Started getting paranoid about my new (old!) 10” meade sct sliding off the mount because the temperature had dropped and the dovetail screws got loose and 13kgs hit the cement pavers !!!
Figured there were at least two ways to stop it. One... use a nylon cord with quick release hooks, with one permanently attached to the mount and the other end clipping somewhere on the rear of the scope. Two.. make a bracket that fits around the back of the dovetail. Didn't have any cord or hooks so the bracket was the go. I think it would hold, might bend a bit but if it saves the scope I can live with it.
Cheers
Stephen
... Now look at the 3 tiny set screws holding that dovetail clamp section to the mount
Couple of weeks ago I drilled and tapped another 3... so now I have 6 in total.
Howevere, this is not critical, I am actually pretty sure that 3 grab screws (M6) are enough.
There is no scneario that can cause this part to disengage and fall off.
Much more likely is that screws may become loose, causing mechanical problems like un-predictable moving of the scope assembly, resulting in star trails during longer exposures.
You can also have a screw head poking out from the dovetail so that if it slides backwards the screw head hits the saddle, stopping the rearward travel.
Tony
That's an even better idea. Might do that as well.
Cheers
Stephen
Quote:
Originally Posted by casstony
You can also have a screw head poking out from the dovetail so that if it slides backwards the screw head hits the saddle, stopping the rearward travel.
Well, seeing as I'm now swinging a 14" newt on this system here's what I ended up doing. Call me paranoid, but at least you won't be able to call me stupid, lol.
John
Can't quite figure out how that's working. Talk me through it willya?
Stephen
Quote:
Originally Posted by asimov
Well, seeing as I'm now swinging a 14" newt on this system here's what I ended up doing. Call me paranoid, but at least you won't be able to call me stupid, lol.
Well I took the counter weight bar out, welded some allthread to it thus extending it, drilled a hole in the top section that is held in by the 3 set screws, cut the allthread off to length & nutted it. As I said, probably a paranoid move but at least I don't have the fear of the 3 setscrews giving way. Hopefully you know what I mean now Stephen.
As I have an NEQ6PRO and recently purchased a 12 inch LX200ACF, I knew I needed a wide dovetail bar and some method of mounting this bar to the OTA.
I ended up purchasing the Losmandy bar and curved blocks to suit a 12'' Meade SCT from Bintel.
When the bar arrived, the thumb screw that sits underneath, at the top end of the bar as a ''safety stop'' came with it.
With my setup, if the thing lets go im a monkeys uncle its got 300mm of double sided dovetail bar grabbing on, its not smooth but not rough either, Ive never seen it slip in 2 year and that's even with 20 deg shift in temp. At the worst case it should get tighter as everything contracts.!
Some mornings i have to work to get the dovetail bolts undone! I know its a piece of mind but shear physics and geometry are why dovetails are selected to do the job!
With my setup, if the thing lets go im a monkeys uncle its got 300mm of double sided dovetail bar grabbing on, its not smooth but not rough either, Ive never seen it slip in 2 year and that's even with 20 deg shift in temp. At the worst case it should get tighter as everything contracts.!
Some mornings i have to work to get the dovetail bolts undone! I know its a piece of mind but shear physics and geometry are why dovetails are selected to do the job!
Agreed Brendan!
I can tell that once those bolts are tightened on the large EQ6 dovetail head................that load may as well be welded to it............it ain't goin' no where!
The screw or bolt head protruding from the dovetail rail like Tony posted is all you really need.
I have them on all my rails, and ADM actually make their rails with provision for this.
Zeiss have had it for years, and their saddles have a groove to allow the rail to slide further in, but never through.
Gary
its got 300mm of double sided dovetail bar grabbing on, its not smooth but not rough either, Ive never seen it slip in 2 year and that's even with 20 deg shift in temp. At the worst case it should get tighter as everything contracts.! 
