Mon Jan 08, 2018 3:55 pm
Daniel,
The friction brake works great on small reels of film however it does not work well on larger reels of film. Here is what happens with the friction brake. You set the tension and start to unwind the film from one reel to the other. The reel
with the friction set has a lot of film on it at the start and the film is given the mechanical advantage over the friction
brake. And of course the empty reel does not have have this advantage. Thus the film will wind kinda loosely onto the
new reel. Okay for sake of point it will be tight cause of the setting of the brake but is still "looser", you will understand
here in a minute.
As the film goes threw the reel you will notice that the friction side start to speed up as film is removed from it. This
is because the wraps are being moved from one side to the other but it also slowly diminishes the mechanical advantage
that once large reel had over the friction brake. Thus the brake now is applying more force upon the film. This acts just
like you have spooled up the friction value, in turn this will make up a tighter winding on the take up side, which now is starting to gain an advantage over the brake. In turn this makes it easier to wind the film up even thou more tension is now being applied to the film! This the outer wraps becomes "cinched" on the "looser" inner warps of film. It is not a
good effect to have on the take up, all kinda of bad things start to happen.
So lets introduce the hand brake. With this you are in control of the friction value at all times. Starting off heavy and
then slowing letting up on the brake as you go threw the reel. It takes a bit of practice to get it working well. But
nothing that can not be learned quickly enough on a junk reel of film.
I hope this helps.
Pookybear