method and apparatus for internal and external trimming plastic frames and the like . two plastic members are joined to bring heated , soften ends into engagement , causing some softened material to be forced out from between the engaged portions , forming internal and external flashing , which is trimmed in a first region by a pair of trimming blades moving along associated guides . the guides are mounted upon clamps holding the frame members , enabling performance of the trimming operation in the first region and eliminating the need for moving to a separate trimming / finishing station remote from the joining equipment . excellent cutting action is assured by locking the guide blocks . various combinations and sequences of repetitive trimming operations may be selected the blades being selectively moved providing a trimming operation which avoids the need for further finishing . trimming may be performed simultaneously on multiple stacks of members being joined . interior trimming is performed by moving an interior trimming member into trimming position along a path which avoids interference with the heating , joining and external trimming members . the interior member has a tool head that can be filled with a variety of different tools .