kfrederick
professor emeritus
Reged: 02/01/08
Posts: 666
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Tried a new way to correct a 20 inch f5 with 40 min work between these two pic . The mirror was on top 25 min and on the bottom 15 . Fullsized polisher mirror on top the more offset the more correction it puts in the center and faster .When the mirror is on the bottom the more offset the faster lap corrects the edge more .just messing around having fun// kevin
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kfrederick
professor emeritus
Reged: 02/01/08
Posts: 666
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here is after 40 min work
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kfrederick
professor emeritus
Reged: 02/01/08
Posts: 666
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Helped the edge i think . When i get close i have EDVARD ZYGO it.
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kfrederick
professor emeritus
Reged: 02/01/08
Posts: 666
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just posted this to show alot of correction can go in fast in a big mirror . it needs more work .i got some of this idea from MARK HARRY.
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Mark Harry
Post Laureate
Reged: 09/05/05
Posts: 3126
Loc: Northeast
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Edge looks better in that last shot. I'm not good on Ronchi, but I think the curve has to be a little smoother before it reverses as you go from top to bottom????
Mark
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So many projects, so little time!
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Mike I. Jones
Carpal Tunnel
Reged: 07/02/06
Posts: 1572
Loc: Fort Worth TX
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I think Kevin has some turbulence in the path. We PM'd about building a bubble wrap test tunnel, perhaps 30"x30" cross section and 200" to 210" long to isolate the path.
Mike
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Mark Harry
Post Laureate
Reged: 09/05/05
Posts: 3126
Loc: Northeast
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I noted the turbulence, but I was referring more to what I think is a fairly well developed hole.....?
M.
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So many projects, so little time!
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kfrederick
professor emeritus
Reged: 02/01/08
Posts: 666
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hi mark the mirror needs more work
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kfrederick
professor emeritus
Reged: 02/01/08
Posts: 666
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a fiew more hours of fun
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kfrederick
professor emeritus
Reged: 02/01/08
Posts: 666
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edge needs more glass added .
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Mark Harry
Post Laureate
Reged: 09/05/05
Posts: 3126
Loc: Northeast
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So it's getting more interesting- When are you really going to test it?
Mark
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So many projects, so little time!
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Mike I. Jones
Carpal Tunnel
Reged: 07/02/06
Posts: 1572
Loc: Fort Worth TX
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Can't wait for him to try his hand at the wire test. I sent him a 6" piece of 0.005" diameter tungsten wire, cut from a 3' length I got from Small Parts, Inc.
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8334
Loc: Bremerton Washington
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Quote:
Tried a new way to correct a 20 inch f5 with 40 min work between these two pic . The mirror was on top 25 min and on the bottom 15 . Fullsized polisher mirror on top the more offset the more correction it puts in the center and faster .When the mirror is on the bottom the more offset the faster lap corrects the edge more .just messing around having fun// kevin
I love the correction and production of your central push and your correction of the edge. Good job.
One observation(It's probably out in left field) 
If you use the mirror on the bottom and use lots of overhang to correct the edge...why put the mirror on top to correct the center.....? Why not simply keep the mirror on the bottom and use less overhang with a modified lap working the center and stroke from center to edge?
In this manner you can spend more time on the center and less on the edge in the stroke and you accomplish the same.
Just a thought.
Rob
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www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
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kfrederick
professor emeritus
Reged: 02/01/08
Posts: 666
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a lot of ways to correct .if you think about the mirror overhanging the lap if you overhang enough the weight of the mirror is balanceing on the edge of the pitch so this makes the mirror to become more concave [puting in correction in the center ] tool on top puts the work on the edge of the mirror. i think .i donot know all. yet . ha ha
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kfrederick
professor emeritus
Reged: 02/01/08
Posts: 666
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MIKE WORKING DOWN TO THE WIRE HERE HA HA WORKING ON SETING IT UP THE TEST .THE WIRE IS VERY STRONG WHEN CUTING SOME .VERY FINE IF YOU DROP IT YOU WILL NOT FIND IT THANKS KEVIN
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8334
Loc: Bremerton Washington
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Quote:
a lot of ways to correct .if you think about the mirror overhanging the lap if you overhang enough the weight of the mirror is balanceing on the edge of the pitch so this makes the mirror to become more concave [puting in correction in the center ] tool on top puts the work on the edge of the mirror. i think .i donot know all. yet . ha ha
No..you're spot on..and the advice you're getting is as such too. However, flipping the tool and mirror to achieve this type of correction has been the method for eons. Making polishers with cutouts..and modifications can achieve the same thing without having to do the *flip*.
That's just me..cuz I'm clueless cuz I've been told so.
Good job.
Rob
--------------------
www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
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kfrederick
professor emeritus
Reged: 02/01/08
Posts: 666
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ROB I am just messing around trying to find my way of doing things i like to work full sized tools .correcting a 20 f 5 fullsized .thought i give it a try
Edited by kfrederick (11/10/09 04:28 PM)
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