The conception of a new 20" Dobsonian. Have been tracking down a local supplier of 1" or 11/4" x .05" round aluminium tube for trusses to suit the Moonlite truss fittings and found for Brissy Dob builders a company called Alspec 25.4mm x 1.2mm x 6.5m @ $16.62.
1.22mm is not exactly .05" ( 1.27mm) but the closest i can find.
Anyone used this size tube with the Moonlite fittings?
I know you can get them machined for the popular 1.6mm wall tube.
Any one know of any other suppliers around S.E. Queensland.
This size wall thickness tube is hard to find. Can't find any one with 31.75mm x 1.22mm.
Mark
Tried Capral and most of the other main stream suppliers.
The replies from them are we no longer stock 1.22mm in 25mm, 25.4, 31.75, or 32mm and 1.6mm is the thinest we have in those sizes.
Its not Sth E Qld, but i bought thin wall alloy tube off a mob called
Light Spars of Australia in Moorabbin Vic a few yrs ago.
They do yacht spars, flagpoles and IIRC hang glider tube.
I got proper 2" and 1-7/8" x 0.056" wt tube from them,
but i think they also did smaller.
May be worth a ring.
Thank for that I will give them a call but transport of long tubes like that ,I wonder how straight they would remain.
As the scope is going to be an f/4 I think the little bit of extra weight over the hassle of finding a thin wall tube is of no consequence. I will just get the fittings machined to suit.
Mark
Mark I've bought aluminium from Action Aluminium at times. They have an on line catalog but nothing in there as this as you want. The round tubes are mostly on the following page. They will generally sell specific lengths rather than requiring full lengths if that helps.
I did come across this wall thickness only after I'd bought the thicker one. I sent Ron over a sample and he machined to suit at no extra cost . They fit so well I've never considered drilling though to fix them to the tube.
Yep have come to that conclusion as well will send a sample over of our 1.6mm wall tube. I allready have some of that in 32mm.
On that note is 32mm over kill for a 20" f/4 as I can get 25.4mm 1.22mm no problems, which means no machining.
Have searched the web and most 20" Dobs seam to be 11/4" allthough the Kriege and Berry book works out at 1" for an f/4 80"focal length??
Mark
I will give them a call but transport of long tubes like that ,I wonder how straight they would remain.
