Post By Jackster
Post By Jackster
New Musica problem. Reducing flow during shot
New issue with my Musica. Initial part of shot seems ok, but the water flow reduces during the shot (as opposed to increasing).
I'm pretty sure I have the logics to figure the issue and resolve it, so really just posting for others who may find a similar issue.
I'm thinking it's the opv is bypassing (I custom shimmed this a while ago, so need to see what it's up to now)
Or the pump is shot.. will need to pull up the pump flow specs and measure its output while making sure the opv isn't flowing.
How's the taste.....earwaxxy....I'm on the French press till I get it fixed. Musica is making hot cocoa and that's about it.
I thought it was my lido grinder, as it was a bit needing realigning after a few flights and rough baggage handlers. But I have straightened it out and shots are the same. Good initially, but petering out.
I think the start is ok as there is like a pipe pressurising pump pulse before the shot. I think this pressure gives the initial flow through the puck, but then not much after...
Last edited by Jackster; 5th November 2018 at 12:37 PM.
Reason: Phone is smarter than me
Jack before you go down the path you described with the machine.
Have you tried changing your puck setup? Just as a test.
A looser shot setup? For instance.
I can induce the same flow response you described when I go toooo tight on the setup with
Meaning the nice drippy turning into a slow syrupy pour, regresses back towards a strained drip.
Say at the *15-20sec mark.
*As an off the top of my head example.
Yes, I loosened off the grinder, and the initial surge seemed the same volume, but quicker duration (as you would expect), then reducing flow.... My tamp is pretty consistent with a esprit clicky tamper.
Will report back, I found the pressure gauge yesterday arvo.
The beans are the same. In portion size (19g) I individually pack and freeze the beans. Grind setting doesn't change even after weeks. I just grab a baggy and grind at that beans setting +0.16 on lido2e
Pump flow is in spec.
Opv is not regular, it's up and down on its pressure. Seems strange as it's just a spring... Have ordered a proper adjustable opv.
Have backed grinder off some more and it's almost drinkable.
I think the beans had some bearing on the issues (probably 95% of the problem) Have some new Crema beans on the sampling table now.
I have my filtered water in use now too. That was a yummy improvement
Looking in another thread I saw a guy was overfilling his baskets. So I googled my simonelli basket number, and my double is 14g basket. I have been using 19g, and thinking the puck was only just touching the centre screw... Nup.
So pulling it back now, and back at 17g and still touching, but will try 16g today.
Casa espresso sent my opv, and it's fitted yesterday. The Oscar kit needs another couple of parts to make it fit, and its pressure is not set.
The rubber group gasket is leaking on my gauged portafilter... Grr.
The opv kit seems to have excellent pressure control.
Also, my pump was being a bit intermittent. Not always flowing properly. I think it was the check valve in the pump extension, it was leaking/hanging up, so not pumping a full stroke. I stripped and cleaned it, and it's ok at moment.
But getting closer again.
Jack when your chasing that 'fine line' or knife's edge of the best quality extraction - consistency is key.
Some other proprietary 58mm group's run a Tapered Head Bolt with a flat blade screw driver style slot. Rather than a hexhead style bolt.
This gives you (est.) 2-3 mm extra puck clearance Without the bolt head disturbing the puck. Not you will have to counter drill the heatsink and find a suitable shower screen, or modify yours.
IMO its worth it.
If you go ahead and do this you can then dispel any doubt as to the Maximum dose any of your baskets run by using the 5cent test. On a one off test.
This will allow you to further hone in on the best grind / tamp combination to suit your Beans / Grinder combination.
What i diagnose is occuring for you currently is that your running a high dose that is -
1/ Being disturbed by the screen retention bolt (head)
2/ Running a large dose That then expands into the screen during extraction at the time when the puck is not fully saturated as the beans want to.
At this point the puck expands to the point where the machine can't overcome the back pressure resulting in a slowing of the flow.
You can of course choose not to modify the screen retaining bolt. And can work around it.
Where your at right now - f you record and measure you inputs / out flows it Will direct you as to which change to make to get the shot flavours / characteristics your chasing.
I was sure I had done the 5c test on this machine. Certain in fact...
But the 16g looks to be ok. Was a good drop, but made around 50g in the 30sec, so bit finer required.
I seem to find that the 30sec provides a reasonable drink, regardless of the actual size. But, I am aiming for the 1:2 ratio.
Problem is, I need to be making more to zone in on the settings. Only so many coffees a man can drink..
I do have the flat slotted screen bolt, not the hex.
But, as I have fixed the pump, fitted a opv, reduced the dose, now I need to tune the grind.
Slowly we catch the monkey.
Oh, this mornings cup was back to a more normal flow. The initial drips, increasing to a stream. So I think I'm back on track.