AndyS wrote:Is it really that hard to design a vibe pump system with some sound deadening? Chris Nachtrieb, Terry Z, are you listening?

I'm listening, but I can't hear you over this damn vibe pump! What was that again?

terryz wrote:I'm listening, but I can't hear you over this damn vibe pump! What was that again?

I rest my case.

I could see the point if it was a piece of equipment used in a cafe. I could see the point if it was going to be used in a house where it would be used at a time where it might awaken small children or a spouse, whose bedrooms might be nearby.

What I can't see is the concern over a little noise for perhaps 2 or 3 minutes a day, in a house, that will be heard mostly by those using it.

There are many aggravations involved in producing fine espresso in a domestic location, everything from roasting the beans to maintaining and fine tuning equipment. This concern over a little noise for a few minutes a day rates a 2 on a scale of 1-10, in my opinion.

ken

AndyS wrote:Yes. The pump uses a diode to produce pulsing DC. This DC repeatedly fires a piston against the resistance of a return spring.

I must confess that this info has been told to me by others; I have never dissected a vibe pump to verify it personally.

Someone who has, please chime in.

Yes! (I know I asked the question in the first place...but...)
I just tested the pump on my Gaggia Espresso (55 watt Ulka) using a piezoelectric pickup attached to the orange pump housing and plugged into a strobe tuner advertised to be accurate to within .1 cents (a cent being 1 of 100 equal increments that separate 2 adjacent keys on a piano). The reading on my tuner teetered between B1 (61.74Hz) and Bb1 (58.27Hz) before finally settling on a flat B1. So in other words, the frequency of these pumps is in fact right at (or at least darn close to) 60Hz.

DISCLAIMER: I have not tested any of what follows in a real environment. All info is based solely on calculations, and practical applications of acoustic principles. By reading further, you agree that any harm, injury, loss, and/or damage and any negative effects at all are your own fault, and that I am basing all of this on a college level acoustics class. I have not tested any of this physically. I will when I get a chance. As always, electricity and water to not mix! Do all work with the machine powered down and unplugged, and make sure there are no areas shorting the circuit before powering back up.

60Hz being the Forcing Frequency in this system, the Natural Frequency of the mounting system should be no more than 6Hz, with a Static Deflection of .27 inches.

So: mount the pump on a set of springs (maybe a neoprene pad) which under the weight of the pump, compresses exactly .27'', and which the whole contraption will bounce up and down at a rate no more than 6Hz, and in theory, you have yourself complete vibration isolation.

I say in theory, because the piston in the pump moves from side to side, not up and down. And while it would not be impossible to do a horizontal mount, it would be much trickier to keep it stable. As long as you have your .27'' of static deflection and under 6Hz natural frequency--with compression springs--it could work. The vertical mounting WILL work, maybe not totally, but compared to how they are stock, it would be significant. A combination of the two would be ideal.

The other issue would be the vibration traveling through the plumbing, and into the boiler/grouphead. This would counteract the pump mount but shouldnt be too much unless the plumbing is rigid metal all the way from pump to group.

As far as transmission through the air, wrapping the pump in fiberglass insulation would help but that would depend on the amount of free space inside the machine.


Conclusion: A decent isolation system shouldn't be too hard for manufacturers to install in their machines, especially those with some extra space inside. I'm not too familiar on the plumbing paths and materials in the prosumer HX machines, but provided the lines arent totally metal tubing from pump to group, it would be significant isolation. For our DIYers, it would be a matter of going to a hardware store and testing out various springs and then figuring out how to mount it. Once I get some extra money for parts for experimentation, I will, and I'll post results unless someone else already has. The easy way to get rid of the noise though, is still to go rotary .

gtrman wrote:The other issue would be the vibration traveling through the plumbing, and into the boiler/grouphead. This would counteract the pump mount but shouldnt be too much unless the plumbing is rigid metal all the way from pump to group.

I "outboarded" my espresso machine's vibratory pump:


Mounting board suspended from bottom of cabinet on rubber o-rings / eye holes

I was surprised how far the vibration would propagate along the water line. It literally would cause buzzing in the mounts 20 feet downstream from the pump. I blame most of this on the pipe material (John Guest LLDPE tubing); changing the hookup to braided stainless steel wrapped tubing with neoprene-padded strapping every 16 inches eliminated the downstream noise and reduced the pump's effective sound level to rotary pump levels.

Woops, miscalculation on my part. My machine has just a few inches of silicone tubing.

gtrman wrote:As far as transmission through the air, wrapping the pump in fiberglass insulation would help but that would depend on the amount of free space inside the machine.

Insulating the pump may reduce the duty cycle considerably as the pump would not dissipate the heat of pumping as quickly.

FWIW, judicious arrangement of the plumbing plus adding a couple of rubber strips have silenced my machine so it less noisy than the Macap M4.
1- add a foam strip along the face of the cup warmer tray.
2- add two rubber strips under the drip tray.
3- add a sink protector cut to fit the top of the cup tray to stop the cups vibrating.

HB wrote: I was surprised how far the vibration would propagate along the water line. It literally would cause buzzing in the mounts 20 feet downstream from the pump.

20 feet!?!

Where did you put it, in another room?

Henry

The 20 feet refers to the water hookup. The filter system is under the kitchen sink and the espresso machine is located on the opposite side of the room, thus I had to run a line under the house. Prior to the last changes I made, the pump vibration would propagate from the vibe pump and rattle the tubing / fittings of the filter system.

Dan neglects to mention that transmitted vibrations caused the guest toilet to flush every time he choked the espresso machine.

ken