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Rob; in the last photo above, there is a small scope, haning seemingly on the wall, on what appears to be a single arm mount, 4.5 inch???

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You are correct. That is a 1950's Laffaette reflector with a helical focuser...and very nice optics I might add. On a homemade single arm Alt/az mount with elevation adjustment.

This is the resting place for this scope when it is not mounted on its cement pier out on the scope field here at GOMOC.

After getting home from a dental convention today...I went out and began grinding on your 3rd attempt mirror....

Probably should change the thread title to reflect the current situation..

The finish is very fine and now I'm working on a 1/4" of the edge to bring it into the sphere...so I set the machine up to work the edge with roughly 1/3 tool overhang during the stroke. Lots of grit and minimal water drip.

Once the edge's worked on for a session(1.5hrs), I will set up for a cross stroke to blend zones...then back at the edge setup. I'll repeat this repetition back and forth for several sessions.

However....the initial hogging went well because I used a smaller diamond blade(4") to hog out the sagitta....instead of the 9" blade. This gave me a nice curface to begin grinding with.

I have dental convention tomorrow as well...but will work on your mirror when I return as well...maybe around 2:00 pm.

I'll put in some time tomorrow and my hope is to be ready for 12 micron early this coming week.

The edge of the mirror is waay better then the last one....there are some edge chips on the back...but compared to your original blank and the last one I cut out...its nice...r.

Sad to say... ..but this last mirror nightmare caused me to re-evaluate some of my techniques and I am glad I was able to make some changes for the better.

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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soooo................are you getting to the "root " of the problem at these conventions????

Ive got a good feeling about this mirror , Ive already asked about finding 14inch tubing ,minimum, in another thread, will worry about spiders and cells and such until such time as I can afford ot buy them or I fall into them,lol

Still like your set up there in your shop.

I have an early/mid 1980 Tasco 4.5 inch reflector that gives sweet images, but its mount is a travesty,lol.
You ever post images for how you made the single arm mount?

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Not on these pages....it was made years ago. Kinda nifty actually. It is hollow and three sides of the four sided arm were built around a wooden core. These 3 sides were formed to fit the mood core exactly....welded together...when all was good..the core was removed and the fourth side was welded on and the whole thing was finished. It's something to see.

Images of it are floating around CN somewhere.....

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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okie dokie then ....a 14inch tube is not going to be easy,lol.
Time to rethink, truss tube???

hows the feline problems working out, air horms working?

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It's been raining and the beasts are in the house. Soon as I walk in the shop I shut the door behind me(looking for kitties as I do). Back to grinding today.

I haven't heard from the fellow who wanted a 13" mirror blank from me about a month ago...and so I'm thinking of putting that blank on the grinder and hogging it out as well. I'm needing a 13" for the Cincinnatti mill pier I've been working on too....so I might do that if I don't hear from this gentleman like soom.

Grinding..grinding today.

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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wow it went way faster this time , nearly polishing after only what a few days, sweeeeet.
In the first picture you can see the donut also, but as a slight darkening with a bright central peak, and a ighter outer ridg.
These images you show are cool.

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Thanks...Andy.
IT'S FUN....I'm kinda like an open book...I got no trade secrets to hide...or protect.

I'm sure the professionals would find lots of things wrong with my technique and approach.

I'm heading out to the shop now to begin fine grinding on your mirror...so hopefully we'll be testing it some time next week. Hopefully....

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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It would surely be interesting just to be able to play with this 8" setup. If I had the time, I'd wonder what it would look like if the stroke were changed to have a 1/4 tool overhang and polish all the way from one side to the other.

Rob....do you use red rouge to polish?

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Actually..no. I use Cerium. I have rouge. and was going to make my own slurry...but lost energy to do so.

I worked that 8" some more and was able to soften that *donut* quite a bit. However the surface is still rough enough that I might go back to fine grinding to clean it up and really take down that donut...then back to polishing.

Andy's finished up last night with good results. Nice finely soft frosting with no scratches at all.

I'll probably run it a bit more today just to be sure before I begin hot pressing the polishing tool for polishing.

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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