Saturday, June 1, 2013

Turn Turn Turn, for everything there is a cliche, turn turn turn...

I apologize for my absence. I've been having a... thing. I don't believe in writer's block so it's not that, it's just... I dunno. You can read about it at Pages to Type if you want: Dumbo's Feather Revisited: Of writers and rituals otherwise, accept my apologies and let us move on to wood spinning in a circle with a blade placed against it...


The Worshipful Company of Turners

My lathe. Up close and personal...
I've never particularly liked turning. Modern lathes are fast and dangerous and freakishly expensive, which combined uncomfortably in my mind with the idea that has often been pushed on me that all woodworkers are aspiring turners.

I am not.

At least not until I discovered that I could build my own lathe, which appealed to my "Make Neat Things" aesthetic and helped me take my first hesitant step onto that slippery slope of wood turning.

The history of lathes is very interesting and rather closely parallels the history of the spinning wheel and the pottery wheel, all of which operate on much the same principals, though not necessarily in the same plane. By the 16th century, there were three kinds of lathe existing side-by-side: the fairly primative bow lathe, the springpole lathe and the treadle lathe, which I gather was a recent invention.

Almost anything that was round in Elizabethan England was turned on a lathe. Even if something was cast, the pattern from which it had been cast was probably turned. Patternmakers love wood and they love lathes.

My old nemesis/muse Jost Amman, of course, has a turner depicted at his trade. The lathe isn't well depicted, but you can just make out the springpole coming across the ceiling and the strap or string that is driving the sphere (apparently) that the guy is turning.
The turner at his trade from Jost Amman's "Das Standbuch" of 1568
I admit I'm curious about why he'd be turning a sphere. If anyone knows, leave a comment. If that's a bowl, he has it on the lathe sideways, but an engraver can't necessarily be expected to accurately depict the nuances of every trade, I suppose.

My lathe was built on the same basic plan as this one I found on Pinterest. I made the heads from two sharpened carriage bolts, which I carefully and painstakingly aligned to give a nice, flat spin for the workpiece.

The string started out secured to the springy limb of a pine tree, a suggestion made by Peter Follansbee in one of his videos, but I confess that I eventually swapped it out for a four-ply bungee rope when I got tired of being whipped by the tree for my temerity. 

Problems to Solve
As you can see from the image below, my oak billet (I'm starting small, a handle for a socket chisel) was chattering something fierce. This happens when the blade of the tool skitters across the work surface rather than biting into the wood as it is supposed. I suspect my lathe tools weren't as sharp as they needed to be in spite of my hours spent honing them. I shall return them to the whetstone again tomorrow and finish off with a good bit on some emery paper and then leather stropping.  

All else being equal, this shouldn't be happening.



Another thing I've decided to add to the design is a drive wheel. I got this idea from an article written by Roy Underhill, who explained that the diameter of the piece affected the speed of the turn. So I sat down with a bit I cut from one end of an old maple rolling pin and milled out a pulley, essentially. The trio of spikes will (theoretically) go into the small piece to be turned and drive it at a higher rate of speed. 

The concavity of the drive wheel should keep the string from creeping, which has been a bit of a problem already.



To compound my sin with the bungee, you can see that I began with a length of nylon paracord that I had lying around. It has abraded with a vengeance and I've already had to deal with broken lines and splicing new bits of line into my machine. 


I will be replacing the paracord as soon as I can with a proper bit of line, hemp if I can find it.

Once I have things worked out and in working order, I will get on with the real task, turning a small wooden bowl like the ones found on Mary Rose. But we're nowhere near there yet.

More to come.

- Scott


Late addition: 
Foot-powered lathes at The Woodwright's Shop with Peter Follansbee and Roy Underhill. Enjoy!

Watch Wretched Ratchet Reading Rack on PBS. See more from pbs.

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