Not What You Think: Variable RPM and Grinder Behavior
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- เผยแพร่เมื่อ 16 ก.ย. 2024
- I hope you enjoyed it!
*Quick correction. The Base burrs actually INCREASED in extraction when redialing.
also, unless stated explicitly, none of this is proven and is purely conjectural at this point based on limited data and experience. This is more to provoke conversation and challenge assumptions.
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TIME CUES
@xllvr
4:57 Coffee of the Stream
Rant Agenda
0:48 Problem Statement of Variable Stream
2:09 What is Variable RPM
2:45 RPM and Fines
++ 3:24 Cone Burrs
4:19 RPM and Heat
Rant Proper
5:18 What is Variable RPM doing? (Peak Particle Size Distribution)
9:08 The Curious Case of Base-min Burrs-ton
++ 10:34 Base Burrs and Cone Burrs
12:04 The (Unnecessary) Quest for Less Fines
14:15 Observation of Faster RPM Faster Extraction...
++ 14:44 Is this real life? Is it just fantasy?
++ 17:14 There May Be Augers
20:50 All Augers are equal but some Augers are more equal than others (Auger Efficiency)
Q&A
27:16 Hand Grinder RPM (Mashing vs Cutting)
++ 41:43 Critical Minimum RPM for Hand Grinding
29:31 Variable Auger Speed
29:58 On the Current Era of Coffee
32:16 Grind Rate at Burr slower than Auger Feed Rate
33:30 DF83 Thoughts
34:32 P100 and Slow Feeding
36:57 Variable RPM Heptagonal Burrs
37:24 Visual Demo of Augers
42:51 Auger Upgrades
43:56 Speed of Slow Feeding
44:19 Efficient Auger Definition
44:48 Does an efficient auger reduce heating
46:02 Grinder with auger and low RPM causing faster shots
47:04 Anyone other Xerno with good burrs
47:33 Auger Prebreak with Blade or Just Torque
48:31 Robust auger and conical grinding
48:52 80mm Xerno
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A little late watching this one. Great info as always. The more testing I've been doing the more convinced I am that the best combo, if clarity is the end goal, is to have a low rpm auger with a pre breaker slow feed burrs spinning at a high rpm. But then again this is one person's palate testing high clarity burrs. There are so many permutations and combinations...
4:57 Coffee of the Stream
*Rant Agenda*
0:48 Problem Statement of Variable Stream
2:09 What is Variable RPM
2:45 RPM and Fines
++ 3:24 Cone Burrs
4:19 RPM and Heat
*Rant Proper*
5:18 What is Variable RPM doing? (Peak Particle Size Distribution)
9:08 The Curious Case of Base-min Burrs-ton
++ 10:34 Base Burrs and Cone Burrs
12:04 The (Unnecessary) Quest for Less Fines
14:15 Observation of Faster RPM Faster Extraction...
++ 14:44 Is this real life? Is it just fantasy?
++ 17:14 There May Be Augers
20:50 All Augers are equal but some Augers are more equal than others (Auger Efficiency)
*Q&A*
27:16 Hand Grinder RPM (Mashing vs Cutting)
++ 41:43 Critical Minimum RPM for Hand Grinding
29:31 Variable Auger Speed
29:58 On the Current Era of Coffee
32:16 Grind Rate at Burr slower than Auger Feed Rate
33:30 DF83 Thoughts
34:32 P100 and Slow Feeding
36:57 Variable RPM Heptagonal Burrs
37:24 Visual Demo of Augers
42:51 Auger Upgrades
43:56 Speed of Slow Feeding
44:19 Efficient Auger Definition
44:48 Does an efficient auger reduce heating
46:02 Grinder with auger and low RPM causing faster shots
47:04 Anyone other Xerno with good burrs
47:33 Auger Prebreak with Blade or Just Torque
48:31 Robust auger and conical grinding
48:52 80mm Xerno
Zerno is with a Z but we figured out what you mean, thanks for the summary :)
Thank you so much! What does ++ indicate?
had my zerno since Nov ‘23 and have been loving it! So glad i got it when I did
thank you so much for sharing and all the hard work you’re doing, loved the visual comparison of augurs, excited to experiment with horizontal hand grinding!
Kaffeemacher measured the PSD of the Timemore 078s at 800 and 1400 RPM (grinding for espresso). The lower RPM had less fines (1.4%) and a wider coarse peak.
Oh nice! OK this is good info. Interestingly, I have someone in patreon who tested with espresso and higher rpm went almost twice as fast as 800 at same burr gap. Hmmm
I'll ask km for data
I love the search for truth. Coffee is such an interesting and complex organic product.
It's the exception to the rule and a weird thing that the Weber EG1 increases shot time with lower RPM (and decreases with higher RPM). People have noticed the same thing with Timemore078s but that might be due to pre-breaker or auger complicating things somehow.
We know you can get the same extraction percentages and very different tastes from experiments done with different temperature brew water.
Regarding fines:
I did find the DF83 before seasoning and declumper mod produced a lot of fines but still made a very nice coffee (just more blended 'conical-like' higher body shots) and still made tasty brew coffee too (just more likely to stall/clog up your filter). I didn't find the fines affected extraction in a very negative way like causing bitterness/over extraction, it was usually very pleasant and smooth still. The same thing with the Weber HG2 or Key, it had more of a micro-fines that didn't seem to affect anything but in that case it did sometimes contribute to a silky body.
I doubt burr heat levels would affect anything outside of like commercial grinding.
I don't think anyone's calculated the grind rate to align with an Auger / pre breaker. If your auger is variable RPM and synched with the Burrs RPM, then RPM should still affect your grind quality potentially.
Hey Lance, thank you so much for the effort and sharing ❤ maybe one thing worth to look into: prebreaking with a handgrinder. I do this with my DF83 and a cheap Hario Mini Mill and it works perfectly. I do not have the opportunity to compare it to other grinders but I get excellent results. Maybe this could be also something to consider for future comparisons. Cheers
My df83v is arriving tomorrow so I appreciate this video and will have to be very mindful of slow feeding times and making sure I’m consistent so I don’t get frustrated.
My interpretation of what he’s said is that, yes, there IS a difference in shot time between slow feed and dump feed of a direct feed grinder, based on shifting the grind distribution peak. I’ve noticed that shot time halves on my P64 with slow feeding. BUT does slow feeding actually make coffee better or the grind result “better”. It’s different, but it’s not clear it’s better.
@@jmvdigital My df83v arrived yesterday and I’m noticing a difference in grind size if I slow feed vs rapidly feed. I need to be consistent to eliminate a variable changing. Trying to decide if counting to 5 during dumping or just rapidly dumping is more consistent. Then I can experiment later.
@@erikasolditFor sure it’s a huge variable. I’m leaning toward not bothering with a slow feed on my P64. There’s simply no way to make it consistent. And again, there’s no proof (yet anyway) that the result is actually better.
For the record, i tested slow feeding on my 078s at the same grind size and it was a HUUUUGGEEEE difference in extraction time. Almost like I took the grind size knob and rotated it literally by 1 full step. Also i noticed it being very unpredictable and hard to dial in unless you slow feed like a monk.
Same here at the 078s! If you go *very* slow (some beans (5-ish) at a time until chamber grinds empty) it becomes consistent again. Taste becomes richer. But a single shot now takes forever to prepare😅 PS: I shake an rotate the grind result in the dosing cup for a few sek (5). Maybe this helps consistency as well
I experimented with 078s and flair 58 with fast vs slow feed and found 3.5 difference on the dial to get same pressure on slow vs fast. Massive. I did super slow, like one bean per second and found I had to grind almost at burr touch to get enough pressure to pull a normal shot. It stressed the machine and took forever so I decided that fast is best as far as workflow and taste. Slow feed shots were not crushing the fast so I’m going with fast! Many other users thought slow feed better for filter. Anyway, that’s where I’m at, but looks like I need a zerno now lol. And that golden lever machine
My z1 sweating buckets hearing Lance talk about an 80mm cousin
Titus EK carrier auger has twice the turn/groove count vs the stock EK carrier so it takes twice the turns to lead into the burrs and take up more of the available room in the auger as well, should be slower. It might also have a tighter fit against the bottom of the auger channel, the top part of the channel is bigger and have room for some beans to move without getting crushed. Could make some difference especially with bigger doses/bags.
Great video! You convinced me to get the Zerno.
What about different bean sizes? A large bean from Chiapas might get broken up in a non-aggressive auger, while an Ethiopian peaberry might not get broken up much at all in the Zerno.
Two possibilities: 1) we should change auger designs to match the bean size to ensure that it gets broken up, or 2) the break up isn’t as important as the size of the coffee that enters the burrs. Maybe the burrs are happy with peaberries that aren’t broken up, because the burr cares about size, not crushing.
today i learned i've been wasting my time slow feeding my zerno!
Why wasting time?
@@CDdogg30323:36 Slow-feeding the Zerno, unlike almost every other grinder even with augers, actually has minimal to no effect on shot time. Simply because the auger is tightly fit to the chamber, meaning that it not only pre-breaks the beans, but also essentially acts as a slow-feeder in itself. Pretty awesome stuff.
I have a DF64V with SSP MP and a slow feeder disc (looks like a pizza with two slices missing) installed on the bottom burr carrier. The beans fall on the slow feeder disc first and while it spins together with the burrs, it let's a couple of beans fall through the gap with every rotation. I use the grinder only at 600RPM, which is the minimum, with light roasted beans and only for filter.
I noticed that when I slowly feed the beans to the grinder, I get a much better cup than when I put the beans in all at once - hot start on both situations. With slow feed the coffee flavours are more nuanced and the cup is fantastic, while without, the brew is still tasy, but boring and common.
Now I wish the DF64V could go to down to 300RPM and even lower...
I also used the SSP MP on a Fellow Ode Gen 2 and didn't like the coffee it made at all, perhaps because it was too fast...
In the past I had a Wilfa Uniform which is a very slow grinder (I don't know it's RPMs). I had amazing cups from it, real sweetnes in the cup and delicious flavours. I was using it without hot start and all the beans in the hopper.
That's why I decided to swap the Fellow Ode with the DF64V, for that low RPM, and I'm so happy for having done that.
so u have the slowfeeding disc and still slow feed ur beans manually with ur hand?
17:27 .... man i LAUGHED !! 🤣
Please let us know about the efficiency of the prebreaker on the Gevi Grindmaster
On mine Sculptor 078 (turbo burrs) I noticed that when brewing V60 (same dose, coffee, grind setting ...) on 800 RPM it consistently brewed about 8-10 seconds faster than on 1400 RPM, and it was little bit less messy when grinding on the lowest RPM. For now I use 800 RPM
Same conclusion with my 078! Do you also slow feed ?
@@a.enguerrand5120 no, I just drop whole dose, I just do little bit of RDT before
I came to a similar conclusion, I dropped rpm to the lowest setting on the 078 and found faster draw downs.
Everyone get your zerno before demand skyrockets! It’s hard to produce the level of low tolerance at scale. It is unlikely any large company will do it without a massive price.
My experience on p100 for varying rpm
Observations trickle feeding the beans. At the slowest rpm, my shots run faster. At the fastest rpm, with same gap and trickle speed, the shots run way slower. Typically I try to feed at a rate that doesn't allow grinds to keep coming out once I am done feeding to reduce chance of regrinding. This results in my feeding a different rates for different speeds and beans. I time the feed.
My experience with trickle vs dumping. Trickle feeding has always given me faster shots. Dumping all in at once gives slower shots. What's interesting is when you dump them in for the slow vs fast rpm. Dumping at slow rpm yields shot times closer to dumping at high rpm. The fast rpm still yields a slower shot, but the difference in time is less drastic. Just some interesting finds compared to yours. No idea what distribution looks like or extraction yield.
I know Lance doesn't prefer the p100, but we seemed to use it differently with feed rates and avoiding regrinding. Thoughts?
Is there any follow up video on this? This was very interesting. So much is still unknown as to what differences in RPM does.
Also sprometheus did a test on auger in the df83v where it showed on highest RPM. Most like 80% of the beans where crushed by the pre-breaker
Thank you Lance.
Slow feeding this back....
There are two possible alternative objectives of variable RPM:
1. Consistency, i.e. regardless of RPM or feed rate, you get the same brew, OR
2. Adjustability, i.e. you change the RPM or feed rate, you get a different brew.
In order to achieve either of those you need a particular auger and burr set.
In favour of consistency: you can load the beans however you want and get the same result.
In favour of adjustability: you can produce a different extraction by changing RPM and feed rate, e.g. with a single burr set, you can get clarity in pour over and body in espresso.
Now, I think Lance has a personal preference for consistency AND clarity, so it makes sense that he likes an effective auger, but that's not the right choice for everyone. I prefer lots of body in my espresso and don't mind sacrificing clarity, so for me, variable RPM without an auger gives me the most flexibility. Without an auger I can choose an RPM and feed speed that causes the beans to back up in the burrs and produce more fines for that classic conical texture profile, or slow feed and get less fines for more clarity.
That's my interpretation of what's being presented, and I think it's important for Lance to be clear about what his preferences are before recommending a particular approach. Personally, I see no value in variable RPM unless I can use it to produce a different effect in the cup.
From what I have learned woth feeding rates and rpm on my p100, I agree with you on freedom to adjust based on what you want in the cup. It's like a lever machine, not consistent necessarily but adjustable.
I always use the highest rpm on my grinder because it gives more clarity.
I made my Jolly Variable speed.. It’s a luxury add on IMO. To me the main benefit is I can crank the RPM briefly and bop the bellows to reduce retention. The flat burrs seem to have behave with slower grinding giving faster shots ( I guess the peak is narrower?) and at higher it is wider..? Seems to pull slower with fast grinding. I totally notice the grinds are warmer if I grind fast.. but weather that means anything I don’t know 😅
There is a dynamic element of grinder rigidity and the centrifugal forces at play for sure, which will vary between grinder models. That all said, I have no intentions to go back to single speed :)
So maybe fast RPM equals slow feeding, when there are no tightly fitted auger? If beans are cut faster (assume for a while - in the same way no matter the RPM) it is like feeding slower. Because beans need some time to go to grinding chamber, but exit sooner. With low RPM beans are squeezing at the entrance to the grinding chamber and between the burrs. But Auger (no matter if it breaks the beans) act as a traffic organizer, because it rotates with the same RPM as burrs. Tight auger would cancel the effects of RPM, because faster RPM makes faster feed via the auger solidly connected to one of the burrs.
Then slow feed would also be possible, but by slowly feeding from the outside, so beans wouldn't be one next to each other through the grinding "pipeline". Auger helical screw couldn't squeeze beans fed slowly from the outside. Auger rotating faster wouldn't have the stuff to push to the grinding chamber.
What is meant here by "efficient" auger is just a capability to steer the input flow rate, no breaking, only speeding up with very fast RPM and slowing down with low RPM
slow feeding hand grinder tek has been my go to now
The bean feeder on my Weber key made a huge difference too when it's restricted to slow feed beans for me
Undeniable difference, but is it better?
@@jmvdigital it allows grinding light roasts at lower rpms which increases clarity if you're looking for that
Late question on the EG-1 you love so much! EG-1 has no auger. Would adding an auger help some of the burr options? Maybe not the core burrs, as you said you found no difference when slowing adding beans, so maybe the Lab Sweet burrs?
what about the slowfeeding disc on the df64v?
So slow feeding a grinder that doesn't have a auger/prebreaker can provide brews just as good as ones with a robust auger prebreaker? Or is the FOMO real?
Yes
Again, it’s different, but he didn’t say it’s better. The shot times are different, suggesting a difference in grind size distribution or peak size. But does that make the coffee BETTER after optimizing each situation.
Now I have even MORE FOBO for buying an electric grinder 🥹🫠 thank you for sharing your insights at length, makes your regular channel videos feel too short almost 🥰
Will be very interesting so hear the results of the testing. I like what you are doing with trying to check the speculations many are doing. It is a slow process and we should expect lots of missed details and new open questions. But that's all part of the process.
You mention that you slowfed in 5 seconds total. So not bean by bean. Any early thoughts on if that is slow enough for all of us without good augers? Or would we benefit from doing it slightly slower? Perhaps it should roughly match the rate the grinder grinds the beans, so the grinding surfaces are kept undisturbed?
I am in Madagascar and just want a good espresso grinder that does light roasted arabica from Madagascar. I am blessed and want a grinder to match it.
Wonderful video again! Do we know (can calculate) the optimal feed rate per burr diameter multiplied by RPM? Only then we would know wether an auger is feeding too fast or too slow. Idea: record the audio of a single bean being ground (for 1g or more), remove the pauses from the audio and you have the optimum feed rate. Values should differ depending on the burr diameter and RPM.
This video got me think to use a cheap $ 20 electric battery grinder to act as prebreaker/slow feed system into my augerless eletric grinder such as DF64... I'm pretty lance or some other already thought of this... ^^
I thought I noticed a big difference on the Zerno Z1 with SSP MP burrs and the medium speed auger (v.2.0) but probably tested doing a regular (not super slow) slower feed, vs dumping coffee in and then starting the grinder. I noticed a big difference in taste too. I think augers are over rated.
Everything should be as simple as possible without being too simple (Einstein). There are a huge number of variables in grinding coffee beans, not to mention the beans themselves and how they are processed. Variable speed is a red herring, not coffee science. No engineer would try to design a reliable repeatable grinder with a variable motor speed. It’s a marketing gimmick.
A thought popped out in my head when you mentioned that the auger chamber was quite large in the Malkhonig 43:23 , couldn’t one machine a tube/cylinder to make the chamber tighter and to slow down the feed rate?
Just a random thought from a person with no engineering knowledge at all 🤷♂️😅
Thanks Lance, this is very interesting.
Thinking about cutting v crushing, will pre-breaking/crushing produce different ratios of particle sizes ?
Augers look as if they will crush more than cut, burrs will possibly cut more than crush.
If the burrs are “overwhelmed” by the feed rate will that reduce the ability to cut efficiently and increase crushing ?
Great video. I’ll be slowing my Kafatek MC6 down quite a bit to test grind size. The faster RPM produced about 20 percent boulders (over 500 micron per Kruve sifter) this morning.
Are there any large flat grinders with an effective auger like in the zerno right now?
Looking for guidance on this: I upgraded my BDB basket to a Pullman 17-19g 876 basket (I use 19g at a 2:1 ratio) I adjusted niche zero grind size finer to achieve same 25-30 9 bar shot with the new basket.
I then decided to try paper filter on bottom of basket like Lance has shown in video.
When I do this it appears to have more clarity.
But when I add filter the shot time speeds up substantially.
Do I have to adjust even finer when using paper bottom filter with Pullman to maintain same shot times? (25-30)
Or is it fine to pull a faster shot?(20-25)
So the Timemore Sculptor isn’t very efficient with it’s auger…?
It look somehow tight.
I guess I should test it .
Is it possible that the burr geometry of the sanremo xone burrs is just very unique? So that it (by itself) does not change the location of the particle size distribution with different speed.
What leads me to this:
You said that (a few) flat burrs do not affect the shape of the particle distribution when changing the speed, but only their relative position. Then on some grinders you would need to go finer with increased speed. And then you say there is the weber base burr which does the exact opposite.
So when i hear there are two burrs which do the exact opposite, then my conclusion is there can also be a burr then sits right in a sweet spot where threre is no change at all with the speed.
That could mean that the auger could have less of an impact than expected. Maybe to rule that out the burrs from the x one could be tested with different speeds in a grinder without an auger? 🤔
with the EG1, how slow do you feed the beans? And what RPM do you use for espresso?
3:40 that's because you're inhaling all them fines 😊
Are the unfiltered discussions no longer posted to the unfiltered Podcast Channel? It seems there the last content is from 14. January
What if we prebreak the beans, maybe with a hand grinder and then slow feed?
I had also some interesting results whit my cast burrs on the df64v. They are different in comparison whit stock burrs or mp burrs. At lower rpm the extraction takes longer. I suspect it's due to the small cut area. With more rpm than 1200, the cutting surface can no longer keep up with grinding and the shots are thinner. My best results are whit 800rpm.
Someone else reported this!
Interesting, I have a p64 and I am curious about the effect in direct fed non auger non pre breaker solution would the rpm setting even matter much?. Zerno seems to be peak 64mm. Wondering if a prebreaker on say a 98-102mm burr would make as big a difference as on 64mm or 80-83mm?
DF83V with SSP Lab Sweet tested with DiFluid Omni Particle results more fines in 300 rpm compared to 1600rpm
I'm not sure I trust that tool especially at espresso settings. Was this espresso or filter? Gagne was telling me it isn't very helpful at fine settings.
Do you have access to the Flat MAX2, which specifically has a pre-breaker. Looking inside the top, it looks like the feed into the pre-breaker is controlled, but I can’t tell. I’m just not sure how to leverage the 5-400rpm capability or if it matters at all. If it doesn’t matter, then what speed would be best to leave it at? So I’ll be interested in your upcoming analyses.
lanceeee, how do you dial in with the new shake method if you say it’s ok for it to run faster? I typically dial in by looking for a 2:1 ratio in 25-30 seconds, you’re saying not to grind finer if it runs faster, is it just dialing in purely by taste??
@lance did you try a zerno without burrs to evaluate the prebreaking?
so, for hand grinders the faster you grind the better? because the blades are actually cutting, right?
heating of the burr wouldn't be a concern?
How are zerno gonna be working on an 80mm model when they cant keep up with the demand for the z1 XD crazy
Wow, I thought the 80mm Zerno was a rumor/wishful thinking. I can't find anything about it on the official website. I was planning on purchasing a high end grinder this year but I guess I'll just wait for now. Speaking of which.
What about the Kafatek Flat Max2? It has a "conical pancake prebreaker" that both pre-breaks and slow feed. It seems to be a unique design (or at least advertised as so on the website). Are you familiar with it? Is it any good? Is it as effective as auger prebreaker like the Zerno?
Can you address auger vs prebreaker in max2? Thanks
Does the timemore 064s or the ode gen 2 have a pre braking auger?
I don't think it's about efficient augers but about bottlenecks. If the burrs get rid of the ground coffee at a higher rate than the auger feeds the burrs, then there's no change in particle size or distribution no matter the RPMs.
One would think if this is the case then the df83 with bigger burrs should do this no problem. But zerno is 64 and was able to
@@LanceHedrickUnfiltered I think the answer to all of this is related to how do we look at the grinding process. As a steady state process or as a transient process. Maybe grinding a big amount (say 30 g) and getting rid of the first grams until just the amount for the shot remains would show us something interesting. If there's a bottleneck then the results will be different. I would refer to grinder typologies as bottlenecked feeded ones or bottleneck free ones 😆
Hi Lance , when you compared slow feeding the DF to the Zerno, I’m curious as to what burrs were in each as that could be another variable as well. I’m wondering if the effect of slow feeding would be less pronounced on very unimodal burrs like the SSP MP and more pronounced on traditional burrs since the fine’s production is more.
Mp in both
Hey Lance, I agree with the comment above that burrs may be making a big difference here. I have a Zerno with CV2s and notice a massive difference when I slow feed versus dump all at once. It could easily go from a 25s shot to completely choking my machine just based on feed rate alone. I was actually having a hard time dialing in my shot when slow feeding because I noticed that my shot time was really sensitive to my feed rate and could never achieve a consistent outcome. I have now resorted to dumping all at once for consistency's sake. Not sure if it also may be related to the auger differences (I believe you have the V1 auger where as all V2s ship with the medium speed auger). There are several of us on the Zerno discord who have had the same experience as well. Just thought I'd provide some extra data points in hopes of helping us all better understand whats going on. Loving the experimentation-focused videos btw! @@LanceHedrickUnfiltered
@@TheEdwinaderI think bean size may play its part here, smaller beans may pass through auger quicker without pre-breaking?
FYI, the link to your main channel in the about section of this channel is broken.
Versa lab best of both?
Very timely matter since I got my df64v yesterday
gearboxing the auger shaft to decouple the rpm of the auger to rpm of the burrs is the next level of grinder development nerdery i think
Separate feeding speed from prebreaker speed and main burr speed 😂
Thank you? I'll try to be a cool cat