Re: Southbend lathe from 1911/12.
toggle quoted messageShow quoted text
No lever on the headstock, with a pair of small gears, secured with a bolt? To reverse the direction you can add another gear into the geartrain. Of course you'll have to make a mounting stud for it. Doesn't matter how many teeth, with all the gears in one plane, only the ratio between the first and last gear matters.
If the chuck jaw isn't messed up too badly, you can grind the jaws. First you need to make or find something to wedge between the jaws that doesn't cover their points, or intrude on the circle described by their points as they rotate. Then you need a die grinder or Dremel or similar with a stone that can reach all the way to the back end of the jaws. Mount the grinder to the compound slide (or cross slide if your lathe only has that) and install the change gears to get the slowest feed you can.
Poke the stone into the chuck then spin it by hand. Adjust the cross slide so nothing hits, then turn the lathe and grinder on and move the cross slide toward you just until the stone makes sparks. Turn off, back the grinder out then back on and make the first pass. Repeat until all three jaws are ground their full length.
What you'll get is a chuck that will hold a workpiece parallel to the spindle at all diameters, and pretty accurately centered at the diameter where you ground the jaws. Centering accuracy at all other diameters will vary, depending on the original precision of the chuck and how worn it is.
As for finding replacement jaws, if there's a brand name and model number on it, it may be possible. There are some used tooling shops in the "midwest" States that have bins full of old jaws for three and four jaw chucks. You have to bring your chuck in and go digging for a match because there have been so many different chucks made in the close to 200 year history of these chucks.
If the chuck is real badly worn, with the jaws flopping and rocking in their slots, then your first purchase of good tooling should be a backplate and chuck. Hopefully the spindle thread on this antique is a 'normal' type for which you can buy an inexpensive, pre-threaded, cast iron backplate.
As long as the chuck will hold work firmly, and you can't grab the end of the work and wobble it around, and the spindle isn't loose in its bearings, you can cut accurately - as long as you do all the cutting in one chucking. Remove the work from a worn chuck and you'll never get it back in exactly the same.
Something to ALWAYS do with a lathe is run the carriage up manually as close to the chuck as you'll be using it, then spin the chuck by hand to ensure nothing will hit any part of the carriage. It was common sense to me from the first time I used a lathe, but going by the damage I've seen on many lathes, especially ones from schools, perhaps not so common... ;) It will definitely save on broken tooling and damaged work.