,m29.happy days but can't wait to look at them with a 560mm scope rather than 70mm binos!!

Clear skies

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have you found your radius of curvature yet? when i polished the 16" i wet it and bounced a  led tourch of it till it foucsed on the wall measure that distance and half it should give you approx FL of you scope.

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I meant the curve being too shallow not the depth which is ok.I had to grind my edge down quite a lot to get my sagitta right hence why I'm worried about the curve.

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Yes but because of the amount of edge I had to remove(as advised) it will have slightly changed the shape of my tool toa shallower curve so despite the pencil test being perfect it may not have been the perfect result for a sphere.Will soon find out :)

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Good luck, years ago I made a 12.5 inch and didn't quite get it right but after correction by Hinds, I think it was called, it was still in use back in 2005 and recoated twice now. I think it was 1976 it was made. You though at 22 inches would laugh at 12 inches I am sure. I hope it all goes well as 100 hours is a lot of work, bet you have arms like Arnold.

 

Alan 

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