If my methodology is incorrect here, please do let me know. Happy to try other things for you all as I'm able.

I think I found a reasonable way to measure the height of the teeth. By keeping the burr carrier in place with a pin (where the flapper usually goes) and rotating the burr only with my fingers, I think I can reasonably show that this burr set has almost no variation in teeth height at the outer edge. This is a burr set from a LS known to have trouble with traditional espresso flow dynamics. I replaced the rotating burr with the stationary burr for the second video, so you're seeing a measurement of both discs:


Rotating Disk: http://www.youtube.com/watch?v=YhaJVTVaDQY

Stationary Disk: http://www.youtube.com/watch?v=Cw_q_8oQzF8




-Ryan

primacoffee wrote: At most, use a torque driver at about 50% power to apply even tension to your burr screws and you're golden.
-Ryan

Hi, Ryan. Thank you for the insight. I did think about purchasing a torque driver for my 807LS. I haven't made my purchase yet, because I do not know how much torque should be applied on the screw. For that reason, I cannot pick the torque driver with right spec. Would it be possible to obtain the torque value? Thanks.

We use a Bosch PS20-2A (I think it was discontinued and replaced with a new model). It has a max of 100 in.-lbs of torque and we use it at about 5/10 for burr screws, and around 4/10 for the T20 torx screws on the stationary carrier. Ultimately it doesn't matter all that much, as long as you don't go unreasonably light or super hard. The main thing is that it's consistent screw to screw.

primacoffee wrote:If my methodology is incorrect here, please do let me know. Happy to try other things for you all as I'm able.

I think I found a reasonable way to measure the height of the teeth. By keeping the burr carrier in place with a pin (where the flapper usually goes) and rotating the burr only with my fingers, I think I can reasonably show that this burr set has almost no variation in teeth height at the outer edge. This is a burr set from a LS known to have trouble with traditional espresso flow dynamics. I replaced the rotating burr with the stationary burr for the second video, so you're seeing a measurement of both discs:


Rotating Disk: video

Stationary Disk: video


image

-Ryan

Pretty crafty, well done! Maybe I find the time to do the same with my 807 at some point to have a reference point for burrs that I believe are perfectly fine.
I also love your commitment!
I am absolutely not sure, hence I want to measure my burrs too, but isn't the deviation kind of big? I mean the teeth height is in the ballpark of 100 microns if I remember correctly. The deviation you show is about 0.001inch for the first video right? Isn't that about 25 microns. That would be a 25% deviation?
Did I get something wrong?

I think you're right, I see about 0.001in variance in each burr, or around 20% variance. But how does it compare to other burrs? I think that's an important question.

Also worth noting: we tried swapping the cast burrs for the E80's machined burrs in our brewing tests to see if the material was at play, and the E80 burr behaved identically to the cast in the LS in terms of flow dynamics.

-Ryan

primacoffee wrote:I think you're right, I see about 0.001in variance in each burr, or around 20% variance. But how does it compare to other burrs? I think that's an important question.

Also worth noting: we tried swapping the cast burrs for the E80's machined burrs in our brewing tests to see if the material was at play, and the E80 burr behaved identically to the cast in the LS in terms of flow dynamics.

Absolutely! And I will try to provide one other data point by the end of the week.

Interesting that the different geometry behaves the same. One question that instantly popped up in my mind is, do 807 LS burrs behave differently in a 804, which I believe has the same burrs as long as Hemro didn't pull more shenanigans on us like with the EK years ago.

coffeeOnTheBrain wrote:Absolutely! And I will try to provide one other data point by the end of the week.

Interesting that the different geometry behaves the same. One question that instantly popped up in my mind is, do 807 LS burrs behave differently in a 804, which I believe has the same burrs as long as Hemro didn't pull more shenanigans on us like with the EK years ago.

I believe the E80 and Lab Sweet burrs have the same geometry, but one is cast steel and the other is machined tool steel.

-Ryan

My bad that is the newer version of the E80 right? I believe there was a E80 once that had a different geometry. Similar to how the 807 has machined burrs and the 807LS has cast burrs.
Anyway, you meant the material and I misunderstood

coffeeOnTheBrain wrote:Absolutely! And I will try to provide one other data point by the end of the week.

Interesting that the different geometry behaves the same. One question that instantly popped up in my mind is, do 807 LS burrs behave differently in a 804, which I believe has the same burrs as long as Hemro didn't pull more shenanigans on us like with the EK years ago.

Hi Ryan,

Thanks for your tests, comments, and commitment to our community regarding this grinder!

Can you confirm what the part number of the burrs you are testing is? I was advised by my local distributor in Australia that the 807 LS burrs were 103993 which is the same as the peak, but that the 804 LS was 105780. I then contacted hemro and was advised the 804 LS does actually use 103993. It would be good to just confirm we're comparing apples with apples here.

Also, do you have any idea whether the differences in the body, chamber, exit chute etc on the 804 makes a difference to the grind distribution and fines production compared to the 807? The 804 has no flaps at all, silicone or metal, and a larger flange area for grinds to exit the burrs and grinder body. I didn't read as many of these kinds of issues with the 804 LS, but I remember there were some that found grinding for espresso Was a challenge on the 804. I personally had no issues at all, and was able to get traditional 1:2 shots with 18g in a vst at roughly 3.5 grind setting with it being calibrated so I can hear faint burr touch when putting pressure on the dial at the finest setting (just below 1)

primacoffee wrote:We use a Bosch PS20-2A (I think it was discontinued and replaced with a new model). It has a max of 100 in.-lbs of torque and we use it at about 5/10 for burr screws, and around 4/10 for the T20 torx screws on the stationary carrier. Ultimately it doesn't matter all that much, as long as you don't go unreasonably light or super hard. The main thing is that it's consistent screw to screw.

So 50 inch-lb on burr screws and 40 inch-lb on the carrier screws? I want to make sure because that would be 6 Nm and 4.5 Nm which seems pretty high (I think a Nw is ~8.8 inch-lb.) Someone here/another coffee forum wrote that Mahlkonig recommends up to 4 Nm on its burrs and they are bigger.