That piece is intended to be a wrench that helps with tightening and loosening the mount to the tripod. When screwed down against the bottom nut on the shaft, it can be used to loosen the mount. When screwed up against the knurled knob/nut it can be used to tighten the mount. When not needed it can be left screwed most of the way to the bottom of the shaft out of the way. The knurled knob/nut is used by itself to hold the spreader tray in position.
At least, that is what I do and it seems to make the most sense. Since there are no instructions I have found, and various images have it in all sorts of places, it is confusing.
I do the same with the spinning barbell thing. It makes for easy work of tightening and disassembling when storing the head and tripod. It also makes a good place for to loop the lanyard of my red light so the flashlight is always in the same place I don't need to search in the dark for where I put the flashlight down last.
Other than that I can't see any logical purpose for the barbell. I do like that with it and the supplied allen wrench I need no other tools for the mount. Nice and easy.
I did add a ADM v-series saddle I had stored away. It was for a project that went in a different direction so now there was no home fo it. I have this saddle. The spacing for the saddle holes are 2in on center and the Twilight 1 mount spacing is a bit different. I don't remember if it was a tad wider or narrower. All I did to the ADM saddle was to carefully file one of the holes into a 1/2 inch long channel as wide. Like what's on this dovetail bar. Then put the saddle on the drill press and countersunk the recess for the bolt head. Touched up with a file and some black paint, good to go. It bolted up good and tight, nice and straight to the TW1. I really like how easily in the dark I can mount and remove my scopes now with the longer clamping area and the two long knobs. Plus no marking of the dovetail bar from the clamp screws.
I don't know for certain, but it does seem to dampen vibrations a bit quicker now. I didn't time the damping time before the swap but having twice the clamping area and a much firmer positive grip on the dovetail bar it makes sense to me if it did help a little bit. If it did help its a bonus.
The reason for even doing this in the first place was I remembered I had the brand new ADM saddle somewhere and no use for it. That's when the light bulb went on in my mind. After seeing it was so close to fitting as it was, I knew it would be a rather easy mod to make work. So I went ahead with it. I knew the ADM would clamp the dovetail more securely and evenly than the stock clamp the TW1 came with. The ADM will not mark up the dovetail bar and it has twice the clamping area. Not to mention, ADM makes quality, nice sturdy products.
If anyone who owns a TW1 and has a extra unused dovetail clamp like this of similar, give it a shot. In my opinion it's easy and worth while. No modification to the mount at all so it can be put back at any time. Just a file and a countersink bit with some patience to file a nice straight channel. If one had access to a milling machine even easier. I would think with an x,y table for a drill press and a good sharp milling tool bit it could (maybe) be done also.
Edited by Allanbarth1, 07 November 2018 - 12:52 PM.