Shopsmith Forums

I do not seem to have much luck using a 4-prong center on either my SS or my mini-lathe, even if I cut across the corners with the bandsaw and drill a relief hole in the middle. What am I missing?

fiatben wrote:I do not seem to have much luck using a 4-prong center on either my SS or my mini-lathe, even if I cut across the corners with the bandsaw and drill a relief hole in the middle. What am I missing?

Do you use a mallet to drive the spur into the end of your turning? The spur needs to be well anchored.

Another factor in addition to Dusty's suggestion might be the tailstock center you're using. You should use a "cup" center. If you use one without the cup, it may allow the wood to move toward the tailstock as the center sinks deeper and deeper into the wood. Another possibility is that you might need to exert more pressure via the headstock on the Shopsmith or the tailstock on the mini. May also be caused by dull chisels.

You might consider making a pencil mark on the way tube when you start turning so you can make sure that your headstock is not slipping on the tubes a tiny bit as you work.


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That hole in the center needs to be a pilot hole, not a 'relief' hole. If it is too big, the pin will rattle around in the hole, and the workpiece will not hold center.

The center pin maintains centering while the spurs provide torque ability.

The spur center is all I have right now, but depending on the hardness of the wood, make sure you cut your kerfs the right depth. With cedar, you don't need kerfs really, as it is so soft and will tap on nicely. With harder woods, you'll split them "tapping" them securing in place if not deep enough. I use a piece of maple flooring between the spur center and the hammer for a flat surface and a cushion.
I would love to upgrade to jaw style.

Rather than tapping the center with a mallet, after making the pilot hole and 90 deg. cross kerfs, I just push the quill, with spur center attached, firmly into the wood against the tail. Always worked for me with red oak.

Guys, drive the drive center into the wood, OFF the lathe, unless you're using real soft wood.

Unless you like changing out bearings.

I have also just pushed the drive spur in with the headstock, but only with some soft wood.

steve

If you cross cut and drill a pilot hole, only the center point is being forced with pressure from the quill. As both centers wear into the workpiece ends, the quill may need to be advanced to take up the 'slack'.

I do not find it necessary to drive the spur into the workpiece when cross cuts are made.