Can someone explain the Normcore tamper to me? - Page 2

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#11: Post by slybarman »

daviddecristoforo wrote:But... doesn't the amount of ground coffee in the basket affect the amount of pressure? If there's more grounds in the basket, the tamper will not "bottom out" on the ring. At that point, would you not be able to apply more pressure?

see video I posted.


#12: Post by espressoren »

daviddecristoforo wrote:But... doesn't the amount of ground coffee in the basket affect the amount of pressure? If there's more grounds in the basket, the tamper will not "bottom out" on the ring. At that point, would you not be able to apply more pressure?
I suppose that's possible. In my experience even with the basket overfilled a bit (the shower screen contacts the puck while trying to attach the portafilter), there is enough room for the ring to touch the basket rim before you put much pressure on. I suppose if somehow you could fill the basket completely or your coffee doesn't compress much it could be an issue.

That's what was so brain bending before I realized there was a second spring because I can see that the distance from the top of the puck to the basket edge is barely enough for the tamper head (10mm), yet you can put the tamper in and push it 20mm into the basket. That's why I say it's kind of like a prop knife, the tamper isn't moving much at all, and what movement it can make is pure puck compression.

As far as under filled basket, with 10mm deep tamper and another 10mm movement available in the handle you're likely to get the same amount of compression regardless, unless your basket is nearly empty and tapered such that the tamper can't go all the way in. Most double baskets are only 24-25mm deep so 20mm of available compression should be fine.


#13: Post by NewCoffeeGuy1 »

Well my Normcore arrived after my morning pulls, so it's a tomorrow thing for me which is fine.


#14: Post by Primacog »

I am looking forwwed to your review of your normcore tamper since i have ordered it. I coukdnt stomach the price of a force tamper or a bravo tamper that are auto level tampers so i hope the normcore will fit the bill.
LMWDP #729


#15: Post by NewCoffeeGuy1 replying to Primacog »

Well it works and I know it works. Reason is I was completely flummoxed by the beans I'm using (Malabar Gold, a dark roast which comes with specific instructions to increase temp to 204+ and grind finer than you're used to).

I could not replicate their "correct" recipe of 18g in -> 30g out in 25-30 seconds. It was always way too fast (and not good), so I kept grinding finer. But then it choked my machine. I suspected my tamps were un-level which would of course lead to this exact vicious cycle. I mean I could see this with the naked eye but even trying really really hard to be exacting, I couldn't tamp consistently level to in turn dial in my grinder.

Tried the Normcore this morning and poof. All of a sudden, on the first pull the grind was close but no cigar. One micro adjustment later, 18g in ->30g out in 28s. Beautiful taste. Had four. Still wired.

I will say that the feel is a little...antiseptic? No tactile sense of pressing against an increasing resistance. Disconnected from the process itself if that makes sense. It's not "bad" just different I guess. It does make me wonder whether the Bravo would feel more connected somehow. Not that it would tamp any more level mind you.

Anyway, glad I got this, especially given the price as compared to the others.


#16: Post by Primacog »

Thanka for your revuew. Do i understand correctly that you dont feel anything at all as you press down? So there is no feeling of hitting the bottom at any point nor is there any tactile response such as a click?
LMWDP #729

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#17: Post by MB »

You just press till you feel or see the handle bottom out against the part that sits on top of the basket. You can't push down any further and the motion stops at that point. It's easy enough to tell when it's sufficient because you can just over press enough to bottom it out each time and not worry about going too far.

Once you have done that, the inner spring between the bottomed-out handle and the tamper face is compressed based on how much space the tamped coffee takes up in the basket. The amount of pressure the partially compressed inner spring puts on the coffee bed is consistent for the amount of coffee placed in the basket. So, for a given basket, dose and coffee, it's the same each time, plus it's a level tamp. Increase the dose and the tamp pressure is somewhat more, of course, but in a consistent manner for that type of change.
LMWDP #472

LittleCoffee (original poster)

#18: Post by LittleCoffee (original poster) »

Well, I've had mine for a day or two and so I'll try to answer my original question - namely how does it work.

First of all, do watch the video @slybarman posted as it is very helpful.

The Normcore has two springs - a very light spring ("alignment spring") and the "tamping spring".

The alignment spring's job is provide sufficient freedom to simultaneously achieve a consistent pre-tamp initial condition which is:
1. The plate which sits on top of the PF ensuring you can only ever tamp in a direction exactly perpendicular to the PF to actually sit on the PF while simultaneously;
2. The tamper rests on top of the coffee grounds, no matter how high or low they are relative to the PF lip and pressing on the coffee with minimal pressure.

In reality I think you could probably even remove the alignment spring and then just rely on gravity to achieve this initial condition, but then you'll have the tamper weight pressing on your puck before you've started tamping and I suspect it won't feel as nice from a tactile perspective.

To tamp you press down from the handle and through the leveling plate (which constrains the motion perpendicular to the PF) and into the tamper through the stronger, tamping spring. Eventually there is enough force going through to compress the tamping spring which sits between the handle you hold and the tamping surface pressing on the coffee. That's it. That's how the Normcore works.

Is it good? Well, I personally got it because I was annoyed with how much effort I was spending to get to a level puck. For this it works really well, it's very easy to have a level puck. And it is very nicely machined and with a bit of silicone oil inside it does have a lovely tactile feel to it which makes me happy.

However, as others have pointed out, the calibrated spring claim is a deceptive marketing lie in the face of physics. I'm sort of annoyed with myself for not figuring this out as it's pretty obvious. The marketing is even more powerful when you see they include three calibrated springs - a 15,25 and 30lb - that sounds really precise doesn't it? Well, it's not.

The concept of a spring calibrated to a single force is complete and utter nonsense. The force needed to compress a spring is by definition proportional to the compression distance relative to the spring's uncompressed length- that is literally the definition of a spring. Therefore there is no such thing as a 25lb spring. There is such a thing as a spring which requires 25lbs to compress a certain distance, and the Normcore comes with springs which require different distances to compress 15,25 and 30lbs. But there is no way to know whether the particular spring you have put in is compressing by 15, 25 or 30lbs unless you're doing it on top of a bathroom scale. So the idea that the Normcore helps you compress to the same pressure every time is utter nonsense - it's just no possible to do that. Sure maybe you can learn the feel of a certain amount of compression for your particular spring and try and achieve that every time, but that's really not that different to tamping a bog standard tamper and learning the feel in your arm for a particular pressure and doing that consistently every time. This criticism isn't really Normcore specific - it applies to every single spring loaded tamper. Addressing this issue is what you're paying for in the Force tamper - but at 4x the price it's just too much for me for such a silly niggle.

What getting the Normcore did for me was to get me to do everything on a bathroom scale and realise that I've been tamping way harder than 25lbs previously - so from that perspective it will lead to an improved tamp for me - and as I say the levelling function is more than useful enough for me for this to be a keeper.

As an aside, i know accepted wisdom is that tamping pressure is not that important as long as it's consistent, but I have to say I see a fair amount of extraction timing difference depending on how much tamping pressure I'm putting through. And this means how coarse/fine one grinds can vary quite a lot and still have the same extraction time for different tamp pressures - while I'm sure the taste will vary a lot as one does this. This for me at least isn't consistent with "it doesn't matter that much".

Hope this helps and happy caffeining!


#19: Post by espressoren »

I see what you're saying about the tamping pressure related to springs. I don't have the normcore, but something like it. There are two things that can provide tamping pressure consistency

1) From what I see there is really not much room for the tamper head to move at all in the puck, so I would believe I'm getting whatever pressure the spring provides at 100% compression, or something near that. The tamper head is 10mm tall, meaning it goes into the basket 10mm before the flange rests on the top of the basket lip. When I'm done tamping the top of the puck is about 10-11mm into the basket. So nearly all of the movement sensation was in the handle spring. And I have to believe that if you're using a properly sized basket for your dose there isn't going to be much variation in that, the top of your puck is generally going to be 10mm in so it is the right distance from the shower head. So it isn't like one day you're compressing and the tamper travels 20mm into the basket and gives you a pancake 4mm puck that is recessed 20mm into the basket, and the spring only compressed 10%, and tomorrow you get no travel and the spring compressed 100%. You're pretty much always bottoming out the handle travel rather than moving the tamper deeper into the basket. Sure maybe one day you dose down a gram and get a 12mm recessed puck... is the movement of the tamper head 1-2mm going to change the spring force that much? Still probably bottoming out the springs compression.

2) The way these kinds of machines work is not to throw in an unsprung spring and let you compress it however you want. The springs are pre-compressed. If you think about a big spring 1 meter long and compress it down to 50cm one time, then 25cm another time, then 1cm, yes you're going to see vastly different forces required to do that. But if you put it into a device and cram it down to 10cm so that it is already 90% compressed, and fully open is 10cm and fully closed is 0cm, that force is going to be much more consistent.

Not perfect, but these two things combined probably make it more consistent than one might think.
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LittleCoffee (original poster)

#20: Post by LittleCoffee (original poster) »

I agree the puck does not compress a meaningful distance during tamping - or at least as a proportion to the spring travel the amount of puck compression I think is noise.

I'm not sure I follow your second point - for my Normcore medium spring (I can't bring myself to call it 25lb spring as that's a lie) the force needed to fully bottom out - i.e. compress it the maximum amount possible is about 40lb - so depending on how compressed my spring is I'm getting something between 0 or 40lbs.

I do think there is a world of educational good to be had tamping with whatever you're tamping with on a bathroom scale - pretty sure most people would learn something if they've never done that before.