Part needed for CST Tripod

With a project coming up for this spring I purchased a used CST model 136 Transit Level and a used CST/Berger Tripod from the same seller. When we finally got around to working on the project, the transit level and the tripod are not compatible as the transit level base has female 1/2-20 in its base and the tripod has a special 5/8-11 'bolt' for connecting to the transit level. As expected, CST/Berger made many models of both transit level and tripods. My research leads me to a model ALC20 tripod. That schematic parts diagram breakdown shows parts number 2-610-A09-026 Clamp Handle as the correct 'bolt'. No supplier of that part number can confirm 1/2-20 thread. Any help is greatly appreciated.

I would suggest looking for a 1/20 shoulder bolt. McMaster should have it or you might find it locally.

This? Which does not look like 20 threads per inch.

Per this webpage, that part number has 5/8-11.
Your part number is the brass bolt with knob, and the part number is third from bottom in description list.

https://www.stakemill.com/tribrach-...-tripod-adapter-5-8x11?cPath=115_283_504&

Look for a replacement tripod on ebay, then sell your old one there for parts.

I have not worked with your instrument nor your tripod, but based on my experience with other instruments and legs, I think you can unscrew the tripod screw from its toggle easily.

From that point, it becomes a matter of replacing the screw. The question becomes one one-time-only or repeated use over a longer term.

For one-time use, a 1/2-20 capscrew of suitable length should slip through the internal thread in the toggle. It wouls be a good idea to put a washer on the capscrew, and a deep socket gripped directly in your hand will provide more than enough torque to lightly snug the capscrew.

If you are looking for a long-term fix, you could either replace the toggle and retainer screw having a 1/2-20 thread, or screw a suitable threaded rod into the instrument base, to be used with the original toggle, a 1/2-20 wingnut, and washer.

It would also be a really good idea to chech, and correct as needed, the adjustment of all instrumeny's level vials. The bubble-checking process is commonly called peg testing, and while there are several variations in the process, I prefer the method Wild / Leica describes in the manual for their NA-2 automatic level EXCEPT for a non-automatic level the adjustment is performed by pointing the instrument to the calculated ros reading and then adjusting the vial, NOT by adjusting the reticle.

Or, the simple alternative to checkin and adjusting the vial is to locate the instrument so that all shots taken at the setup are at the same instrument-to-rod distance

That is the correct part except for the 5/8-11 thread. My thinking is that CST made the 136 transit level and a compatible tripod with 1/2-20 thread. Most
likely all three items were sold as a combo with transit level, tripod, and grade rod in the combo as well as all three items for sale individually. If I could
find the correct model for the tripod it would be a step in the right direction for the correct part number for the clamp handle. The 5/8-11 'bolt' looks to be
made of brass, is hollow inside, and appears either pressed or hot molded into its plastic handle. It is frustrating as one expects both items sold by the same
seller would be able to be used together.

Something like this, maybe? Third item; ADP005.

https://www.dpcanada.com/en/stone/accessories/adaptor-male-female.htm

Except that I need the reverse adapter.

That is exactly the part that I need, just with 1/2-20 thread instead of 5/8-11 thread. Now to find a source. Logic says that CST/Berger made a tripod for its
136 transit level to sell as a combo with a transit level, tripod, and grade rod in a package deal.

I must be misunderstanding what you need then. Sounds like the tripod already has a 5/8-11 bolt, but your transit needs 1/2-20 bolt. The adapter I linked to can screw on to the tripod's 5/8-11 bolt and then you have the adapter's 1/2-20 threads ready for the transit. So wouldn't this be what you need?

The adapter I linked to is 5/8-11 female (for tripod) and 1/2-20 male (for transit).

CST Berger Tri Pod Adaptor 5/8-11 To 1/2-20 #61-2509
CST Berger Tri Pod Adaptor 5/8-11 To 1/2-20 #61-2509
Click image to open expanded view

Brand: CST/Berger
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It seems like your linked part will be too long. Check out CST 61-2509 for a better picture. That looks like the correct tripod adapter but it appears
discontinued around 2004 or so. So I will continue the search and hope for a miracle. Per a Bosch representative (Bosch purchased CST/Berger years ago)
CST/Berger model ALQC121 is compatible but I cannot find one of those either as it was discontinued in 2004.

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You are correct; that is the exact correct looking part that I need except with 1/2-20 thread.

If it is this, looks like it would not take much to have one made?

Bingo; that is it!

We are almost done with the project that I bought the transit and tripos for so it may be best just to sell everything and cut my losses, hoping that others can use the two pieces separately. A grade rod goes too.