Wood turning on a metal lathe

Everybody walking past said "You need a wood lathe for that". However I learned how to turn the lathe handles in the complicated fashion needed to make the curves of the knob. I finished off with some bits of sandpaper. I didn't use an angle grinder!
Here's the finished knob and the scrap timber that I made it out of:
http://i40.tinypic.com/34rvibs.jpg
I think it's mahogany. Inside the knob is a metal bearing. The knob turns on the metal spindle. I had to use a boring bar to widen the hole to half way down. I'm not sure how I could do that on a wood lathe. Anyway I like to keep my hands well away from spinning objects. The round bit of timber is a plug for the top of the hole.
Here's a very old knob of a different design:
http://i42.tinypic.com/r1djl4.jpg
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I did the sanding using a drill press going at 120 rpm.
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Nice job :)
NT
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After the success of this job, I'll be wanting to make another dozen knobs. Since I don't have a wood lathe, I propose making a tool about two inches wide that is curved to the shape of the knob and just wind it straight in. Of course I can grind the tool to a suitable angle and put it at the right height. I don't see why that wouldn't work. I suppose I'll find out!
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That's a form tool. Effectively a shaped scraper, sharpened as a scraper edge (80 degrees or so - a right angle with no rake and a bit of front relief). Works OK (not well), but only in mahogany (or similar) and you need to use a form tool lathe to work it. Absolutely _massive_ things. The forces involved in shoving such a form tool into the timber need a thick slab of HSS to make the tool from (otherwise it chatters) and you need a guide slot on the lathe, not just a tool rest. It's HSS because you don't want to have to re-sharpen it frequently, but it's thicker than power hacksaw blade. You can grind these out of other lathe tools (a cheap source of HSS bar with a handle on it) or go traditional and rework old files. NB - files need to be softened before use, their teeth taken off (angle grinder!) and their tangs checked for robustness. Use a lathe tool handle (bigger, stronger), as file handles on lathe chisels have been known to break. The re-hardening and tempering is in any school metalwork textboook of the 1950s - I assume we've all got such a useful thing.
I use form tool scrapers a fair bit, but none more than 1/2" wide and I don't have a lathe solid enough to be useful with one more than 1/4" wide. They're a good way to make beads (semi-circular raised ridges) where you want repeatable consistency between many, without being a virtuoso of the skew chisel. They'll also make pairs of adjacent beads, something that's hard with a skew.
Form tools were never used like this for your handles. They don't like squared or newly split timber and the forces were too big. Production work like this was instead done on a back-knife lathe. These were (and still are) very widely used for staircase spindles etc. They use a chisel-edged knife, not a scraper. <http://commons.wikimedia.org/wiki/File:Back-knife_lathe_ %28Carpentry_and_Joinery,_1925%29.jpg>
What I would suggest is that you build yourself a wood lathe conversion. Read some stuff on wood turning and see what the tools ought to look like, then emulate. Find a medium sized metalworking lathe - Colchester Student or similar, but an ML7 just doesn't have the space. Kit it out with a woodworking drive centre in the headstock (buy a drive centre, or re-grind a spade bit). Put a dead centre in the tailstock, or a live centre if you want less of a divot left behind (dead is easier on wayward chisels). Build yourself a woodturner's slide rest - Either fit a real one with lashed up clamps, weld one up from heavy steel angle, or just clamp a hefty bar in the four-way toolpost, if that's the best you can do. Really you want something that's supported from beneath, not in the way at the sides (why the toolpost cantilever doesn't work well) and is also height adjustable. Cutting angle in woodturning is controlled by the chisel position, not the tool grind, so it's crucial to adjust this by adjusting the toolrest height. If you can't do that, you might even want to stand on a box to adjust yourself to the right height! It's that important.
You need some chisels (4 minimum). Basic set is a Big U Gouge, used for turning random split billets into well-behaved, balanced cylinders. Then a small gouge, with a fingernail grind (you have to put this onto cheap sets yourself, but it's worth it as it's so much easier to use). Then a skew chisel that's either oval or with well- rounded corners. Also a scraper. You'll use the gouge to make things about the right size (nothing else works), then probably use the scraper to make the shape you want, because it's easier than the gouge. Don't even pick the skew up until you've read something like Keith Rowley's "Woodturning foundation course" book, or at least a website that explains about "rubbing the bevel" and "lifting the chisel to cut".
Best starter chisel set around is Axminster's http://www.axminster.co.uk/axminster-axminster-hss-woodturning-tools-set-prod822073 Add a square ended scraper to it as well, and maybe another big gouge if you're doing bowls. Then re-sharpen two of the gouges with fingernails and keep one big one for bowls.
Then ignore the beast, and go find a woodworker with a proper lathe. Get them to teach you how to do it right, under optimum conditions. If you're now slightly skilled in the way of doing it right, then you'll be able to cope in extremis far better. You might even just borrow their lathe for a while, or get them to turn it for you. Woodturners _love_ an excuse to turn wood, especially if it's not just more fecking bowls to clutter the house up with.
I'd also consider just getting a wood lathe. They're cheap - a decent cheapie is less than the price of the full set of chisels and gubbenry to go with it. If you have the space and the recurrent need, then it might be a sensible approach. There's not much woodturning in a tram or steam train, but there's an awful lot in station fittings of that period.
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