Hello, everyone!
I've recently bought a NS Oscar II, and it's my first semi-pro machine, before that I had a simple Delonghi.
So I'm a little confused with so many variables and the top thing that gets me confused - coffee starts dripping after 18-20 sec after I press the button.
Now all the conditions:
1) The dose is ~14-15 grams (my scales are 2g precision, shame on me, I'll buy new soon)
2) The output is ~35-40 grams
3) The time is 28sec exactly (water flow starts 3sec after turning on)
4) The tamping pressure is around 10-14kg, not more.

All the videos I've seen with this machine, the flow starts at about 5-7sec. of extraction.
And if I grind coarser, I get higher amount of output, which is not great.
But still, even with very coarse grind it never starts before 12-14 seconds.
I can provide the video, if that would be any helpful.

How does the coffee taste ? That's the key as opposed to timings other people post on clips
As you know you need new scales a 2g dose variance won't help you make accurate adjustments

I'm not sure I ever tried a "proper espresso", so I can't say for sure, but I'd say it's rather sour every time
I've bought 0.1g scales, and now I have a new important question
Is the machine supposed to pour same amount of water with the fixed time?
I programmed a button for 28sec, and ran it without portafilter 6 times with random intervals between
I got: 261g, 197g, 191g, 196g, 168g, 171g

I ask because with scales I've noticed I get 30-40g of espresso with everything the same (grind, tamping pressure, dose etc.)

okay guys, I have some updates. I wasted 1kg of coffee for the experiments and had a long chat with NS support
here's what I have now:
1) If I do a cooling flush before the 1st cup (8-10 seconds), I get 30ml and it starts dripping after 15sec.
2) If I don't do a cooling flush, I get ~70ml and it starts after 6sec.
3) If I ever do a flush between cups I get 30ml again
4) If I do a short 1-2sec flush I get ~62ml

NS support guy tells me not to flush or do short flushes.
Is this okay? Is it supposed to work this way?
Shall I just adjust my grinder to get 30ml with no flushes and live with it?

I haven't used the Oscar, but based on what I've read, it's a Dragon, meaning a short flush and pull is the best temperature management approach. While I'm handing out links, have you checked out Newbie Introduction to Espresso and Managing the Brew Temperature of HX Espresso Machines? Toss in the Home Barista's Guide to Espresso and you will have answers to all the questions you are likely to have in the first 3-6 months of making espresso at home.

As a general recommendation, resist the temptation to reduce making espresso at home to numbers. That's what Mrboots2u was driving at when he asked how the espresso tastes. That said, there's value in reducing error in mechanical steps, e.g., by weighing the coffee dose, beverage weight, and pour times. But don't get all hung up on one particular measurement, since for every 3 measurements you take, there's another dozen that you're ignoring.

Thanks a lot, and sorry I didn't read everything you provided before asking questions here.
I was just worried something was wrong with my machine, because the process a bit differs from what I saw in lots of videos.
But seems every machine is different and this one is not reviewed well, since it's a new model.

Take it FWIW, I do not have an Oscar II but do have an HX machine. And after all the fussing and fighting with flushes, etc I simply settled on the "HX Dragon" flush and then pull my shot. I have learned the simpler you make it the more repeatable the shots.

The more you over think it and the more numbers/variables you throw at it the less you will enjoy your machine.

I know this may not help your particular issue, but with HX's try not to over think it too much IMHO...........

deusdeorum wrote:I programmed a button for 28sec, and ran it without portafilter 6 times with random intervals between
I got: 261g, 197g, 191g, 196g, 168g, 171g

That much variance doesn't seem right to me - every machine I've ever had was far more consistent in unrestricted flow than the +32% / -17% range you measured. My Oscar (the original version) puts out the same volume per second every time, with less than 5% variance. I flush into my 6 oz (?) cappuccino cup, and it fills to the rim in a counted 20 seconds every time (don't ask me why, but I stand there watching and counting 1-1000-2-1000-3-1000...... every time I flush, even though I try hard not to. And I have no other OCD-type tendencies.)

I don't understand the variance in volume and delay time with flushing, either. 30 ml starting at 15 seconds vs 70 starting at 6 seconds seems to me to be far too wide a range to attribute to the machine. Inconsistency in grind, tamp, distribution etc seem far more likely to be causing this kind of variation than any mechanical factor within your Oscar. And I've never observed flushing to change flow that dramatically - and I do forget to flush sometimes if I'm engaged in conversation or trying to get back to something with the next cup. In fact, I've never noticed any effect of flushing on flow rate of the next shot.

I must admit that my few calls to NS for tech advice have not been completely fulfilling. My wife wanted to put Oscar's drip tray and grate in the dishwasher, so I called to ask if that was safe or if it was known to cause warping or discoloration. Neither of the two people I asked on different calls had any idea. I also got a confused response when I asked if they offered alternative size water line fittings into the machine (mine's a direct connect model, and it comes with a right angle metal swivel fitting that accepts 1/4" - probably really 6mm - flexible hose). The tech I talked to seemed to have no idea what I wanted and kept telling me I should use their flex tubing.

I'm very happy that someone agrees with me, that it's not normal.

Inconsistency in grind, tamp, distribution etc seem far more likely to be causing this kind of variation than any mechanical factor within your Oscar.

It would be for me either, but this deviation is really consistent. I mean doing a long flush (>7-8 seconds) _always_ leads to this "late start, low volume" thing, and not doing a flush or 1-2 seconds flush always leads to "early start, high volume". And that inconsistency kills me, because 1 second change of flush duration gives me different volume and I feel kind of stupid, when I interrupt the flush when the water is still hissing and boiling.

My newbie guess is that something is wrong with the pump: when it runs without resistance (a coffee puck) it gives low pressure, or something like that. But since I'm really a newbie, and not completely understand how my machine works, I'm trying not to tell anyone my hypotheses.

The complication is that I don't have any local NS services in my country.

And my plan was to make a handmade portafilter pressure gauge and do some measures to prove if there's really something wrong with pressure. Do you think that's a good idea?

deusdeorum wrote:I'm very happy that someone agrees with me, that it's not normal......And my plan was to make a handmade portafilter pressure gauge and do some measures to prove if there's really something wrong with pressure. Do you think that's a good idea?

I can't promise you that it's not normal, but it certainly seems unusual to me. You're describing inconsistency in the volume of water delivered from the shower screen with no portafilter in place, so there's no back pressure at all beyond that in the internal plumbing. I don't know what you'd learn about this with a PF-pressure gauge, as pressure measurements in a closed PF wouldn't seem to have any relationship to unrestricted flow volume unless it shows your your pump to be incapable of generating usable pressures under load. This doesn't seem to be the case based on the times and volumes you describe for your shots. Again, this kind of variance in shot times & volumes is most often the result of poor or inconsistent grinding, dosing, distributing and/or tamping.

It might be instructive to build a PF / pressure gauge with a variable orifice in the bottom, e.g. drilling different size holes down the center of a few bolts with the same thread as the spout's shaft. Looking at pressure vs volume flow with progressive restriction might reveal a pump problem as back-pressure increases. But it's very hard for me to believe that a faulty pump is causing 35+% variance in unrestricted volume delivery per unit time, especially if it sounds normal while running and isn't making weird extraneous noises.

I've never seen or heard a complaint about a defective pump in an Oscar that was relatively new and/or had little use. I'm always trolling for posts about Oscars because mine's now several years old & I want to know what problems await me in the next few years. Oscars in general seem to be among the toughest machines on the market, though, with no reason to believe that the Oscar II is any less robust than the original. When my trusty old friend dies, I suspect I'll buy an O II because it's fairly priced and I'm about to retire. As much as I'd like to have a Linea Mini or a GS3, Oscar makes fine coffee that I can enjoy fully for the rest of my life at a price that leaves me more $$ for other joys.