After a month of using a single hole tip on my La Pavoni, I have decided to switch back. I just haven't been pleased with the foam I'm getting. The GS3 I use at the Cafe I work at has single hole and I get pleasing results with that, but I'm not sold for my single boiler lever.

The construction of one hole steam tips makes a LOT of difference. I like the ones pointed like a bullet. The diameter is also critical and depends on engineering formulae. If you apply these formulae, for a 0.7 or so bar La Pavoni the diameter needs to be very close to 1.4mm. For an Elektra Micro Casa a leva with its typically slightly higher pressure and slightly lower element power the optimal diameter seems to virtually the same. A little bit too small and it works very poorly. A bit too large results in boiler pressure falling during the steaming operation. The 1.4 mm diameter results in essentially all the heat energy being fed into the machine being used to produce steam. The pressure remains unchanged and the element stays on!

The substantially higher velocity steam from a single hole tip denatures milk proteins more efficiently and makes a much more rigid foam.

It is the one from Orphan Espresso, so I am assuming it is proper size n stuff. I just did not like the foam I was getting. I stuck with it, thinking I just need more practice, but it never changed.

I have had issues with either so I'll have to check dimensions. I use a frother to help. It does make me question my element as my travel machine seems to steam better than my home machine.

I've used the original 3 hole, a homemade 1 hole and OE 1 hole. All work okay, and all have their issues. My biggest problem was getting the steam wand at an angle I like that yields great latte foam. (In other words if I pull it down from the shelf today I'll start steaming milk that looks crappy in the beginning until I've got things adjusted right.)

For my tips I found that riding with the tip almost out of the milk, especially in the beginning, really helped get a good stretch. If you lift it out of the milk you'll have a mess, so be diligent in watching that. Also I would rest the pitcher against the steam wand to steady my movements slightly as everything helps.

These little steamers are pretty low power, so you have to spend alot more time babying the milk. A more powerful machine makes milk easy by comparison.

For small reservoir machines the rate of steam release is best set so that the all the energy supplied to the boiler from the heating element is used to generate the steam. With large boilers you can take off steam and the heat capacity of the water and steam in the reservoir will allow you to continue to take off steam at an higher rate than it is being produced but not indefinitely.

With small machines the important thing to know is what it says on the little power label. For the La Pavonis of recent vintage it is 1000 watts. The enthalpy of vaporisation of water is 40650 J/mol. The heat capacity of water is about 75.32 J/mole/degree. Milk is mostly water, so it has a similar, though slightly lower heat capacity. (molecular weight water is 18g/mole)

If we steam 5 moles of milk, we need about 375 J to raise the temperature 1 degree. Temperature of steaming 5 moles (90 grams) milk should thus rise with a 1000 watt element at over 2.5 degrees per second with an optimal steam tip. We can utilise the heat capacity of the boiler water and take off more than this for a while, how long that is depends on the quantity of water in the boiler.

From the enthalpy of vaporisation of water one can compute water loss from the boiler from steaming. A 1000 watt element will be able to vaporise 1000/40650 moles of water per second. i.e. about 18 grams every 40 seconds.

The variable, of course, that controls how fast steam is released is the diameter of the hole or holes in the steam tip.