Mounting Work on Mandrels To machine a workpiece of an odd shape, such as a wheelpulley, a tapered mandrel is used to hold and turn the work.The mandrel must be mounted between centers and a driveplate and lathe dog must be used. The centers must be alignedand the mandrel must be free of burrs.
Rotifers: the wheel animalcules. Rotifers are microscopic aquatic animals of the phylum Rotifera. Rotifers can be found in many freshwater environments and in moist soil, where they inhabit the thin films of water that are formed around soil particles.ther animals with a pseudocoel, such as rotifers and acanthocephalans, appear to be more closely related to Lophotrochozoa, a large alliance of protostomes that includes molluscs, annelids, brachiopods, etc. Phylum Rotifera is divided into three classes: Monogononta, Bdelloidea, and Seisonidea.
Members of the phylum Chordata are bilaterally symmetric, deuterostome coelomates, and the vertebrate chordates display segmentation. Hemichordata, which includes the acorn worms, has been presented as a fourth chordate subphylum, but it now is usually treated as a separate phylum.hordates form a phylum of creatures that are based on a bilateral body plan, and is defined by having at some stage in their lives all of the following: 1  A notochord, a fairly stiff rod of cartilage that extends along the inside of the body.