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Cunneen Hacksaw
Unlike the straight stab or keyhole saw, a metal-cutting hacksaw
will work effortlessly when it has two important properties:
there must be a high degree of tension in the blade and the
blade must always be inserted with the teeth oriented toward
the front. This is due to the fine teeth and type of set for
this kind of blade.
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Close-up of the teeth. |
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Blade tension mechanism and patent stamp. |
The
cut is made on the push stroke. Ideally, the blade is lifted
on the return stroke, the same way a file is used, to avoid
premature dulling.
Tensioning of the blade is almost always accomplished by inserting
it into a frame or holder. Early metal-cutting tools of this
type often had a springy frame, so one inserted the blade much
like stringing a bow for archery. In fact, the fret saws used
by jewellers and the coping saws used for wood still utilize
this method to achieve blade rigidity.
Tensioning
of the blade allows for a clean cut and, in some cases, facilitates
the use of thinner blades, creating less waste and finer control.
The use of modern alloys in blade manufacture has now made this
type of saw very practical for cutting metal by hand.
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