If no bidirectional valve in piston, or other mechanism avoiding creating vacuum in the group after extraction, when piston goes up, thus absorbing grounds through the shower screen, then a paper disk cut from a paper filter cone was a big improvement long time before issue of actual mesh filters.
Personally used Aeropress filters, because they have the right size for 58 portafilter, but custom cut from V60 filter paper works the same.
Just give it a try.

zix wrote:I have never used a top filter on my Strietman, and I don't expect to need one on the Argos either.
The Strietman just needs a good grinder, as most lever machines do, and, I suspect, as will the Argos.

Agreed, that had me scratching my head. I used a Strietman just fine for 3 years without a screen or filter on top. I don't see why the Argos would be any different, especially if they have a solution for the vacuum effect on the puck, which it sounds like they do.

bgn wrote:Great to see a video. I was surprised by the use of a filter screen on top of the puck. I've never used one on any machine. I'm not opposed to it but it surprised me and reading about Strietman users "needing" a top filter is one if the reasons I lost interest in that machine. Still really looking forward to using this machine but am wondering if it will become a weekend toy instead of replacing my Cimbali lever.

I have not read about Strietman users needing a top filter. wouter the creator of the machine doesn't use one and does not recommend one (i asked him personally earlier this year) and I certainly don't. Just mentioning this in the off chance that you may be the victim of misinformation. Worth considering the Strietman. It's the favorite of the four levers I've owned so far.

I would talk about misinformation after trying at least a paper filter cut on basket size. Or an aeropress filter borrowed from a fellow.
You have too many confidence in "creators"... they are just humans.

As far as I know the whole puck screen usage started with the La Pavoni because of the high pressure squirt from between the piston and the water inlet hole. Some were already using a paper filter because Scott Rao made it popular but it also solved this specific issue with the LP. Then BPlus came up with the metallic version. Someone correct me if my history knowledge is wrong.

I don't think the screen is necessary with the Strietman as (again AFAIK) the water enters the brew chamber through a valve of sorts straight from the top and furthermore not pressurized. Contrast this with La Pavoni (and Cremina?) where water is pressurized and enters from a lateral hole that for a short while is partly blocked by the piston and the gaskets. This might be the case on many lever machines, also the spring levers, though they may have more inlet holes to perhaps mitigate this issue.

Now, I havent checked how exactly this part is designed to work on the Argos but if it is similar to La Pavoni and Cremina you do run the risk of "squirt".

Apart from this issue the screen has other uses or advantages but that has been discussed multiple times.

renatoa wrote:I would talk about misinformation after trying at least a paper filter cut on basket size. Or an aeropress filter borrowed from a fellow.
You have too many confidence in "creators"... they are just humans.

I guess you mean "wouldn't". Very true about them being human. A helpful reminder but a bit wide of the mark in this case. I've tried paper on top, paper below, paper above and below and a bplus. But reverted to no filter. Improves work flow and the espresso is superb with or without them.

But we should really get back to the Argos I have one on pre order with 6 and 8 bar. I doubt that it will arrive before Q3 but it will interesting to try the different configurations.

tompoland wrote:I have not read about Strietman users needing a top filter. wouter the creator of the machine doesn't use one and does not recommend one (i asked him personally earlier this year) and I certainly don't. Just mentioning this in the off chance that you may be the victim of misinformation. Worth considering the Strietman. It's the favorite of the four levers I've owned so far.

Off topic but curious which lever machines you owned? Interesting to see what users think of their machines.

There is a lever pulling technique that may cause the need for a puck screen. Moving the lever (and consequently moving the piston) slowly (in order to not disturb the puck) as the water inlet hole is revealed will cause a jet of high velocity water to hit the puck causing problems. A puck screen is one solution but so is moving the piston quickly past the hole.

On my La Pavoni if you go fast past the water inlet you get instant channeling that is obvious post pull. Slow and not fully opening inlet is an easy way to limit the forceful jet.

The problem I am talking about is that going slow as the piston just starts to open the hole can cause a downward jet that disturbs the pu k. This is somewhat dependant on the seal, piston, and shower screen geometry.