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  #81  
Old 19-10-2018, 10:32 AM
Billyboy78 (Bill)
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Quote:
Originally Posted by Lognic04 View Post
sounds like you didnt use foil over the mirror?
You use foil for pouring the pitch but not for cold pressing.

https://www.youtube.com/watch?v=s4mXM7HyVJk&t=130s
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  #82  
Old 19-10-2018, 12:15 PM
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Lognic04 (Logan)
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Thanks!
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  #83  
Old 20-10-2018, 05:32 PM
Billyboy78 (Bill)
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No more Mr niceguy! Laid the mirror/ tool on the patio floor, tied the mirror to a post, then got my 1/2 ton block and tackle around the tool and pulled! YAY, moved it. No apparent damage. Shelved for the moment though due to interest in the secondary, in that I'm on coarse grinding and I've got #46 grit everywhere.
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  #84  
Old 20-10-2018, 06:51 PM
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46 Grit on an 8 inch?!!
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  #85  
Old 20-10-2018, 08:23 PM
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I like living on the edge!
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  #86  
Old 20-10-2018, 08:47 PM
sharpiel (Les)
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Quote:
Originally Posted by Billyboy78 View Post
No more Mr niceguy! Laid the mirror/ tool on the patio floor, tied the mirror to a post, then got my 1/2 ton block and tackle around the tool and pulled! YAY, moved it. No apparent damage. Shelved for the moment though due to interest in the secondary, in that I'm on coarse grinding and I've got #46 grit everywhere.
I wish you were videoing or at least taking pics of all this. Seems a shame...
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  #87  
Old 22-10-2018, 02:49 PM
Billyboy78 (Bill)
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I'm not too pleased with the resin lap that I have. The surface is quite sticky and if I start using it, it is going to lock up again, so I've ordered some Acculap and I'll toss what I've got. The plaster tool is junk also, I'll make a concrete one like the grinding tool.
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  #88  
Old 23-10-2018, 05:46 PM
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It would seem the fixed post doesn't like fast mirrors. I think Logan found this out also. Yesterday afternoon I worked for several hours on the 8" with the 6" tool to deepen the centre with #220 using a variety of overhang settings, but without success. Sag went down to 3.6 mm but no further. Then I resorted to manual grinding with #80 using very short strokes COC, small W's and anticlockwise circular motion against the flow of the turntable. So, after a couple of hours we are down to 4.12 mm with a target of 4.5 mm. Pretty pleased with that. Downside is I'll have to finish of the mirror manually including polishing.
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  #89  
Old 25-10-2018, 01:42 PM
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Manual grinding was not in this job description! Did I mention I was 74? After 15 minutes of stroking and my arms are dropping off. Should I shelve it? NOT ON YOUR NELLY MATE!!! Things are getting interesting.

Sag reached, Sharpie good, on #500.
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  #90  
Old 25-10-2018, 05:42 PM
croweater (Richard)
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74 wow Bill. Keep going mate. Watching with interest (and admiration). Photos if you get time. Cheers, Richard
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  #91  
Old 27-10-2018, 04:18 PM
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Fine grinding done. Waiting on the Acculap. Making up a variety of different size tools for the pitch.
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  #92  
Old 27-10-2018, 05:18 PM
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Quote:
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Fine grinding done. Waiting on the Acculap. Making up a variety of different size tools for the pitch.
Ive found acculap works great!
I know it is necessary with a 20, but i wonder if subdiameter tools are useful on a 6?
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  #93  
Old 27-10-2018, 07:27 PM
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i wonder if subdiameter tools are useful on a 6?
It would be good to target a particular zone without ruining other zones.
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  #94  
Old 01-11-2018, 09:47 AM
Billyboy78 (Bill)
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Acculap has arrived in just 9 days from USA. Excellent service.
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  #95  
Old 01-11-2018, 12:21 PM
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How much did you buy?
Acculap is great!
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  #96  
Old 01-11-2018, 03:54 PM
Billyboy78 (Bill)
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How much did you buy?
!
2 KG / 6 packs. Intermediate
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  #97  
Old 02-11-2018, 09:15 AM
Billyboy78 (Bill)
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Originally Posted by sharpiel View Post
I wish you were videoing or at least taking pics of all this. Seems a shame...
Really all you have to do is look at Gordon Waite's tutorials on making a 20" f 4.5 and you see mine. I'm following it to the letter.

When I see the high standard of workmanship on this site makes me want to not show off my stuff-ups. Besides I need to tie down my daughter to load the pics because I am a total noob on that sort of thing.
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  #98  
Old 02-11-2018, 11:40 AM
Billyboy78 (Bill)
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Made up the new polishing lap using Acculap. Came to making channels and started using a saw. Too slow! Broke out the angle grinder with a 1 mm blade, had them done in a few minutes. Interesting phenomenon, the pitch came off in the finest gossamer spiders web. Would have been good for Halloween. My patio was covered in it.
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  #99  
Old 03-11-2018, 12:22 PM
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About 1/2 hour polishing. Took a look at the surface to see what it looked like using a ronchi made out of a fine piece of wire. Straight as a die, very pleased.
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  #100  
Old 03-11-2018, 12:27 PM
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Pics! Pics! Pics!
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