Versalab M3 Grinder thoughts - Page 3

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TrlstanC

#21: Post by TrlstanC »

The one thing that's probably kept me from pulling the trigger and buying an M3 grinder at some point over the years is the hybrid burrs. I think a lot of people on here eventually figure out that they prefer either flat burrs or conical burrs. Either because of the kinds of coffees they like to drink, or whatever quirks of their workflow or because different burrs just taste different. I'll probably only ever buy a conical grinder, unless some flat grinder comes out that just blows everyone away, and I suspect that there's a decent percentage of people on here with similar preferences.

A hybrid burr set might seem like the "best of both worlds", but in practice it seems like it likely just grinds like a flat burr grinder with a fancy auger (which makes sense), so it's probably not the grinder for me. If there was an option to choose a conical burr set, that's something that would definitely be interesting.

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#22: Post by versalab (original poster) »

thirdshifter wrote:Whoah so I coulda gotten a white one? I've never seen pictures of ones in other colors. Can you give an idea of the cost if a customer does want (say) a white or red one?

Edit to add: a red Versalab would look so boss
At present it adds $350 to the price.

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samuellaw178
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#23: Post by samuellaw178 »

Here's a wish/improvement list on my mind after using a second-hand Versalab made/ordered in ca 2013 for about 2 months (in early 2017).

(i) I would love not to have the grinder running when pouring in beans (just load, then turn on the motor). The rate of pouring beans in seems to affect the grind consistency/fineness (pour in slower = faster flow).
(iii) I would love the Versalab grinder to be able to handle the lightest roasts I would encounter (motor seems to have just enough headspace - it can stall even with a tooth-belt when an unusually light roast was involved)
(iv) I would love to not have to change the flat belt every year or so (significant maintenance cost for non-US customers), and not have to maintain the belt by using acetone (harmful solvent) etc. No other grinders seem to require that level of maintenance.
(v) I would love to see a grinder with less run-out (<= 0.05 mm). I saw a significant runout on the burrs (on the magnitude of 0.1 mm and slightly more). Alignment can affect particle size distribution greatly which in turns affect result in the cup. https://www.instagram.com/p/BVpA-vMj8YF/ Mazzer aims to have 0.02mm (can't vouch whether they achieved it or not) http://sprudge.com/mazzer-factory-tour-44860.html

Why did I not contact Versalab? From everything I can gather, it seems to be within spec and was working within Versalab's expectation (but not up to my admittedly fussy expectation which I had expected of a premium grinder). I felt like I was required to work for the grinder (making compromises), instead of the grinder working to my requirement.

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AssafL

#24: Post by AssafL »

versalab wrote:I have no idea why you ran into the trouble you had after changing the burrs. Odd.
Ok - Coffee was gushing and it was impossible to grind fine enough to clog the espresso machine. So to try to understand what was going on I measured runout with the lever indicator today (with the encouragement of Terranova).

I measured two planes: 1. The cutting face of the burr (I think it is called end-face measurement). 2. The reading at the circumference of the burr. I used a Bestest (TESA, Brown & Sharpe) 0.01 lever, that isn't calibrated - so the readings are not really FIM or TIR as the dial reading was never calibrated to the lever displacement.

I got about +- 0.05mm full reading. However, the circumference reading was almost +- 0.1mm.

Opening the bottom burr carrier screw and shifting the burr carrier a bit (so as to get a maximum of +-0.05mm on the circumference) resolved the issue and it is now indeed possible to get fine grind. Will need some more work if one wants to reduce the numbers even more.

My observation as to why this trouble?
Since the bottom burr carrier is not centered on the spindle (not pins, not any sort of centering mechanism). It is possible to lock it in place with a bit of radial outrun.

Now this is a 2011 model - Perhaps this was improved in later production runs.
Scraping away (slowly) at the tyranny of biases and dogma.

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#25: Post by versalab (original poster) »

Is this a recent thing? You are telling me that a TIR of .004" (.1mm) will cause the grinder to not grind fine enough. Does not make sense to me.

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AssafL

#26: Post by AssafL »

Well, it isn't new. Any time I changed burrs in the past It was a pain to get it back into alignment. I used to mess with a feeler gauge but this time around I couldn't make it work.

So what is new is the lever indicator (which Is something I do not really know how to use properly - but am learning):
1. As I stated - It isn't calibrated (meaning I don't know if the probe is the correct length for the indicator, since a lever actually measures an arc; if the lever is too short it will over read. If it is too long - under read).

2. I know I did not affix it to be parallel to the circumference. Meaning I get a cosine error. If it was at a 45 degree angle (not unlikely) would mean the result would have to be multiplied by 1.4 or so.

Which means the TIR figure is probably off and I don't know by how much. But what I was aiming for to see if I could reduce it. So keeping the lever in the same position, lessening the bottom carrier and pushing it sideways to minimize the error (not eliminate - cut it by half) - now means the grinder can grind fine.

Prior, even if the burrs rubbed the grind wasn't fine enough.

One of these days I'll try to measure runout more accurately and see if I can minimize it more.

BTW - you ask why people have issues and don't call. When I first replaced burrs the VL stopped grinding well. At the time I did not have a refractometer and did not understand alignment and wasn't even able to put into words what happened. I knew new burrs didn't work and neither did the old ones. The move you posted on YouTube was pretty clear so I assumed this was the way it was. Only when NickW and Terranova started talking alignment did I realize it may be orientation and playing around with the burr carrier was able to be back in business.

I did not even have the proper question to ask of Laura so instead ended up being irritated with the VL. At that time, (early 2015 or so) I was ready to swap to a Kafatek (if it had existed back then).

I now know more and will do what it takes to get the grinder back in alignment. Even if it takes me a week or more.

I don't know why a small TIR means gushers. I can propose hypothesis - anything from number of boulders to radial TIR causing axial runout to be multiplied (Pythagoras). I really don't know. What I do know is that there is substantial play closing the bottom screw which destroys the output of the grinder if done incorrectly.

My recommendation to owners is to never open the screw. But if anyone did and they have a similar grinder and "problem" - they would need to think about this.

Circumference measurements:



Face measurements:



NB (edit) - I am not alone in this experience. I may be alone in trying to resolve it myself.

Here is the original thread I started on alignment: Aligning the Versalab burrs

Here is another:
My Versalab was getting worse but now it has been fixed
The owner resolved his issue - but quite a few had issues and ended up replacing the VL.

Another thread: Versalab M3 vs. Others
Rush was unable to align his VL on that thread.

Obviously there are many others...
Scraping away (slowly) at the tyranny of biases and dogma.

pizzaman383
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#27: Post by pizzaman383 »

From pictures it appears that the edges of the flat face of the burrs is fairly narrow. Any face misalignment would allow bigger pieces to go through the larger gap. Any circumferencal misalignment would bring the cuts in the burr closer to the edge. With some of both types of misalignment there would be an even bigger channel during the time in each rotation where the two spots align that would allow even bigger pieces through. Also, the minimum gap between the burrs even when touching is the size of that bigger channel.
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#28: Post by versalab (original poster) »

Several thoughts about this.

I would expect it to need a large amount of misalignment to cause the exposure of the flute of the burr enough to change the grind. Unless...we have encountered flat burrs with an excessively large exit channel. The manufacturer did not grind the working surface of the burrs far enough. In some cases espresso could not be made with the burrs almost touching. If anyone can show a picture of the burrs that are having this critical alignment it would be useful.

I am amazed at the need to realign the grinder after changing the burrs, or even to realign at all. The bottom burr driver (as we call it) does have clearance on the shaft but to position it centered shouldn't be that hard even by eye, or using a fingernail to feel where overlap is. But to need to take the top plate off is crazy. I don't get it.

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Terranova
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#29: Post by Terranova »

versalab wrote: If anyone can show a picture of the burrs that are having this critical alignment it would be useful.
Hi John, I don't think that it is a matter of burr geometry.
All tolerances meet at the burrs and as you know there are many parts involved.
versalab wrote: I am amazed at the need to realign the grinder after changing the burrs, or even to realign at all.
This is really a bit of a strange phenomenon, but there is one part involved which is for me the key element for a good alignment (if all other parts are machined correctly).
It is the inner conical part of the conical burr set.
If the bore hole is not 90° to both sides of that little part, then the rest of taking care of alignment makes no sense.
That part (inner conical) is not made by Versalab but I can only recommend to measure it and sort it out.
versalab wrote: The bottom burr driver (as we call it) does have clearance on the shaft but to position it centered shouldn't be that hard even by eye, or using a fingernail to feel where overlap is.
Only to sort out the radial alignment with your finger nail or a torch or whatsoever, but the axial run out is a much more complex problem and yes, 0,1mm can be enough not to grind fine enough a light roasted coffee.

Did you ever read or hear anything about a grinder which is called EK43 ?
10 years ago probably the most important thing for grinder manufacturers was "not generating heat".
Since the EK43 which runs with 1400 RPM grinding / shredding beans getting the most uniform particle size with their 98mm burrs things have changed.
Light roasts benefit from that narrower particle size. Even avoiding fines became less important like avoiding the bigger particles (boulders) which will get under extracted.

I am a big fan of your design, "improving and copying" an existing principle is much easier than inventing it like Versalab has done.


A quote from Henry Royce which became a slogan of Rolls Royce company says:
Strive for perfection in everything we do. Take the best that exists and make it better. When it does not exist, design it. Accept nothing nearly right or good enough.

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#30: Post by versalab (original poster) »

Thanks for your thoughts Frank. I am surprised that you think us so unaware of the tolerances and design criteria for our lovely product!

Regarding the inner conical. It is not the hole alignment that is required, it is simply that the hole is large enough - and other dimensions do not interfere - so that the inner conical fits true to the face on the center shaft. This then makes the precision of the parallelism of the top and bottom of the inner conical the major precision criteria. The burr driver that holds the bottom burr can then accurately provide a high precision (extremely low axial run out) mounting place for that bottom burr.

All the way back in the early design stages the inner conical and its requirements were obvious. We did let a few clangers go through perhaps where other parts interfered with the preferred alignment stated above. Those perhaps have caused some of these problems.

And we do make the inner conical and the outer conical. Always have.

Axial run out is a serious problem that shouldn't exist providing the second paragraph above is met.

The problem that I mentioned regarding the larger than correct exit channels causing serious problems is an absolute fact. Any of the flat burrs that can't grind fine at a reasonable setting are flawed. We don't know where users are sourcing their flat burrs but they need to be aware of this problem. Turkish/Greek coffee size grounds regularly come out of our grinders.

I understand that you are a fan of our basic design and I see that the Royce quote provides you with the excuse to copy our basic design.