+2 on the questions about the benefit of conical burrs on lower end grinders...
Whats the deal with the reduction speed on the Lux? Ive read that it switches between 800 rpm and 11000. Does the speed switch automatically or is there a adjustable somehwere. If its automatic, and pretty much uncontrollable, I dont see how this would be anything more than a marketing gimmick.
While on the subject of gimmicks...is there much benefit to the conical burrs on these smaller grinders? Also, Ive always found it strange that you find the conical burrs on the cheap grinders, and then theres none to be found until you approach the 2000 dollar range. More marketing tactics at work or is there a justifiable reason for this? I dont know very much about mechanics, but wouldnt it be possible to put a slower motor in a midrange grinder with conical burrs and keep the price under 1000?
+2 on the questions about the benefit of conical burrs on lower end grinders...
For the low end cost and compactness of the conical burrs compared to flat burrs that need bigger and more solid everything to make them work at the same delivery rate.
As to why no mid range conicals good question, I wouldnt mind betting we will see more of them over the next few years in the Mazzer and Compak ranges at least. I still think the slow revving motors and the gear drives to make them work well will see them price in above the planer burrs for the same kg rate?
My Lux knowledge is somewhat dated but there were just fixed gears to reduce the standard speed of the AC motor down to the speed the burs rotate at - no adjustment, automatic or otherwise.Originally Posted by 2D202B28332B2822440 link=1272288185/0#0 date=1272288185
Im not sure why - either conical burs work best at slower RPM than flat burs or its harder to make lowish RPM motors of that size, torque, or whatever.
No wonder the Lux motor at 11,000 RPM + gears makes such a racket! *(compared to my current K3T whose motor is only 1,300 RPM but is umpteen times the size).
Gday "idolwolf"....Originally Posted by 535E55564D55565C3A0 link=1272288185/0#0 date=1272288185
Answering in the order highlighted....
A) As pointed out by "scarey", there is a reduction gearbox between the motor and the main burr drive.
B) Yes. Conical Burrs have more cutting surface area than equivalent sized Flat Burr types, so it comes down to more bang for buck in one sense. Replacement cost for a set of these burrs though is more than twice the cost of a set of Rocky Flat Burrs for example, due to increased costs related to machining and sharpening of conical Burrs.
C) Its more a matter of throughput rate in a commercial situation. Because of the increased surface cutting area mentioned above, Conical Burrs can not be run as fast as Flat Burrs because the significantly greater cutting area requires significantly greater torque as a result. If you were to rotate the Conical Burrs at the same speed as an equivalent output set of Flat Burrs, so much friction related heat would be generated that the coffee would most likely be burnt, to say nothing of the temperature that the burrs themselves would get to.
D) Correlating the information provided above, the actual output from a so-called mid-range Conical Burr grinder would not be able to compete, even remotely, with a similarly priced Flat Burr grinder and given that scenario, what sort of commercial outfit would want to be lumbered with that.
The reason Large Conical Burr grinders commence at around the $2,000 mark is due to the extra cost of design, engineering and manufacturing. There are significantly greater (lateral) forces created within a Conical Burr arrangement and this then dictates that all load bearing components are designed and manufactured accordingly, in order to ensure that the relative alignment of the burrs is maintained within an almost Zero range. Anything less would just lead to unsatisfactory grinder output at best and burr pair contact at worst...
You have to remember, grinders above a certain output rate are almost exclusively manufactured for the commercial market and as a result, are manufactured to very stringent minimum standards.
Thanks for all the useful information. Ive been wondering about these things for a while now. Mal, your point about the lateral forces in conical grinders is very interesting. I never thought about how the increased surface area would create a need to stablize the lateral movement of the burrs. I guess this would create a drawback for the small conical grinders? I doubt they would have the stability of the larger grinders.
Its all very interesting. Who would have thought it would be so difficult to grind coffee beans! :D I suppose its like anything else that requires a high level of precision.
[QUOTE=25080C000D610 link=1272288185/4#4 date=1272364165]Originally Posted by 535E55564D55565C3A0 link=1272288185/0#0 date=1272288185
Excellent reply Mal and if I knew how to, I would give it a "toppie" ;) !
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On your behalf Attilio ;)
Aw shucks....Originally Posted by 1C283F29320519353C3C3F3F5A0 link=1272288185/6#6 date=1272408861
why so sad mal? I had a laugh, that embarrassed emoticon is too sad for my liking, you can be emabarrassed and happy too!
Yeah, its a bit sad looking isnt it...
Ive changed it :P
The burr set used by the Lux (and Iberital Challenge, Ascaso, Isomac Gran and Sunbeam EM0480 and EM0450) is MUCH smaller in diameter than those of commercial conical grinders so there is correspondingly less leverage from the force applied by the beans as they resist being ground down so the burr assembly does not need to be anywhere near as strong/stable. The grinder certainly has faults but burr stability is definitely not one of them.Originally Posted by 636E65667D65666C0A0 link=1272288185/5#5 date=1272405247
Some people in the past have derided this grinder for plastic being used for the upper burr carrier but I have found that this allows the threads to have a slight interference fit. This means that the burrs are actually more stable than for metal burr carriers that are not stabilised with a spring loading like the Mazzers (a side benefit of the Mazzer stepless adjustment mechanism). Grinders like Rancilio Rockys and the Macap series often benefit from having their upper burr thread wrapped with some teflon tape to increase its stability.
Some great information there. Thanks guys. Now I know why the $2000 grinders burr RPM is only 750 give or take.
Spot-on Greg... 8-)Originally Posted by 53595956595F5D380 link=1272288185/11#11 date=1272490750
The little Lux grinder I had a few years ago maintained a very nice interference fit, the only negatives were the noise generated through the drive train and the large step changes with the adjustment collar. Did a very decent job though.....
Have to say though, the precision fit of the brass Upper Burr Carrier of my previous LSM SM-90A was a delight to use - very close fitting, no binding and indexed to 3 degree step changes on a thread pitch of 1.5mm.
Yeah, the variance in the fit of the threads is per grinder rather than per model. You might get one that is spot on or you might get one that is a touch loose but thats a consequence of mass production.
Well mate, I tried several LSMs and other makes of the same vintage and category before buying mine. Id have to say that pretty well all of them had quite precision fitted threads... The only grinder I have used that displayed a poor fit, was the Rocky, bought around 2004/05....
Well, it would make sense that a higher priced item (all other things being equal) would be made to tighter tolerances than a cheaper one. Ive come across a couple of Rancilio ginders (Rocky and MD50) and a Cunil that all had a VERY slight wobble in the upper burr carrier fit.
The unsung beauty of the Luxs plastic burr asumbly is that it pretty much assures great stability without needing precision machining - one migt be a bit stiffer than another but thats all. The downside is lower longevity but that should not be an issue in a domestic environment.
Now if they only fitted them to a low speed induction motor...