On Fri, 15 Jul 2011 08:50:03 -0400, Randy333
wrote:

On Thu, 14 Jul 2011 21:13:28 -0700, wrote:

How much force does a common shop vise develop in its jaws? Google was
pretty unhelpful on this - the only reference I could find suggested
up to 7000 lb. Another paper suggested that a minimum required
clamping force for machining is much less - up to 1000 N.

I am interested because I am trying to guess how much force I can
develop in this press:

http://www.flickr.com/photos/2768312...57622484352534

Right now my answer would be "not enough" (see the following photos if
you are interested in the process).

Can anybody suggest how such force could be measured?

Michael Koblic,
Campbell River, BC

Use a trailer tougue scale or a Snap on brake force gage. I happen to
have a snap-on brake force gauge set, they are only 1/2" thick and
made to go in a caliper in place of the brake pads to check caliper
pressure. Measure 0-5000 pounds.

http://www.sherline.com/lm.htm



Thank you and all the others for helpful information.

To answer some of the points that have been raised:

1) There is no question in my mind that two *heated* rollers would be
the way to go. I have looked at several solutions including laminators
but nothing fit the bill.

2) Up to now I have been heating the workpieces on the same 1/4"
aluminum plate and then going over them with a hard rubber roller.
Using a bathroom scale etc. I estimated the pressure developed this
way at 21 psi. The results are reasonable with temperatures in the
region of 160-170C but the bubbles are a problem as the pressure is
applied *after* heating. No amount of rolling will get rid of them
then. Often they are in a place where they can be re-touched but
sometimes they are not and the piece is scrap.

3) The reason I do it this way after five years of experimenting is
that I found the recommended method by Press-n-Peel quite useless. It
works on PCBs. On anything thicker - not so much. There are others who
have described successes with the Press-n-Peel iron-on method but the
big question is always consistency. I did look at the Hobby Lite press
from HIX but before I spent $325 I wanted to make sure that the press
is suitable for what I wanted it for. The company was not particularly
helpful or forthcoming with information.

4) I jury rigged a press using two clamps. There is no question that
on small pieces at least I develop higher pressures this way. This has
reduced the number and size of the bubbles. However, the rub is that
sometimes the pressure is too much and fine detail gets obliterated (I
did this today with a 7 in2 piece which I only took up to 130C - one
tiny bubble but I shall have to go over the details with a needle).

5) I knocked my version of the press together from whatever I had in
the house. Frankly I did not expected it to last very long. Using the
two clamps was a pain and sometimes there was a clearly discernible
pressure gradient across the piece. I was hoping that the central
screw will provide more even pressure distribution and better pressure
control. I was disappointed at its performance but in retrospect I
should have expected that as the whole area under pressure is 80 in2
thus to produce the same pressure as I do manually with the roller I
would have to develop over 1600 lbs force. Of course the idea was to
produce more.

6) The press reminded me today that the force developed is not
inconsequential as it blew one of its legs off. Still, I learned a
fair bit from the effort.

7) Thanks to the gentlemen who provided me with the formula. I found
it independently in the Machinery' Book late last night after I
posted. I should have found it much sooner if I fed "jackscrew" into
Google. Such is life :-). The figures I got was 125x multiplier
without friction. I tried to do the calculations with an assumed
coefficient of friction of 0.2 and got a multiplier of 31.5. Seems
kind of small. I haven't the foggiest what kind of force I put on the
end of the lever (3" long, BTW, the pitch is 0.151" and the pitch
diameter roughly 0.6").

8) Version 002 is in the works with many changes. I am still not sure
how to achieve a consistent force (it is much easier to manipulate the
temperature). I wonder if a torque wrench would be the answer if
somehow incorporated in the top lever.

Michael Koblic,
Campbell River, BC