Another pre-infusion mod

Need help with equipment usage or want to share your latest discovery?
SylvainMtl
Posts: 138
Joined: 18 years ago

#1: Post by SylvainMtl »

Here's an easy pre-infusion mod. Maybe too easy and nobody thought it was worth a post.
Anyhow, my goal was to simulate the functionality of the GS/3 paddle group as I understand it. What I did was install a second switch between the primary lever and the 3 way valve.
The second switch I put in place has 3 position, line pre-infusion, off, and normal operation. Like this I can easily pre-infuse / post-infuse manually and experiment with varying times. And my wife still has the regular mode available.

Here is the resulting behaviour.
As a bonus I was able to verify my assumption about my issue with the high remaining pressure after running the pump that I used to have (I did post about this here a few months ago). After some experimentation, my guess was that the 3-way was closing some moments before the pump was stopping, resulting in a high pressure readout. After doing a post-infusion with the new setup, the pressure gauge shows the proper line pressure.

And for results well shots appear easier to execute with regard to the bottomless portafilter, but I'll reserve my conclusion about the taste after more testing.

Sylvain

Billc
Posts: 304
Joined: 15 years ago

#2: Post by Billc »

Very much worth noting. This is exactly what Synesso does with their machines. There are 2 switches in the group top. One turns on the valve and one turns on the pump. The valve is first then when you want to turn the pump on and off you push it further to activate the pump. Also Slayer does this similarly.

FiftyKilo
Posts: 4
Joined: 14 years ago

#3: Post by FiftyKilo »

Sorry Bill but you are wrong, Slayer doesn't do the same.
Ralf

Billc
Posts: 304
Joined: 15 years ago

#4: Post by Billc »

Yes you are correct... not exactly. But the result is essentially the same. At least this is what I saw on the machine that I had the pleasure of seeing.

Bill

FiftyKilo
Posts: 4
Joined: 14 years ago

#5: Post by FiftyKilo »

The result isn't the same. Slayer doesn't use the term pre-infusion, because of the much longer time it is more like a pre-brewing. On a Slayer you can have on each group independent pre-brewing pressures between 0-9 bar.
Ralf

Billc
Posts: 304
Joined: 15 years ago

#6: Post by Billc »

Yes, understood. The terms also get confusing I did propose we re-name all processes so it more reflects what is currently happening in the coffee world. With changing pressures there is hard to define the "pre" time.

For the last 4 years or so a common time for a low pressure period was about 15-18 seconds, then higher pressure and then low pressure at the end. But finishing still with a 25 second (approx) shot.

When I worked at LM the issue was choosing between a stepwise change (digital pick a few pressures) or a gradual change (allowing for an actual programmed profile). The hard part was finding people that could actually taste a change. There were some but few (at the time).

The most important thing about all this is where the machine is measuring pressure. Some machine may look like they have a pressure profile but in fact there is little change in the portafilter. Make sure you know where this.

User avatar
cannonfodder
Team HB
Posts: 10497
Joined: 19 years ago

#7: Post by cannonfodder »

On my Faema, I installed an adjustable delay on make relay on the pump. I could dial the infusion time in to get a fully saturated puck before the pump kicked on. I think I was running around 3 bar on the mains, dont remember what the infusion delay time was. The switch is an easy way to do it but you have to use a stopwatch to get the infusion time the same for every shot. With this guy I could dial it in and forget about it. If I wanted to turn it off, I just turned the dial to 0 seconds.
Dave Stephens

SylvainMtl (original poster)
Posts: 138
Joined: 18 years ago

#8: Post by SylvainMtl (original poster) »

Dave, I've been reading that optimally I'd want to obtain full puck saturation (that I translate to a first drop of coffee out of the basket) before running full pressure.

I'm assuming the parameters may vary (from coffee to coffee or as coffee ages) and so you'd need to either adjust line pressure or the timer from time to time (I have no idea how frequently).

For the record, right now I'm at 2 bars and getting the first drips around the 6 second mark using 5 day old 49th Org.

User avatar
Stuggi
Posts: 440
Joined: 17 years ago

#9: Post by Stuggi »

cannonfodder wrote:On my Faema, I installed an adjustable delay on make relay on the pump. I could dial the infusion time in to get a fully saturated puck before the pump kicked on. I think I was running around 3 bar on the mains, dont remember what the infusion delay time was. The switch is an easy way to do it but you have to use a stopwatch to get the infusion time the same for every shot. With this guy I could dial it in and forget about it. If I wanted to turn it off, I just turned the dial to 0 seconds.
Sorry for resurrecting this thread, but Dave, could you give a bit more details about your setup? Are you using any kind of commercially available timer or?

To the OP, how exactly did you wire in this switch?
Sebastian "Stuggi" Storholm
LMWDP #136

SylvainMtl (original poster)
Posts: 138
Joined: 18 years ago

#10: Post by SylvainMtl (original poster) »

The electrovalve, pump indicator light and Gicar box are all energized in parallel from the brew activation switch. I've inserted my switch before the valve. You can check my quick drawing to get a better idea.

Post Reply