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Post by boomboom on Sept 3, 2013 0:03:18 GMT -5
For the last year I have been working out which refractor to build and have finally made a decision. A couple of days ago I ordered a 6" f12 Objective. This will be built into a 152mm aluminium tube with wooden cells at both ends, largely as I don't have a lathe but have done a lot of work with wood. Hopefully this will work otherwise it's over to Cramach for the bit's! Done a full ray trace ad figure the tube will be 1500mm long leaving around 320mm to the focal point...if that makes sense? Baffles will be cut out of plywood and held in place with three stringers. A GSO linear bearing focuser I have will be reused on this scope. Tube rings might be DIY but also Skywatcher make a 160mm that will need a bit of packing out and should work, are avaliable locally and cheapish at least compared to Parrallax ones. Going to go for the traditional white tube, although reading other threads it seems that green should be the 'correct' colour. That's about it so far. I'll wait til I get the objective before cutting tubes but can start on baffles (four or five not sure yet) and the focus end. Any input will be most welcome. Last time I made a scope was as a kid in 1979...a 6" Newt, it worked sort of. My first question is the GSO focuser has only 50mm travel. All my eyepieces come to focus some where mid point in the travel so I should try for the same in this scope...correct? I need to use a 50mm extension tube too but remove that for bino viewing which I do a lot of. To start with here is a pic of the tripod with the NEQ6 and f8 at full height next to it. The wooden tripod is 70x35mm legs and 500mm higher than the metal tripod. Matt
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Post by Mike on Sept 3, 2013 9:15:15 GMT -5
Hate to tell you this but nothing astro related will be coming out of Crawmach. I spoke with Danny Crawford two weeks ago and he said he is done with the astronomy end of the machine business. He took down his web site. He said although he enjoyed working with astro related items he was losing money on it. I have been attempting to contact him by phone for a few unfinished items we working on but no one picks up. Only a machine answers. I am hoping he is not sick or something happened to him as this is not like him. The astro community has lost a good friend. However, you can't lose money and stay in business.
Mike
Also, since he took down his web site, email just bounces back.
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Post by bn1777 on Sept 3, 2013 20:35:38 GMT -5
Yes I heard that as well Mike , a sad day for everyone when we loose a supplier, he makes ( made ? ) fine focusers for us that own and still use our little 60mm refractors .
Matt , congratulations mate ! looking at the tripod you made at 500mm taller than the EQ6 one it should be fine but if its not it will be easy to make longer bottom pieces , that's the beauty of building your own , it can be changed as the design needs change . You told me once that the timber is 'Tasmanian Oak' ? if so I don't think there is a better timber for a tripod , awesome timber !. In NZ we call it 'Kauri' and its what the Poms raped out of NZ by the 100,00 thousands of acres in the 1800-1900's to use in ship building , it is the best in the world for mast's , and as well as the rest of the sailing ships built back then .
I have seen 'Tane Mahuta' a living Kauri that's over 2000 years old , its 14 metres across over 50 metres tall and over 500 cubic metres of timber !! , like a rock face in the bush , but living and simply awesome! .
Look forward to regular updates with lots of photos Matt and welcome to the club .
Brian.
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Post by boomboom on Sept 4, 2013 2:14:09 GMT -5
If Danny is out it is a sad day indeed. I guess it's back to the wood then. Yes Brian it is Tassie Oak ,brilliant wood so hard and good looking too. For the rear cell I have bought from Agena Astro a GSO 96mm focuser adaptor like what is on the rear of the Synta scopes. Should be here in a week. I'll need to bolt that to a wood ring at the back and then the focuser will screw on to the adaptor...easy! Just the front to worry about now. That's it so far....waiting for the objective to get here...
Matt
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Post by Mike on Sept 4, 2013 10:43:32 GMT -5
It's going to be a few days before I ship that lens Matt. As I have mentioned we are at the tail end of our rainy season and it's been weeks since I was out. I have four telescopes and a few lenses lined up for star testing. I'm really hoping to have a night or two of clear skies coming up. Actually, all I need is few hours of holes in the clouds. As you know I can't ship untested lenses. So, hang in there a little while longer. Would you like me to send a drawing of the lens cell?
Just a few more weeks then it's clear skies for several months. I can't wait!
Mike
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Post by boomboom on Sept 4, 2013 18:20:21 GMT -5
Thanks Mike. I can hang on for as long as it takes. The last time I had my scope out was 10 weeks ago. A few more isn't going to hurt. For the lens cell I'm doing a cross between Sean Cunneen's Istar refractor and Andy's 5" Plyscope. I'll draw it up and send it to you. Matt
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Post by Kitch101 on Sept 6, 2013 0:46:47 GMT -5
Looking forward to seeing the fruits of your labours Matt. I myself have been downsizing and now have the Tak TSA120 and the FS60CB as well as 4 other refractors (Custom, Carton, Berry&Mackay and a little Polarex) but might go down the Istar path again in the future.
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Post by boomboom on Sept 9, 2013 19:07:05 GMT -5
Not good about that Matt, hopefully you will hear back at some stage. Your dog avatar looks a bit scarier than mine Mike, I'm trying to do a drawing of the cell but it's a bit hard without knowing exact dimensions of the objective cell so here is a wordy description! My tube internal dimension is 147mm so the objective will have to be out of the tube so I don't cut the aperture down. Its only 3mm but still.... The counter cell will be marine ply glued together with the objective sitting in that, with three aluminium bar inserts for the push pull screws. Over the top I intend to use a retracting dew shield that will cover the ply cell. The ply cell should be 24mm thick around the tube and ?mm long. Will be making it up as I go along once I have the objective....gulp. It's my normal way of working with this kind of thing. Will laminated ply be strong enough? I think so but any other opinions out there? I was trying to do a hardwood one which would involve glueing several rings together but the widest width is 185mm boards and I need 197mm. Any lathe owners wanna do a bit on the side??? In the mean time I have started with the baffles Thats about it so far pics to follow, damn shame I have to work for a living, sure gets in the way of telescope making.... Matt
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Post by Mike on Sept 9, 2013 20:52:11 GMT -5
Matt, I can send you a lens cell drawing. Will that help?
Mike
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Post by boomboom on Sept 10, 2013 4:49:08 GMT -5
Thanks Mike, sent an email.
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Post by boomboom on Sept 26, 2013 1:46:58 GMT -5
Today the objective arrived! Now its on with the build. A magnificent looking bit of glass too. Hope to have the scope built for the southern summer. Winter here has been the worst for years. I hope the curse of the new scope does not apply to ATMing Pictures to come but so far I have cut baffles, front and rear cells and collected tube rings, a Losmandy dovetail and the aluminium tube. What can go wrong...... Matt
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Post by Mike on Sept 26, 2013 10:03:18 GMT -5
Really looking forward to it Matt. Hope you intend to post some pictures of the build.
Mike
What's your latitude?
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Post by bn1777 on Sept 27, 2013 17:53:03 GMT -5
Well done Matt , I am also looking forward to the build photos , good luck mate . Brian.
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Post by Kitch101 on Sept 28, 2013 5:18:48 GMT -5
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Post by boomboom on Sept 28, 2013 8:15:35 GMT -5
Ok here is the only photo I have been able to do, not very exciting as you have seen this sort of thing before. There...when I can I'll get a shot of what I've been up to. Lots of round wooden circles! Matt PS Mike my latitude is roughly 38ยบ South.
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