Brew Pressure - Bricoletta Rotary

[Grant]

Needing to replace the power cord on my Bricoletta (it came with about a 3' cord and is making me insane), I have the case etc. all apart to get at the electrical, and I noticed on the pump the large brass screw which I believe (from seeing other posts) will adjust the pressure output.

Now, not having a brew pressure gauge on the machine, and not having a gauged PF, is there any advice anyone can give on "zen" pressure adjusting.

Any thoughts on what the "factory" brew presure is set to?

Any idea on the rotary pump of how many "turns" of the screw translates into what change in pump pressure? Clockwise/Counter Clockwise to decrease brew pressure?

On my old Silvia doing the OPV mod, I used various thicknesses of copper washers (gradually increasing) and general knowledge gained from the community, until the espresso taste, flow, etc. just "seemed" right.

While certainly not scientific or technically the correct way to do these things...sometimes you just have to play to learn as well....

Any advice?

Grant

[Balthazar_B]

I think I've seen brew pressure modification mentioned somewhere else, but you may need to buy/borrow a portafilter with a gauge to do precise enough adjustments. My guess is that the Monster Bricc project referenced elsewhere on HB will include a brew pressure gauge, but you'll need to wait until January for details...

[miKe mcKoffee]

My advice would be to spend the $25 to $50 or so for the proper tool for measuring pressure (price depending if just gauge or need fitting(s) and/or another PF), readily available places like Chris' Coffee or EPNW. Maybe a very experienced mechanic would set the ignition timing on a Ferarri without a timing light...same thing IMO. I don't have my Bric yet so can't give you any ballparks, beside who's to say two different Bric's will behave identically?

Recently opv pressure gasket adjusted two different Silvias. One took a single additional sanded gasket for 8.75bar. After adding the one gasket pressure plummeted from 16bar to 7.5bar so sanding the gasket thinner was necessary! (4yr old Silvia) The other under a year old Silvia took two additional gaskets (3 total) to bring it down from 12bar to 9.75bar. Didn't have another gasket handy or would have tried 4 total and he didn't want to file the spring to bring it down any further so left it at 9.75bar.

[HB]

Now, not having a brew pressure gauge on the machine, and not having a gauged PF, is there any advice anyone can give on "zen" pressure adjusting.

Unless you can adjust pressure by taste alone, there is no choice, you must get a pressure portafilter or install a brew pressure gauge. Since I twiddle the pressure a lot during an evaluation, I install a temporary external gauge for those that don't come with one out of the box:


See Channeling woes / Check rotary pump machine's brew pressure? for more details

[Grant]

OK...I have a gauge fitted PF coming shortly, but I am trying to figure out how to properly adjust the brew pressure on my Bric. I am going to do some "playing" beforehand, and make some up/down adjustments and see if I can detect any taste variation "blind".

Looking at the pump (rotary), there is a large brass screw which I am assuming is the adjustment mechanism. Can anyone point me in the direction of a guide, or advise me on the procedure for brew pressure adjustment? i.e. is increasing/decreasing pressure = clockwise or counter clockwise. Does power need to be completely disconnected while this is performed, or is the switch off enough? etc. etc.

Grant

[mteahan]

The adjustment screw is at 90 degrees on the inlet side of the pump; clockwise higher, counter clockwise lower.

If you are looking at a large cap and chamber at an angle to the inlet/outlet, the pump may be fitted with a filter. Leave it alone; not all of them have filters. If there is a locking nut on the adjustment, simply loosen it before you start.

If you are testing the machine while hot, expect the gauge to read a little higher than actual. Cold should be 9 bar, hot maybe 8.25 to 8.5.

Good luck.

[malachi]

[quote="mteahan] Cold should be 9 bar, hot maybe 8.25 to 8.5.[/quote]

Depending on coffee and personal taste, brew pressure can be optimal anywhere from 8 to 10 BAR.

[mteahan]

True, a range is appropriate. I was just saying that the pressure measured with a PF gauge on a hot machine will run a little higher than that measured from a machine based gauge measured before the heat exchanger,.

There should never be absolutes in espresso--except absolute crap.

[malachi]

I think I've experienced that one absolute...

Grin.

[terryz]

There should never be absolutes in espresso--except absolute crap.

Hey, Whats a matter you? Angelo's coffee is better than that, I'm sure

[mteahan]

Angelo's desk, unlike mine, is neat and tidy. His portafilter, however. . . .not so much.

Definitely the odd couple around here.

[erics]

Seems kind of nuts to have to adjust the relief valve on a positive displacement pump to get the "brew pressure" you want. If this is a Procon pump, they (at least on their website) recommend NOT using this as a pressure regulating tool.

It would seem that there is some other "device" on this relatively expensive machine to more easily adjust pressure.

Eric S.

[malachi]

I think you're confused.

[erics]

No, not yet - but I'm sure it will happen soon because it definitely has happened in the past.

I do understand (now) that the only way to change brew pressure on an otherwise unmodified Bric and, likely, any other machine that has a rotary pump is to adjust the pump's relief valve.

You said "Depending on coffee and personal taste, brew pressure can be optimal anywhere from 8 to 10 BAR" and, in your very fine and well written review of this machine on this site, you certainly wrote about the access difficulty to the pump adjustment.

Maybe the day will come that roasters stamp their recommendations for brew pressure and temperature on the bag.

So do I think its nuts to remove sheet metal, pray that I don't mishandle an allen head screw into never never land and then make adjustments to a relief valve that the pump manufacturer tells me I shouldn't be doing (although, again I acknowledge its the only way) just because I changed from brand A to brand B beans? Yes.

And do I THINK there's an easier way - sure. Just add a OPV valve or a more precise pressure control valve from Swagelok and dump the excess to the drip tray that already has a drain attached.

Eric S.