Arco by goat story - Page 2

Grinders are one of the keys to exceptional espresso. Discuss them here.
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#11: Post by another_jim »

You're right, the Trespades have five ribs on the inner burr, and the Italmill six. They are about the same size.
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#12: Post by leozava (original poster) »

Does seem a bit on the "fat" side from this video. I still really like the design, I'm curious to hear how loud and the pitch of the sound coming from the motor ... 2s6iahw2i8

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#13: Post by Willinak »

Any idea how these burrs would do for espresso grinds or Turkish?


#14: Post by malling »

I have backed it, I'll let you know what I think when it arrives next summer.

But I mostly backed it as I needed a new handgrinder as the old one is pretty banged up after several trips.


#15: Post by BeanPoet »

That was an astonishingly quick Kickstarter. A thousand backers and $450k plus in two days! ... escription


#16: Post by malling » replying to BeanPoet »

Yeah even within the first hour about two-hundred had already backed it. The early bird slot where entirely gone I think within the first two hours.

John Michael Hauck

#17: Post by John Michael Hauck »

Please help me confirm/dispute my maths:
  • According to the creator's (Anze) comments, the burrs move 33.3 microns per click. "The 33.3 microns you've read per click is the vertical movement of the burrs per click." ... r/comments
  • There are 30 clicks per revolution (per the website).
  • That means the vertical movement per revolution (thread pitch) should be 1mm.
  • However, I calculated the markings are 3mm apart from the attached picture in this way:
  • The red line shows the width of their grinder (which they say is about 60mm) (489 pixels in this picture)
  • The green line shows the distance if you were to spin the dial three times (from 1 to 4) (73 pixels in this picture).
  • If you do the math, the pitch is not 1mm but actually 3mm. (73pix * 60mm / 489 pix = 9mm for three turns - or 3mm per turn).
  • That means each click is not 33.3 microns, but rather 100 microns.
Where did I mess up?

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#18: Post by graphidz »

Try calculating the line level on the left side. You can see that the numbered level is not linear to the left side.


#19: Post by renatoa »

The image could be distorted somewhat, or is computer generated... I found this trying to skin the cat a different way...

Assuming the diameter is indeed 60 mm... btw, which diameter? of collecting recipient, or the dialing ring ? I think 60 mm should be for the ring, because the can is less than 58 mm, you can see in the video clip how it is inserted into a portafilter basket. ;)

If we go with the assumption that dialing ring is 60 mm, then the marking spacing should be 6.28 mm

click = 2 * PI * 30 mm (radius) / 30 (clicks/markings)

Measuring the distance between 12 and 13 markings on the picture I found 59 pixels, so the 60 mm diameter on picture should be 563 pixels, significantly more than the 489 you measured for the lower diameter. But still not matching the pixels size of the ring of the picture...


#20: Post by malling »

Measure from a picture is at the very best questionable, all lenses have some distortion that is typically corrected in body in jpg format or in post processing if shot in raw.

Then angel view can also screw it up and so forth. Therefore I have far more faith in the numbers given than someone calculating from a picture.

Besides your calculating the wrong place.