**Description**
In 1986 the lost motion clampup method (BUCA) was utilized on the web side of a spar riveting machine.  It was not a precise process and the part was moved back and forth randomly.  The BUCA process is now in use on over fifty drilling and riveting machines at several major airframers.  This paper will track the development of this process to its current utilization on a gantry drilling machine.  Any time it is your intention to clampup on a part where the part is and not move it to where the machine is then you need this process which is not widely understood.  This paper will explain BUCA in detail.

**Author(s) - ranked in descending order of contribution / as it should appear when published**
Peter Zieve PhD



The Backup Carriage Advance (BUCA) method of Machine Clampup

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