User experience - Niche Duo 83mm flat burr grinder - Page 15

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

I take "efficiency depends on grinder models" as healthy skepticism about how useful those tests are. It's hard to imagine any "dry" test of a grinder that is not rigid to be viable. Some grinder models fail simple tests of being coaxial and parallel where it matters without any load.

tompoland
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#142: Post by tompoland »

Thanks and also to @Jonk

Do you have a guide/video that you'd recommend for effective burr alignment?
A little obsessed.

malling
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#143: Post by malling replying to tompoland »


There no effective way unless you can machine them yourself, people grinded down their burr chamber taping the two burrs together and using the backside to grind it to better precision. Otherwise we are basically at shimming where people used different stuff for that.

But obviously you can't really machine or grind down a Niche Duo as it's plastic. You can really only shim it and hope for the best.

PPapa
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#144: Post by PPapa »

malling wrote: There no effective way unless you can machine them yourself, people grinded down their burr chamber taping the two burrs together and using the backside to grind it to better precision. Otherwise we are basically at shimming where people used different stuff for that.

But obviously you can't really machine or grind down a Niche Duo as it's plastic. You can really only shim it and hope for the best.
I guess deflection gauge is the only way to check for the alignment - but I'm not aware of any other one than the Titus. Not that I would suggest paying that much to align a Niche...

https://prima-coffee.com/equipment/titu ... nment-tool

malling
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#145: Post by malling replying to PPapa »

Fundamentally yes, but can find something similar on the net, I know others used that to check other grinders. yes the titus is perhaps a bit steep for just checking the lower burr on a Duo, you can like get them for 30-50€ on sites like Amazon.

Unfortunately there really no way to reliably check the upper burr carrier

DaveC
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#146: Post by DaveC »

malling wrote: There no effective way unless you can machine them yourself, people grinded down their burr chamber taping the two burrs together and using the backside to grind it to better precision. Otherwise we are basically at shimming where people used different stuff for that.

But obviously you can't really machine or grind down a Niche Duo as it's plastic. You can really only shim it and hope for the best.
It's not plastic? The burr carriers are Aluminium, as is the chamber. The lower burr has a bean feed impeller that is polymer (which plays no part in alignment). The upper burr has a pressure plate which is also polymer (and very accurate). You are talking about the chamber though, so it's unclear what you mean by taping burrs together and using the backside? This method can't work.

In general for any grinder

If the lower carrier is out on any grinders, or the burr in the carrier is misaligned, how does taping them together and grinding the "backside" increase precision. All you would do if you ground the top burr carrier backside is move the error to the top carrier as well and the rotating bottom burr would still be misaligned? Alternatively grinding the back of the lower carrier would have no impact at all

If it's the upper burr that is misaligned...you can't grind the "back" of the lower burr carrier, it won't change anything. if you grind the back of the top carrier for a burr misaligned within the carrier, that transfers the alignment to the carrier top, causing off centre pressure as the carrier is pushed down by whatever mechanism is used. This off centre pressure would then misalign burrs again

The other problems is even if you can grind down the top carrier ...how would you do that if the amount it's out is 20-30 Micron. You would have to use specialist equipment or you are quite likely to make it worse.

Have you actually done any of this yourself, or measured the accuracy and success of this...or is it something you have read on a forum? From an engineering perspective this simply isn't right, as I am sure any engineer would tell you.

malling
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#147: Post by malling »

DaveC wrote:It's not plastic? The burr carriers are Aluminium, as is the chamber. The lower burr has a bean feed impeller that is polymer (which plays no part in alignment). The upper burr has a pressure plate which is also polymer (and very accurate). You are talking about the chamber though, so it's unclear what you mean by taping burrs together and using the backside? This method can't work.
The burr chamber isn't purely aluminium it's also polymer at the bottom.

Also the taping the burrs together was in no way related to this grinder, it was only mentioning of what people have done in the past on other grinders that doesn't have a lower spinning burr carrier, I also didn't say whether it was a good idea or not just what people have done to "improve" alignment.
In general for any grinder

If the lower carrier is out on any grinders, or the burr in the carrier is misaligned, how does taping them together and grinding the "backside" increase precision. All you would do if you ground the top burr carrier backside is move the error to the top carrier as well and the rotating bottom burr would still be misaligned? Alternatively grinding the back of the lower carrier would have no impact at all

If it's the upper burr that is misaligned...you can't grind the "back" of the lower burr carrier, it won't change anything. if you grind the back of the top carrier for a burr misaligned within the carrier, that transfers the alignment to the carrier top, causing off centre pressure as the carrier is pushed down by whatever mechanism is used. This off centre pressure would then misalign burrs again
As I wrote above it wasn't related to this grinder, just what people have done on other grinders. It obviously would not be possible to do on a grinder with two burr carrier only on grinders where the burr is directly mounted on the chamber. Again I never stated it was actually a good idea, just passing on what people have done in terms of alignment.

Which was a direct reply to what people do to align grinders.

The other problems is even if you can grind down the top carrier ...how would you do that if the amount it's out is 20-30 Micron. You would have to use specialist equipment or you are quite likely to make it worse.
Which was kinda my point. That you fundamentally need the specialised equipment to align the Niche and frankly most other grinders. Shimming is at best half baked solution, it's not exactly a marvellous or precise practise, why people started to grind their burr chamber by taping the burrs together, I'm not really advocating the method just mentioning what people done in the past to try "improve" alignment across the field. Some of those are clearly not invented by engineers or machinists but are home cooked solutions trying to solve an issue with whatever people have at hand. As you say yourself people don't have access to the gear so they will try fix an issue as good as can be done, whether it actually fixes it is an entirely besides the point. Because you can't really fix it unless you have the equipment to do so.


Have you actually done any of this yourself, or measured the accuracy and success of this...or is it something you have read on a forum? From an engineering perspective this simply isn't right, as I am sure any engineer would tell you.
I measured it myself but I can guarantee I never grounded the burr chamber, I never found it to actually be a good idea, I only measure I don't even bother trying to align them because without the equipment to do so your not really fixing anything, but it might make you feel better.

PPapa
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#148: Post by PPapa »

DaveC wrote:The upper burr has a pressure plate which is also polymer (and very accurate).
What is this statement based on, and are you able to provide data to back it is accurate?

Imaginex20
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#149: Post by Imaginex20 »

My grinder had issues with burr alignment. When I reached out to Niche I was told a marker test was not accurate way of testing alignment. Before I shimmed I was getting a lot of channeling, after it worked as I expected it to. Niche customer service was less than stellar.

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Jeff
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#150: Post by Jeff »

They were factually correct. The marker test is easy without precision tools, but not "accurate", especially when burr load while grinding is considered. It is complicated by some grinders, such as DF64, going out of alignment when the adjustment collar is turned. Not all exhibit that, but if you "drew the short straw", you can have nearly perfect wipe at chirp but be so far off a fraction of a turn away that you can't pull shots. The marker test is, however, sometimes better than nothing.
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