Owner experience with HG one grinder - Page 62

Grinders are one of the keys to exceptional espresso. Discuss them here.
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TomC (original poster)
Team HB

#611: Post by TomC (original poster) »

HG one wrote:......... Mazzer's reasoning behind changing the finish was to simply improve speed.

This is why we chose to TiN coat our burrs. It wasn't to improve corrosion resistance or for the vanity factor. The TiN process for us, accomplishes a couple of things. It increases the surface lubricity or provides a lower coefficient of friction, which is good for hand grinding, and it improves the durability of the burrs.

Paul & Craig

Thank you Craig for sharing this. Can I ask you to clarify if Mazzer is claiming the speed issue is speed of production on their end solely? It seems slightly vague and open to misinterpretation.

And do you guys care to comment about the long term durability of the coated burrs, or reply to the claims that they may be more prone to long term damage, if the micro thin surface is as hard as a diamond (not literally) and the base metal of the burr is now softer, due to the high heat they experience during the coating process?
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Hugonl28

#612: Post by Hugonl28 »

Bravo! I'm learning so much here. Thanks Paul & Craig, your explanation seems very accurate and plausible.
In that case I'll skip the stock burrs, since I'm pretty happy with the very easy cranking.
I also haven't had any static whatsoever, even with 1 month old decaf beans requiring a very fine grind.
So, since there is apparently no degradation of taste in the cup, I'll be happy with rust free sharp burrs for the rest of my life.

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dsc

#613: Post by dsc »

JohnB. wrote:When I received my HG-One (71mm #3) the burrs were definitely not aligned properly. At pump machine settings the burrs contacted between the 4:00 & 6:00 position. According to Paul & Craig ALL of the grinders in that first batch needed to have shims placed between the gearbox case & mounting plate to properly center the inner burr. Supposedly mine had "slipped through the cracks" during preshipment prep as it had no shims. Properly aligning the burrs by shimming drastically improved the grind quality but it made no noticeable difference in grind time. Right out of the box grinding an 18g dose at a normal cranking speed took approximately 40 seconds until the burrs were clear. After the alignment that time was still in the 40 second range.

One other thing that will affect burr alignment is the amount of grease on the outer burr carrier/holder threads. If the threads are very lightly lubed you will see a far amount of outer burr movement when you loosen & retighten the locking knob. If the threads are well lubed to the point that the grease oozes out when the carrier is first installed you will have very little carrier movement.
This is exactly why I've said that the design doesn't allow for much X/Y alignment. Press fitting bearings into a plate / box section is all fine and dandy, but you need to make sure all dimensions are bang, otherwise you put load on the bearings and other elements, things don't align etc.

As far as grease goes, have you measured the amount of movement with / without grease or is this is this a purely visual check? you will indeed have less carrier movement with grease when stationary, but I'm sure it's not so great when running and grinding, with much higher forces acting on the burr mount.

Regards,
dsc.

pechelman

#614: Post by pechelman »

from an earlier post of mine almost 2 wks ago
HG one grinder - a precision hand grinder
pechelman wrote:....

I'm not sure I totally understand the phenomena here, but it seems like one large mechanism causing increased grinding revolutions for a set dose is the increase lubricity on the crushing faces of the burr. Rather than the uncoated steel faces grabbing onto these beans, perhaps now the propensity to slip and\or "pop corn" off these platens increases, which will require more turns to feed beans down into the cutting edges.
HG one wrote: First of all, the TiN coating provides a lower coefficient of friction for a surface.

The set of burrs that our grinder originally shipped with were Mazzer's Pre-Seasoned version. From what we've been able to discern, part of the process involves a micro-bead blast and edge prep. This surface treatment improved the surface lubricity of the burr. As a result, the torque requirements for turning the flywheel (100 lb inch peak / 50 lb inch avg), was much lower than with an untreated or raw metal burr set. Surface lubricity or the coefficient of friction is one of the determiners of grind speed. The more "grabby" a surface, the faster it grinds because it pulls the beans through the burrs at a faster rate.

Paul & Craig
so what do I win?! :lol:

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orphanespresso

#615: Post by orphanespresso »

HG one wrote:First of all, the TiN coating provides a lower coefficient of friction for a surface.

The set of burrs that our grinder originally shipped with were Mazzer's Pre-Seasoned version. From what we've been able to discern, part of the process involves a micro-bead blast and edge prep. This surface treatment improved the surface lubricity of the burr. As a result, the torque requirements for turning the flywheel (100 lb inch peak / 50 lb inch avg), was much lower than with an untreated or raw metal burr set. Surface lubricity or the coefficient of friction is one of the determiners of grind speed. The more "grabby" a surface, the faster it grinds because it pulls the beans through the burrs at a faster rate.

Paul & Craig
I am really trying to get a handle on the effect of TiN coating of burrs in general, and not on this particular grinder per se. We actually may find some benefit to this and want to use it on a grinder someday...so I continue to struggle through all of the contradictory statements and illogical results to try to find some clarity. Maybe I am just dense, but in the above statement, a more grabby surface makes a faster grind. In a previous post the "honing" process decreases the surface grabbiness but results in faster grinding??? It seems that everything one does not only results in faster but easier grinding. If this is the case we will definitely want to use the coating on our next grinder project since at some point it seems the beans just more or less grind themselves with little or no effort on the part of the user :) .

It all makes my head roar so at this point I am going to turn my brain off and assume all is well.

pechelman

#616: Post by pechelman » replying to orphanespresso »

I think it's just a matter of thinking about the different parts of the burr and what they're doing.

We've established, or at least plausibly theorized, that the crushing faces feed beans into the cutting edges. It's makes sense then that a lower coefficient of friction will result in more bean slipping and slower feeding and vice versa.

More down on the burr to the cutting edges , and the mechanism is one of "bean transport". With that image in mind, it becomes clear that a honed, smoothed, polished edge, one free of these inconsistent micro serrations, as they are generally called, is an edge which will cut more cleanly and allow the bean to be drawn down along their length, in the progressively narrower gap, more quickly and with less resistance.

If you've ever shaved with a straight razor directly off the hone, you will know its a slow and jerky and grabby process. (And potentially dangerous one)
Throw it on the strop, to remove the micro serrations left from even a 16000grit stone, and it just glides across the skin.

kwantfm

#617: Post by kwantfm »

pechelman wrote: If you've ever shaved with a straight razor directly off the hone, you will know its a slow and jerky and grabby process. (And potentially dangerous one)
Throw it on the strop, to remove the micro serrations left from even a 16000grit stone, and it just glides across the skin.
Nice
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TomC (original poster)
Team HB

#618: Post by TomC (original poster) »

orphanespresso wrote:I am really trying to get a handle on the effect of TiN coating of burrs in general, and not on this particular grinder per se. We actually may find some benefit to this and want to use it on a grinder someday...so I continue to struggle through all of the contradictory statements and illogical results to try to find some clarity. Maybe I am just dense, but in the above statement, a more grabby surface makes a faster grind. In a previous post the "honing" process decreases the surface grabbiness but results in faster grinding??? It seems that everything one does not only results in faster but easier grinding. If this is the case we will definitely want to use the coating on our next grinder project since at some point it seems the beans just more or less grind themselves with little or no effort on the part of the user :) .

It all makes my head roar so at this point I am going to turn my brain off and assume all is well.

I might be mistaken, but I think I'm reading it a bit differently, or seeing their conclusions to two separate data points, where you might be seeing it as one(?) which no doubt, leads to some confusion. I'll take a stab at explaining what I mean and hope for the best.

I think they've tried to explain how the cutting edge geometry at a microscopic level cuts more aggressively and faster when more of those microscopic (wwwwwwwww) "teeth" are aligned at the same height. This makes sense to me and, short of having a high powered microscope and a bunch of lab equipment, has to be taken at face value. No where that I can find (and I may be wrong) does HG claim that the TiN coating has anything to do with this specific phenomena at the cutting edge. To me, it wouldn't make any sense to argue that it does, since the coating is only micrometers thick and it shouldn't be capable of rounding over the tops of those microfine sharp edges, nor filling in the little valleys. Where that's happening, (if it is) is from the surface prep before coating.

They've also just said that the TiN coating provides a lower coefficient of friction for a surface. This lower coefficient of friction would create a negative user experience (inferred but not simply stated) because the beans would be more prone to slipping and sliding around before eventually working their way down to the cutting edge. The result would be a grinder that takes more revolutions to finish the job. This doesn't seem to be caused by changes to the burr cutting edge, but the slippery nature of the coating elsewhere on the feed paths of the burr. But the upside to that negative user experience of longer time cranking their arms, is less torque effort on each revolution.

If you can alter the quantity of beans meeting their demise at the cutting edge by a slim factor, you can also lower the torque required to do the work, it will just take longer.

From all I can gather from what they've claimed to find about the TiN coating process, seems to be focused more on the increased lubricity of the burrs now resulting in lower heat production in the final product, which too, makes sense if you're transferring less energy via friction creating heat to the grind. ( I think ultimately though, this is a huge grey area, that is poorly understood by likely all of us, since we don't fully understand what's happening very clearly, but are making educated :?: guesses).

But I don't think they're inferring that the TiN coating specifically alters the cutting edge geometry. Those wwwwwwwww's, if they are there before the coating process, are going to be there afterwards.

What I still cant wrap my head around is this notion that a relatively soft structured carbohydrate via partially cooked dried rice, is going to have any effect whatsoever on any surface as hard as TiN. I don't see how it can be hard or abrasive enough to alter that edge geometry, unless someone is inferring that it's slightly denser mass is transferring friction and pressure to the edges faster than coffee would, and effectively pushing the edges teeth into a more level alignment (akin to the stropping analogy), but I'm still skeptic. I did however, just use raw rice a month or two ago, to speed up the break in process on my large Ditting 1203's new machined burrs, to great and clearly noticeable effect. But that's not comparing apples to apples, I'm just mentioning it offhand.
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jedovaty

#619: Post by jedovaty »

orphanespresso wrote: a more grabby surface makes a faster grind. In a previous post the "honing" process decreases the surface grabbiness but results in faster grinding???
The first statement: it takes fewer turns, but more force/effort to turn the crank. The burrs grind the beans faster provided you exert enough power. Friction keeps the beans in place (think gecko on glass).

Second statement, it takes more turns, but you need less force/effort to turn the crank. You can spin the crank faster because it takes less effort, thus resulting in a faster grinding speed provided you do it long enough (think sharp knife through tomato).

espressotime

#620: Post by espressotime »

40 seconds is a lot.I hear all kind of grind times on different forums.But 40 seconds for 18 gram... :(
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