I’m a ATM living south of France, on the limestone plateau of Larzac and I make dobs since 1993. A 16” was the first one, a 22” follow and later a 32”. All are visible on
http://www.astrosurf.com/altaz and some got an article in English at :
Few years ago was the start of the last project, a pair of 40” instrument. The goal was to make to identical dob structure, one for the optician and one for me. So I made two structure. Basically, the 40” use most of the technique used to make the 32”. Plywood over Styrofoam, astatic cell and carbon truss. On the 40”, the cage is full carbon, including the spider (it’s a one part piece). The scope is around 280 kgs. They could have been made lighter but it was not the goal. The goal was to be able to use the FD3 primary at is maximum potential, so, the stiffness of the structure was more important than save few pounds. All alu part are anodized
It’s all home made, except the clement focuser and the motorisation from Siderealtech.
The motorisation is the last part of the job, got to set it up to see if everything is alright. I haven’t run it yet.
It takes me about 2000 hours for the structure, on 3 years. Not include a couple of year to design it. The scope is setup in about 30 minutes bye one person.
The jump from the 32” is obvious at the eyepiece. My 40” saw its first light last Saturday with some friends, Philippe Tosi, a French ATM was specially enthusiast as we can see on some pics !
I have never seen Saturn Nebula orange on all its edge or so warm color on some of the M27 parts. The Veil is so complex that it’s beyond description…
You can see some pics at :