# Rocket cincuantotto pressure problem



## Robert nyc (Jul 5, 2021)

I'm having a problem. Just got my Rocket Cinquantotto. Anyone here there's a problem with their chassis bending?

this is the second one I've received with the chassis bent. They're semi-new, from Seattle Coffee Gear, which inspects them and then sells them. They're costumer returns.

anyway, my dials are reading strange. When heated the boiler pressure gauge reads 1.25 and the pump pressure (not engaged/not brewing: in stop mode) measures 3-5.

any ideas?

can I change this?


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## MediumRoastSteam (Jul 7, 2015)

My understanding is that it's normal for the brew pressure gauge to read around 4 bar after brewing. It's a "feature" of some machines. I've watched in some videos. I'm not sure why it happens, I'm assuming is pressure trapped in the brew path. Doesn't do any harm I don't think. All the machines I had or have (see signature) never had this.

see his video as an example:






the person finishes brewing, lever all the way down, but the manometer on the right is still pretty much around the green zone.

as for the bent chassis&#8230; no idea, sorry.


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## Rob1 (Apr 9, 2015)

Bent chassis, probably have the couriers to thank. Contact retailer, check things inside aren't damaged, bend back into shape yourself or get it returned.

The manometers sound to be fine. 1.25 is the service boiler right? The group pressure should move when you're pulling a shot. Against a blind filter it should go to whatever your opv is set to, and when there's nothing in the group fairly certain it should read 0 or very close anyway. When idle you can see 'false' pressure.


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## Robert nyc (Jul 5, 2021)

Rob1 said:


> Bent chassis, probably have the couriers to thank. Contact retailer, check things inside aren't damaged, bend back into shape yourself or get it returned.
> 
> The manometers sound to be fine. 1.25 is the service boiler right? The group pressure should move when you're pulling a shot. Against a blind filter it should go to whatever your opv is set to, and when there's nothing in the group fairly certain it should read 0 or very close anyway. When idle you can see 'false' pressure.


 Yeah, 1.25 for the service broiler. Rocket says it should read 1, but green is from 1 to 1.5. Right now it's reading 1.3. Do you know of any way to change that?

when I brew coffee the brew head pressure gauge, the other one, goes to 9 and when I bring the lever down, it goes to 5. I think it's supposed to go back to 0.


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## Rob1 (Apr 9, 2015)

When you just lift the lever with nothing in the group what does it go to? Should go to 0. There doesn't sound to be an issue with either. To change the boiler pressure you either need to decrease the temperature via pid settings if it's pid controlled or alter a pressure-stat. From what I can see this machine is PID controlled. Is it plumbed in? I wouldn't turn the service boiler down to 1 bar.


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## Rob1 (Apr 9, 2015)

Is this the machine?


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## Robert nyc (Jul 5, 2021)

Rob1 said:


> When you just lift the lever with nothing in the group what does it go to? Should go to 0. There doesn't sound to be an issue with either. To change the boiler pressure you either need to decrease the temperature via pid settings if it's pid controlled or alter a pressure-stat. From what I can see this machine is PID controlled. Is it plumbed in? I wouldn't turn the service boiler down to 1 bar.


 With nothing in the basket it goes to 9 bar. What I have noticed is that when I make a coffee and pull down the lever it can go to 5 bar. If I bring it up a tad without reengaging the pump, it goes to 0.

it is PID controlled but the pid on this machine controls temp, not pressure.

with the Rocket Appartmento many people change the boiler pressure to change the temp. This is dual broiler. Yeah, it's the one from the video you sent.


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## cuprajake (Mar 30, 2020)

Changing temp changes the pressure in the boiler. 👍 Whats it currently set to?


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## MediumRoastSteam (Jul 7, 2015)

Rob1 said:


> When you just lift the lever with nothing in the group what does it go to? Should go to 0





Robert nyc said:


> With nothing in the basket it goes to 9 bar


 It's a rotary pump. That's the normal behaviour. Pressure is measured at the head of the pump rather than the group or near it.



Robert nyc said:


> If I bring it up a tad without reengaging the pump, it goes to 0.


 Trapped pressure somewhere. It's just how it's designed. I wouldn't worry about it.


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## MediumRoastSteam (Jul 7, 2015)

Robert nyc said:


> Yeah, 1.25 for the service broiler. Rocket says it should read 1, but green is from 1 to 1.5. Right now it's reading 1.3. Do you know of any way to change that?


 The PID controller should allow you to change brew temperature and service boiler/steam temperature. As Jake says, pressure is a result of the temperature set in the service boiler.

for a dual boiler, your pressure is spot on. The more the better in a way. On an HX machine like the Appartamento, they say to set to 1bar because on that machine the pressure in the boiler also sets the brew temperature, requiring a longer cooling flush. Your machine being a dual boiler doesn't have that issue as the boilers are independent. 👍


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## DavecUK (Aug 6, 2013)

Robert nyc said:


> I'm having a problem. Just got my Rocket Cinquantotto. Anyone here there's a problem with their chassis bending?
> 
> this is the second one I've received with the chassis bent. They're semi-new, from Seattle Coffee Gear, which inspects them and then sells them. They're costumer returns.


 The reason machines bend is the basic construction used and where the mass is located (in the main body with boilers, pump etc.). In the crude diagram below, yellow represents the hi density polystyrene (it still can deform a little). If this couldn't deform, damage would still occur as the leg rails would simply distort outwards. Motion downwards as in being dropped can cause damage, but also motion forwards. The effective pivot point for these forces is shown by the green circle. ACS doubled the thickness of the base plate (on my advice) on the Minima. and ensured the base was supported as below...but you can only do so much. Eventually the couriers can damage anything. Forces on a drop can reach.









Based on a "heavy bit" of 20kg. For a 1M drop , an impact force of approx 450 lbs is exerted through this point, and for a 2 m drop almost 1000 lbs. If the force is at an angle..e.g. a 45 degree drop onto the forward corner, it probably makes things worse.

P.S. Physics nerds, please don't bother correcting my approximations....I'm fully aware of the simplifications I have had to make.


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## Rob1 (Apr 9, 2015)

Robert nyc said:


> With nothing in the basket it goes to 9 bar. What I have noticed is that when I make a coffee and pull down the lever it can go to 5 bar. If I bring it up a tad without reengaging the pump, it goes to 0.
> 
> it is PID controlled but the pid on this machine controls temp, not pressure.
> 
> with the Rocket Appartmento many people change the boiler pressure to change the temp. This is dual broiler. Yeah, it's the one from the video you sent.


 The PID controls the temperature. The pressure is higher with a higher temp (that's how it gets hotter than boiling point). Pressure is dependent on temperature. If you want to run the service boiler at a lower pressure you do so by decreasing the temp but as I said not sure why you would do that. As you see in the video pressure drops to around 1 bar when steaming, I don't think you'd want it to drop lower than that.

If the machine is plumbed in fairly certain you'll see line pressure on the gauge. Doesn't sound to be an issue in any case.

If you aren't happy with the machine because it's been banged up a bit in transit then send it back.


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## Robert nyc (Jul 5, 2021)

Wow! Thank you all for your remarks. It's nice to get feedback.

I'm starting to get a hang of things.

anyone help with ratios?

I'm thinking 1:2 for espresso. 15grams in, 30-35grams out. What type if time, 25-30 sec or a bit longer?

I have the Rocket Fausto grinder


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## DavecUK (Aug 6, 2013)

Robert nyc said:


> Wow! Thank you all for your remarks. It's nice to get feedback.
> 
> I'm starting to get a hang of things.
> 
> ...


 *Start* with those ratios, better to do 17 or 18g in and 36g out usually....then work up or down from there on weight and time until you get the taste you want.


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## MediumRoastSteam (Jul 7, 2015)

Think those baskets that come with the Rocket - if you are using the original ones - can easily take 18g. If you have a naked PF, the basket usually takes something crazy like 22g. I'd be caffeinated for 3 days if I drink that amount! 😂

So, try 18g in, 36g out over 30 seconds, and then go by taste. I personally keep to a 2:1 ratio.

Have fun!


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## DavecUK (Aug 6, 2013)

@MediumRoastSteam beat you to it...


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## MediumRoastSteam (Jul 7, 2015)

DavecUK said:


> beat you to it...


 I seriously need to give up on the secondary monitor... It causes too many distractions 🙂


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