Source for OTA tube

[Glenhuon]

I've recently bought an 80mm x 400FL objective and an 1 1/4 focuser. Looking to make a short tube (F 3.75 ?) OTA for solar observing. Can anyone advise a source for 100mm ID Steel or Aluminium tubing in NSW. Would be good if it could be purchased to quoted length and ends machined square as I don't have easy access to a lathe nowadays.

[Omaroo]

I just bought the same objective assembly as you Bill - the 80x400. I'd be interested to see what you come up with - as long as I don't find it first (in which case I'll let you know)!

Aluminium and a good textured powdercaot in off-white. yummm

Cheers
Chris

[bird]

Gary Mitchell in Sydney made the aluminium tubes for my last 2 scopes, highly reccommended. Look him up in the book, G.N. Mitchell, Condell Park.

cheers, Bird

[Omaroo]

Thanks Anthony - will do :)

Cheers
Chris

[netwolf]

Well I to have been following the SS lenses for sometime on the CN Forums and they seem to be pretty good. Here is a thread on a particular tube design that seems fairly easy to DIY.
http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/1630554/page/0/view/collapsed/sb/5/o/all/fpart/2/vc/1

There a number of "not a nother SS shed telescope" threads on this subject.

Regards
Fahim

[Glenhuon]

My thoughts at the moment are to dummy it up using 100mm pvc so I can work out the required tube lengths etc and then replace it with metal. Did have one thought later that car exhaust tubing is pretty thin even at 100mm ID, and would even be lighter than the heavier grades of pvc, so will look into that with the exhaust shop up the road.
Thanks for the advice re the alloy tube Bird, will look up the supplier when I've worked out the required length.
Interesting threads on the SS 80x400 Netwolf, given me a few other ideas, thanks mate :)

Glenhuon

[Glenhuon]

Just finished the prototype using PVC stormwater fittings.
The focuser fits just nicely inside 90mm stormwater pipe and is held in place with a couple of self tappers as it isn't a push fit.
The objective holder is a perfect fit inside a 100mm Pad Repair fitting. A 100x90 reducing bush is stacked on the other end. The ridge the pipe normally butts onto was removed with a file and a bit of work with a scraper took enough pvc off the inside to let a 90mm pipe slide through. At present the two outer fittings are held together with gaffer tape, might glue them later.
The tube just slides through the ridge on the inside of the pad repair fitting so the tubes remain parallel as they are slid in and out. The inner tube initially goes right down so its end contacts the objective housing.
The outer tube is 245mm from the end of the objective housing to the end of the reducer fitting. After a bit of trimming and testing the inner tube was cut down to 260mm. Thats a trifle short but by sliding the inner out a bit the best length can be arrived at.
Materials cost so far $20, 2hrs of assembly.

First light is tonight :)

[netwolf]

I was thinking of making one like this for a Guide scope, but i dont have the tool skills. Glen a howto illustrated write would be great.

Regards

[Glenhuon]

Once I've finish the assembly intend to write a blow by blow account, Another thought occured, since I've seen people talk about focal extender/reducers for imaging this design might be a good way of varying the focal length without resorting to the purchase of "extra bits".
netwolf, very little is required in the way of tools or skills. If you can cut a straight line with a hacksaw, you'll do it easily.
Tools used so far are :
Philips screwdriver, Hacksaw, piece of A4 paper to wrap around tube to give straight line for cutting, half round file to remove ridge inside fitting, some rough and smooth sandpaper or a triangular scraper to open out the inside diameter of the 100x90 reducer, a drill for the self tapper holes in the tube, and of course a tape measure for the tube lengths. As the saying goes, it ain't rocket science LOL


Cheers
Glenhuon

[Glenhuon]

Well, just had a look at Jupiter, and while I can bring it to focus, there's a bright, slightly off centre halo around it. Same with any bright object. Back to the drawing board, this requires more thought and tweaking :)
Could be the coating on the objective or an internal reflection in the tube/focuser. Hhhhmmmmmmmmmm!!

[Omaroo]

Bill - are you going to try flocking it? Maybe I'd try a couple of concentric internal baffles as well.

Cheers
Chris

[netwolf]

I wonder if Flat Black spray paint would do the trick.

Regards

[Glenhuon]

I had a look this morning at the internals and we're both thinking along the same lines netwolf and Omaroo. The (plastic) focuser tube has a chrome coating and the inside of the tube is still plain white PVC. I'll have a look in the hardware shop later for some sort of flat black paint. The internal baffles also occured to me, but will try the paint first.

Cheers
Glenhuon

[Omaroo]

Bill - forgetting the halo for a moment, what is the quality of the focused image like? What EP were you using for the test?

Cheers
Chris

[Glenhuon]

Quality was a bit ordinary, but it was hard to tell with the halo around it. The edges looked pretty sharp. Tried it with a 25, 15 and 6mm plossl. Noticed that the halo was absent with dimmer stars.

[Omaroo]

Bill - did you get around to flocking or baffling this machine? My objective hasn't arrived yet (ordered it on 28th Sept, 8 working days so far) but I'm keen to do an aluminium tube for it if it's at all worthwhile. From what you've experienced so far it isn't looking at all promising though..... :shrug:

Cheers
Chris

[Omaroo]

Hi Bill - just got mine in the mail today.
There is a sheet of paper in with mine explaining that you use it the other way around from what you think. The part you actually have inserted into the tube (judging by the photo) is actually where the dew shield is meant to slide on. The actual scope tube is meant to slide INSIDE the other end. It explains that if you have it the wrong way around you'll get flaring. It goes on to say that as long as you keep the two elements relative to each other - turn them around inside the objective cell and you should be OK!!

Cheers
Chris

[Omaroo]

My effort: http://www.iceinspace.com.au/forum/showthread.php?t=24721

[Glenhuon]

Thanks Chris :) Had me scratching my head after blacking the tube inside etc.
Here's my latest incarnation. The dew shield and cover are made from a Pad Repair Fitting and 100mm pipe cap. The Repair fitting is a lovely tight fit over the front spigot, no fixing required. I cut the minor diameter section back 50mm from the angle, this allows the end of the lens housing to just protrude through into the major diameter.
Was wondering why your lens fitted neatly over the 90mm tube as mine was a bit sloppy. Found that heavy duty 90mm did the trick as it has slightly thicker walls.
I've used a plastic focuser so assembly comes in at 1Kg with the 25mm eyepiece fitted.
You've done a beaut job of yours. JJJnettie is right, it sure is nice when you look at it and think "I made that" :)

Cheers
Bill

[Glenhuon]

Now with the rings attached. If the clouds would only go away :(

[Omaroo]

Top effort Bill :) The new build should provide a far better view for sure.

If I were to go in to Bunnings and ask for a 100mm Pad Repair Fitting, would they know what I was asking? Looks the goods on the end of the scope!

Cheers
Chris

[Glenhuon]

Yes, they should do. I got mine from Mitre 10, nearest Bunnings is Wagga.
I get some strange looks when I walk in there with a telescope in hand looking for pipe fittings :lol:

[Omaroo]

I know that feeling.... :rofl:

[Glenhuon]

Mounted on the EQ5, note the clouds. No rain, just clouds, Kym reckons it didn't cost enough to get rain :lol:

[Glenhuon]

It seldom happens (or so my good woman tells me :)) but she was wrong, we got 3 inches in the rain water tank. The scope is completed, and has an appropriate name.

[Omaroo]

Looks fantastic Bill :)

Love the name..... and the comment from your uvva arf. :D

How's it go? Mine works surprisingly well I think. I might go for the larger cell now and try it out....

Cheers
Chris

[Glenhuon]

Its going well, images are very clear and sharp now that the lens is around the right way :lol:
I've added a Sol Seeker for Sun observing and will be putting a bracket on for a red dot finder I just bought on the site.
I looked at the 102 mm objective and was very tempted, have to get the Mrs in a good mood before broaching the subject ;)
Did you get one of those Pad Repair fittings for yours ?


Cheers
Bill

[Omaroo]

Hot yet Bill - I haven't had the chance to get down to Bunnings for a little while. I plan to go today and get one of these fittings as well as some 1" aluminium truss tube for the bino project.

I notice that Surplus Shed is out of stock or the 102mm cells anyway..... (saving me from having to buy one on the sly...)

Here's mine at Magellan Observatory last weekend:

Cheers
Chris

[Glenhuon]

Here's mine with the DSI set up. Not having a lot of luck with that yet, but progressing slowly. Kym asks you pay particular attention to the "counterweight" :)

Cheers
Bill

[Omaroo]

You mean there's something strange about a hammer stickytaped to the counterweight bar? :shrug:

This is ATM!:D

[Glenhuon]

First image through the 80mm. Stacked 200 images from avi file using Agent webcam, no filters just bare CCD. (given up on DSI for the moment, pain in the nether regions).

[Omaroo]

Good to see Bill. Hmm.. might need a filter or two there! I have a 2" moon filter but only a 1.25" MV. I'll give it a go tonight as well....

Cheers
Chris

[Glenhuon]

Can't put filters on the webcam at the moment but I have ordered a couple of internally threaded eyepiece barrels from SurplusShed. The webcam body is tubular and just 0.5mm smaller in diameter than an an 1 1/4 eyepiece so I should be able to fit the internals inside one of the barrels. Fun this ATM stuff, innit :D

Just had a thought and found that with the application of a little thread tape an 1 1/4 IR filter fits neatly inside the end of the Webcam body (original filter was removed with the lens housing). With a bit of clear sticky tape applied to the outside for extra security I now have a thread to attach more filters :)

Cheers
Bill

[Omaroo]

OK Bill - here's mine.

Nikon D40 at 160th sec ISO400

Actually surprised me!

Cheers
Chris

[Glenhuon]

Nice one Chris.
I've posted a few more on the Agent webcam thread, stacked the polarizing filter, made a big difference. These are pretty good little 'scopes :)

Cheers
Bill

[Omaroo]

Not bad at all Bill!!

:) As soon as the 102mm becomes available again I'll be getting one as well!

[Glenhuon]

Next version of the 80mm. The original plastic focuser stripped its rack very quickly, but since it was better than expected visually I've fitted an Aquila Optics 2" focuser and shortened the tube 15mm. Note the sky in the background, its living up to the family name :lol:

Bill

[citivolus]

This is the first time I have noticed this thread, and I must admit that scope is rather impressive :)

[Glenhuon]

Thanks citivolus :)

[Omaroo]

Good stuff Bill! :) The new focuser should be far better in the long run. I don't know about you, but my home made jobbie is rapidly becoming my favourite scope. I've now drilled and tapped a 1/4" x 20 thread into the dovetail so that I can mount it on my tripod - as well as piggyback it on Zane's guided GM200/SN10 at his Magellan observatory. I go there again next week foranother deep sky session and I can't wait to see how this little fella goes with some DSO's.

I sent a few images of my finished scope and the moon photo to Surplus Shed and they responded with a big thank you and a nice message back from them stating that the 102mm cell should be in next week! :) :) :)

Cheers
Chris

[Glenhuon]

I'm very pleased with it too Chris, and yes, I seem to use it more than the 150 newt. :)
Should finish the dovetail bracket for the red dot finder today and if the clouds will just go away for a while I can give it a spin in the dark.
I've put the 102 on my wish list and SurplusShed will drop me an email when they come in.
Been too cloudy here for about a week to do any observing and my drive hand controller went weird on me. Just got the replacement from Andrews this morning and theres a bit of blue sky showing. Keeping the fingers crossed for the weekend.
Clear skies for the Magellan session, post us some piccy's :)

[Omaroo]

:cool:

[Glenhuon]

Finally got a session with clear skies to continue the testing of the Mk2. Tube is still a bit too long and I can't quite get focus with a couple of my longer bodied eyepieces when using the 90 deg diagonal or barlow. Looks like final tube length will be 145 - 150mm, but reached the limit of trimming with the existing mounting ring arrangement. DSI and Agent webcam focus with about 25mm of inward adjustment left.
Bracket for the red dot finder has been made and fitted, works a treat :)


How did yours go at Magellan Chris ?

[Omaroo]

Grrrr.... clouds, Bill :(

Got another session booked for mid-week. I'll probably head down Wednesday arvo for the night. I'll post results!

Cheers
Chris

[Glenhuon]

Looking much better here, hope it was the same for you at Magellan.

The Rainmaker Mk2 is finished at last. New rings fitted and tube cut to final length. Everything focuses with the star diagonal and the barlow or straight through. The finder bracket is a home made job. Base is a short lenth of 25mm square tube cut in half along its length and squeezed in the vise with a piece of 12mm round bar till it spead out to the correct angle. The angled upright is 1.5 mm steel plate silver soldered into the groove made by the bar.
Top is a flat steel plate with a shaped piece of aluminium screwed on top to suit the finders clamp. Little bit of flex in the upright but its fairly springy and doesn't bend permanently. Very happy with the 80mm. When the 102mm objectives come available again I'll start on its bigger brother :)

[Omaroo]

Excellent Bill - that's really looking like a great scope!! :thumbsup:

Here's one from the night before last through mine - not brilliant, but not bad either!

Cheers
Chris

[Glenhuon]

Looks pretty good to me and Kym was most impressed :)

Cheers
Bill

[Glenhuon]

Going fishing Tuesday/Wednesday to Lake Tantagara, decided to give Blowering (AKA "Lake Disappointment" :)) a miss this time. Going to take the 20 x 80 Binos and the 80mm refractor for at night as the rods will be set off the bank and I can observe and listen for the bell tinkling. If the Force is with us ;), we'll have a feed of Trout to bring home and some dark sky sights to remember.

Cheers
Bill

[Omaroo]

Tantangara? You'll be just up the road from Omaroo! If you want a few hundred metres of Murrumbidgee (which, at our point, is fed from Tantangara), some good dark sky and nothing to disturb you.....

[Glenhuon]

Oops! I missed this one Chris.
Had to cancel at the last minute on the fishing trip. It clashed with a trip to Sydney that the Mrs had arranged earlier. We had a good time, had afternoon tea with the governor (lovely lady) and a look around the residence, took a trot around Paddy's Market and a long look at the contents of the Powerhouse museum. I had to endure 2 x 5hr trips on a train (not my favourite mode of transport) but a fun time non the less.
I'll take you up on the invitation one day, thanks for the offer :)

Cheers
Bill