Revamp of club 12" Dob scope commences.

Dave Lillis · Post by **Dave Lillis** » Thu Jun 11, 2009 6:32 pm

Cool, so long as it wont break and doesnt weigh a ton.
Its worth a try.

Frank Ryan · Post by **Frank Ryan** » Thu Jun 11, 2009 7:36 pm

I cant say it won't ever break because obviously
it's not unbreakable but Unless the whole thing is dropped onto concrete upside down from a height or
someone drops a heavy object onto it it should be fine.
Even at that,
if in the event someone did,
it wouldnt shatter or break into pieces, just crack
and hold togeher.
I can silicone it onto a light timeber backing (such as the black one
already on it) and it could be repaired in the future if needed.

I don't think youll get anything smoother.

Dave Lillis · Post by **Dave Lillis** » Sun Apr 17, 2011 12:50 pm

Hi All,
Well, we all saw the big coffin hard at work in the recent GAM event, personally I'm delighted with it, gone are the embarrassing nights where you couldn't aim it, cant find anything through it, it was basically useless and would put anyone off!!

It's now easy to use, the telrad is the bees knees.!!!!
I used my laser collimator to collimate it, its optical quality is excellent, and using it with the telrad is a dream.
One last issue is the azimuth axis, it's a little stiff.

Frank,
Have you been able to get the glass you mentioned previously, getting this sorted would be fab as its the scopes last remaining problem.
The spring has helped to some extent but not as much as I had hoped, one thing it has fixed is the wobble of the tube on the rocker box.
So astromart beckons as we need to get the following,

1, A nice 1.25-2 inch adapter, one with 2" threads so we can put in a filter when needed.

2, A sliding counterbalance weight system, like one for a 14"lx200 would be ideal, especially if we get heavier eyepieces.

3, An eyepiece case like the one used with the 10" scope, from maplin.

4, Eyepieces, I know we decided to get some a year or 2 ago but never did, now we should as this scope is now viable and quite usable. We need to decide a budget for these as you could go too far, also keep in mind thta this thing is an F5, not every eyepiece will work with it.

5, A good laser collimator.

6, mirror recoating, this can wait till last to be honest.

so guys, anything else, what do you think?

Frank Ryan · Post by **Frank Ryan** » Sun Apr 17, 2011 1:25 pm

Whats the measurement of the base again?
I think it was 505mm x 505mm?

Dave Lillis · Post by **Dave Lillis** » Sun Apr 17, 2011 2:47 pm

well Roy, can you get out the measuring tape when u get a chance.
interms of the collimator, a 2" laser and a glatter tublug would be ideal.

http://www.optcorp.com/product.aspx?pid ... -137-12347
&
http://www.optcorp.com/product.aspx?pid ... -137-12343

& this for the counter weight
http://www.optcorp.com/product.aspx?pid ... 3-184-2485
I have this on my 12", I like it as its effective, very low profile and hugs the tube so doesnt get in the way.

and this for the 2"-1.25" adapter
http://www.teleskop-express.de/shop/pro ... mring.html

Will I put up an ad. in astromart for these ?
I'd recommend we hold off with eyepieces till we see what this lot could cost us.

Dave Lillis · Post by **Dave Lillis** » Sun Apr 17, 2011 4:35 pm

and just so people know what was done to the scope so far (no need to thrawl through 5 pages of stuff)

1, new sturdy primary mirror cell
2, new secondary spider and mirror cell
3, removal of old heavy tubular inner mirror supports
4, access panels for the primary and secondary mirrors, aids collimation and mirror removal/cleaning
5, new 2" focuser
6, addition of a telrad finder, dumped old (useless) finders.
7, addition of counterweights in the base and top of the scope.
8, addition of a tension spring for the altitude axis
9, varnishing of all wooden outer surfaces
10, addition of brass carrying/lifting handles
11, complete replacement of ground section of the rocker box
12, center dotting of both mirrors

Frank Ryan · Post by **Frank Ryan** » Mon Apr 18, 2011 6:12 pm

Not to mention the many nights of
talking to her and telling her
"it'll be ok Dobbie, we're all here round you,
stay away from the light..
STAY AWAY FROM THE LIIIIIGHT!"
..and such

John O'Mahony · Post by **John O'Mahony** » Tue Apr 19, 2011 10:19 pm

That scope was truely resurrected from the dead. It should be nicknamed "Lazarus"

Dave Lillis · Post by **Dave Lillis** » Wed Apr 20, 2011 9:46 am

hmmm, looking again, that collimator is bloody expensive and from what I read its for off centered (possible) primary mirrors, i.e a primary on a sling, the dobs mirror is in a metal frame, it's centered and cant move, so a simpler barlow will do.

Dave Lillis · Post by **Dave Lillis** » Wed Apr 20, 2011 8:10 pm

There is no massive rush on any of this, we can discuss this stuff in the may meeting.

Dave Lillis · Post by **Dave Lillis** » Mon Jan 23, 2012 3:18 pm

Hi All,
With the IYA April observing sessions in mind, I got the 12" scope from Gerry today and am in the process of tidying it up abit, it needs some small routine maintainance. I got some black paint for the inside and some more antique pine varnish for the outside, It needs a recoat to liven it up abit.

I've taken off the stickers, most were destroyed anyway and will need replacing, I've taken the primary mirror out and will be giving it a good clean and recollimation when I put it back in.

I've also angle-grinded off any sharp screw ends, and taken off the extra thread bars on the spider vains,

The primary mirror hasnt degraded at all since the revamp a few years back, a testament to Frank and Gerry who've looked after it properly, welldone guys !!

With Gordon and I at astrofest in February, we'll be keeping an eye out for a good counterbalancing system and the tublug laser collimator.

Dave Lillis · Post by **Dave Lillis** » Sun Feb 12, 2012 9:09 pm

Hi,
Ive the scope varnished up and new black paint done on the inside, its looking brand new now. Ive also cleaned the mirrors.

Astrofest was a bust for parts.
The meade counterweight system is just waaaay too expensive online and cant be got secondhand.
So, I had another look and this is what I've found at scopestuff.com

#MRDN , a 24" rail
#CWD3, a slider for the rail for mounting a weight (weights we already have)
Also, the yellow altitude bearing is looking worse for wear, so the following will fix it.
#LE14

So thats a total of $57, I'm gonna ask them whats the shipping.
So thats the altitude axis and counterweights sorted.

Also, Gordon and I had a discussion about the stiffness of the azimuth axis. Its on the verge of making the scope unusable. We have teflon down there but the sheer weight of the thing makes it very stiff.
We're goona try out 4 small castor wheels on the base of the rockerbox, I'm hoping it'll be better then whats there at the moment.

Dave Lillis · Post by **Dave Lillis** » Tue Feb 14, 2012 2:37 pm

Just to keep you all updated.
I put 3 wheels on the base of the rocker box,
omg, OMG!!, WHY DIDNT WE DO THIS BEFORE, ITS PERFECT!!
its now as good as any rockerbox dob you could buy.

I'm pricing the counterweights and tublug, I'm hoping to order them over the next 2-3 days or so, and have them in the next 2 weeks,
and then all we need organise is the mirror recoatings, which we couldnt try before the April events anyway incase we didnt get them back in time.

Simon Kenny · Post by **Simon Kenny** » Tue Feb 14, 2012 7:50 pm

Well done Dave.
Simon

Frank Ryan · Post by **Frank Ryan** » Thu Feb 16, 2012 2:17 am

Sweet.. no glass so...
say, is it really that stable?
Lookin forward to seein it now.