The taper shank of the arbor and the hole in the spindle should be wiped clean and free from oil or grit. Should the outer end of the arbor be supported by a pointed center or a bushing, it will not be difficult to keep it in place; but if not so supported, it must be driven tightly into the spindle, using care that the flattened end or tang fits perfectly into the slot provided for it. If it is noticed that the arbor does not fit fairly into the spindle, it should be removed and examined to see that there are no dents or bruises on it, and that the tang is not too long or too thick, or the shoulders not cut back far enough to permit it to fit properly. When arbors work loose, it is on account of some one of these causes.

If the arbor does not run true when the cutter is mounted and the clamp-nut screwed up, the nut and collars should be removed and examined. Fine chips or dirt are likely to be found between the collars, or between them and the cutter, causing the arbor to spring when the clamp nut is screwed up. The parts should be cleaned and again put in place.