La Cimbali M32 Bistro Single / Wildly inconsistent shots

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
F9zSlavik

#1: Post by F9zSlavik »

Hello all, my name is Gabriel. So I decided to try and open up a coffee shop. I am still trying to figure out the ins and outs of the business while learning to make espresso's. I still haven't found a location YET, but I did manage to get a hold of a M32 Bistro Single Group, none electrical version (analog??). I bought a water pump from amazon, rated at 40 PSI (2.8 bars) that's plugged into a 5 gallon jug of purified water. I bought this from a respectable seller in Los Angeles, I had to drive 3-4 hours one way to get it. I am having wild inconsistent shots its been driving me crazy. I have 3 commercial grinders, I've used them all on this machine all with the same results. I;'ll either make a good shot and 10 bad shots or make 10 bad shots and make 1 good shot. At first I thought it was just me, I am new and probably suck at this. My friend on the other hand has been a barista for 5 years and is the head of one franchise here. He can't seem to find the sweet spot on this machine. We are thinking this machine might be busted.

Here what I have done.
When I first had this machine, when ever I would pull a shot, I would hear a thumping sound coming from the water pump and espresso. I shot a video and sent it to the guy who I bought it from and he said "pump pressure seems high. you hear the regulator. So he had me adjust the PUNTER located on the left side, I turned it 180 degrees or half a turn. It helped with the thumping sounds, it no longer makes that sound. But my issue still persist. If I dont put a portafilter and just run the water, it spews out a high amount of water and then it tapers down significantly. But then other times, it WILL NOT spew out high amount of water at all, it will just throw out what looks like low pressure water. It's like the difference between opening up the faucet al the way and just opening it half way. The m32 either starts with faucet open all the way and then tapers down or it starts with the faucet half open. I hope that analogy makes sense. Either I am doing something wrong, and my friend too who is an experience barista, or the machine is busted in some way. Currently using an amazon water pump with a 1/4 inch plastic tubing to plugs into a the 3/8 part of the m32. Is it my water pump? Or is it the m32? My friend has been over 3 times and this time, he feels like there is definitely some off with the unit. If I am to open up a successful shop, I need consistency. And just for clarification, I'll have 18 gram of coffee in the portafilter, normal tamper press, and have 36 grams of liquid get dispense within like 24 seconds. And you do it 2, 3, 4 times more, and ya will get 36 grams of liquid in 40 seconds or 45 seconds. If I make it finer, sometimes it wont even give me any liquid at all or very little. If I go down 1 and 2 lever on the coarse side, it will spew out liquid like crazy. There is zero consistency. I tried searching, reading, asking for advice from the few people I know, I really don't know what to do. It's a beautiful machine.

The grinders I have is a Rossi rr45, Simonelli MDX aka older RR45, and a Cimbali Grinder. I don't think its the grinders lol. I can post videos if ya guys need them.

JRising

#2: Post by JRising »

F9zSlavik wrote:If I dont put a portafilter and just run the water, it spews out a high amount of water and then it tapers down significantly. But then other times, it WILL NOT spew out high amount of water at all, it will just throw out what looks like low pressure water. It's like the difference between opening up the faucet al the way and just opening it half way. The m32 either starts with faucet open all the way and then tapers down or it starts with the faucet half open. I hope that analogy makes sense
Is what you're describing maybe... Sometimes when you start with no portafilter in place, the water in the brew circuit is above boiling temperature? Thus, the opening of the valve lets the superheated water boil, the steam expands to fill the circuit displacing the water which is blown out through the wide-open grouphead until the steam has lost its potential and the flow settles down to pump rate? Does it do the spew after it has been sitting for a while, idling, unused, allowing the heat exchanget to rise above boiling temperature?

The preceeding paragraph is very normal behaviour for heat exchange machines. Learning to do a cooling flush before putting the portafilter back into position will come naturally once you've formed the habit. If the water isn't boiling furiously on the showerfilter, then you don't need the flush that time, if it is boiling let it flush until it is back to liquid, then brew.
Lowering the boiler temperature can greatly reduce the length of the required flush.
There are a lot of threads on these forums with far more info about maintaining temp on various machines. Stay busy, don't let it idle too long, A quick cooling flush isn't a problem.

F9zSlavik (original poster)

#3: Post by F9zSlavik (original poster) » replying to JRising »

Thank you for responding. I've been closely monitoring this for a response from someone.
To your questions about "Does it do the spew after it has been sitting for a while, idling, unused, allowing the heat exchange to rise above boiling temperature?", YES IT DOES. I been toying with it this morning and realized, if I let it sit idle for maybe 5 minutes, and then turn the water on with no portafilter, it spews out hot water like crazy. That's typically when my shots come out great haha.
So I have been doing this wrong then. So, to summarize, before I pull a shot, if the machine has been idling for a while (5 min or above or whatever), let water spew out from the showerfilter, wait for the needle to build back up, then pull a shot? So I should NOT be so focused on the initial BURST OF WATER as that is not the normal state of the machine, I should be focused on what comes after that, which is NOT the high boiling pressure water.
I am going to try that. I need to buy cheaper coffee beans. I've wasted so much time and money. I am new at this and my girlfriend today asked me, I think you might be over thinking the problem and need to take a step back. Which is a common phrase I use for fixing computers.

F9zSlavik (original poster)

#4: Post by F9zSlavik (original poster) »

I think you solved my problem JRising.
Before a shot, I let out the initial hot/steaming water that spews out initially, give it a few seconds to build up pressure and then make the espresso. 19grams of Coffee Beans from Veracruz Mexico resulted in 3 shots being a second or 2 apart resulted in 27 seconds @ 38 grams of coffee and 2 shot were roughly at 24 seconds @ 38grams (probably tampered is less than the other 3?). So I am OBVIOUSLY GETTING much better consistent results.

So I was basing my shots on the first initial shot with the hot spewing water when I should of been more focused on releasing the initial pressurized steaming water and then work off the water that comes out of that. Is there a way I can donate to this site? I am still continuing to make shots, I want to remove all doubt by doing another 5 more shots. So far so good though.

JRising

#5: Post by JRising »

There are many opinions on doing the cooling flush... You can read many threads here if you want too much info, but I will try to keep it simple.

Do a little flush before brewing just to see what's going to come out.
If it's steam (you'll see the water suspended below the bubbles of steam on the showerscreen) let it run until it's liquid (or mostly liquid) again.

Lowering the boiler temp reduces the maximum steam pressure available and slightly reduced the overall volume of steam available, while reducing the length of cooling flush required after an idle period... Reduce it to where steam and cooling flush are reasonable for your use.

prust
Supporter ♡

#6: Post by prust »

Research temperature surfing on a heat exchanger machine. There may be a mod you can do to add a thermocouple into a spot where there is a screw on the group head. This gets connected to a digital thermometer and you can flush water until you hit a temperature, put in the portafilter and pull the shot. These machines are designed for a cafe where you are pulling one shot after another with just enough time between shots for the temperature to recover. I had an Elektra heat exchanger machine for years and it produced great shots once you learned how long to flush it for or when I added a thermocouple and used a thermometer to be more precise.

FYI a heat exchange machine has a boiler under pressure that is partially filled with water. When you open the steam valve, it allows the steam in the boiler to escape and you get steam. The water in the boiler is well over 212F / 100C because it is under pressure. The water you brew coffee with runs through a coil inside the boiler. Cold tap water into the coil gets heated then goes to the group head when you pull a shot. If you let the machine sit, the water in the coil becomes the same temperature as the water in the boiler - too hot and it turns to steam when you let it out. The flush purges this super heated water. The delay after the purge allows the water in the coil to come up to a temperature. The longer you wait, the hotter it gets. You can therefore change the brew temperature by waiting longer or shorter times between shots.

Hope this gives you some context.

F9zSlavik (original poster)

#7: Post by F9zSlavik (original poster) »

Thank you both JRising and prust.
So I have been practicing, and while my shots are a bit more consistent, I still run into the same issue where my shot either pulls too quick or pulls too short. I played around with the grinder a little, tuning it one level up or one level down but I always go back to the same level. This machines just seems a bit TEMPERAMENTAL! I do let the steam/hot water out after every shot but man, even then it's still not always consistent. I still wasting so much quality coffee and its frustrating.

I don't feel comfortable opening up a coffee shop with this unit to be quite honest. Like its to a point where I am about to hire a tech to come take a look at this.

Here is a MAJOR update, I manage to get a hold of a Cassadio Dieci A1, fully serviced by Jim Duke here in San Diego. Machine looks beautiful. I am still waiting for my amazon pump so in the mean time, I bought a water pump to use on a 5 gallon jug. I turned on the Cassadio, took a lot longer to warm up vs the Cimbali, it took only 2 tries on my RR45 grinder to calibrate the grinder to the right size, and I made 3 shots and they were ALL consistent! She was much easier to use. She doesn't spatter out steam/hot water like the cimbali. So the only difference between the 2 other than the obvious, is the water pump. They are both rated at 40 psi (probably closer to 30-37), one cost 75 bucks and the home depot cost 150. I plan on switching the water pump on the cimbali tomorrow to see if MAYBE that makes a difference.

In 3 days I get the Cimbali Jr, it was too good of a deal for me to pass up on (700 bucks). So I will have another machine to test the results with. Quite honestly if I was to open up shop tomorrow, despite the Cimbali being the superior model, I would use the Cassadio because of the consistent shots I was able to pull and how easy the machine was to use.