Bosco group: double vs single spring version [video] - Page 2
- Whale
- Posts: 762
- Joined: 15 years ago
TX, I had never seen that one.
Back on topic.
I do not understand why, if all parameters are the same except for the peak pressure, the pour would occur in the same time duration?
I understand that the yield will be the same since the coffee puck has the same composition and same saturation. The volume output will be the same as it is driven by the cylinder volume.
With a higher pressure there should be a higher flow through the puck (same composition and same saturation) that has the same resistance. Unless the pressure on the puck actually increases the resistance?
Back on topic.
I do not understand why, if all parameters are the same except for the peak pressure, the pour would occur in the same time duration?
I understand that the yield will be the same since the coffee puck has the same composition and same saturation. The volume output will be the same as it is driven by the cylinder volume.
With a higher pressure there should be a higher flow through the puck (same composition and same saturation) that has the same resistance. Unless the pressure on the puck actually increases the resistance?
LMWDP #330
Be thankful for the small mercies in life.
Be thankful for the small mercies in life.
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- Posts: 270
- Joined: 9 years ago
As an example, the difference between 8 and 10 bar is 29 psi.Whale wrote: Unless the pressure on the puck actually increases the resistance?
If you are tamping a 58mm diameter puck with 30 pounds, you are only generating 7.33 psi on the dry puck.
The additional 29 psi of the water column should increase puck density / resistance.
- naked-portafilter (original poster)
- Posts: 698
- Joined: 10 years ago
If you have a proper prepared coffee puck and you push stronger on the lever (manual) your flow will stay the same more or less (above a specific pressure of course). If the grind isn't fine enough you can play with the flow of "coarse" .Whale wrote:TX, I had never seen that one.
I do not understand why, if all parameters are the same except for the peak pressure, the pour would occur in the same time duration?
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- Posts: 1751
- Joined: 14 years ago
Did that on my Pompei and put it back in real fast.TomC wrote:Nice work! I pulled the second spring out of my LSM group long ago and never looked back.
Didn' t like it.
Espresso tasted softer as if mixed with water.
Not to my liking.
- JohnB.
- Supporter ♡
- Posts: 6579
- Joined: 16 years ago
If it's like the Pro 800 dual spring set up removing the inner spring leaves you with a spring that peaks at 7 bar. The single spring versions of the same group used on the Pro 800 use a spring that peaks at 8 bar. If someone wants to convert a dual spring group to single spring they should source the correct spring.
LMWDP 267
- naked-portafilter (original poster)
- Posts: 698
- Joined: 10 years ago
This is another proof for me:espressotime wrote:Did that on my Pompei and put it back in real fast.
Didn' t like it.
Espresso tasted softer as if mixed with water.
Not to my liking.
1. that this discussion about the dual and single spring groups is partly a discussion about taste
2. You can not directly compare a single spring lever with 3bar pre-infusion with a double spring model with boiler pressure pre-infusion without knowing how they really work. With given setting parameters single and dual spring groups could deliver the same or at least very similar pressure profile.