Live center for my new lathe

ericc

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I made a live center for my new lathe. The lathe was missing a lot of tooling but had a bar of approximately the right size. It was just not tapered. There are instructions on the internet that say chuck an existing taper and adjust the compound angle so that the compound feed tracks parallel to the taper. This instruction is not useful unless the taper is available. Another way is to adjust the compound so that the difference between the distance to center divided by the traverse length is equal to the tangent of the half angle of the taper. It is difficult, however, to measure the second distance, since the compound is what is moving, and without a fixture, it is difficult to correctly align an indicator tip. Joe pie has a video on YouTube, but this relies on the tailstock barrel parallelism and the accuracy of the compound screw. The latter is poor in my Craftsman 109 lathe.

The new instructions gave a two part method. First, cut the taper as suggested by marking the adjacent side on the bar with a grease pencil or sandstone with a ruler. This is rough. Cut a taper, but not as deep as final. When it is done, indicate straight down the taper with the carriage feed. The huge key here is that the latter distance can be measured with a drop or an indicator mounted on the front way. If the reverse angle matches, you're good! But it won't. Use the deviation to correct the compound in the obvious way. Finish the cut. It works. The taper as cut hit in 3 places evenly down the shank and only required a touch with a file. The trick is the trial cut.
 
Here is a picture of the second measurement. This little Craftsman 109 is working pretty hard.

20170820_154034.jpg
 
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