Bob, I'm familiar with the Ukranian sights sold by Sergio. The ones I mentioned were hand made by a guy who used to set up at the Baltimore antique gun show. His were exact copies of the original as close as he could make them with the correct knurling pattern and correct screw sizes. He was older than me and now that I'm old he doesn't seem to be at the show any more. I know who bought the last one the guy had. I can contact him for more information as to how close a copy it really is.

I'll see you over the weekend. I've got some new toys to show off at Bruce's place

Orin,
The markings begin .680" from the staff bottom with 0. Each small division is .020" long and each major division is .200". There are divisions to 120, that end at the top just at the beginning of the top arc but the markings end at 110. My second Maynard sight has no markings and CB reports that he has one with very fine markings, so there may be multiple variations in the venire scales.
I don't have a Hadley rack and pinion sight to give you the measurements to complete the project, but maybe they can be obtained from another forum member.
Rebel
Can you tell us the diameter of your eyepiece and the diameter of its screw. Also a picture of the back of the sight staff, with the eyepiece removed, would be much appreciated.
Bruce,CP, John and any other forum members. We are looking for the following photos and dimensions of the rack and pinion (R&P) mechanism:
Number of teeth on the rack per inch
Photos of the front and back of the R&P mechanism with and without the eyepiece.
Diameter of your eyepiece. CB reports a unthreaded diameter of .202" and 30 tpi. This is close to a 12-30 but a little small. Might be good to have a few more measurements of the thread diameter and pitch.
Diameter of the gear drive knob
The R&P mechanism should be .515" wide, We need the length to the bottom of the gear enclosure and the length of the front flat area above the gear drive.
Diameter of the gear housing.
Otto

ron wrote on May 21^st, 2015 at 5:36pm:

Ron,

I finished the changes that John and Otto have made and will send drawings to them this evening for a final check.

Orin

Ron,
This project is being done in two parts, the standard tang sight and the Hadley rack and pinion tang sight. 
We found early on that Hadley simply added his patented rack and pinion mechanism to a standard Maynard tang sight. The dimensions to the standard sight were readily available, so that was the first sight modeled. 
There has been a slight delay in completing the project as all three of the forum members, who have an example of the Hadley R&P mechanism, have been out of town and unable to provide the needed dimensions.
In an attempt to achieve a historically correct model, we thought it best not to estimate the dimensions from the patent drawings, but to await for some hard data.
Otto

Chipmaker

Thanks for the update. I am very interested in the rack and pinion model.   

ron

Your dimensions must be pretty close for it to look that good. I want to see the printed rack & pinion and see if it works. Those dimensions came from Leo Remiger.

chipmaker
nice development work. will you be making one form metal ? to all of you guys who provided the info, thank you.

ron