Lyman M77 Globe Sight
Restoring a Lyman M77 globe sight using old and new school techniques.
by John Baxter
The model files for the globe sight inserts in .STL format for readers that to want to 3D print the inserts. Feel free to add this to your library.
From author John Baxter:
“I put an Armstrong peep sight on the receiver, and I’m pairing it with a Lyman M77 globe on the nose. I think both have been bouncing around in the spare parts bin from my grandfather’s collection.
“Here’s the interesting part: the M77 is made to mount to a male dovetail on the barrel, and features similar replaceable inserts to the M17 which uses the more common female dovetail in the barrel. So I build a dovetail to screw mount to the barrel. Also, as far as I know I do not have the sight’s insert assortment. I suspect they are the same as the Series 17 sight, which are out of stock at many suppliers (Midway, Lyman, etc.)
I modeled the inserts (along with the rest of the sight) in a free online CAD program Onshape (https://www.onshape.com/en). Onshape is a professional-grade package. I rendered the entire range using a parametric program. Onshape allows users to select specific configurations or even create new configures like unique aperture ratios from within the program. From there, I 3D printed the inserts to complete a set.
The full print article about this process of printing the inserts with a link to the STL files (solid model files, which people could take to the library to have printed) and the CAD files on Onshape is interesting. I completed the job using conventional machining of the front dovetail mostly on my 1940s-ish Burke mill.