Tamper bottoms: Flat or convex? - Page 2

[miKe mcKoffee]

I use an RB convex. It arrived the day before Miss Silvia 3+ yrs ago. Since then got a couple flat Thor Tampers. While they're beautiful works of art and fully functional, I use the RB daily. Guess it's what I'm used to and comfortable using.

[buzzword]

malachi said he'd like to see a better s/n here than at CG.

I'm an almost complete rookie (to old to be a noobie), and I feel the same way.

So I'm going to post my signal to noise ratio: .1. 1 part signal to 10 noise.

If there were a problem with my 'clicker' (not really a valid name, you'd have to be Paul Bunyan pressing into a concrete block to get a respectable click), it would be the least of my problems.

It is helpful though, what was said, because it makes me see that SNWE with an Espro is not an undertaking for the new.

I used the Espro this morning in the center only, and then packed pretty recklessly with the plastic convex that Oscar brought. Not bad by .1 standards.

I've got an RB tall US curve on the way, flatter handle.

[HB]

All the convex tamper pistons I've seen have the "American" curve shown below. I've noticed that often the perimeter beads moments before the center extraction begins and wondered if a more prominently curved one like the Euro curve would change the initial extraction dynamics. Has anyone compared the two extremes "flat" and "Euro" curved pistons? I ordered one and am experimenting this week...

And a question for the mechanical engineers out there: Assuming an initially level and uniform layer of coffee, what effect would you expect as the curvature of the base increases in terms of the edge and center resistance to pressure? Here's my thinking based on my vague recollection of two years of college physics: The center will ultimately end up thinner (= less capable of resisting), but more tightly compressed (= more capable of resisting). The edges will end up thicker (= more capable of resisting) and pressed harder into the side walls (= tighter adhesion). So a bulging tamper piston will INCREASE the likelihood of the center extracting more quickly relative to the edges (?).

PS: Yes, I know about the "Gourmet Espresso Tamper" (it's concave). Following the same logic above, it's ideally designed to maximize side channeling.


(Image courtesy of RegBarber.com)

[bobroseman]

Okay Dan here is my thinking. Force is proportional to the sine of the angle between the surface and the direction of application. Calculating the angle of a right triangle that is 29mm on the adjacent side and 1.6 mm on the opposite side, I get 3.2 degrees. The force acting at the edge is therefore acting at an angle of 90 - 3.2 degrees. The sine of 86.8 degrees is .998. Thus the force at the edge is 99.8 percent of the force in the center. Jeez! I don't know for sure but I think that is too small a difference to be significant.

What is clear is that the edge will be 1.6 mm thicker and very slightly less compacted.

Bob

ps and of course if you "rock" the tamper to the slightest degree then all bets are off. You have essentially, an unpredictable or repeatable situation. B

[Kelpburger]

the clicker is a useful training tool. seriously.
would i use it to actually make shots? no.
but i used it in every training session i've done since it came out.

as for the flat vs convex thing... seriously, it doesn't make any difference that i can discern. i've cupped a whole lot of coffee from all sorts of tampers trying to taste minute changes. i've evaluated tons of shots through a naked portafilter trying to identify altered extraction. so far, there is a lot of theory - but at the end of the day it's what's in the cup that matters and i see no difference.
use what makes you feel good.

personally, i think handle length, balance and weight are all FAR more important that the shape of the bottom of the piston.

It seems the experts only use the espro/clicker tampers as training tools.

What if you had a tamper that actually gave you a pressure reading? No pressure surge click. You would just know the max pressure exerted during your tamp.


As you're pressing you would know exactly how much pressure you're exerting. 25lbs for this shot, 35 for the next. precisely adjusting tamp as you would your grind.

Do you think a tamper like this would actually be considered more than a tool?

Just a "what if" question really. Not that anyone could ever make one of these.

[malachi]

You'd be looking at the measurement and not what you're doing.
You'd also not be paying attention to the feel - and just looking at the measurement.
Thus, not as good a training tool.
Would I use it in practice? No. It's trying to solve a solved problem. Training with a Clicker or the like and then practice has solved this.

[JonR10]

Just a "what if" question really. Not that anyone could ever make one of these.

It could be done, for sure. I can easily imagine using a small load cell like the type used in digital scales.

But I would not have a "live" readout to watch as you tamp because (like Chris said) then you'd focus on the reading and not the technique. Instead, I would likely have a small digital readout in the top of the handle that you could see after you were finished (it would be covered by your palm while you were tamping and the reading could just stay there for some specified amount of time or until you used it again).

[darrylr]

What if you had a tamper that actually gave you a pressure reading? No pressure surge click. You would just know the max pressure exerted during your tamp.

Actually a tamper like this exists. It's called the M3 packer from Versalab (http://www.versalab.com). I own one and it works very well--adjustable pressure over a large range and the action is super smooth with no click. It's also automatic--driven oddly enough off of a water line hookup (that's its one disadvantage). It's not an electronic device, just water powered. It was $295.00.

Darryl

[AndyS]

Actually a tamper like this exists. It's called the M3 packer from Versalab (http://www.versalab.com). I own one and it works very well--adjustable pressure over a large range and the action is super smooth

Darryl:

What effect has the M3 packer had on your espresso shots?

[BrewHaHa]

the clicker is a useful training tool. seriously.
would i use it to actually make shots? no.
but i used it in every training session i've done since it came out.

May I ask why you wouldn't use a clicker tamper to actually make shots? Do you feel that a clicker results in an inferior tamp, or is it just that in your case you personally don't need or want to use it?

Thanks,

John

[Walsty]

The only tamper I've known is a Reg Barber flat. I like have always liked it and never felt a pull to change.

[Jeff Burgess]

An interesting discussion of tamper shape. Seattle Barista Academy recommends that a flat bottom on the tamper. The rational is that a flat pack will more likely lead to an even extraction. It is thought, and some of their 'experiments' seem to support this idea, that the rounded pack can lead to overextraction because of pooling and underextraction at the sides of the pack. Hope this helps the discussion. Regards. Jeff Burgess, Director of the Seattle Barista Academy.

[Everman]

It doesn't matter, at least for me. But maybe the outcome would be different depending on the machine, grinder, and beans?

Interestingly enough about 2 months ago I walked into this restaurant supply store in Perth where they have a self-serve 2 group machine by the door free to use for customers. The person who brought me there said they use it all the time, but of course I had my doubts about the quality, I gave it a go anyways. There was no tamper here, just the one attached to the grinder. So I dosed some grounds and tamped lightly, and pulled a pretty good shot! It wasn't fantastic but shockingly good. Perhaps it has something to do with a coffee roastery on site. Just to prove it wasn't a fluke I did it again on my way out

Moral of the story? Perhaps tamping is overrated, maybe I'll attach the tamper to my mazzer and start using that

[Psyd]

>Total engineering geek-out snipped< ; >
What is clear is that the edge will be 1.6 mm thicker and very slightly less compacted.

'Kay Bob, what if the bottom of the basket emulated the gentle curve of the tamp? Wouldn't those two surfaces, being parallel, pretty much even out the force all across the surface and compact the puck evenly? Would that make the curved tamp appropriate for curved basket-bottoms?
It's the 'LM-styled' 14G baskets tha tI got from 1st Line a few years ago. Came with a gentle curve, reminiscent of the 'American Curve', and seems to perform a tiny bit better with the curved tamps.
Just a hunch, mind you...

[IMAWriter]

[snipped]

Or you just won't improve because you're lazy, and complain about how you wish you had a different type of tamper, because of course, if your espresso sucks, it's your equipment, not your technique, right?

Interesting you say that. I somewhat equate folks having 4 or 5 tampers for the SAME machine as to golfers who constantly "upgrade" their putter,(or ALL their clubs) as that is easier than practicing, or maybe improving technique with lessons. Having said that, I do think it's fun having both a flat and convex as I do for my Cremina.
What I've found is for my smaller cremina basket, the thinner piston of my Richard Penney tamper helps me level a bit better, while my 58mm Reg's thicker piston did the trick for that basket size. Might be just me.