Assert the pressure use in manual press

[tgvp]

I'm the happy owner of a small manual rosin press (that one) which is branded as having 600kg of "pressure". But as far as physics is concerned, the pressure between the plates depends on how much strength I have to put on pushing the lever down as the "torque" will "amplify" it (all those quotes are due to the fact my physics classes are quite far away, but I hope it's still understandable if not totally correct). As an example, if I have two bags of 10cm^2, the first filled until it is 1cm of height, the other 5cm (with similar density), the pressure per area of surface will not be the same with the exact same plates distance setting. In the first, I need to push very gently to "close" the press and in the second, I even risk of bending the crank.

So how do I assert the pressure between the plates?




P.S. To be honest, this will probably not be revelant anymore soon as I plan to buy an hydrolic press with a manometer and move the heating plates and controller on it

 

[Cheebsy]

The pressure on the puck is most important, that's affected by the size and shape of the puck. This thread shows solve examples of the calculations

Rosin press pressure, formula-

Hi, I need help determining working pressure (PSI) on a small plate/ low pressure setup please. with 3.0" x 1.5" plate, you have 4.5 sq in of plate If max pressure is 700 lbs, what is the working pressure (PSI) for: 1. 1" x 2" puck (2 sq in) 2. 1 x 1" puck (1 sq in) 3. tricky one...

fuckcombustion.com

 

[tgvp]

The pressure on the puck is most important

That's exactly what I'm trying to estimate. As I know my bag is 7cm wide and I fill it as a tube (bottle pressing method? a name like that...), the pressing surface will be around 31cm² and the height will depend on how much I fill it. My press being supposed to deliver 600kg which means in fact ~60N, so I get 450PSI on my bag.
But depending of the height of the bag, I will need to put more or less strength on the crank to toggle it down, so the pressure won't be always at 60N, if the bag is less filled, the pressure will be lower but if the tube is taller, the pressure will be higher.
The press has a screw to change the distance between the plates, so how to know how to set it up for the right pressure?

 

[Cheebsy]

No need to estimate, you can calculate the maximum pressure, unfortunately you still haven't provided enough information.

You say you're doing bottle tech so the puck will be cylindrical. You need to calculate the area of the circle at the end of the cylinder.

To try to clarify a little let's imagine your puck has an area of 1 square inch, your press is capable of 600 kg, or 1322lbs. So one that imaginary puck you'd be getting ~1300 lbs over 1 sq in. or 1300 psi. If you're puck has an area of 2 sq. In. You'd get ~650 psi at full pressure.

Hope that helps

 

[FlyingLow]

I kinda throw numbers out the window. Press till you have a blowout, then slowly back down till you find that balance of maxing out without blowing your bag.

 

[tgvp]

ow. Press till you have a blowout, then slowly back down till you find that balance of maxing out without blowing your bag.

That's kind of the empirical method I use As a rule of thumb I decided that the 60N force is when I need a mild force (very well defined technical term!), thus I start pressing at lower than that and then slowly increase up to the point I have to use lot more of force to pull the crank down. But no need to go too strong cause anyway, the results usually gets stickier, darker and harsher in test...
Until I decide to put my heating plates on an hydrolic press with a dynamometer, this technique will prevail, but as I can press at least 15 or 20g with my current setup, which is plenty enough for my own usage, I'm not sure the investment is worth the added precision.