On Tue, 15 Mar 2005 07:19:43 -0500, "George" george@least wrote:


"igor" wrote in message
.. .
When a company says that its clamp can extert X amount of force, what does
that mean? Before the clamp will snap? That a user will not be able to
tighten it any further?

Specifically I am interested in the specs on the "Quick-Grip One-Handed
Bar
Clamp / Spreader" shown he

http://www.coastaltool.com/cgi-bin/w..._bar_clamp.htm

It says that the clamp "Exerts up to 250 lbs of clamping pressure". I've
used this clamp and tightened it as best I could by hand, squeezing the
trigger. Assuming I have a "normal" strength grip, would that mean that
at
that point the clamp is exerting 250 pounds? What might the multiplier
be?
What if I used another clamp to squeeze the trigger of the first clamp?


Lots of replies, but the real answer is up to the point of clutch slip or
screw jamming.

The type referenced are used to hold things in place in lieu of a helper in
my shop. Though primarily "extra hand" devices, they can also be used
effectively as clamps, especially on properly prepared material.


Thanks, all, for the replies. I brought up the question because of some
_rough_ stress testing to failure. (Maybe I should have said "OT", since I
raised the question not in the context of clamping wood?) I had set up a
bench tester and used the quick-grip clamp to generate the force to stress
a part between two components of the tester. You see, NASA has been
bugging me and I was behind schedule on a part for the next Shuttle launch
.... But seriously, ladies and germs. I had not been able to cause failure
using my 200# weight at the end of a lever (much more force than the clamp
could apply because it was near he base of the lever), but I was hoping the
clamp could give me some sort of rough _perceived_ metric -- such as, "as
shown in this photo, part did not fail when 250# of force was applied."
Yes, I could try to do the math, based on the length of the lever and my
own weight, etc., but I thought the clamp looked better in a photo than
would me hanging on the end of the lever. Looks like maybe I should get a
pulley, a bucket, and some sand.

Also, with the discussions here about tool "ratings", such as hp, I thought
the clamp rating numbers deserved an airing. Again, thanks. -- Igor