rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8681
Loc: Bremerton Washington
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Quote:
Rob; hey dumb question here, but as your grinding and polishing , regrinding and repolishing, so on.... does the mirror reach a point where you really cant work on it any more??? just a guess but at f/3 thats pretty deep curve, does the center reach a criticle thinness?
Im just wonderin..... 
Generally the distances are not that extreme..and are hardly noticeable. However...working with polishing tools that are not in full cantact can remove glass that is wanted and correcting the anomalies removed glass best left alone.
I am..again remaking my pitch tools..and using softened pitch. The colder weather is just a nightmare for using harder pitch. It just isn't conforming and when it doesn't do that it acts like a cutting tool instead. 
My stove top for heating pitch just burned out and I need to get a new one before I can begin remelting pitch and adding turpentine to soften it.
I'm also quite distracted with my renters moving.... 
Rob(I suck)
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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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droid
rocketman
Reged: 08/29/04
Posts: 4258
Loc: ohio
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Bummer dude.why are the renters moving? I was only asking because I do microstructures here in the lab. And I make blacks to fill empty slots in the holder, and they wear down after only 3 uses.
So will you have to go back to grinding again???
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12 inch Truss Reflector "John"
102mm Celestron C102HD " Carl "
Tasco 7TE5 60mm Classic
Tasco 9TE5 60mm Classic
Celestron Ultima 2000 SCT "Wilma"
Celestron Comet catcher(orange tube)
1960 Edscorp Space Conquerer 6inch f/8
10x50 Bushnell Binoculars.
60mm Telescope Club
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8681
Loc: Bremerton Washington
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I m so embarrassed...I wish to be removed from any mention/association of/with the word *expert*.. 
I was going along very well and had achieved a nice smooth sphere with a slight centeral zonal hump.....easy to remove.
I decided through pressures internal and external to make new polishing tools. (Wize move really)..... 
I made a new subdi tool(with same old pitch) in the hopes it would increase productivity toward smoothness and central hump removal.
The new tool acted like a scoring blade and raised havok with the mirror. I left it to polish(actually destroy) the mirror while I attended patients during the day.
I assumed contact was good and let-er go. However it has been revield that the new tool had serious issues...namely an abrupt edge..not withstanding its poor contact.
Wile running(spinning) off center it roughly dug a trough and hole in the mirror....
I took these shadowgrams 2 days ago....afterwards I went into a deep depression....
Heck! So I ripped all tools to bits and began to start from scratch(no pum intended)
I followed Mark's instructions and softened the pitch with lots of turpentine.
The firt attempt I couldn't get adequaate central contact...  grrrrr.
I had to redo it again. Next time the tool was better and actually was pretty hard to remove from the mirror.
After it was poured I let it run for roughly(not another pun) a half an hour before channeling to permit it to gain full contact.
After less then an hour on the machine ..I will let it run for another hour..then test to see if I had any effect on correcting the trainwreck the subdi created..days earlier
Man..I was so close...it makes me sick.
Well..after picking myself up from my puddle of tears...I'm back in the swing of things.
I'll take images of the next shadowgrams later this evening.
So here are the images of 2 days ago..the day the earth stood still.
This is inside ROC..
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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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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8681
Loc: Bremerton Washington
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Outside ROC
Looks like a freekin hubcap.
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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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droid
rocketman
Reged: 08/29/04
Posts: 4258
Loc: ohio
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Wow the first photo looks liek and innie and the second looks like an outie.Cooool
If it is an outie look at the bright side, it should have a lon.........g focal length now. 
ok....Im sorry dude.
Youll get it, just taken time to figure out , hey would an electric space heater help??
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12 inch Truss Reflector "John"
102mm Celestron C102HD " Carl "
Tasco 7TE5 60mm Classic
Tasco 9TE5 60mm Classic
Celestron Ultima 2000 SCT "Wilma"
Celestron Comet catcher(orange tube)
1960 Edscorp Space Conquerer 6inch f/8
10x50 Bushnell Binoculars.
60mm Telescope Club
Edited by droid (10/27/09 07:48 PM)
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8681
Loc: Bremerton Washington
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After polishing for barely an hour.
If nothin else...my shadowgrams are lookin nice....
--------------------
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
|
rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8681
Loc: Bremerton Washington
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Oh...don't forget the ronchigram from hell.......
It shows you how one poorly adapted tool can make things go South quickly.
The fix for this is a heavy stroke.
I'll first set up for a stroke...then once the defects are minimized..I can go back to spin polishing.
Rob(looking for a bridge to jump off of)
--------------------
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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mark cowan
Vendor (Obsidian Optics)
Reged: 06/03/05
Posts: 2316
Loc: salem, OR
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Hey Rob,
I've seen much worse, and they all eventually straighten out.  Just keep going, the experience is valuable if nothing else.
Best,
Mark
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Brian Engel
member
Reged: 08/25/09
Posts: 95
Loc: Cincinnati,Oh
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Given you are using #73, I don't see how you could ever get good contact.
At those temperatures I would go with #55 - but I am no expert.
BTW if you are planning to make a lot of mirrors it might not be a bad idea to make a pitch hardness tester. That would take the guess work of the pitch hardness.
Quote:
Quote:
I hope you meant it was 32 degrees outside and not inside your shop! 
I think it might be 47~50 in there...... 
I don't have to worry about waiting long to test after polishing....... 
Is that bad...short of the fact I need warm clothes...?
Rob
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8681
Loc: Bremerton Washington
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Quote:
Bummer dude.why are the renters moving? I was only asking because I do microstructures here in the lab. And I make blacks to fill empty slots in the holder, and they wear down after only 3 uses.
So will you have to go back to grinding again???
The renters can't pay the rent......simple.
I don't think so on the regrind...a new pitch tool and a stroke pattern should do the trick to even up the mess...plus I want to avoid too much edge work..I don't want a TDE too.
I'll let it work an hour then test to see if the corrections needed are happening. I'll post images to show any change.
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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droid
rocketman
Reged: 08/29/04
Posts: 4258
Loc: ohio
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ok dokie. I was just thinking that if you were regrinding, it would give you the chance to lengthen the focal length,lol.
Still want to retire to mirror making
Wow I never knew so much frustation went into mirror making.
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12 inch Truss Reflector "John"
102mm Celestron C102HD " Carl "
Tasco 7TE5 60mm Classic
Tasco 9TE5 60mm Classic
Celestron Ultima 2000 SCT "Wilma"
Celestron Comet catcher(orange tube)
1960 Edscorp Space Conquerer 6inch f/8
10x50 Bushnell Binoculars.
60mm Telescope Club
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8681
Loc: Bremerton Washington
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Quote:
Hey Rob,
I've seen much worse, and they all eventually straighten out. Just keep going, the experience is valuable if nothing else.
Best,
Mark
I'm proceding on my schedule.....I will stroke polish for an hour to attempt to eliminate some surface defects...then go back to spin polishing.
The turpentine worked and softened the pitch. I had to use more then I assumed I would..but I was able to get far better results using it.
I'm ordering several softer pitches for these colder days in the shop.
Rob(thanks)
--------------------
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
|
rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8681
Loc: Bremerton Washington
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Quote:
ok dokie. I was just thinking that if you were regrinding, it would give you the chance to lengthen the focal length,lol.
Still want to retire to mirror making
Wow I never knew so much frustation went into mirror making.
It's not mirror making..it's mirror making with a machine.
There is no hands on pressure to correct certain defects..you have to utalize stroke and position and tool size. I will get through this..it really isn't a set back but a step ahead in understanding and experience.
I'll fix it.
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
|
droid
rocketman
Reged: 08/29/04
Posts: 4258
Loc: ohio
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Any snow out your way yet Rob?
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12 inch Truss Reflector "John"
102mm Celestron C102HD " Carl "
Tasco 7TE5 60mm Classic
Tasco 9TE5 60mm Classic
Celestron Ultima 2000 SCT "Wilma"
Celestron Comet catcher(orange tube)
1960 Edscorp Space Conquerer 6inch f/8
10x50 Bushnell Binoculars.
60mm Telescope Club
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8681
Loc: Bremerton Washington
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Quote:
Any snow out your way yet Rob?
Only in the mountains currently. However it was 32* again last night..since it cleared up and the moon was a good winter target with Jupiter near by.
I had some CN friends drop by and I gave them the tour and showed them your mirror on the machine and on the test stand.
They were quite impressed actually...and were moved at the actual detail that can be seen on a mirrors surface.
They too commented on the *inny and outty* views...as you had mentioned. They had a blast visiting...and I enjoyed being their host.
Yours is back on the polishing machine getting corrected.
I'm cutting another blank and have one on the generating table.......
I'm going to cut the one on the table to an f/5...I will be fine grinding it soon and might be persuaded to...trade.
Rob(I would rather work on this other mirror at my own liesure and actually get one to you)
--------------------
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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droid
rocketman
Reged: 08/29/04
Posts: 4258
Loc: ohio
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Your lucky to live close enough to cloudy nighters to have visitors.
Wow , were going through a slightly warmer phaze currently been around 60ish day time and low 50s or high 40s at night , but a couple weeks ago we got slushy rain snow mixture.
"I would rather work on this other mirror at my own liesure and actually get one to you"
you would rather work on this problem mirror at your own leisure, and do another for me, or you would rather work on the one your grinding now f/3?? ish one to me and worry about trading later?
god i cant spell, and Igive up trying,lol.
--------------------
12 inch Truss Reflector "John"
102mm Celestron C102HD " Carl "
Tasco 7TE5 60mm Classic
Tasco 9TE5 60mm Classic
Celestron Ultima 2000 SCT "Wilma"
Celestron Comet catcher(orange tube)
1960 Edscorp Space Conquerer 6inch f/8
10x50 Bushnell Binoculars.
60mm Telescope Club
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8681
Loc: Bremerton Washington
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Quote:
Your lucky to live close enough to cloudy nighters to have visitors.
Wow , were going through a slightly warmer phaze currently been around 60ish day time and low 50s or high 40s at night , but a couple weeks ago we got slushy rain snow mixture.
"I would rather work on this other mirror at my own liesure and actually get one to you"
you would rather work on this problem mirror at your own leisure, and do another for me, or you would rather work on the one your grinding now f/3?? ish one to me and worry about trading later?
god i cant spell, and Igive up trying,lol.
Sorry for the confusion...
I'm grinding out another 13"f/5 mirror and am currently making a new grinding tool for yours.
I plan on regrinding it.....I just can't stand the error and I don't wish to fight with it...so it's getting reground back to a sphere then repolished.
Now...I can either keep on track with yours or just give you the new guy at f/5.
Now new course of problems lies with to hard pitch for the climate. I ordered Gogulz #55 #64 much softer pitch for this coldness. They also are more adaptable.
I'm strugling with pitch that won't adapt well and thustly it figures in all kinds of error. Sooooo
Forget this playing catchup stuff. I'm getting the right pitch for the environment.
So...is it the reground f/3..ish or the new f/5?
I'll get the pitch in a week so I have lots to do by then.
First..making a new grinding tool for both mirrors.
Rob(walking quietly and caring a BIG stick)
--------------------
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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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8681
Loc: Bremerton Washington
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OK....now the verdict.
After I saw these shadowgrams this morning I decided...I'm done trying to use the wrong pitch...trying to correct a trainwreck...and so... Made a new grinding tool(curring over night) and I'm gonna grind the daylights out of this thing and bring it back to sanity.
I am not skilled enough to hand figure out all these errors.
Andy has been notified of the changes and a new mirror is being ground as we speak. An f/5 as originally agreed upon.
This mirror(Not remotely) will get reground back to a sphere and then...when the new pitch arrives(I ordered Gogulz #55,#62)
I'll make a new full size polishing tool.
My bigest mistake was not taking into account the severe change in the weather...when using #73. It's hard stuff and adapts poorly in cold weather. It was OK during the summer months when the shop was 75~80deg.
This thread is not changing...but evolving.
I am still going to make Droid a 13"f/5 mirror..if it kills me to do so.
Here is the last images of the mirror that sent me packing.
Next time you see this trainwreck it won't be recognizable as a hubcap.
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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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8681
Loc: Bremerton Washington
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It's almost a joke.......Like it was my first mirror or something.......
This thing has micro ripple, a central hill with a plane, a 6 zone rile, and a TDE..not to mention poorly adapted lap artifacts.
Looks like something a kid made in woodshop on the wood lathe.....
No more...no more monkey business. Bad pitch and bad decisions created this monster...and only a diamond cutting grinding blade can remedy it..by making it go away.
Stay tuned cartoon viewers......there is more to follow.
One day you can all look back and say.......Rob who?
Me(kids these daays)
--------------------
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
|
rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8681
Loc: Bremerton Washington
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Before I go..thought I'de share some freeky looking shadowgrams of the trainwreck mirror.
Notice the concentric rings around this one.
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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