In the "steam drilling engine" article by Mr. Phillip Hill in ME 4426 pg 461 photo 5 a boring head is shown facing a casting. The boring head's slide is extended past the centre screw and the boring bar is in the middle end hole of the slide. This is a dangerous practice, as the slide is not fully supported when so far out of the head, and is clamped by only one screw. At best, the facing may not be flat, at worst the slide could come out of the body and fly off, possibly injuring the operator.
If the bar were in the outer end hole the slide could be moved farther back into the head's base, and clamped by two screws. This would be far safer since the slide would be properly secured and the bar would have a far better chance to make a flat face.
JD
Edited By Jeff Dayman on 29/04/2012 01:39:42