After finding a natural barley twist while holidaying in Queensland, Geoff has sent a couple of photos in of a barley twist lathe that he has acquired (but yet to use).
It is interesting to study, just to see how simple an arrangement it is, and with a little bit of work, pretty easy to duplicate – especially (but not limited to) those with Torque Workcentres.
It would be pretty easy to add this functionality to a real lathe (but NOT switching the lathe on!!!) A lathe with an indexing ring would be excellent for this
I’m not sure the drive mechanism for this lathe – it may be from pushing the router sideways, but I suspect you manually turn the black winder in the second photo. In that photo, you can also see an indexing ring, which is essential for setting the workpiece to the next start location. Depending on the combination of how far around the workpiece is indexed, the router bit chosen, and the setting for how fast the router moves relative to each rotation of the workpiece will dictate resulting effect.
A barley twist lathe can be regarded as a glorified Beall Pen Wizard (or is it the other way around – the Beall is a miniature barley twist lathe?!)
Back to Geoff’s lathe – I can’t see how the gearing is regulated, but I assume it can be changed.
So that is a barley twist lathe. Do an image-search on Google for Barley Twist will reveal over a million examples of this ornamental feature being used in different projects, with varying degrees of success! In some instances it is beautifully complementary to the overall object. In some other cases, it has obviously been included without any understanding of how such an ornate feature should be used.