dsc wrote:Hi guys,

I got the bits today and will be testing out the manual operation after work. The only thing I'm a bit worried is the ball valve itself which seems to be lubricated with some rather smelly grease/oil. Do you think it's going to be a problem, ie. the water is going to taste different when passing the valve? I'd say no as it is hot/cold water approved, but maybe I should switch to something more food safe?

Regards,
dsc.

At the very least you should make yourself sign a waiver before consuming any espresso from the machine.
Personally, I would go for more food safe

dsc wrote:I got the bits today and will be testing out the manual operation after work. The only thing I'm a bit worried is the ball valve itself which seems to be lubricated with some rather smelly grease/oil. Do you think it's going to be a problem, ie. the water is going to taste different when passing the valve?

I wouldn't use it until you are able to thoroughly clean the valve (via flushing or if possible, disassembly).

Hi guys,

it's all ok, the valve isn't greased, it uses a round teflon 'washer' which presses against the ball and makes it water tight. I put everything together last night and it does work, but sadly I'm getting water leaks here and there and will have to use a few different fittings before using it again.

Regards,
dsc.

dsc wrote:smelly grease/oil

Your concern reminds me: one thing that I don't believe has been mentioned much is "new machine taste/odor."

In the world of automobiles, "new car smell" is a positive. I believe there are even aerosol products designed to give your 100,000 mile beater that "just-out-of-the-showroom" aroma.

But for espresso machines, it's definitely NOT desirable. On the rare occasions when I've taken possession of a brand new machine, it's generally taken several hundred shots to get the oily and/or metallic tastes to fade.

This obviously makes a "first look" type of machine review more problematic.

Hi guys,

well as Greg said earlier it works, but:

- I will have to use a smaller ball valve as the one I have now let's too much water through and it's hard to adjust the pressure

- to make the whole thing smaller I will have to use smaller pipes/tubes/ fittings

- with a broken pressure gauge on my Elektra I had to watch a pressure gauge that was stuck just after the tee with the valve and so it was hard to adjust the valve, watch the pour and watch the pressure changes

- I will have to buy a new pump as the one I have is rather noisy (it was like that before)

Here's a short clip showing how it all looks like:

http://vimeo.com/3174090

The concept is simple and with a proportional valve it can be quite easy to control pressure, but it's still a pain to connect everything together. I will try to get a 3/8" ball valve and some fittings to go with it.

Regards,
dsc.

Nice!

Maybe putting a long handle on the valve would make it easier to control. You could mount it on the machine so adjusting it was like playing a slot machine in Vegas



Regards, Henry

Hi guys,

I'm pretty sure that I will remove the pump/motor from the machine and mount it under the kitchen sink, thus giving myself a bit more space for all the additional piping.

With the pump partially dead (noisy) I started thinking whether it's possible to damage the pump by using this kind of bypass? It's true that the pump was a bit faulty before but now it has gotten rather noisy and I'm curious what's the cause of it.

Regards,
dsc.

dsc wrote:With the pump partially dead (noisy) I started thinking whether it's possible to damage the pump by using this kind of bypass?

Not by the bypass itself. After all, the rotary vane pumps used in espresso machines have a similar built-in bypass.

The pump could be damaged if particulate matter is allowed to enter the inlet. This sometimes happens accidentally when plumbing is modified.

Hi everyone,

I just finished writing the software for the pressure profiling system and I'm now waiting for the hardware bits (stepper motor and elements to put together a power supply for it). To bore you a little bit and update this topic I thought I would explain how it's all going to work.

The PPS (pressure profiling system) will offer the following functions:

- full Manual mode in which the user can open/close the valve as much as he/her likes, adjusting the pressure within a range of 2-9bar. Control of the valve will be possible via a mom-off-mom toggle switch on the control box. Keeping the switch in the 'up' position will close the bypass valve thus increasing pressure and keeping the switch in the 'down' position will open the valve and decrease the pressure on the group. The 'pump on' signal won't affect the valve control in any way which means you can adjust the valve with the pump engaged or not.

- full Auto mode in which a predefined pressure profile is being executed when the 'extraction' button on the front of the machine is pressed. The system offers three custom set pressure profiles (see Programming mode) and one Default profile which is a 'preinfuse for 3s at 2bar - ramp up to 9bar in 3s - ramp down to 6bar within 21s'.

- Programming mode in which the user can set his/her own profile (via manual mode) and save it under one of the profile buttons (three buttons are available labled P1, P2 and P3). The buttons are the normal push-to-make momentary type and allow to both save (long press) and load (short press) previously configured profiles.

Switching between the Auto/Man mode is possible via an on-on toggle switch and Programming mode can be turned on/off via a mom-off-mom toggle switch to eliminate accidental activations. The control box also has 4 red LEDs to show which profile is active at the moment and 2 green LEDs for 'Pump On' and 'Programming On' indication.

Here's a drawing which shows how the faceplate of the control box will look like (it doesn't show the Programming ON LED):



Hopefully the whole thing should be working before the end of April.

Regards,
dsc.

Hi guys,

because I'm slowly finishing my programable pressure profiling system (PPP as I like to call it) I'd like change the place where the pressure is being measured. Currently the PT (pressure transducer) is connected to the 4 way junction where the water inlet is connected (it's water coming from the pump under the sink). The idea is to remove that link and hook the PT with the group via 1/16" tubing and an M4 Beswick fitting (courtesy of Nicholas).

I've ordered some 1/16" tubing and it arrived today, but I'm not sure how it should be routed inside the machine. Should I run it as low as possible (near the base of the machine), with the least amount of bends and turns, make a coiled section or simply run it however is easiest without worrying too much?

By the way for pressure upto 10bar do I need a fancy 15bar-certified copper tubing or is ordinary tubing ok? it was advertised as:

1.575mm OD, 0.787mm ID Seamless Copper tube grade C106

Great for modelling and live steam systems (so I guess it can take some pressure).

Regards,
dsc.

Hi Nicholas,

thanks for the info!

I will bend the tubing the same way you did on your TC:



[dry fit]

I will run it around the solenoid, inside the machine, behind the group, maybe create a small coil positioned horizontally and then connected to the PT via Swagelok's tube fittings.

Regards,
dsc.

dsc wrote:By the way for pressure upto 10bar do I need a fancy 15bar-certified copper tubing or is ordinary tubing ok? it was advertised as:

1.575mm OD, 0.787mm ID Seamless Copper tube grade C106

1. That tiny tube will easily handle 10 bar
2. Will it clog up with coffee solids after a while and cease functioning?

Hi Andy,

crap haven't thought about that, although there should be no coffee solids behind the bell, as you've got the dispersion screen, the dispersion block and a lot of tiny holes in the bell/group itself to effectively block any coffee going back up. I guess I will just have to wait and see.

Regards,
dsc.

Hi Nicholas,

the PPP system is not going to have feedback (at least not at the moment) as it uses only the valve position info to drive the valve. This means that even if the tube gets clogged the valve will continue to operate as normal, never raising the pressure above 8.5bar. The PT will be there simply to check what's going and whether my calculations were correct or not (and to calibrate the valve min/max positions).

As you say testing it with all the elements in place will be the best way to check our assumptions.

Regards,
dsc.

dsc wrote:there should be no coffee solids behind the bell, as you've got the dispersion screen, the dispersion block and a lot of tiny holes in the bell/group itself to effectively block any coffee going back up.

I see what you're saying, but of course some solids make it back up, or periodic backflushing would not be necessary....

shadowfax wrote:isn't it basically true that if you're running a couple feet of 1/16" tubing and hooking it up to the pressure transducer, aren't you using air in the tube as a buffer to water under pressure? and isn't air pretty compressible? It seems like the gauge line will fill partially with water as the air compresses during brewing, and then that water will be forced out by the compressed air when the solenoid valve opens up at the end of the shot.

A tiny amount of that air will dissolve in the water each cycle, so the quantity of air will slowly decrease. Despite that, the pressure measurement will probably be just fine for a long time. I guess Tom will see soon enough.

Hi guys,

well it looks like it might take a while to connect everything, even though I'll have the Beswick group fitting tomorrow. The reason for this is the 1/4" BSP thread on the PT which apparently is something out of this world (at least to Swagelok). There's no 1/4" BSP to 1/16" tubing adapter available of the shelf and to make one I'd have to buy 3 parts which might not fit under the PT:

- 1/4"BSP to 1/4"NPT adaptor

- 1/4"NPT to 1/4" tube fitting

- 1/4" tube to 1/16" tube adaptor

To make things worse they don't make the BSP- NPT adaptors in brass which means they cost more then the two other parts together (which are brass).

I guess I'll put this on hold for now as it looks and sounds awfully annoying and overcomplicated.

Regards,
dsc.