Tel Making

[Orion]

What about a forum on telescope making. Just an idea:confused:

[iceman]

I'm not sure whether there'd be enough interest in it at this stage, but as the forum grows there could certainly be enough interest down the track..

For now just post ATM stuff in the Equipment Discussions forum..

Thanks for your suggestion!

[mch62]

I'm with ya Orion , an ATM section would be great , for those of us who like to to dabble in this rewarding field.
Mark

[Striker]

I think it would be a terrific forum topic......their is no way I would attempt making a telescope but I have the highest respect and admiration for those who do.....go for it....it may get more people intersted if they could get the required information and support of the forum....good luck...

[mch62]

I've had a few questions from inspiring minds about building a Newtonian and there are a few of us that have already done so , so it might be slow at first but there is interest.

I am no expert but have sifted through all the different ATM forums for ideas and info on the techniques and optical theories involved.
It took me several months of procrastinating and I think I surfed the web from here to the US and back several times before taking the plunge , but have never looked back .
I am an ATM for life now.

Remember amateur astronomy has it's roots with home built scopes . It's the only way most of us will ever be able to afford top quality large scopes.
Then there are those that just want the challenge and pride in making his own .

Mark ATM

[seeker372011]

I think it would be good , particularly as most sites are US based.
If they tell you to find something-say a sonatube it is hard to find the Australian equivalent

help in finding local sources would be very valuable.

for example Iam right now looking for a low cost home made focuser idea for the 3 inch newtonian I am trying to build with surplus shed optics..any suggestions would be welcome

(BTW the idea of this particular project is to build the whole scope for under 50 bucks.Others have done it elsewhere-the so called "mini-dobs"-there was even a webpage devoted to the mini dob on the ATM web ring )

[mch62]

Actually i saw an artical about a 4"newtonian that packed up into a small carry bag made and it was made from bits and pieces.
looked interesting.
Also saw something on a drain pipe focuser somewhere but can't remember.
I think for a home made focuser a heleical housing from a camera lens would work.
I stripped the elements from a camera lens for a project and the housing left over would have been perfect for a focuser.
The camera lens cost $5 from cash converters.

Mark

[Orion]

I believe that you get a lot of satisfaction in building a telescope and I find it very rewarding looking through a telescope that I made. The telescope that I have is the second one that I built and as always the next telescope gets bigger in aperture. Not to mention all the $$$ you save by building it yourself.

[Orion]

QUOTE]Originally posted by mhodson

I am an ATM for life now.[/QUOTE]
So am I!! :work: :thumbsup:

[mch62]

Orion you must get some great DS views out of that beasty.

I have a couple of questions for you .

I am in the early stages of building my observatory for my 12.5" f6 Newtonian (two posts in :work: )and have designed the observatory to take up to an 18" (I hope) .

What is the overall length of the OTA ?

Do you know roughly what the distance from the balance point to the frount of the OTA is ?

What's the coma like at f4.5 and do you use a Comacorr ?

I am not is the immediate market to upgrade yet but I know what apperature fever is like , it pays to plan ahead !

Mark

[Orion]

Yes Mark the deep sky views through the 18" with a 24.5 SWA meade eyepiece are great!

The balance point is at the top of the mirror box and the OTA is 1621mm
I did the drawing on the CAD before I started building anything so I wouldn’t get any surprises half way through the building process so any measurement is no trouble at all.

I haven’t tried a Comacorr yet there is a bit of coma there but nothing that I’m worried about at this time.

I don’t know what type of telescope you are going to build but if it is anything like an Obsession I suggest you to get the book.

Happy ATMing!
:astron:

[mch62]

No , any upgrade will be a larger version of what I have in the Avtar pic , on the fork mount that I am building .
Twin truss OTA .
I am just making sure that any upgrade will fit between the forks and within the dome.
It will just be an f5 next time to keep the overall length with in the 3.4m dome .
At this stage it will only be a 16" as that is the largest that Rob Royce does in the conical cross section Mirrors.
I am how ever hoping that by the time I am ready to upgrade , larger sizes are available in the Conical Mirrors.
What thickness mirror is the 18" as that has a lot to do with the balance point.

[ving]

I am with you on this. and you can have TOO many forums too.... how about one on cats? :P
just kidding bout the cats btw.:cool:

[Orion]

It's 30mm in thickness.

[ving]

no one wants a forum on cats?
;)

[Vermin]

An ATM forum would be appropriate as I've just heard that my Telekit has shipped and I should get it in the next week to 10 days!!

Wooohooo! :jump2:

[ballaratdragons]

I imagine we won't hear from you much in about ten days.

Busy, busy, busy, build, build, build!

[Vermin]

Probably, but there is a fair amount of waiting for epoxy to set so I should get a few posts in. Just depends on the state of my arms after all the sanding and routing.

[ballaratdragons]

And the state of your brain cells after epoxy fumes! :P

[cometcatcher]

I'd like a forum on cats. Mmm, think I'm going to have to post a pic of my cat neow in the camera section. No that wasn't a typo. :P

My 16" dob cost around $1000 to build all up. That was back in 1991.

Most of my scopes were kept cheap by using PVC pipe for focusers. However I like the feel of a rack and pinion better. Much smoother. And it makes me taller too. Oops. :whistle:

[ballaratdragons]

It is amazing how much PVC pipe gets used in Scope making! I have made 2 scopes using it for nearly every part.

For my old Reflector I used 6" Sewerage pipe for the tube and I made a finderscope for it out of 1.75" waste pipe with a dew cover from 2" waste pipe. To hold the finder in place I fashioned mounting rings from 3" spouting. The main tube dust cover and mirror cell holder were 6" sewerage pipe end caps.

For my old Refractor I used 90mm heavy storm-water pipe and
for the focuser I used 2 sizes of PVC tubing from a kids swimming pool frame!

Good stuff PVC.

[cometcatcher]

This is my 11" f5.2 scope on a Samson mount. There's a piccy in the deep space forum somewhere with the Horsehead that it took.

[cometcatcher]

Unfortunately after a rather wet night and not letting it dry properly the entire inside of the wood tube is covered in mould. It's eaten into the paint and won't wipe off. Getting at this type of tube with inner rings seems impossible to clean. The mould smell is a bit overpowering also.

The mirror has been taken out and put away. Any ideas of last minute rescue before the tube goes to the dump?

[Vermin]

Dude, I wish I had met you before I started this project.

[Vermin]

$1k for a 16"???

[mch62]

To get ride of the mold , try using some pool chlorine .
You will have to soak it down for a few hours or more with the chlorine , which will kill the mold and then a repaint but use a wood sealer first before the flat black.
Make sure it is well and truely dry before painting.
Use the dry chlorine and mix up a slurry , but do this out in the open and use gloves as the stuff is very corosive. Eg skin and body parts tend to fall off and don't breath the stuff .
I know it sounds terrible but it works.

p.s. remove metal parts as well or don't get it on metal parts .
If this is not possible smear grease over them first.

[cometcatcher]

Mmmm, thanks for that, though it's going to be difficult to get to some places inside the tube.

Would I sponge the stuff on? How would I get the chlorine out/off afterward?

Yes Vermin about 1K or a little more. The main mirror blank I think was $200 back then. It's 30mm plate glass. I made the main mirror mount, made the spider too so saved $ here also.

Unfortunately it's also in very run down condition lately, and so am I so I don't really have the energy to fix it. Mirror need a recoat and the bearings need cleaning.

Since I've been unwell I've been drifting to smaller and smaller scopes these days. I love my 6 inch F5 and F6 Newtonians. Very light and still good for astrophotography. A bit dim for the eyes though, especially after being spoilt by a 16"!!

[Orion]

Thats great enjoy the construction. I know it's a pleasure to do your observing through a telescope that you put together yourself.

[seeker372011]

BTW John Dobson-yes the man responsible for the dobsonian revolution-is scheduled to make a trip to Australia and I think New Zealand in March.

If all goes as planned I believe he will be making a presentation to the ASNSW (march 18) and Sutherland Astronomical society in Sydney

[mch62]

You could either use a sponge or a paint brush and use plenty of the solution.
After an hour or so wash it down with a hose and use plenty of water to flush all the chlorine out.
Just monitor the timber to make sure that it doesn't deform from the solution .
if in doubt use a week solution first and see how that goes.

Lucky it's summer , so just let it dry in the sun for a few days and then seal it before a new coat of flat black.

It got moldy before , most probably because flat black by nature is porous and would not have done much to seal the timber.

When I made the middle section and the rings for my Newtonian (see avatar) I actually painted all unfiberglassed timber surfaces with fiber glass epoxy resin to seal the timber.

Hope this helps as it looks like you spent some time and effort to make that tube and it would be a shame to see it thrown out.

It looks great and you should be proud of it.

Mark

[ballaratdragons]

Kevin,

A fix for your tube:

*Spray bottle - approx 1 litre
*Caustic Soda - 1 tablespoon
*Water

Mix the Caustic Soda with the bottle of water. Make sure it is completely dissolved.

Spray lightly inside scope tube.

If mold does not turn black, spray again (heavier coat).

Once mold is black use an old broom or Hand-broom, and brush the mold of the surface. Give interior of tube a final clean out with a sponge or rag and clean water. Dry.

When the wood is dry, paint with anti-mould paint made for bathrooms. When paint is dry you can paint over it with black if you want to.

Even if you never use it again, don't chuck it out. Someone will want it one day.

[ballaratdragons]

Kevin,

Also nice to see that I am not the only one that used a riflescope as a finder. (see cometcatchers photo)

I was told by fellow society members that it would'nt work, but it was perfect! And I could clearly see the cross hairs.

Onya Kevin :cool2:

[cometcatcher]

Okay thanks, I will give it a go when my energy levels are up to it.

I reckon rifle scopes make great finders. I like the zoom ones best and they are right way up. I'll use a good rifle scope any day rather than the average astro finder. I have rifle scopes on most of my telescopes.

[cometcatcher]

Was just thinking, I have a bottle of exit mould here I use to clean the bathroom with. How would that go sprayed on the wood scope?