La Marzocco Linea Mini Flow Control Mod

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cf

#1: Post by cf »

WE DID IT.

This Linea Mini has the famous Jake valve controlled by a profiling wheel located on the opposite side of the temperature wheel. A huge shout out to Jake for his support in helping me get this mod working, and also to my father who spent tons of time tinkering on this machine with me!

I will describe the process I went through and the parts used to accomplish the mod, however, there are ways to make the installation easier which I'm sure will get discussed below. I will also include a parts list and links to where I was able to make the purchases.

THE CIRCUIT

The basic concept of the mod is to route the hydraulic circuit that feeds the IBG (integrated brew group) through the needle valve, allowing the user to control flow. In my case, this was done by replacing the LMLM cross where the hot, cold, IBG, and pressure gauge connections meet. I replaced the LMLM cross with two BSPT Tees (number 7 in the picture below).

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The Tees had two male BSPP connections and one female. To complicate matters, the LM copper pipes for the hot, cold, and IBG are flared connections. I believe they are JIS (Japanese Industrial Standard) 30 degree cones, which requires a corresponding JIS flare male connection.

LMLM Cross pictured below. Notice the flared male connections.

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Tee with (2) BSPP male and (1) BSPP female. Notice the lack of flares on the end of these connections. That's a problem. The other piece in the picture was a prototype we didn't end up using.

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To make the Tee work for the hot, cold, IBG, and pressure gauge connections I had to use a JIS cone adapter between the LM pipes and the Tee male threads. They worked great. However, it may be possible to order a Tee with two JIS male ends and one female end and that may work as well (no adapter should be needed).

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On the female end of the Tee, I used Jake's recommended Male BSPP x Metric Push Connect so we could easily insert PTFE tubing to route the Tee to the needle valve.

Replacing the LM cross and following the path of the hydraulic circuit, I've got the first Tee with a connection to the hot and cold on the male ends with the cone adapters between each. On the female end, I have the Metric Push Connect that feeds a PTFE tube to the input of the needle valve.

The needle valve uses a "Metric Push Connect x Female BSPP Fitting M5"on the inlet (bottom) side. For the output it uses a "Metric Push Connect x Male BSPP Fitting M5" to the feed the output of the needle valve back to the second Tee.

The second Tee uses the "Metric Push Connect x Male BSPP Fitting 4mm" to connect to the needle valve's output. Then I used (1) cone adapter in-between one male connection for the IBG. The other connection is for the pressure gauge, and that gave me trouble. I thought because the pressure gauge didn't have a JIS flared connection it would be fine to connect as is to the Tee, but it leaked when I turned it on. Instead, I opted to use a cone adapter here but it was grinded down to allow more surface area contact for the nipple of the pressure gauge. After inserting the modified cone adapter the pressure gauge nipple centered beautifully and no more leaks. This was the only piece of the whole install that isn't "off the shelf" and perhaps could be mitigated by using a female JIS connection with a beveled edge much like the stock.

Pressure Gauge Nipple

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Beveled interior edge of the LM cross that it was connecting to stock. We grinded down a cone adapter to mimic this shape and inserted it into the male end of the second Tee.

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That completes the hydraulic circuit! Beautifully simple and works great! Again, there may be better options for Tees that will be commented later.

THE MOUNT

But I'm guessing that's not the whole reason you're here. You saw that wheel on the right side of the Mini, you know, the one that looks exactly the same as the one that's on the left side for temperature control. That's right, the most beautiful part of this mod is how it's implemented. You see, LM was kind enough to give us an equally slotted opening on the right side of the machine as the left which allows for this mod to be controlled with a wheel. This solution gives the user a familiar way to interact with the machine and keeps with the overall aesthetic. Heck, it adds symmetry!

Thanks to Jake and his engineering prowess, we have some source files for 3D printed wheels and mounting brackets to make this a much more aesthetically pleasing and functional mod.

The mount as currently designed has one screw connection onto the chassis and two 'rest' points that secure the whole assembly in place. It's a really sturdy and rigid well thought out design.

In the photo below, you can see the custom 3D printed mount in white with the needle valve being held in place. The only screw where you need a screw-driver is the top-most screw, with the other screw to the left and the bottom being 'guides' where you can rest the bracket onto the back of existing screw threads. They work great for guiding and holding the whole assembly in place.

Harder to see yet is the beveled edge right under the needle valve holder and above the bottom most screw, you can see the bracket also rests on another edge within the case. Jake was able to calculate all these positions and come up with a perfect mounting position without ever having actually worked on this machine. That's an awesome engineering feat, well done Jake! Kudos to La Marzocco for making their CAD files available online as well to make this possible.

3D printed bracket with 3D printed wheel, along with needle valve connections for quick connect fittings.

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Mounted bracket, resting on the bottom screw and interior edge of the LM chassis.

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Photo below showing the fully connected and mounted bracket.

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In our case, we had to insert the case cover on first and then drop in the bracket very carefully. You may be able to secure the mount on with the cover off, make all the connections, and then put the cover back on. In either case, we had to add the 3D printed wheel with the cover on by sliding it from the bottom of the opening and up through the case, and gently sliding it's 6mm hex interior onto the needle valve knob (also 6mm hex).

That's it!

PARTS LIST AND 3D FILES

Below are the parts that I used for this mod, although after talking with Jake I think there could be better parts used. For example, instead of the BSPT Tees and cone adapters I used, we could have used Tees with JIS connections to avoid using the adapters. I haven't tried it myself so try it at your own risk.

Much of this parts list was taken from blondica73's post in the LMLM flow profiling thread, thanks blondica!

From www.hoseandfittings.com
1. Male BSPT TEE w/ Female BSPP Run Adapter (2)- 2118-04-04-04 - to replace the current mixing cross (Part 7). https://shop.hoseandfittings.com/catalo ... 04-04.html

2. Metric Push Connect x Male BSPP Fitting (2) - HF68PL-04MM-04BSPP - to connect the needle valve to the two tees https://shop.hoseandfittings.com/catalo ... 4BSPP.html

3. Metric Push Connect x Male BSPP Fitting (1) - HF68PL-04MM-M5 - to connect the side of the needle valve to the 4 mm tubing https://shop.hoseandfittings.com/catalo ... MM-M5.html

4. Metric Push Connect x Female BSPP Fitting(1) - HF66PL-04MM-M5 - to connect the bottom part of the needle valve to the 4 mm tubing https://shop.hoseandfittings.com/catalo ... MM-M5.html

5. BSPP to JIS Conversion Seat 1/4 JIS SEALING SEAT (4) - for insertion between the LM pipe connections onto the BSPP Tees. One of these was grinded down in my case for connection to the pressure gauge. --removed original link as they may be carbon steel. The vendor below offers stainless.
https://www.malonespecialtyinc.com/prod ... sion-cone/

As mentioned, instead of buying the BSPT Tees and cone adapters (numbers 1 and 5 from above), this Tee may work as well. Try at your own risk.
Male JIS 30° Nose by Female JIS 30° Flare Swivel by Male JIS 30° Nose TEE Adapter --removed as this is listed as carbon steel, not for use with water--


From Amazon:
Clippard M-MNV-1K Needle Valve, M5 Ports with Knurled Knob (1)
https://www.amazon.com/gp/product/B01A6 ... UTF8&psc=1

PTFE Teflon tubing 10ft- 2mm ID X 4mm OD for 1.75 Filament Bowden 3D Printer -Allen Tech PTFE Teflon Tube (1)
https://www.amazon.com/gp/product/B073R ... UTF8&psc=1

Optional: PTFE Teflon tube cutter, cut up to 3/4'' OD tube- Allen tech (made it easier to cut the tubing for me, but a razor blade should work) (1)
https://www.amazon.com/gp/product/B0756 ... UTF8&psc=1

3D FILES

There may be updates to these files in the future. For the bracket I had to bore the screw hole to be a bit bigger than designed using a drill bit, that may get updated later. I used Shapeways.com for my 3D printing, but any company with 3D printing capacity should work. For Shapeways, I opted to use PA11-SLS plastic material for the bracket and Black-PA12 material for the wheel. The SLS plastic material has a high melting point, and the wheel I liked that I could get it printed in black.

Wheel:
https://drive.google.com/file/d/1E1IRAs ... sp=sharing

Bracket:
https://drive.google.com/file/d/11ClCGu ... sp=sharing

NEW Bracket Designed by Jake 06/01/2020
"No section to catch on the cover and a bigger screw hole."
https://drive.google.com/file/d/1XNAKPl ... sp=sharing



FUTURE IMPROVEMENTS

The aforementioned updates to the 3D models will help make installation easier. My father and I are also working on another 3D printable bracket that is fully mounted onto the outer case that should hopefully snap into place (yet to be printed and tested). Either solution should work.

Where to go from here? I'm not sure. I think controlling the needle valve from the paddle as opposed to the wheel would be nifty but that's asking a bit much. For now, I'm more than excited with the wheel solution. Thanks again to Jake and the awesome Home-Barista community for making this possible for me. Hopefully, this guide makes it possible for you too!

BONUS VIDEO
Cause who doesn't like videos? In the first video I'm opening the needle valve much more than it needs to be. It's my understanding that only a few turns of the wheel is all that's required for a full range of flow control, given that there is still a restrictor upstream of the needle valve restricting flow more than the needle valve can allow. All that is to say, you may not need to move the wheel so much in actuality
★ Helpful

michael_pl

#2: Post by michael_pl »

Well done. Fairly simple and elegant (as the best solutions often are) implementation.

How well does it work in practice? ( ie - got any videos with a portafilter locked in???) Any thought to a pressure gauge so you have an idea of what flow you're delivering? I imagine it would be tough to be repetitive without an indexed zero position and measured flow for each "click" or rotation away from zero.

Good work though, fun to watch people mod their machines.

Michael

cf

#3: Post by cf » replying to michael_pl »

Thanks Michael! At the moment I haven't taken any videos brewing but I'll get to that in the coming days. I'm trying to understand exactly how to work the machine now that is has that capability and what the pressure gauge reading actually means throughout the brew process. I had a BDB before which was a top notch machine and that read the pressure at the brew group, whereas this reading is upstream of the brew group so I keep having to remind myself of the difference.

blondica73

#4: Post by blondica73 »

Jake sent me the bracket design and I printed it and it arrived today. I mounted it, however, I couldn't put the cover on. I spent almost an hour fiddling, but could not do it. I just realized that you put the wheel on after installing the valve and putting on the side cover.

User avatar
Jake_G
Team HB

#5: Post by Jake_G »

blondica73 wrote:Jake sent me the bracket design and I printed it and it arrived today. I mounted it, however, I couldn't put the cover on. I spent almost an hour fiddling, but could not do it. Suggestions?
In my mind's eye, the plan was to install the bracket with the cover installed. It never dawned on me that the cover would be removed as part of the process but it obviously makes sense that it would be in hindsight!

Due to the way the ear on the outside indexes to the nutsert on the cover, you can't mount (nor dismount) the cover with the bracket installed. :|

I suggest hacking of half of that ear so that the cover can slide in behind the bracket and the counter bore for the nutsert can still help locate the bracket in the machine. I'll update the model with a slot for the nutsert along with increasing the bore and counter bore for the main screw. The cover should drop straight down, right?

Excellent work, Carlos.

Cheers!

- Jake

User avatar
TomC
Team HB

#6: Post by TomC »

This is really cool! Well done!

Am I correct that this in its current configuration is still fully manual?

When I installed a needle valve in my Linea Classic, it paired perfectly with a ShureShot controller, since the controller could activate a solenoid and bypass the needle valve after a pre-set preinfusion time. Is there enough space inside to add both on the LMLM? I haven't followed too closely all the developments of the LMLM as far as the newer shot timers and controllers available in the aftermarket, but it would be a compelling setup if both would be available for it.

cf

#7: Post by cf » replying to TomC »

IMO the best looking off the shelf shot timer for the Mini is the Ace DotShot, they are the same people behind the ShureShot (Alcorn Cafe). I don't see why it can't be installed alongside this mod. The best display I've seen for the Mini was from the Coffee Machinist / Rick Bond where a display is built into the paddle housing and shows the temperature when not brewing, and starts the timer when brewing. Cool stuff.

Ace DotShots
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Coffee Machinist Link
https://www.instagram.com/p/BZfMxLHB2xo ... _copy_link

joey22

#8: Post by joey22 »

Wow! This is awesome.

I have been reading through the various threads and had reached out to Jake but couldn't really figure out implementation of the mounting bracket in an elegant way and this is a pretty sweet solution. Thank you so much for posting such a detailed write up and parts lists. I'd like to dive into installing this on my LM in a couple of months.

One question for you, it's cool to see how fast the brew gage responds to the needle valve adjustments. When you run it wide open does the brew gage match what is was before it mod (i.e. if it was set to 9 bar before does it still show 9 bar now with the needle open) or did you have to adjust the pump following the install of the mod?

yertchuk
Supporter

#9: Post by yertchuk »

Thanks Carlos and Jake. This is very interesting. Now I'm intrigued with the idea of using a proportional solenoid valve, driven from a potentiometer attached to the paddle shaft!

cf

#10: Post by cf »

joey22 wrote:Wow! This is awesome.

I have been reading through the various threads and had reached out to Jake but couldn't really figure out implementation of the mounting bracket in an elegant way and this is a pretty sweet solution. Thank you so much for posting such a detailed write up and parts lists. I'd like to dive into installing this on my LM in a couple of months.

One question for you, it's cool to see how fast the brew gage responds to the needle valve adjustments. When you run it wide open does the brew gage match what is was before it mod (i.e. if it was set to 9 bar before does it still show 9 bar now with the needle open) or did you have to adjust the pump following the install of the mod?
Hey Joey, good question. When running with no resistance or portafilter, the pressure gauge tops out a little over 6 bars. I think previously it went full 9 bars with no load, not sure. I haven't measured the grams/sec to see what kinda flow that is wide open. With coffee, the gauge does slowly ramp up to 9 bars as the headspace above the puck gets filled with water regardless of how low a flow I have, it will happen eventually. After talking with Jake I think that could be the ideal time to ramp up the flow and accelerate the shot as the pressure is building. Still learning myself.