I finally decided to add the conical (needle) valve to my E61 mushroom cap and I wanted to find out how much interest there is in doing it yourself too? My plan is that it would simply involve changing the mushroom cap and possible the gicleur if we decide to use a specific taper. I've started discussions with a US needle valve manufacturer and ordered some extra mushroom caps to fiddle with. The design so far looks to take up part of the space of the gicleur screen, which I didn't think was a problem since I have 7 months on mine and zero scale (but I used Jim's insanely long water thread to be sure of that ... Thanks immensely Jim!!!) Who knows what the valve folks can come up with though, if we think that is an issue. I was just using COTS (commercial off the shelf) parts.

So why am I doing this when you can buy one? 1) Well, I just bought my Mara a few months ago, and buying one costs almost 3 times as much. 2) I've been doing mechanical engineering for decades and am retiring in a few months, so what better task to work on. 3) I realize the technology is so simple it's just a matter of doing it. Although we may learn some things along the way, the probability of failure is about nil. 4) I also looked to buy one and I did some comparison shopping and if you look at what the available machines cost overseas compared to here (given exchange rates), well that was enough to kick me into gear.

Also, I'm not planning on making money on this. I just want a nifty needle valve on my E61 and to make it available to as many others as possible. I may put together group buys or whatever makes sense, especially if there are some development costs with the valve supplier that I can't swallow myself.

My machine is a Lelit Mara, so if you took advantage of the 1st-line special I can almost guarantee that if it fits mine it will fit yours. I'm also planning on including some travel in the threads to accommodate any reasonable variability in the distance between the mushroom cap and gicleur.

Please list any concerns or questions so I can keep them in mind in discussions with the valve maker. If anyone has any experience with how different E61s can be from different manufacturers, that would be good to know, although keep in mind it's just between the mushroom cap and gicleur that matters.

Let's do it! What do you say?

Note that this is simply a needle valve added to the E61 like the original one (see part #1 below). The Bianca is a dual boiler, rotary pump machine with, I expect, a defeated E61 preinfusion function (probably a drain valve spring where the preinfusion spring goes). Those mods aren't within the scope of this project. Only the needle valve addition is planned. Cheers!

I would be interested in modifying my Izzo Alex Duetto IV.
Have you thought about the actual paddle design and which pressure gauge to use?

Hi Aldo, Honestly, paddle design will likely be the last thing I'd think about. Let's get a working valve first. As far as the gauge, that's down the road too. Right now I have erics enhancement pressure gauge to work with. I don't know that I would even tackle the gauge until I have a working valve in place. First things first!

I saw your E61 group for sale too, and I'm seeking to collect variability data. I'd be curious to know if it is about 0.75" from the cap seal to the top of the gicleur? And is the gicleur hole tapered? Also, is the cap thread M16 x 1.5?

Jim, thanks for sharing this project with the HB community! I'd be interested in purchasing a tried and true fully functioning system. I'm not much of an engineering type, and as a busy doctor with three young kids at home, I have very little time to tinker. That said, I'd love to expand what my Pro 500 can do if it's a simple install where not much can go wrong. Keep us posted Jim!

Jim,

Since you will want a maximum flow that is comparable to an existing typical gicleur, which is 0.7mm and you'll also want to have the ability to effectively stop the flow, you'll need an orifice much larger than a typical gicleur to achieve both end conditions within a half turn of the valve.

The COTS valve I'm using is a 0.070" orifice and a 15° taper with micrometer threads. Based on the published C_v curve for the valve and the calculated C_v of my 0.5mm gicleur based on measured water debit numbers, this geometry should provide what we're looking for. It is also available in 5mm as well as 10-32 threads, so it should conveniently fit behind the mushroom cap when threaded into the mushroom in place of the gicleur with an appropriately threaded bushing. I have 18mm from the "floor" where my gicleur threads in to the face of the sealing washer for the cap.

Just food for thought,

Cheers!

- Jake

So, like that which the Lelit Bianca features?

Randy,
I believe that is what Jim is implying with the term "Bianca-fy", yes

Tonefish wrote:I saw your E61 group for sale too, and I'm seeking to collect variability data. I'd be curious to know if it is about 0.75" from the cap seal to the top of the gicleur? And is the gicleur hole tapered? Also, is the cap thread M16 x 1.5?

Yes, it's about 0.75" from the cap seal to the top of the gicleur.
I think the cap thread is M16 x 1.5 but have no way to verify. Haven't removed the gicleur so can't verify if the hole is tapered.
The E61 grouphead I have for sale is identical to the one in my Alex Duetto IV.
It is a standard E61 grouphead.

Jake_G wrote:Jim,

Since you will want a maximum flow that is comparable to an existing typical gicleur, which is 0.7mm and you'll also want to have the ability to effectively stop the flow, you'll need an orifice much larger than a typical gicleur to achieve both end conditions within a half turn of the valve.

The COTS valve I'm using is a 0.070" orifice and a 15° taper with micrometer threads. Based on the published C_v curve for the valve and the calculated C_v of my 0.5mm gicleur based on measured water debit numbers, this geometry should provide what we're looking for. It is also available in 5mm as well as 10-32 threads, so it should conveniently fit behind the mushroom cap when threaded into the mushroom in place of the gicleur with an appropriately threaded bushing. I have 18mm from the "floor" where my gicleur threads in to the face of the sealing washer for the cap.

Just food for thought,

Cheers!

- Jake

I think a lot would depend upon the thread pitch, and I wasn't necessarily set on a half turn since I may prefer better pressure adjust-ability rather than big changes in small angles.