Re: Looking for useful impact wrench on a budget...

["Fred Munro" <munrof@isys.ca>]

-----Original Message-----
From: Aleksander Mierzwa <alex@matrix.pl>
To: gerard@dockside.co.za <gerard@dockside.co.za>; quattro@coimbra.ans.net
<quattro@coimbra.ans.net>
Cc: gerard@dockside.co.za <gerard@dockside.co.za>
Date: Saturday, January 09, 1999 10:48 AM
Subject: Re: Looking for useful impact wrench on a budget...


[snip]
>
>I seriously doubt if you really need an impact wrench. While it may seem
>nice to have, it's pretty dangerous. For example, what if a bolt is
>_really_ frozen? You attack it with your impact wrench, BANG, the bolt head
>breaks off, what now? If you use a long breaker bar instead, you can apply
>force in a controlled manner and usually avoid such problems.
>Impact wrenches also shouldn't be used for tightening things.
[snip]

    In my experience, Aleksander, it is much easier to break a bolt with a
breaker bar than an impact gun. Because the impact gun delivers torque in a
rapid series of impacts, it does not rotate a frozen bolt far enough to
shear it off. If the bolt is frozen, it twists a very small amount with the
impact and returns to it's original position before the next impact. I
suppose if you rattled away long enough it would fail from metal fatigue,
but I think the arm holding the impact gun would fatigue first. The on/off
nature of the impact can free fasteners which would break off if a constant
torque (a la breaker bar) were applied.
    It is possible to round off bolt heads and wear out standard sockets
with these guns if you do not use the sockets designed for impact guns.
     You are completely correct in saying that an impact gun should never be
used to tighten ( or more correctly, torque) bolts - you can run them in
with an impact gun, but make darn sure they are not cross-threaded. I never
use my impact tools for running in or tightening fasteners because I like to
feel the torque required to run the fastener in - it can identify problems
with the fit of the threads.

Fred Munro
'91 200q  266k km