This is how I use a pocket mirror to see the bottomless portafilter and the pressure gauge at the same time from in front. (Just a demo photo; normally that Cafelat cappuccino cup is empty when I pull a shot into it.)

Spitz.me wrote:I know for certain that one of the best ways to ruin a shot is to Putz with flow or pressure during a shot. Pressure or flow profile has a material effect on your output.

I'll try Sam's method of lumbering over the Cafelat like I'm shielding it from gun fire and see what I can muster.

I'm not sure what you mean by "Putz" with a capital P but I can believe that erratic changes in pressure could have a negative impact. I use a hybrid grip/stance to maintain control, pushing with one arm and pulling with the other. I've hit 13 bar without undue physical strain. Whatever works.

What isn't clear to me is whether following a specific pressure profile recipe like cooperpwc detailed above makes a difference compared to just pulling with a gently declining pressure. My suspicion is that it's mostly coffee voodoo. But I'm willing to read a carefully conducted study of it.

Haha I don't know why my phone capitalized the word "putz", but it's not defined in the way I used it. Just doing "whatever" for pressure is going to ruin a shot unless, by some dumb luck, you find some interesting pressure combinations that create the most godliest shot of all-time. You can experiment, but what I described isn't experimenting, it's erratically increasing and decreasing pressure. What you described doesn't sound erratic. My experience is that I've been very erratic because as soon as I stop focusing on the pressure I basically ruin the shot by letting up accidentally.

We have machines designed to manipulate pressure and flow to create exceptional espresso. Pressure and flow are part of espresso recipes. The fact that we need these two parameters manipulated "just so" in order to get great results means that erratic changes during the shot tend make something go from potentially great to "meh". I can control my flow on-the-fly with my BDB and I have first hand experience of how bad your shot can be if you aren't considerate of pressure/flow during a shot.

jpender wrote:I finally took a closer look at that photo. I had assumed you meant the rails on the portafilter itself but that's a photo of the underside of the Robot body. When I turned my Robot upside down and compared them I couldn't for the life of me figure out what you'd done. For one thing your Robot seems to have paint where mine is clean (I have the polished aluminum model). Second, it looks like you've not only trimmed the rail but actually cut through it. It just makes no sense to me at all.

John - If you look carefully at how the portafilter locks into the robot you see as you turn the handle, the 2 wings on the pf must ride up high enough to rest fully on the 2 aluminum rails. Those 2 rails have blunt squared off ends and the pf wings can bump into those when they first touch and not want to easily ride up onto them, which is why it is sometimes fiddly. All I did was cut a small angled "ramp" where the pf wings first touch the rails in order for the pf to smoothly ride up onto the alum rails. Very simple once you understand. Cutting the stainless steel of the pf wings makes no sense. My robot is blue powder coated. PM me if still confused.
Rich

AZRich wrote:John - If you look carefully at how the portafilter locks into the robot you see as you turn the handle, the 2 wings on the pf must ride up high enough to rest fully on the 2 aluminum rails. Those 2 rails have blunt squared off ends and the pf wings can bump into those when they first touch and not want to easily ride up onto them, which is why it is sometimes fiddly. All I did was cut a small angled "ramp" where the pf wings first touch the rails in order for the pf to smoothly ride up onto the alum rails. Very simple once you understand. Cutting the stainless steel of the pf wings makes no sense. My robot is blue powder coated. PM me if still confused.
Rich

I finally see it. What appeared to be a "cut" to me is actually just a shadow. It makes perfect sense now. Thanks.

Spitz.me wrote:My experience is that I've been very erratic because as soon as I stop focusing on the pressure I basically ruin the shot by letting up accidentally.

I think you just need to experiment with position. While the Robot may not be appropriate for a 98lb weakling a typical adult should be able to apply sufficient force. I'm fit but not particularly muscular.

That said, I think the Robot's usability would be improved with slightly longer, more ergonomic handles. This is a modification I intend to make to mine eventually.

Spitz.me wrote:We have machines designed to manipulate pressure and flow to create exceptional espresso. Pressure and flow are part of espresso recipes.

Once you decide on grind, temperature, brew ratio, and time, average flow rate is determined. Pressure and flow are dependent variables. But that does leave room for pressure/flow variation during the shot.

I'm an espresso newcomer which means I know nothing. I'll have to do some more reading.

Paul_Pratt wrote:My first time to hear of this. I would remove the seal, clean it with a cloth and then reinstall with a light sheen of the Dow 111 Molykote that was included. Having a light sheen is enough, no need to have a tonne of it on there. The Molykote on the inside diameter helps it seat properly in the piston groove. To help it seat properly just run a finger around it.

Once in a while you could again run your finger around it to smooth it down.

Well I solved the problem. I replaced the seal with a new one and the problem went away. I think somehow the one I had issues with somehow got stretched and became too loose.

Studying ROBOTics







I gave the parts to the turner this very morning. We discussed a bit how it could probably work with our Smart Espresso Profiler and a few hours later he gave me back the first proto-type. I can't believe.... He should belong to the espresso machine tuners hall of fame. That's how the scuba diver ROBOT works:

naked-portafilter wrote:Studying ROBOTics...

I gave the parts to the turner this very morning. We discussed a bit how it could probably work with our Smart Espresso Profiler and a few hours later he gave me back the first proto-type. I can't believe.... He should belong to the espresso machine tuners hall of fame. That's how the scuba diver ROBOT works...