My own saw frame needs a fair amount of force to move it even the
slightest bit to tension the blade. If I do it the "normal" way, I
don't get enough tension, and the blade bows when I try to use it.
Saw blade bowing out is a problem. But it is not caused by lack of
tension. It happens when frame does not secure the blade well
(tensioning pads warn out, dirt, etc…), and sideway pressure is
applied during sawing.
Over-compressing the frame masks the problem, but not fixes it. When
frame is over-compressed, the geometry of tension vector is changed.
Tensioning force is not only acting along the blade, but also along
circumference with radius equal to the distance, between the blade
and the back of the frame. This does locks the blade, but the
sideway pressure on the blade remains. It causes blade to wear out
more quickly, causes more frequent breakage, and the worst of all, it
makes precise sawing next to impossible.
My advice would be to correct factors causing sideway pressure. It
could be technique; body position in relation to pin; failure to
maintain wrist aligned with forearm, which could be caused by
fatigue; and other factors. If you have a camcorder, it may be
worthwhile to film oneself while using saw, and see if you can
pinpoint the problem.
The second part is to maintain your saw frame. Tensioning pads should
be cleaned regularly, and replaced if necessary. Incidentally, it is
over-compressing which caused tensioning pads to wear out quickly.
Jumping in here, with my own extreme-sawing tales. I use normal
sawblades, mostly 1’s and 0’s, and smaller down to 4/0 for detail,
sawing tool steel plates into pancake dies. Normal ‘rules’ no longer
apply, after all it IS extreme sawing (^8. Early on I got tired of
stripping out thumbscrews (no, normal tighness doesn’t keep blades
from slipping out), so I stared using socket head screwes because of
the extra tightening leverage I could get with a hex key (allen
wrench). Then I got tired of stripping out saw-frame threaded
receptacles (what’s the name for that anyway?) so I made hardened
steel plates. Now I strip out the socket screws, but only every month
or two. I do need to make some hardened pads, because clamping blades
in so tight wears grooves in those little pad plates. When the 3/0
and 4/0 blades slip out, even when the screw is tight, I know it’s
time to file the pad down again to take that groove out. I have ski
pole handles mounted to my saw handles, and the rubber bases of those
prevent bruising, because I do bend the frame about 3/8" when
loading. The custom 8" frame Lee Marshall made me years ago, made
from solid 1/2" square aluminum bar stock, that I use with the custom
prototype gearmotor saw he made me ‘back then’, is an even more
extreme setup. I’ve abused several of the old -style BD sawguide
carriages, built one out of steel from scratch recently, and am
working on a sleeve-bearing-designed track system for the gearmotor
saw now.
It’s the extra power I’m sawing with, leg power on one saw, and
gearmotor power on the other, that calls for tighter-than-normal
(normal = hand-powered sawing) blades. I did normal sawing for a
long time before I ever started doing dies. Dies are a whole other
world of ‘fun’. I was thinking briefly about my whole gig as Le
Pancake Die Chef ; the thought was “right person, right place, right
time, right obsession”.
First to James Miller, come on over to visit, the door is open for
you and yours. Today was 74 Fahrenheit, and tomorrow forecasts 75!!!
For my saw, I fit the blade in top and bottom, then I loosen the
cross bar screw, standing up, I put the saw frame handle on the
bench surface, and push down on the cross bar, tightening that screw
when it feels firm. I then give it the ping test.
Works for me. I will be looking for Lee Marshall in Tucson, for
sure. I just love new tools, especially Lee’s.
I will be looking for Lee Marshall in Tucson, for sure. I just love
new tools, especially Lee's.
Unfortunately, My wife is scheduled for an eye operation on the 2nd,
and I will not be able to come to Tucson. This event was just
scheduled, and everything else pales in comparison.
However, Robyn Hawk will be there with the set of three saws,
carrying them around during her rounds, and they will be donated to
the winner of a drawing to be held at the Orchid dinner.
By placing your business card into a bowl, some lucky participant
will get to take them home. The winner must be present.
Rick C.: I use the same technique to tighten my blades, I found it
in Tim McCreight's, "The Complete Metalsmith" {page 49, Method #2}.
I used it while in University, and broke 1/3 to 1/5 the blades
others broke while learning to pierce and cut!
I was beginning to think I’ve been doing it wrong all these years
and may have opened up a can of worms. But having Tim McCreight
document it in his book gives the procedure about the greatest amount
of credence attainable.