These comments were written with out reading any of the prior posts to avoid prejudicial information from influencing my experience, so if this is redundant, my apologies. I probably bent the rules a bit, but hey, that's what rules are for.
It's important to note that these remarks apply ONLY to MY equipment and are as much a comment on my technique as the tamper performance. One cannot discount muscle memory as a large contributing factor in evaluating something as personal as a tamper. For example, I drive 60 miles to have a bowling ball drilled because the same fellow has drilled for me for over 25 years and the ball always fits like a glove. Others can drill with the same numbers, but it just doesn't feel exactly right. To unlearn my old tamper and learn a new tamper, never mind 15, in a few days takes a younger dog than I.
I chose to divide the trials into three parts :
Phase 0 - Just heft all the tampers to see if one called my name. None did.
Phase 1 - Randomly try all the various tampers with a standard grind, dose and tamp [SGDT]. In this phase, I was more interested in the feel of the tamper in the hand than pulling great shots.
Phase 2 - Adjust grind, dose and tamp for tampers I found comfortable in Phase 1 until I could pull consistent shots or gave up trying.
In preparation :
- As I home roast, purchase sufficient commercial roast to remove that variable.
- Clean grinder, Macap M4 doserless, to remove old coffee.
- Clean group, screen and backflush Vibiemme Domobar Super to begin with a clean machine and basket.
- In the interest of time, use a bottomless PF.
My hand size is "medium" and my current tamper is "Stainless Steel Flat with Rosewood Handle, 57.05mm, 370g" The tampers that most closely approximates its shape and feel are the Reg HB and the Bumper.
I use Synesso ridgeless double with about 16g and a 20+ish pound tamp. I grind per shot and as the M4 is doserless, grind into the PF with a yogurt cup funnel and Weiss DT to distribute. I use a stainless spatula to level the grinds in a WENS motion. Depending on the coffee, I may vertically tap the PF once or twice to increase the dose. My tamper is about 1mm small, so I SE/NW gently prior to full pressure tamp in the center. I press on the piston, with almost no pressure at all on the handle. Finish with a light lift off twist to polish. I include this information because if your technique is markedly different, you'll know to read these comments with a large dose of skepticism.
Phase 1 :
At random I selected a tamper and tried it. Whether or not it is a learned response from prior tamper use, I don't know, but a tamper that has the weight concentrated on the piston felt most comfortable. Try as I might, I could not get comfortable with the Thor or the Lava Import. The Thor is too fat for my hand and does not have a definite bearing surface for the thumb and forefinger. The Lava felt too light in the hand and didn't naturally 'orient' itself. None of the rest stood out, but I definitely found I had a preference for a sloped piston top ala Reg HB, Radical Pro, Compressore, Coffee Lab, La Forza and Bumper. Something I found was that I got more channeling using my SGDT with the tampers with the most convex shape, Radical Pro and Lava Import.
While completing Phase 1, I examined the pistons and found 'significant' variation in diameter, shape and bottom edge 'hardness'. When half a turn on the M4 makes a difference in the shot, .6mm MUST be 'significant!' The diameters vary from 57.7 to 58.3 mm and convexity from 0 to 3.1mm.
Tamper Case Layout
[Number at lower left is Diameter, lower right is convexity.]
Another variable is the 'hardness' of the radius of the piston 'corner'. Some are gently rounded and some are almost square. Most sides are vertical but some slope inward slightly.
There are an almost endless number of permutations with the various diameters, flatness, edge hardness and handle shape. As none of the tampers stood out as making a marked improvement in shot quality, I decided that for Phase 2 I would limit the testing to the three that felt most comfortable and had the same diameter and also include two others that varied slightly. The Bumper, Reg HB and Radical Pro are all 58.1mm. The Pullman is probably the 'ideal' diameter for the Synesso basket. As the Pullman and Bumper are both flat, Pullman was number 4. I also included the Clicker as I've always been curious if a mechanical tamp would make for a more consistent shot. It's only 0.2mm smaller than the Reg HB and is similarly convex so could perform similarly to the Reg HB at the trip pressure.
I started by dialing in the SGDT with my normal tamper.
Once I'd pulled 3 consistent tasty shots in row of ~50mL in ~25s with a trial tamper, I felt confident I could proceed on to the next. If I failed on 4 attempts in a row to make any progress, I would move on regardless. I figured that would give me enough shots per tamper to get in the ball park without burning through all the beans on a complete mismatch, either to my hand or the machine.
As I'd failed to make a decent shot with this tamper in Phase 1, I started with this. Yikes! Three of the first four shots covered the front of the machine in coffee. Thinking something possibly amiss with the GDT, I tried my normal tamper and pulled 3 decent shots in a row. Try as I might with this tamper, no combination of GDT gave a great shot. I found the handle comfortable, but I think the narrowness and height didn't mate well with my muscle memory. If I concentrated on orienting the tamper, I got better results.
This and the Bumper have the closest physical feel to my standard tamper. First shot was a bit thin, so 1 rap of he PF prior to tamp. Bullseye. 3 in a row.
I was quite interested in this tamper as it maybe the ideal size for the Synesso basket. First shot channelled badly, puck was sloppy. -1 turn on the grinder and 3 taps on the knock box was the ticket. About 18g. The handle fit the hand nicely, but the ridge at the piston / handle junction is annoying. If the contour at the base of the handle was curved and the top of the piston sloped, this could have been number one. I definitely liked the engraved lines around the piston. They give an immediate indication of tamp depth and symmetry. Number 2.
Prior to Phase 2, I measured the tamp of this with a scale that holds the maximum pressure applied. I found trip yield is consistenly 30.5 ± 0.5 pounds. I found I could apply ~28± pounds and not trip the tamper. A bit more than my normal tamp, but very consistent. I'd like the trip to be more muted. It's a very sharp snap. My wife came from the other end of the house when I was measuring and asked "What's all that clicking?" The long and the short of it is +2 turns on the grinder plus 4 taps on the knock box using the tamper to just before trip. I gave up trying using the trip as I never got a good shot. This is more than likely due to the 50% increase in tamp pressure over my normal pressure. The handle feels fine, but the extra height over a fixed tamper is a bit off putting, as is the travel. For the first few tamps in Phase 1, I found myself stopping well below the trip point as the travel length was fooling me into thinking I'd gone through the bottom of the basket.
This tamper could also be considered ideal for the Synesso basket. It's almost identical to the Pullman except 0.2mm smaller in diameter. The edge is about a .3mm chamfer on both. Perhaps I was over caffeinated, but I never found the optimum with this tamper. I expected it to be identical to the Pullman, but it was +3 turns on the grinder relative to the Pullman. As a reality check I went back to the SGDT with my standard tamper and pulled 3 in a row, so I obviously had not yet found the sweet spot for this tamper with my gear. It could be the sharpish corner on the handle gives me the false impression of correct pressure vis a vis the more contoured handle of the Reg HB and Pullman. Another variable is the grinder was quite warm by this time, but it did not appreciably affect 3 shots with my standard setup. Number 3.
My complete unfamiliarity with convex tampers, which probably require a complete rethink on GDT, prevented me getting a good shot with the Radical Pro. Perhaps the profile is poor match to the VBM. Other than that, I'm certain a few days use of any of the tampers which feel comfortable in the hand would yield a consistent pull. I'm confident that if I'd started with any one of them, I'd be perfectly happy. I do like the feel of the snug basket fit of the Pullman, so perhaps I'll wrap a layer or two of duct tape around my tamper. Recommendations on best color tape for espresso greatly appreciated.
Reg HB. A classic. Feels good, looks good and I definitely prefer the feel of wood to rubber, plastic or metal. As comfortable as a pair old slippers.