(12-05-2021, 09:47 AM)Halfathumb Wrote: Turning spindles for a chair I'm refurbishing. I have little experience wood turning and very little experience with a duplicator. On the Shop Smith one has limited speed selections. I've experienced some of the thinner spindles braking, quite possibly I get to aggressive trying to remove to much at one time. Other than the obvious, any suggestions. FWIW I've gotten help from a member with my local wood turners club. He also sold me the duplicator for $100.00 with cutters.
Jim
On the Shopsmith, the speed range is fully appropriate for spindle turning. The low end is around 700rpm.
Be sure that you are not changing the speed when the drive spindle is not turning.
$100 for a SS duplicator with cutters is a good deal. I paid more for mine. The cutters do get dull. So, make sure that you are using a sharp edge.
Replace the cup center in the tailstock with a live center. That is easier than learning how much wax to put in the cup center and how much pressure to apply to a dead center. That will reduce the number of spindles that you break.
When you are turning the spindles, don't just start at one end and turn to the finished size along the way.
Turn the whole length of the spindle that you want round to round at the largest diameter.
Then, work your way a bit at a time with the square cutter until you have the profile roughed in.
Then, use the round cutter to refine the shape.
Only then do you use the diamond cutter to gently finish the coves and any detail grooves.
Do the smallest diameter spot last.
If any of the spindles break using this process, then your design is bad and the legs are too spindly to support a chair.
Remember to orient your template so that, looking at it from the end, the square portion is a diamond. (not flat on top like it would be if laying on a table top)
If you are using 2-D template, make sure that you have it positioned properly and that your template-follower and cutter are directly above each other (with the table and the SS level). If you turn the largest diameter of the spindle to round and it is too small, then something is off in your setup and all of your diameters will be undersized.