DIY flow control E61

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jb-0101

#1: Post by jb-0101 »

Has anyone attempted a DIY flow control device for an E61 machine? In Australia a purpose built e61 flow control device costs $350+ which seems excessive when I've seen the clippard valve that others have used on other machines costs $10 USD. Add a few pipes and connectors and a pressure gauge and I reckon it could be done for sub $100 with a couple of hours of tinkering.

Has anyone tried? Would it be possible? Surely...

coffeeOnTheBrain

#2: Post by coffeeOnTheBrain »

Surely possible and a valid idea. However, a few things to consider.
First of all the romantic of a purely mechanical mechanism is lost, I understand this is no concern given the price difference. What makes this approach a little harder is that usually machines that are modded with these electronic parts have plastic tubing while e61 typically have metal tubing. Also a flow control valve has a more direct effect when it is close to the group, surly you can fit it close still.

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Mayhem

#3: Post by Mayhem »

A member of a Swedish forum machined his own flow profiling parts for an E61 grouphead, of a similar design to the commercially available kits which fit a needle valve at the top of the group. So yes it can certainly be done if you are an experienced machinist with access to the necessary tools, but if you are not then best to just pay up and smile...

https://riktigtkaffe.se/kaffe/hembyggd- ... ost-151880
Too much is not enough

jb-0101 (original poster)

#4: Post by jb-0101 (original poster) »

Yeah definitely not going to machine so it fits in the mushroom, but could you attach a flow control valve to another part of the brew path like this one Synesso Cyncra Needle Valve Mod

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Jeff
Team HB

#5: Post by Jeff »

Consider that you need a thermosiphon (or other source of flow) for an E61, HX or DB. There are two tubes to an E61. It isn't as simple as a BDB to put in a single valve.

JRising
Team HB

#6: Post by JRising replying to Jeff »

It's nearly as simple, though. All you need to do is to tee off from anywhere in the brew circuit (Including the plumbing before the check-valve). Consider in the Rockets with vibe pumps, they have that little manifold with a spare (plugged) manifold in them where the brew and steam circuits separate from each other.
An elbow in there to replace the plug, a needle valve operated at the back-bottom corner of the machine, basically in parallel with the smaller OPV (brew pressure OPV) and another plastic tee so that it can feed back alongside the brew pressure OPV and Roberta's your aunt.

Make it even fancier, put a check valve inline with it with a heavier spring than the machine's brew-check-valve so that with the needle valve wide open, you still have a specific pre-infusion pressure. Then your aunt Roberta's coming over for an espresso every Sunday.
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Jake_G
Team HB

#7: Post by Jake_G »

John's suggestion is about as good as it gets for a cheap solution on an E61.

As Jeff mentions, there are two thermosyphon tubes feeting an E61, so there isn't an opportune spot to fit a flow control valve into the plumbing aside from where the gicleur typically resides. I suppose one could fashion a variable restrictor into the actual E61 plug where Eric's thermometer or a group pressure gauge can reside, but that really isn't any easier to pull off than the mushroom location and then you've precluded the option of having a group gauge.

No fun.

John's idea is not flow control, but bypass, and this approach works just fine. Provide a low resistance path back to the tank and the water will take it, reducing the pressure at the group. There are limits, however.

Since this bypass is on the cold side, you are limited to no less pressure than boiler pressure, and your shots will always start (if however briefly) at the expansion pressure. In an HX, if you bleed off pressure to below that of the boiler, the water in the HX will boil and you will have odd effects (HX stall, sluggish pressure response, etc) until you restore the pressure. With a DB, you have a more open window to work with, but it still depends on the offset between the boiler and the group. If the boiler temperature is higher than the boiling temperature of water, you still get boiling if you vent the bypass and try to preinfuse at too low a pressure. The idea of adding a check valve to the bypass is a great way avoid all of these issues, you just need to make sure the cracking pressure of the check valve is higher than the saturated steam pressure at whatever temperature the brew boiler/HX happens to be. That's relatively easy to achieve.

Now.

Trying to put an actual flow control needle valve into the brew circuit before the HX or brew boiler is just not a good idea. The expansion that occurs between the cold water entering the needle valve and the hot water entering the group is too great and you end up with all the issues mentioned above as well as the inability to actually limit the flow, because if you boil 1 ml water, you must make room for somewhere between 1000 and 2000 ml of steam (at atmospheric pressure the number is 1600:1). So closing the needle valve for a bloom simply does not work in this situation.

When you close off the flow after the heat energy is put into the water, there is nothing downstream to cause expansion and the valve works as intended. When you close the valve, you have high pressure upstream, in the HX/boiler which prevents the creation of flash steam and you have low pressure downstream, which allows for good control.

I managed to integrate one of the $10 Clippard valves into my Rancilio S20 MIDI CD years ago with only two parts needing any modifications. I took a standard jet cap (think mushroom cap on an E61) and bored it out to fit an O-ring that fit the clippard valve and then I threaded the head of an M6 bolt with an M5 thread to seat the valve on. The head of the bolt was the perfect height so that the Clippard valve fit under the jet cap with the knob sticking out so I could turn it and it worked perfectly.

I never tried this approach with an E61 because Bianca had come out right as I had finalized my design and Coffee Sensor and others started slinging FCD kits for E61 boxes shortly thereafter.

I'm sure it would work, but you still need a lathe to modify the jet cap and adapter for threading the valve into the mushroom.

Cheers!

- Jake
LMWDP #704

jb-0101 (original poster)

#8: Post by jb-0101 (original poster) »

Wow thanks for the super detailed reply Jake, that really helps me understand some of the dynamics better to what won't work and why. My very basic and summarized understanding of what you're saying is that you can't put a needle valve on the cold water side due to the change is water dynamics after it heats. So a needle valve needs to go on the hot water side.

It looked from your GS3 thread that you put your needle valve in between the HX that goes through the steam boiler and feeds the brew boiler - is that right? I have an Alex Duetto 2 which has a HX that feeds the brew boiler, so would I be able to put it there and get a similar result your GS3?


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Jake_G
Team HB

#9: Post by Jake_G »

If your brew boiler offset is low enough, that location will work. It all depends on whether or not the water in the brew boiler is above the boiling point. If it is, it is a poor location for a needle valve. If it isn't. It's a great location!

Cheers!

- Jake
LMWDP #704

jb-0101 (original poster)

#10: Post by jb-0101 (original poster) »

Just checked my offset - it's 10C, so with my brew temp at 94 degrees C, the coffee boiler is sitting around 104 (+/- a couple of degrees with fluctuations). Therefore I'm guessing the answer is - not a good location for a needle valve.

Shame