Posted Sat May 19, 2012, 1:04pm Subject: Re: pressure profiling with vibe pump
yeah i'm pretty sure you're right. if the rubber is flexible enough and big enough, it'll probably just bend around the wall of the basket. might need something that is food grade with high temp resistance. maybe food grade silicone rubber.
i dont want inner tube rubber tasting frothed milk. :P
Posted Sat May 19, 2012, 1:17pm Subject: Re: pressure profiling with vibe pump
LOL... didn't know that 53mm blind baskets even existed. You're probably right about the rubber causing a taste... not sure... but I'm thinking all you would need is a plug to cover the bottom of the basket.
Posted Sat May 19, 2012, 5:52pm Subject: Re: pressure profiling with vibe pump
FWIW, the spring in my Gaggia Espresso 'boiler valve' would hold about 2 bar of steam pressure, and about 2.5 bar when the pump was full on with no portafilter/puck. I had a couple of those valves and they both measured about the same.
Posted Sat May 19, 2012, 5:55pm Subject: Re: pressure profiling with vibe pump
ah...that's somewhat reassuring. it would be nice to be able to get water to flow by about 3psi. i guess i'll just have to play with the spring pressure. hmm wonder if there is a shim i can insert so i dont have to buy a bunch of springs and test different lengths
*thoughts of measuring internal diameter of the valve holder and finding tiny washers to increase and decrease heights with a cut spring*
Sashas Senior Member Joined: 2 Nov 2011 Posts: 23 Location: Vancouver, BC Expertise: I live coffee
Posted Wed May 23, 2012, 4:28pm Subject: Re: pressure profiling with vibe pump
Just connected 600w Leviton dimmer (serial, didn't connect ground wire) Gaggia Baby Primavera and it works great while the boiler is steady on or off. With PID correcting the temperature, pump speed is not stabile on lower settings. Anyone experienced something similar?
Posted Wed May 23, 2012, 4:44pm Subject: Re: pressure profiling with vibe pump
I am not using the dimmer, but have a PID. The PID cycles the boiler quickly and is on and off frequently, as I am sure you know. The boiler uses much of the available current, leaving the pump without, more noticeable at low pump setting. I can hear pump changes as the PID cycles the boiler on, but I am using the PID to raise the temperature of the brew water by turning on the boiler with the brew switch, not the PID function but alarm function of the PID. That means more "on" time of the boiler, and a definite pump change. Hope that made sense.
Posted Thu May 24, 2012, 8:27am Subject: Re: pressure profiling with vibe pump
I don't have a PID (yet - thinking of ordering one) ... but, yes, I notice that the sound of the pump drops slightly when the heater kicks on. For my machine with a 3-way solenoid valve, this makes very little difference in flow/pressure - it is only a slight drop in pump output.
But for machines without the 3-way - I will again state that you will see much larger swings in flow/pressure at the brew head for small changes in pump power.
The PID will be cycling the heat on/off through the shot so you will hear the pump change in power as the boiler sucks all the current for a second here and there.
In my setup, I get my boiler to the right temp (I have a thermocouple mounted digital thermometer showing me the boiler temp) and give it a couple of seconds head start (kick on the heat for 2-4 seconds) just before I start the shot to compensate for the rush of cool water that is about to enter the boiler. My heater doesn't kick on during the shot so for me it's a non-issue anyway.
tracerbullet Senior Member Joined: 13 Feb 2012 Posts: 168 Location: Saint Paul Expertise: I love coffee
Posted Mon Jun 11, 2012, 11:44am Subject: Re: pressure profiling with vibe pump
I have a dimmer but haven't gotten around to this yet. Do you recall which wire you stuck the dimmer in with?
I know that with pneumatics, placing a flow restriction before or after something you want to slow down changes the way it works. Not sure about this - I'm guessing electrical current flow is current flow and it doesn't matter, but figured I'd ask. Light bulbs don't care about polarity or much else - does a vibe pump?
I suppose that once I have it apart it's easy to stick the dimmer in at different points and just find out, but again - figured I'd ask. Thanks!
Posted Mon Jun 11, 2012, 1:23pm Subject: Re: pressure profiling with vibe pump
The dimmer I used has two wires that matter and a ground wire that doesn't really matter. The two wires go "in series" with the pump. So it doesn't matter which direction (polarity) it goes (because this is AC not DC) as long as it is in series. The pump works on AC current, not DC, so there is no polarity - though at the risk of confusing you, there is a Diode inside the pump which converts that AC to DC pulses (60 per second) which gives the vibe pump it's motion. The older Ulka pumps (I have one on my very old Gaggia OWC) had an external diode that also goes in series - oddly, it doesn't matter which direction you put the diode - what matters is that it causes pulses rather than a smooth, AC sine wave to the coil ... it doesn't seem to matter which polarity the coil gets since it is pulling a ferrous slug that is not magnetized with any polarity ... it simply pulls and releases the moving slug and doesn't care which polarity the magnet has. Yeah, I was afraid that would just confuse and pollute the discussion.
But the newer Invensys and Ulka pumps that I have seen all have the diode hidden away inside where you can't see it. You have AC going to the pump through two wires ... it doesn't matter which of the two you splice the dimmer into ... just pick one and put the dimmer between the one leg of AC and the pump ... the other leg of the AC to the pump is left alone.
AC --------------------------PUMP AC --------Dimmer---------PUMP
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