I strongly recommend the safety screw. Better, install one at each end.
I do tighten things but one day my TOA - which was held by an A-P DOVE08 - slipped all the way to the screw. It's next stop would have been the concrete floor of my balcony. And tears. Lots and lots of tears.
I never really confirmed the cause for the slip but I suspect temperature changes coupled with a heavy load and a poor clamping knob design. Nevertheless, I removed that saddle the same day and I didn't observe until I'd replaced it.
Generally speaking the issue hereis not following the same logic that is used when you tighten the lug nuts of a car wheel. When you tighten the lug nuts of a car wheel it is best to go down to moderately tight then use a star pattern Will you skip the immediately adjacent lug nuts and go to the one across from the one you just tightened.
When all the lug nuts have been moderately tightened you can then finish the job. I note that if you're doing it right you will use a torque wrench so you don't over tighten on the final step. If you just cramp things down as hard as you can by jumping on the lug wrench and such stuff you may succeed in warping your rotors.
But I digress. When you have two clamps on the dovetail if you just tighten one as tightly as you can because you're paranoid and then tighten the other one as tightly as you can, it can lead to the odd situation where the exaggerated pressure on the first clamp may make you think that the second clamp is tight when in fact it isn't. That's because you can't move the dovetail that last 32nd or 64th of an inch against the pressure of the first clamp. The result is an incomplete clamping which can lead to the consequences you describe.
The best way to avoid these surprises is tighten the first clamp just enough to provide moderate pressure while you tighten the second clamp. That one should also be moderate pressure. Then tighten the first clamp all the way down and then tighten the second clamp of the way down. It's just a version of what you do when you have lug nuts or any multi-screw system that has to be tightened down.
The ergonomics of handle design is important in this process and you are right that knobs which are too small aren't very helpful. Knobs which are too big present their own problem.
I won't go so far as to say it is the best possible system but it is a widely used system that allows a person to have one or two mounts and be able to use a large number of telescopes with them. So nearly as I can see the industry trend is toward an expansion of dovetail use. The DM6 discmount for example is a side mounted altaz rail type system. And as I indicated in a previous post Celestron has moved to this system for the SE and Evo lines which is kind of cool because now you buy a 6-in SCT with go to and if you want put a 4-in refractor on the mount and take the SCT off. Or vice versa. Vixen, l o s m a n d y, and astro-physics have been using the system for decades.
They are manufacturers who want their mounts to accept as many different telescopes as possible in order to widen the market. It has the interesting effect of encouraging people to own multiple telescopes all of which can be well mounted.
Edited by gnowellsct, 28 July 2020 - 07:22 AM.