shawndo wrote:Slayer has a different philosophy. That manipulating the flowrate during preinfusion has much more value than the ability to manipulate pressure during a shot. I don't see them adopting anything from this MP design. Its going in a different direction.

I'm also not really a fan of the MP design (despite owning one of these groups). I much prefer repeatable electronic control.

PS I'm not 100% sure that I'm being understood (or explaining, what I think I know, correctly) so definitely don't make any buying decisioned based on my words!

Actually this really helped crystallize this in my mind. So if I understand correctly:

GS3 MP - you can manually control the pressure throughout the entire shot.

Slayer - you can set up a preset flow rate, and a preset extraction pressure. Pre-infusion is at the fixed flow rate, then you swing the lever to go to the preset pressure for extraction, then swing it back to go back to preset flow rate at the end of the shot if you want.

Does that sound right?

Bingo! One can adjust the extraction pressure by adjusting the pump pressure directly on the pump (default 9 bar) but not during a shot.

Viernes wrote:In my opinion, no. You can reach 9 bar while maintaining ultra low flow in the Slayer. This is not possible with the GS3/Strada MP.

Only if the coffee is ground fine enough to allow 9 bar at the reduced flow setting. While it can happen, I doubt you'll be wanting to do that more than once. It's kind of like saying a Slayer can reach 9 bar at the ultra low flow setting against a blind portafilter, it can, but so what?

And why would it not be possible on a Strada or GS3? They're not restricting pressure, they're restricting flow the same as Slayer, just using a different mechanism.

Depending on who describes how the Slayer works, what you're told may not match reality. Took me a while to convince the person explaining it to me that I was knowledgeable enough about hydraulics to know the explanation was wrong and that I actually understood what was going on, but in general, the average shop owner buying a Slayer only cares what it does, not how it does it, so the explanation can lead you to believe it works in ways it doesn't unless you understand the physics. It doesn't generally develop 9 bar against the puck in the low flow position. It develops 9 bar against the needle valve during pre-infusion and 9 bar against the puck when full on, if your machine is set so it develops 9 bar against the puck in both states, it probably needs calibration.

Ira

ira wrote:And why would it not be possible on a Strada or GS3? They're not restricting pressure, they're restricting flow the same as Slayer, just using a different mechanism.

Correct, but only for the MP models of the Strada and GS/3. The EP model of the Strada does it differently: the pump speed is varied instead of the orifice size. I believe the Vesuvius does it that way, too.

You can look at the Slayer/MP models as using a constant motor speed against a variable orifice size, and the EP/Vesuvius models using a variable motor speed against a constant orifice size. Note that the flow rate does change when the motor speed is changed, as it does when the orifice size is changed. Also, after the basket fills with water, the pressure against the puck changes with the motor speed and orifice size.

The biggest difference between the two approaches is that varying the orifice allows the flow rate to go below the flow rate of the input line, all the way down to zero (orifice completely closed), while varying the motor speed only allows the flow rate to be reduced to the input line flow rate (motor off). This limits the lowest rate of preinfusion you can achieve. However, if you use a high-quality (consistent) line pressure regulator, you can get the line flow rate low enough to do a reasonably long, slow pre-infusion (say, 15 seconds), which in turn allows you to grind much, much finer to compensate for very light roasts.

On the other hand, the limitation of the Slayer approach is not being able to vary the orifice size on the fly to further profile the shot. The limitation of the MP approach, which does allow you to vary the orifice size, is not being able to use a microprocessor to exactly reproduce the profile from shot to shot. Another limitation as far as profile reproduction is concerned may be not having fine enough control over the orifice size, as with the original GS/3 MP mod.

An interesting tidbit about the EP is that it shows you realtime flow rate on the screen during the duration of the shot in cc's. There's a video on YouTube showing the single group pulling at 1cc/sec, which is a flowrate of 1ml/sec, which seems pretty low to me?

The big question I have is this :: what pressure does the single group EP pull when using the tank? Literature seems to state that the EP can go from 0-12bar in realtime. You're right when you say the minimum is line pressure, but if using the built in tank, can one pull at 1bar? I guess I'll have to run some tests when my EP arrives, since I can't find the answer online anywhere!

ira wrote:Only if the coffee is ground fine enough to allow 9 bar at the reduced flow setting. While it can happen, I doubt you'll be wanting to do that more than once. It's kind of like saying a Slayer can reach 9 bar at the ultra low flow setting against a blind portafilter, it can, but so what?

And why would it not be possible on a Strada or GS3? They're not restricting pressure, they're restricting flow the same as Slayer, just using a different mechanism.

Depending on who describes how the Slayer works, what you're told may not match reality. Took me a while to convince the person explaining it to me that I was knowledgeable enough about hydraulics to know the explanation was wrong and that I actually understood what was going on, but in general, the average shop owner buying a Slayer only cares what it does, not how it does it, so the explanation can lead you to believe it works in ways it doesn't unless you understand the physics. It doesn't generally develop 9 bar against the puck in the low flow position. It develops 9 bar against the needle valve during pre-infusion and 9 bar against the puck when full on, if your machine is set so it develops 9 bar against the puck in both states, it probably needs calibration.

Ira

Well, of course you need finer grinds to do a slayer style shot. That's the advantage. The possibility of using ultra fine grinds.

On the other hand...



I can not fully saturate the pucks in my GS3 MP at slayer flow rates (60ml/30s) There's not enough pressure, and water does not penetrate. To rise the pressure I need to open more the paddle to get, for example, 2 bar, but then the flow rate is high, and no way near the slayer rates.

shawndo wrote:Mine is a Shot Brewer not GS3, and it came with the Strada MP spec .6mm ruby (This one wasn't a mod)

I found this doc a while back, but it doesn't address the gs3. Still some good info and part numbers for both ruby and brass versions:
http://www.lamarzoccousa.com/wp-content ... Guide.docx

Is there a difference between a ruby gliceur and a brass gliceur other than the material itself? (Forming of scale? Form-factor?)

Peppersass wrote:Correct, but only for the MP models of the Strada and GS/3. The EP model of the Strada does it differently: the pump speed is varied instead of the orifice size. I believe the Vesuvius does it that way, too.

Correct.
I like this new GS3 MP better than its predecessor, no need for the strada-mod anymore and a better valve.

BTW The V always uses water from the tank, even when plumbed in. And it can pre-infuse without pump-pressure. (That surprised me, I thought it would need pump pressure since it is always fed from a tank in the machine itself.) This severly limits the flowrate when compared to the lowest pumpflow.

so the tail off in pressure on the slayer at the end of the shots is just the result of moving the paddle back to the preinfusion mode?

are there then only 3 "stops" on the slayer paddle, off, preinfusion and brew

Viernes wrote:Well, of course you need finer grinds to do a slayer style shot. That's the advantage. The possibility of using ultra fine grinds.

On the other hand...

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I can not fully saturate the pucks in my GS3 MP at slayer flow rates (60ml/30s) There's not enough pressure, and water does not penetrate. To rise the pressure I need to open more the paddle to get, for example, 2 bar, but then the flow rate is high, and no way near the slayer rates.

I'm a little confused, and it might just be because of communication breakdown. By your previous post you made it sound like the Slayer can reach 9bar of pressure in its 'pre-brew' mode, which is not correct. It's 9bar when you push the paddle into 'brew' 'mode, where it switches from the needle valve path to the full pump pressure path.

To see those same results on your GS3 MP you would pre-infuse like you were doing, then push the paddle all the way over for full brew pressure. Is that what you were doing to accomplish your shots above? Or are you saying that the pressure of the Slayer at 60ml/30sec is HIGHER than the pressure on the GS3 MP at 60ml/30sec? I'm no mathematician by any means but that just confuses me.