Drive Types – Pros and Cons
Philip Greenwood looks at the pros and cons of drive types
You may ask how many drive types are there? ‘A lot’ is the short answer. Which type of drive you use depends on a few factors: this can include the size of timber being turned and whether it is dry
or wet wood. Wet timber can affect which drive type you use due to the timber fibres being more flexible, which means the drive centre may not grip as well with some types. Be aware that wet timber, which has tanning acid in it, can turn the timber around the drive centre position black if the drive centre is made of steel.
A 4-prong centre is the most common drive centre; this is normally the one that comes
with a lathe as standard. The most common 4-prong centres come in 1 and 2 Morse tapers
for woodturning lathes. As the name implies, it has four prongs. This is used to drive a
square piece of timber between centres. This can be used in both wet and dry timber.
A 2-prong is also good for driving square timber, but more especially if the end of the timber is not square. If a 4-prong was used in this case, only one point may be driving the timber, meaning this could come loose when turning and may come off the lathe. This type is also good for turning natural-edge bowl blanks due to the radius on the bowl blank top. I tend to remove the bark where the prongs sit, so the prongs will go into the timber and give a better grip. Drive this in with the prongs running parallel to the grain on a bowl blank.
How to use
2- and 4-prong centres are driven into the timber with a mallet, never a hammer as this will damage the end of the Morse taper, which in turn will damage the shaft in the headstock. When mounting between centres just tighten the tailstock sufficiently to hold the centre in the timber. Over-tightening can damage the bearings in the headstock and the centre in the tailstock. You can also use a small saw to cut two diagonals lines for the prongs to sit in. This is not a method I use, but I know some people do this.
Place a mark on the timber opposite a mark on one of the prongs; this means if you remove the item from between centres that you can replace this in exactly in the same position on the same prong.
A steb centre is one I use a lot. I don’t have to drive the centre in with a mallet due to this having a spring loaded point that retracts when I tighten the tailstock, engaging the teeth in the end of the timber. This type is not suitable for wet timber due to the small teeth, which don’t grip very well in the wet fibres.
Ring centres are the best type if you have to remove the item from the lathe and replace this back in the
lathe later; this is due to the drive being a centre point surrounded by a ring. The drive is pure friction;
this can be an advantage when learning due to the timber stopping if you have a dig in. With this type of centre, your tool control has to be good to maintain drive.
A step centre is the one I use to turn items that have a hole in both ends; this again is a friction drive so good tool techniques are needed or the timber will just spring on the centre. I use this to turn light pulls or is good for any item that you have drilled a hole in the end of.
Types of tailstock centres: revolving, standard, steb, ring
The most common tailstock centre is a revolving centre which comes to a point; this is used for most of my turning where I need tailstock support. The down side is it can leave a large hole in wet timber due to the fibres compressing. The revolving ring centre is a good choice with wet timber and also segment work or glued-up pieces such as those for inside out turning. A standard centre in this case can cause the joint to split; a ring centre would prevent this. Mine is part of a set from which I can change the tips in the revolving centre. A revolving steb centre is also a good choice for split turning or turning wet timber. The point on this centre retracts on tightening the tailstock.