Another tamper? Yes, but it was not like I was shopping for another tamper. Quite the contrary. I had merely posted a reply to a thread on Home Barista.com where the original poster was asking about The Force Tamper. The thread was later locked, and shortly after I was then contacted by Zubing Sun, the inventor of the tamper, and I was asked if I would like to try the tamper in exchange for my opinion. I will say that it is rare that I receive unsolicited requests such as this from companies with which I have had no previous contact. I replied that I would be glad to test and review the tamper. Who could say no to another tamper?
He even said that I did not have to review it. He just wanted my opinion.
WHAT IS INCLUDED
The Rising Force tamper comes nicely packaged in a semi-flexible, plastic jar and is well protected for storage as well as shipping. The jar includes the tamper, a soft travel/storage pouch, a flat and a riffled base in the size of your choice from those available, and a rubber protection resting base.
It comes in four base sizes (53, 58, 58.35, and 58.5mm) and your choice of three different handle shapes:
- Ball (a small sphere)
Mush (a wider, mushroom shape)
- Jelly (sort of an in-between shape like a somewhat flattened ball).
All the handles are wood, and all feature their logo in the center of the top of the handle which is part of the plastic threaded insert for attaching the handle to the tamper's body.
Due to its narrow metal body it appears tall, but comparable to my other tampers.
A DIFFERENT KIND OF TAMPER
Just when you thought it was safe to make espresso, along comes yet another tamper design. I have seen tamper designs that may market well but make no real sense. There was one I remember which only adjusted to a depth. This made absolutely no sense to me. It was the equivalent of using a ruler to see how much something weighs. The Force Tamper is not one of those. I had doubts upon seeing it described on a coffee forum but after putting it to use my opinion of this device has become quite positive.
The rising force tamper is designed to perform two major functions. It has a secondary plate the rests on the top of the portafilter to hold the tamper level when in use. This plate has a small ridge that sits inside the portafilter and keeps the tamper in place. It has its own return spring which returns it to its resting spot on top of the tamping base after use. The leveling plate's long collar which rides on the main shaft makes it virtually impossible to tamp in any way but level.
What makes this tamper special is the method it employs to apply a force to the coffee which, to my knowledge, is quite unique in function as well as design. This deserves an examination in detail.
SUDDEN IMPACT FORCE
Most tampers which regulate the tamping force use some feedback function such as a tactile click or a compression spring which "softens" the force applied to the coffee at a predetermined level of force. One tamper forgoes tactile feedback by using a digital display. The Force Tamper takes a different approach. Pressing down on the handle of the tamper compresses a spring. At a point controlled by an internal mechanism, the spring's energy is released and that potential energy turns kinetic, "slamming" a piston down onto the base, compressing the coffee. The ingenuity of this mechanism deserves a detailed examination:
Here is the tamper, mostly disassembled, with the parts laid out in order of assembly. While few users are likely to have to get to this point, it is nice to know that it is possible.
Above are the parts of The Force Tamper that make it special. The shaft is what holds then releases the piston to cause the tamping force to take place. The green circle around the base of this shaft shows the bottom of this part which rests in a machined recess in the tamping base. Notice the way its large end is radiused.
The inset image in the upper left shows the shaft and its spring assembled on the base. The red arrow is indicating the last turn of the spring whose end is bent outwards. That is resting on the tamper's base. The blue arrow indicates the opposite side of the spring which rests on the flared base of the shaft. When the shaft's spring is compressed it forces the shaft to tilt slightly to one side.
Off to the left is the piston. Note the hole in the center of the piston. While the user is pushing down on the tamper's handle, the tip of the shaft is resting, off-centered, just to the side of that hole. As the handle moves downwards the tamping spring is being compressed because the release shaft stops the piston from moving with the handle.
When the pamper reaches a design-determined depth, the release shaft it force to stand upright and the top of the shaft aligns with the hole in the piston. The piston is now free to travel downwards, powered by the force of the compressed tamping spring.
Confused yet? Don't feel bad. It took me a couple of days of investigation to figure this all out. Here is a video that may help clarify this difficult-to-explain mechanism:
So why bother with all the complication of that mechanism? It is a matter of physics. The release of the piston to "slam" the tamping base into the coffee takes place over a relatively short distance; a much shorter distance than it took to compress the spring. The benefit of this is two-fold:
1 - The release of the stored energy to create the tamping force means that the tamp is virtually exactly the same every time because the human factor is all but removed when the tamper is used in a reasonable manner.
2 - Because a lower amount of force is being applied by the user it is less stressful and thus has the potential of eliminating repetitive stress injuries. This would be particularly beneficial in a commercial setting or for people with physical limitations. A very rough estimate showed me that a 30 pound tamp can be accomplished with only about 15 pounds of pressure on the handle.
Once I figured out how all the parts go back together, the only difficulty was with dealing with the leveling plate and its spring.
The spring which keeps the leveling plate in place on the portafilter basket is shown above. It fits over the captured collet (indicated by the blue arrow) then is captured by sliding down the outer sleeve (green arrow). Note the outside threads on that part. These treads engage into the leveling base, and that is were the user must take a bit of care. If the spring is pinched between the outer sleeve and the leveling plate, the spring will cause binding and the plate will not move freely. The trick is to make sure that the end of the last winding of the spring's wire where it rests on the leveling base is not trapped between the outer sleeve and the base. I did it by manipulating and tilting the parts as they join together and the threads of the two parts begin to mesh. I understand that is a bit confusing, but it is easier done than described.
ADJUSTING the APPLIED TAMPING FORCE The tamping force applied to the coffee is adjustable. Adjustment is done by first unscrewing the handle from the tamper's body. Under the handle is a washer which is used as a driver to turn the threaded ring retaining the tamping force spring. There is no calibration or vernier scale to judge the tamping force. The release at the adjusted point is quite violent so I could not use our glass-top bathroom scale to judge the the tamping force. I tried to quantify the range and setting of the tamping force that this device delivers to no avail. I contacted the inventor and learned that there is no way a home user can measure the tamping force. He told me that he uses an, "industrial high-speed shock sensor with corresponding instruments to measure the released impact. The impact happens in less than 0.01second." That certainly explains it!
The adjustable range is about 24 to 40 lbs. Every 2 threads (two full turns, or 1mm of compression) increases the force applied by about 1 pound. Full adjustment distance is about 15mm. I had played around with different settings before I had this distance:force information. I then measured and found that I had the spring compressed to about 5mm, which coincidentally enough, computes to about 30 pounds.
I have disassembled The Force Tamper at least a half dozen times during my first week with this device. I am not an engineer, but have had my hands on and in enough mechanical devices to know a quality one when I handle it. Beyond being ingenious, the quality of the manufacturing process and of the materials used is excellent. The fine threads for the force adjustment are about 50TPI, are very smooth and well cut. Most of the parts are stainless steel.
When The Force Tamper first arrived I was slow to accept the principle. Of course, we all realize that level tamping is critical, but beyond being a useful tool for those with physical difficulties in achieving that, I personally never had a problem with being able to tamp level. And for over a decade ago I realized that the range of tamp force that resulted in acceptable extraction was so wide that having an adjustment for tamping force was unnecessary in most cases.
But after a week's use I have come to appreciate the overall function and design of The Force Tamper, a Red-Dot Award winner. The effortless nature of the action of the device is such that I can easily tamp at about 30 pounds with just my thumb pressing down on the handle. Not only can the release of the spring be accomplished that way, but the tamper stays level as well. The travel distance from at rest to just before the release point is about 19mm (0.7").
But this is not tamping as most of us have come to know that function. As opposed to a downward force applied over a period of time, this is impact tamping. A spring is loaded and then suddenly released resulting in what can easily be referred to as "sudden impact tamping." Is it an effective method? I have found it to be just that. My findings in the short time I have been using The Force Tamper indicate that it improves consistency and has lessened sprites (not that they were much of a problem for me previously).
At rest it is the tallest tamper I have, but at the point of release it is the shortest of my tampers.
A short list of negative comments I can make at this point:
Coffee grounds get trapped between the leveling disc and the tamping base. This is only a problem when you forget and handle the tamper outside of its normal environment. If you pullback the leveling disc the coffee grounds spill out. It usually is not much, but can leave a small amount of coffee behind on the table, or possibly on your shoes.
The lack of a method to quantify the tamping force may be a problem for some people, but my advice is to not worry about it. Turn the spring down so the retaining screw is about 5mm to 7mm from the top and tamp on without further thought or worry.
And just to be picky, the adjustment washer stored under the handle in the base rattles if you shake the tamper. In actual use you will never even know it is in there.
In terms of dose and further preparation, distribution is the key to a good extraction. Proper distribution can also one of the more difficult things to achieve in that regard. Some grinders make it nearly impossible to evenly distribute the coffee without some further effort like stirring the coffee with a needle-like device. I think a lot of home baristas will find that all they need to do with The Force Tamper is give a gentle shake and possible a downward tapping of the portafilter before tamping which achieves anything resembling a level distribution and just let The Force Tamper take care of the rest. It is a little early make any such statements, but after a week's use I think I have found my new favorite tamper.
Handles are $19 each, replaceable bases are priced at $19 to 29 each, and the packaged tamper as described above sells for $199. While not readily available as of the posting of this review it is available directly from the company's website, "The Rising Force Kitchens Co. Ltd" in China. It is also available, shipped from the Far East, from one seller on Amazon.
So the $200 question is, do you need a $200 tamper? From my brief experience with this device, my advice to you is, if you absolutely do not want to spend that much on a tamper, DO NOT borrow one from a friend! A day's use of it and you will want one.