One of my projects is fixing up an antique Craftsman Model 80 6" lathe, usually just called a "109" lathe. Built by AA for Sears in 1949, its model number is 109.21270, sometimes listed as 109-21270. It has a capacity of 6" swing over bed and 18" between centers. Many machinists consider them toy lathes since they were inexpensive, common and easy to break. But I've found it to be reliable if treated with care.
I slowly removed rust and grime from all the components. It was taken almost fully apart to it's basic parts. Rust was removed with a phosphoric acid solution. I would have used an electrolytic process if the rust was worse, but it's only a surface coating with little to no pitting. I degreased the parts with Simple Green, I wanted to stay away from difficult to dispose of degreasers. I then repainted with a color close to the original dark gray, I couldn't save the original Craftsman label though.
I built a backsplash to keep the chips and oils from getting everywhere. Then I mounted the lathe to a solid base. The lathe came with a couple missing change gears for setting threading and feeds. I ended up finding the two I needed on E-bay.
The lathe must not have been used too harshly, most of it shows very little wear, just neglect. The 4-jaw chuck shows the most problems, the jaw screw threads show either rust damage, or poor quality manufacturing. The screws hold, but the threads are missing in many places. Even so, it holds stock tightly and squarely.
The threading chart in my lathe was a little worn in spots, I've reproduced the chart in a few formats. On my old website I had charts posted that included metric thread setups; but most of the setups were impossible to mesh using the 109. I've changed my setup calculations to include gear meshing, so the two vertical charts now include metric threads.
The look of the original Threading Chart (no metric threads):
Or, as a vertical 11x17 sheet, including metric threads in either white or black backgrounds:
Now I have RPM speed charts for belt and back gear combinations:
All of the above charts, and the formulas used for generating thread pitches and feeds can be found in this Excel file: Sears_109_Lathe-charts.
The charts are free to use and modify, but if you share it with others please give me credit for it. I put a lot of effort into making these charts.
I found a copy of the original Operating Instructions for the 109 Craftsman Lathe: