King Seven wrote:However, I've seen shots slow waaaaay down when nutating quite aggressively in the tamp. Which kind of freaks me out.

+1 to this. The difference on my Nino was staggering and made me wonder if I was getting some type of rotationally symmetric channeling without nutating. That's vs. the way the Nino 'distributes' as if doses, though. Seems to be pretty mitigated with WDT and a usual tamp, though the aggressively nutated tamps still were a bit slower.

Aren't these differences fascinating?!

I'd be interested to know what tampers you are using.

My experience with a vigorous nutating tamp is that it can help with convex tampers like the Barber c-flat, but not with a flat tamper.

With a flat tamper (my preference) I get more consistent pours and more even extraction with a straight-down light tamp with maybe only the slightest nutation to level the top.

For what it's worth, my own personal belief is that in the former (heavy) case the nutation is correcting the deficiencies of the c-flat design, whereas in the latter it is helping with levelling the surface before the tamp "proper".

With my Ninos I find no need to do anything other than a quick succession of finger "karate chops" to distribute and then tamp.

Is there a measurable difference at lower deltas?
Say 5lbs to 60lbs?

I did Andy's 30 second test. 2.5 lb tamp vs. 40lb test and found the same, higher tamp more= weight in the cup. I did notice though, the shot forms slower and much more even with the 40 lb., but somehow it passes up the lighter tamp in weight.

Jepy wrote:higher tamp more= weight in the cup

Amazin', ain't it?

Interesting discussion. I would swear that varying the tamp pressure made a difference in the shot speed on my A3 but it comes to pressure in about 3 seconds. I will have to play around a little when I have some time. I have another machine (E61 rotary) on the bench beside it so I could compare the two. Hard part will be getting a reliable, consistent pressure on the tamps. I could use some lead weights across the top of the tamper. Or I could use a couple cases of shot shells, those flats are probably 60 pounds each.

Jepy wrote:I did Andy's 30 second test. 2.5 lb tamp vs. 40lb test and found the same, higher tamp more= weight in the cup. I did notice though, the shot forms slower and much more even with the 40 lb., but somehow it passes up the lighter tamp in weight.

Hmmm....
Very interesting.
You willing to compare at different doses? Would love to see if this is true also when down dosed and up dosed.

King Seven wrote:However, I've seen shots slow waaaaay down when nutating quite aggressively in the tamp. Which kind of freaks me out.

I've made exactly the same observations a couple of weeks ago. Interesting. I attributed it to better "interlock" between particles (pressure is not only from the top, but also from the sides) thus the more "tight" puck and increased water flow resistance.

cannonfodder wrote:Hard part will be getting a reliable, consistent pressure on the tamps.

Bathroom scales are like, $10 at Walmart.

Yes, but it is still up to me to deliver the exact same weight every time. Using a weight would take the arm wobble out of the equation especially since the entire point is to test tamp pressure.

I've never noticed a difference between different tamping pressures at home with the vibe pump; nothing in the range that I can apply seemed to make any difference - as long as I didn't screw anything up. I usually just give a light tamp now.

But I was able to pull a few shots on a GB5 which ramps up much more quickly (I'd guess 3 seconds to full pressure), and I did notice a difference between a lighter and heavier tamp - in how long to see the first drips, how long the shot took, and the taste in the cup.