After lots of looking I was able to find the post that claimed that with a stock BDB that we can already do some profiling on the end of the pour.
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1) On an utterly stock machine, because you can set your pre infusion pressure (and duration) in the stock machine, you can set it low as you like, and pre infuse as long as you like, usually until you start seeing first drops, then you can let it run up to normal pressure. You can even ramp It down a bit on an utterly stock machine, toward the end of the shot.
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>You can even ramp It down a bit on an utterly stock machine, toward the end of the shot.

I don't see how we would accomplish the above, so if anyone can fill me in that would be much appreciated.

Thanks,

M./

You ramp it down by cracking open the hot water valve*. This exhausts some of the pump output into the drip tray via the water spigot. Sounds inelegant, but that was state of the art, a year ago and is how the conical valve GS/3 MP does it. (Well, it exhausts excess pump output into the drip tray, just not through the water spigot.)

*If you want full authority top to bottom pressure control WITHOUT using the needle valve, you move the microswitch out of it's mount and push it out of the way and you can exhaust excess pump output into the drip tray to your heart's content.

-Peter

You can alter the pressure at any point during the shot by turning on the hot water during the shot. As long as you don't hit the point where the cutoff switch stops the flow to the puck and all flow goes to the hot water spigot. Some of our machines are more or less sensitive on this point: mine will allow pressure to reduce to approx 3-4 bars indicated, while some have reported 6+bars as the cutoff point.

This is a fully stock machine alternate-capability.

One of the mods (that I have not yet done) is to reroute the hot water needle valve to instead be in the shot path, and directly control the flow to the puck.

Short of that, some have modified the microswitch on the hot water control so that it does not cutoff at all.

Greetings! Been an 'almost never post' member for a long time, and this is the first time I've posted on the BDB. I have read the threads on the BDB carefully these past months with real interest, and finally took the step, joining you guys with a new BDB, upgrading from a 13 year old Elektra Semiautomatica that I had recentlypulled out of an 8 year retirement and rehabbed with *some* success (still have a leak I can't trace down). I would never have done this if it weren't for all the work you guys have put into exploring this machine, repairing it and modding it. Thanks to you all for your creativity and patient work; these threads are quite a read, and need an index of their own!!

Even before I turned it on, I opened the BDB up when I got it to begin familiarizing myself with the insides, as I hope to do the OPV/brass Pump and PP mods. I have one of the late ones (serial # 1850...) with the nuts on the boilers. Got it from WLL.

After a look around, I closed it back up and set it up and started pulling shots. I love the early results with the BDB in every way, and am taking some weeks to settle in before I do the mods. I have most of the parts and have walked through (in my head) a few of the procedures. I have some questions before I proceed, and I'd be grateful for any advice...

On the OPV/brass Pump Mod:

Peter you posted, "Any prosumer Brass OPV. I used one from a Vibiemme DD that I got from Stefanos. You will need to get the fittings for 4mm tubing, to attach the 4mm Breville tubing to the OPV. In the case of the Vibiemme OPV, it was a single 1/8" BSP-to-4mm tubing adapter. I used "quick connect" but you can use compression too. Ebay or Amazon for the fittings."

I have no experience with the tubing adapters, and when I search Amazon and eBay for these things, the choices are overwhelming. I get that I need BSP threading on the brass screw-in fittings, but when assembling, should I tape the threads with plumber's tape or just screw them together firmly?

Most of the adapters seem made for pneumatic (air) systems. Will these work in a high temp food grade fluid system like our espresso machines, or am I looking for a specialized adapter? I don't want to put in an adapter that will fail on me, obviously.

Did I see in one of the photos of your OPV install (Peter - post #182 on the 'Slayer Shots thread) that you had a right angle adapter coming out of the top? Can you give a good link for these adapters?

I also have a question on the PP Mod, which I will post in the 'Slayer Shots' thread.

Thanks for any help!

Geoff

Hi Geoff. Well done on doing your homework here. It makes giving help easier.

1) Re "food grade"... You will have to decide your own comfort level. The plastic pneumatic quick connects look identical to the plastic quick connects used in Ascaso, Saeco, and Jura semi auto and super auto machines. Also, copper and brass which are common in espresso, are not "food grade". There is an old joke in traditional espresso about slowly being poisoned by your equipment. Most people don't believe it any more than they worry about getting arsenic poisoning from peaches and apples just because there are trace amounts of it in the seeds. Anyway, you can use plastic with quick disconnects. Or plated brass with compression fittings. Or brass with quick connects. I would bet that they are available in stainless with compression fittings, but will not be common or cheap. You would have to dig. Aliexpress might have them. Let us know if you go that route. Add to the body of knowledge.

2) I used an elbow on top of my OPV, but I am told by others who did this, that there is plenty of room even if you don't.

3) Tape or no tape? There are BSPP and BSPT. The first is "parallel" threading and might not need tape. I am not very knowledgeable on British plumbing standards. The second is "tapered" and almost certainly needs sealer. Since I couldn't be certain, I used it whether it needs it or not. No leaks.

-Peter

Bret wrote:Short of that, some have modified the microswitch on the hot water control so that it does not cutoff at all.

Thanks for the reply. This is the route I will end up taking.

I no longer feel the need to push the envelope as far a I possibly can (unlike years past).

Max./

pcrussell50 wrote: *If you want full authority top to bottom pressure control WITHOUT using the needle valve, you move the microswitch out of it's mount and push it out of the way and you can exhaust excess pump output into the drip tray to your heart's content.

-Peter

Thanks for the tips.

Should I be looking for that near the left side with the hoses? Or will it just be readily apparent once I get the top off?

Max./

maximatica wrote:Thanks for the reply. This is the route I will end up taking.

I no longer feel the need to push the envelope as far a I possibly can (unlike years past).

Max./

is this the mod you guys are referring to?

Brew pressure experiments with Breville Dual Boiler

Thanks, Peter. One more Q. on the connectors - the ones listed for pneumatic systems are good for fluids as well?

And while I have you... my boiler like yours have the nuts on top connecting the hoses, not the clips. Anything special about swapping hoses to those inlets/outlets when I take on the PP mod? Just unscrew them and swap?

Geoff

For the profiling tubing reroute, you don't need to touch the hex nuts on tops of the boilers. The three tubes you care about are all of the the hairpin clip and o-ring variety. It's all pulling hairpin clips and re plugging that tube to another fitting which also uses a hairpin clip.

-Peter