Nice work Tom, keep the photos and reports coming. I'm sure that despite the problems the final result will be awesome. After seeing your efforts, a couple of us here in Lonny are thinking of building truss dobs, hopefully scratch built if it's not too ambitious. Maybe when you've finished you could document and get mike to put in the "how to" pages...... Can anyone recommend a good book and or plans for a truss dob??
If size is a concern I would not recommend the Telekit (I could fit an 18" mirror in my 16" Telekit mirror box if I used a Kriege/Berry style mirror cell).
Also had another couple of setbacks, the lower truss blocks are not square and I'm waiting for another set to be shipped out, and the azimuth brake is too short (I've made it higher with an additional furniture pad on the underside).
Apparently Astrosystems have had to fire one of their junior staff who was responsible for making these and many more mistakes.
Thanks Tom, I'll order a copy of that book; it's quite cheap. I'll study up a bit and work out what bits I'm capable of building then if it's OK, pick your brains for more info when I'm better informed. Unfortunately the junior thing is all too prevalent these days; inexperience, overconfidence and no pride in their work.
Last edited by acropolite; 25-03-2005 at 06:00 PM.
I pulled my finger out this weekend and got back into working on my scope after a long break.
I finished off the lower truss blocks by cutting some new bases and gluing them together.
I spent a while positioning and gluing the lower truss blocks and filling all voids and imperfections with wood putty ready for final sanding.
Tonight I did a dry assembly (no bearing surfaces) to determine the best focuser position.
The first thing I noticed was the size of the assembled scope. It's huge! See attached photo.
The second thing was how concentric the scope is. When positioned vertically and rotated through 360° the edge of the secondary cage did not deviate from a mark on the ceiling. and the gap between the mirror box and rocker was constant when moved in altitude (the boxes are square). YAY! The hours of careful attention to accuracy have paid off.
The third and final thing is that I prefer the focuser on the right side of the scope (looking from the front). I'm going to make a post surveying this preference for Dob owners, just out of interest.
Just a bit of assembly to go, but a lot of finishing sanding and varnishing/painting too.
I'm feeling much more happy about how this scope is going now.
yea....if you put the focuser on the right side of the scope it will be in just the right position. The ways it is on now it looks way too low.
---------------------------------
Mark
12" gso scope
It should be perfectly balanced on the Alt bearings when fully assembled Ken, so the centre of gravity is over the base.
Phil, I've got sand paper down to 400 grit, and enough Wattyl satin varnish for 3 coats (last coat by spray can). The first coat is 50/50 varnish and thinners for better penetration.
You know, I was just thinking about Tom over the last couple of days.. haven't seen him around here in *ages*. It's been over 6 weeks since he's last logged in.
Nice work Tom, keep the photos and reports coming. I'm sure that despite the problems the final result will be awesome. After seeing your efforts, a couple of us here in Lonny are thinking of building truss dobs, hopefully scratch built if it's not too ambitious. Maybe when you've finished you could document and get mike to put in the "how to" pages...... Can anyone recommend a good book and or plans for a truss dob??
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