Union Jubilee Clutch.

[Yorkie]

3000 rpm sounds a frightening amount of revs to a non lathe person. Do you really need that much?

Gary

In a word, yes - certainly for spindle work or you end up having to do a lot of sanding to get a good finish.

The aim in woodturning is to get a good finish 'off the tool' to minimise sanding. To achive that objective, the smaller the diameter of the object being turned, the faster must be the speed. Something like a pen blank will only have about 1.5 inches of wood passing the tool for each rev, whereas a 10 inch diameter bowl blank will have twenty times that amount of wood passing the tool for each rev - approx 30 inches.

There is a basic rule of thumb for working out the lathe speed, which is: Diam in inches x RPM = 6,000 to 9,000. Hence, the speed at which a ten inch diam bowl blank is turned should be 600 - 900RPM. However, a 2 inch diameter blank for say a stair spindle would need to be run at 3,000 RPM. Theoretically, using this formula a 1 inch or less diameter spindle (pen blank, lace bobbin etc) would be run at 6,000 - 9,000 RPM - far beyond the capacity of the lathe. (The longer the spindle, iif being turned without a 'steady' the slower will need to be the sped or the wood will 'whip').

In my experiece, novice woodturners tend to scared of wood flying off the lathe due to a 'dig in' from poor turning technques, so tend to run the lathe at too slow a speed with dissappointing results, but as I've said before, the greatest hazard with woodturning isn't flyng objects the inhalation of dust, especially (hough not exclusively), laburnum, yew and iroko. Ineviably novice also tend to practice on softwood as it's plentiful, which is fine to practice techniques upon, but given that novices are generally not good at getting a decent finish 'off the tool', they end up spending more time sanding than turning. Oak is also not easy to turn due to its open grain.

It's perhaps worth saying that for sanding and friction polishing, the lathe should be run at a much slower speed - say 500 RPM or the heat generated by sandibng risks cracking or distorting the item if it's a bowl, vase, hollow form etc. The aim should always be to 'sand the shape of the wood' - not to 'sand the wood to shape'.

Back in August 2012 I posted a thread entitled 'Woodtuning Lathe Speeds' which went into a bit more detail on this topic.

Hope that's of interest and doesn't take the thread too far off topic!