I received Eric's dispersion screw gicleur inserts last week, a whole set of 4 ranging from ~0.6-0.9 mm.

They install pretty easy. I had a friend tap some extra dispersion screws that I had, so I didn't receive one that Eric made. It happened that my friend tapped the internal M4 threads into the screw much further than needed, so I set mine in pretty well with a judicious application of PTFE tape. Here's how it looks:


Sorry, the orifice is just out of view. It's a black hole. In the center. (Flickr link)

They work. However, there are a couple of weird things about them. Like you would expect, you get a jet effect from the water shooting through a tiny orifice and spattering against the inside of the dispersion screw. It disperses a little less evenly as a result (if you watch it without the screen installed). With the screen installed this effect seems to be diminished, and I think it's fine.

The other issue is that air in the feed tube is audibly forced through the orifice with this configuration, and this results in an audible gurgle when flushing. It sounds a bit like mild flash boiling on an HX machine, but luckily doesn't result in the messy spatter associated with flash boiling. The noise here is the only irritating thing, and it's worst with the 0.6 mm gicleur. It gets milder as you go to wider orifices. I've been using the 0.8 mm orifice, and I like it for my profiling setup pretty well. However, this would give you a substantial reduction in natural preinfusion from the 0.6 mm gicleur, if you have a regular pump. It might reduce the 'forgiveness factor' that you experience.

Those are my thoughts. At this point, it might be best to stick with the serial solution of the M5 orifice and screen combo if you're worried about clogging the gicleur. For firsthand info on that from me, check out the second part of this post—I wanted to keep my discussion of gicleur clogging in the relevant thread, so there it is.