Apologies for this people, but having only signed-up for this forum a couple of weeks ago I'm going to take the liberty of revisiting on or two of particular interest to me.
Ash is usually cited as the wood to use for handles, and the contributors to the previous thread all subscribed to this. Its prime quality for this kind of use is its elasticity, and it was the wood of choice for such things as cart shafts, pitch fork handles and axe and sledge hammer handles. All these items have length as a uniting factor, and as the length shortens so ash's virtue declines. It is probably still the best wood to use for hammer and hatchet handles, but for chisels it will be no better than most any other woods. Indeed, one of its other virtues, the ease with which it can be cleft , now becomes a vice and makes it more liable to splitting when hit than many other species.
Its widespread use for chisel handles probably has much to do with the facts that most aren't hit, that you can always hoop it if it is intended to be hit, and that if you have a workshop full of ash for making rake, axe, sledge and other handles, it is easest to use that wood for chisel handles as well.
What then is good for hitable chisel handles? Anything with a twisted, interlocked grain that's a pipper to split is the answer. Hornbeam, holly, hawthorn, elm box and apple would suit well and aren't too hard to get hold of. Norman G. rates robinia and I've had a lot of trouble splitting eucalyptus in the past, so that ought to be good. Rhododendron might be worth a try as well. Bear in mind that hardwoods split much better green than when seasoned. Wood from the base of a trunk will also have a much more interlocked grain than that from a little higher up, so if you're going to cut some ash take it as low down as you can.
The other thing to consider is the design. Hooping has been covered and is well worth doing (the wood needs to be seasoned when you do this). If you haven't the time for this then make sure that you dome the end of the handle (if you're turning it) or chamfer the edges if you're carving/whittling it. Nothing is guaranteed to break away quicker than an unsupported edge being hit by a mallet.
And talking of mallets, the handle would best be of ash but you probably wouldn't lose much by using other strong, long grained wood (anyone got any oak?). The important thing here is to make sure that the grain is straight and runs the length of the handle (which should happen automatically if the wood is cleft. With sawing you have to be more careful). The head could be any of the woods (above) that you might use for your chisel handles. I really don't know why beech has been so widely used for mallet heads - it's a short-grained wood that splits easily. As with ash and chisel handles it probably has most to do with its widespread use in joinery and the fact that it is heavier than ash.
Happy hitting.
