attila
Moderators: Head Monkey, kelvin, bigKam, skidesmond, chrismp
I tried to make a slack line (climber tightrope type thing) out of a ratchet strap and some webbing. It was fairly good sized, but broke easily. The weak part was the pawl. Depending on how many you use and what strength they are rated at, it could work. I'd be pretty worried about all of the energy stored in the press causing the ratchets to become a domino effect of projectiles. Once one broke, I could see the stress shifting and causing the rest to go in sequence. From my recent adventures with bladders, I'd say this isn't something that corners should be cut on.
as i started with this idea i also had ratchets in my mind. but as APS already mentioned there are a few problems.
it`s really important for such a frame to distribute the pressure evenly over the whole lenght of it. this is the reason why the cloth of my frame covers nearly the whole mold (the gaps between the single cloth tubes are only about 1inche long). the longer the cloth, the less pressure a single cloth-fibre has to take.
secondly you have to make sure that every "fibre" of your press frame has to take up the same load - that the pressure is evenly distributed. otherwise the domino-effect can happen, as APS named it. to fullfill this criterion the fibres have to be the same lenght and in the same distance from each other.
the easiest way to achieve this is to put the whole mold in a tube out of cloth. if you work properly all the fibres have the same lenght, the are distributed all over the press which means that the load is minimized as much as possible and the fibres all are evenly distributed over the whole frame - so all in all your frame has to take up the same load in every area.
now if you wanted to do this with some ratchets you`ll get following problems:
i suppose you wanted to wrap around the straps of your ratchet several times to cover as much space of your mold as possible. by doing this you had to shift the strap a little every time you wrap it around. here`s the first problem: the "fibres" in your straps may not have the same lenght and may have to take up different loads - domino effect!
an other problem: if you wrap around the straps several times you had to make sure that you wrap them with a constant "tightness", which means that you use the same lenght of strap for one wrap around. because again, if they don`t have the same lenght the load varies and may cause the system to collapse
and last: you may need more than one ratchet - which makes it even harder to get an evenly distributed pressure.
so all in all i`d say it`s nearly impossible to distribute the pressure evenly over your whole pressframe if you use ratchets. and so there is a high risk of partially overloading your system and causing some accidents...
it`s really important for such a frame to distribute the pressure evenly over the whole lenght of it. this is the reason why the cloth of my frame covers nearly the whole mold (the gaps between the single cloth tubes are only about 1inche long). the longer the cloth, the less pressure a single cloth-fibre has to take.
secondly you have to make sure that every "fibre" of your press frame has to take up the same load - that the pressure is evenly distributed. otherwise the domino-effect can happen, as APS named it. to fullfill this criterion the fibres have to be the same lenght and in the same distance from each other.
the easiest way to achieve this is to put the whole mold in a tube out of cloth. if you work properly all the fibres have the same lenght, the are distributed all over the press which means that the load is minimized as much as possible and the fibres all are evenly distributed over the whole frame - so all in all your frame has to take up the same load in every area.
now if you wanted to do this with some ratchets you`ll get following problems:
i suppose you wanted to wrap around the straps of your ratchet several times to cover as much space of your mold as possible. by doing this you had to shift the strap a little every time you wrap it around. here`s the first problem: the "fibres" in your straps may not have the same lenght and may have to take up different loads - domino effect!
an other problem: if you wrap around the straps several times you had to make sure that you wrap them with a constant "tightness", which means that you use the same lenght of strap for one wrap around. because again, if they don`t have the same lenght the load varies and may cause the system to collapse
and last: you may need more than one ratchet - which makes it even harder to get an evenly distributed pressure.
so all in all i`d say it`s nearly impossible to distribute the pressure evenly over your whole pressframe if you use ratchets. and so there is a high risk of partially overloading your system and causing some accidents...
plywood freeride industries - go ply, ride wood!
