Power draw bars

Managed to get the couple of pages finished on power draw bars.
They can be viewed at http://homepage.ntlworld.com/machines

As to regards the Bridgeport quick change ones coming loose I may be able
to shed some light on this.
I presume that we are talking about the type that you use a 'C' spanner to
loosen off 1/2 a turn and take the cap off.
I had to do some assembly and development work on a large multi spindle
boring machine that had seven heads on with this fitting. As they had to be
quickly moved on the head to line up with previously welded fittings they
were designed to run on large geared air motors with this fitting built in.
They were made in house by copying an existing fitting - with one
difference. They copied an earlier fitting and the retaining thread was
courser that the later type.
This caused the caps to come undone when you closed the air off sharp. As
they had no big mass like a milling spindle they stopped very quickly but
the nose would unscrew and even fell off at times.
It was cured by re-machining shrunk on sleeves with a finer thread and new
nose pieces.

Perhaps the loose ones are the courser earlier pattern.
--

Regards,
John Stevenson
Nottingham, England