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close to my desired sagitta

crashtestdummy

958 views

Well as per, ive not had much time to grind but ive made the most of the time I have and im now just short of the 12mm sagittal that I was aiming for!!!

Im still in two minds if I should go a little deeper before I cast my tile tool as its much easier to shallow the sphere off during second stage grinding than it is to deepen it if I go too shallow(need to cast a new tile tool and re hog out the depth again).My target sagittal for my focal length is 9.75mm so hopefully 2.25mm is enough extra depth to get me through second stage grinding but I may go to 12.5mm for extra security.the curve doesn't show up well in camphone photos but it looks amazing to the naked eye!!!!hopefully by the end of next week I will have cast a tile tool and started grinding with it :)

11.5mm

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nice curve

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curve doesn't quite show in photos

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close to 40 hours hogging to get to this point!!

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tbh the hardest parts are yet to come.While hogging out is hard work its not particularly intellectual, anyone can do it with a bit of practice but the next stage will involve interpreting a ronchi screen to tell me if im grinding right so its a bit scary.

Big changes are afoot in my life too as im moving from west Yorkshire to Portsmouth to be with the gf full time so we are currently house hunting but think we have found a nice detatched bungalow with a garage which will be my grinding den!!this will put me further away from my mirror knowledge support base so may need to make a few trips back up north every now and again for council :)

nearly 6000 views now,well humbled.hope everyone keeps looking and hope to have another update in a week or so :)

clear skies Rich

addition: a better set of pictures showing the curve as it looked to have a flat/turned down edge in other pics

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Well done Rich all that grinding slurry reminds me of a few week's ago and I need to crack on with mine again.

I've cleaned the edge up on my cement tile too today after the week its had to set but still not got the tiles to stick on as I've been busy with the builds fella.

Should have some more pics to email you shortly.

I'm beginning to see distant galaxies at the end of the very long tunnel!

Let me know when you want the former as your not far off now ;-)

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may pop up some time early next week if that's ok?i actually have some old tiles in the garage that wer can have a look at using if you like although probably better just to sort some mosaic tiles.may be having Friday off,if so will try and sort some out :) thinking I may definitely go for 12.5mm to make sure as its only another hour and a half grinding.

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I'm sure things are fine but looking at the top phot the level looks to be sitting on a flat outer rim? its easy with deep curves to go down to the right depth in the centre only for the curve not to extend right to the edge. Hope I'm wrong.

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It's just shadow from the angle,it's pretty uniform all the way round :) will try nd get some better pics or a pic with the tool on the edge

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Great stuff Rich.

I've no idea what all the mirror grinding jargon is all about but it all sounds good anyway. :)

 

Any ideas where your going to observe from when you move to Pompey?

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theres a few decent areas up near petersfield and the new forest,both about 30-45 mins away then maybe a bi monthly trip to Dartmoor/Exmoor or isle of wight.

 

I have a similar grasp of mirror grinding jargon ,im just well practiced ;)

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Nice one Crash, its really coming along nicely. Looks like a nice even curve so hopefully the next stage will go just as well.

this is gonna be a monster scope once done .

cheers

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