Mrboots2u wrote:Surely that's impossible to answer ?

Not at all. A more modal grind results in a more even extraction results in a sweeter cup.

That they are getting a 27sec shot of a light roast up at 21% really says everything.

The reason my EK doesn't choke my GS/3 while someone else's may be in the fact that big burrs require insane tolerances to remain parallel enough to have a fine grind although that I roast very light could also have something to do with it. However, the K30's at my customers' locations have no problems at all.

Instagram/twitter for mahlkonigusa show a video of interface, looks great!

endlesscycles wrote:Not at all. A more modal grind results in a more even extraction results in a sweeter cup.

That they are getting a 27sec shot of a light roast up at 21% really says everything.

The reason my EK doesn't choke my GS/3 while someone else's may be in the fact that big burrs require insane tolerances to remain parallel enough to have a fine grind although that I roast very light could also have something to do with it. However, the K30's at my customers' locations have no problems at all.

Ok i can dose 20g into 42-44g with an Ek43 with coffee burrs of a light roasted single origin or blend ( and have done this with some roasters " filters roasts " ) and got 25 seconds plus shots at 21% ey ....

I understand more modal = sweeter cup , i was saying that until there are out in the wild, with some more data and tasting attached to it and tasted by more than one person , we are all spitting in the wind a bit ....

I can do similar. I have choked my machine at nine bars with more traditional espresso roasts (i.e. fc+), but those types of roasts aren't the EK's forte, obviously, and I don't pull them very often. Without getting too far off-topic, I'm assuming you're using some combination of updosing, nutation, and lower pressure to achieve short-ish shots.

I do think this is relevant because the question is "Is the PEAK actually able to produce a finer modal peak (i.e. has tighter tolerances) or is it producing more fines to help choke shots?"

NoStream wrote:
I do think this is relevant because the question is "Is the PEAK actually able to produce a finer modal peak (i.e. has tighter tolerances) or is it producing more fines to help choke shots?"

Likely the later.

boar_d_laze wrote:. The properties of cast and forged steels are different.

In terms of burrs, I don't really know how the differences affect performance, but would guess that in terms of the ratio of crush/cut, that forged burrs take and hold a sharper edge and tend more towards the cut side of the continuum. Some Ditting/Mahlkonig cast burrs can be resharpened; but I don't think any of the forged ones can. Like I said though, I don't really know. Maybe someone who does can jump in.

Rich

There is a Utube vid of a tour of the Mahlkonig factory...
where they show burrs (some very large..150mm+ dia !) being manufactured. They clearly show the burr blanks being sawn from billet (bars) of steel which are heat treated and fully CNC machined before finish grinding. Different grades and sizes of steel bar stock, Cast burrs are also commented, but No mention of forging at all .

Richard,

Thanks for the video link. I learned a lot from it.

I'm glad I said I was guessing before, because my guess that the machine burrs were forged was -- as you point out -- wrong. So... from a properties standpoint, the burr maker uses either tool steel or cast steel. And from a manufacturing standpoint, the tool steel rod-stock is cut into blanks, the blanks are heat treated, drilled out, and then the teeth are CNC machined; no forging.

Rich
(Just another Dick)

Always entertaining watching an executive explain manufacturing that he clearly doesn't fully understand.

"Tool steel" is absolutely meaningless to anyone who machines precision parts from steel. That term refers to any one of literally dozens of different specs of steel, all of which have distinct properties. The discs are sent back to heat treat not because they are uneven, as the white shirt claims, but because even with "through-hard" you have a "case" depth of rated hardness on the surface and a softer interior. Cutting exposes the softer interior. The discs would be cut, possible heat treat, rough machining to form the teeth, heat treat, and then grind. The total number of processes, heat treating (could happen multiple times during manufacturing,) gas nitride, ion, etc.. is very difficult to pin down. There is a multitude of ways to make a part. How exactly they are doing it is pure speculation without a process sheet.

Forging vs. casting is really more about cost effectiveness than anything else. In a situation like a bulk burr where you're not machining the full tooth profile a casting is far more cost efficient. You can get the same result with a forging, but it will cost a lot more with no real gain. If the design calls for the full tooth profile to be machined to a tight tolerance, a forging will be the more cost effective option (you'd scrap too many castings due to defects.) It really depends on what you are trying to accomplish as to what you select. As a simple block of metal, forgings can offer some limited benefits over castings in extreme applications, but in the coffee burr world this is not relevant. The grain structure of the metal isn't really a design concern here.

I'm in workholding. The indexer on their surface grinder is something I'm rather familiar with. We often source exotic alloys for various components. If we used the term "tool steel" with our clients they'd hang up the phone on us. Then again, our clients are machine builders and manufacturers, not coffee shops or other end users.

Eric, thanks for the interesting info.

Good wrapping up of the material info! Thanks! Don't overestimate the use of different steels and processes! As a producer you aim for a very narrow range of used steel materials. So you can b e sure that the goal is to use the same steel and process on as many different discs as possible. And grinding discs is by far not as scientific materialwise as we like to believe Steel producers laugh about the demands of steel of a disc manufacturer. So the supply of different (on of course very, very special) steels is nearly impossible for them. The benefit for us in the cup needs to come with the disc design afterwards...