For very heavy work of considerable bulk, an open-sided planer is used. This is somewhat similar to the planer just described, except that one of the housings is omitted.
Another type of planer designed for planing off the end of a large forging, too long to rest cross-wise of the planer bed, is the rotary planer. The work is secured to a fixed base plate, and the end is presented to the face of a heavy revolving disc which carries many cutting tools. As the disc revolves, the tools cut the end of the work, which is fed in a direction parallel to the face of the disc.