Go get em! Just took some videos of the burrs rotating next to a stopwatch. Had to colour one augers black so when its slowed down you can see which is which. Anyhow, confirmed its rotating at pretty much 420RPM, which is what it should be doing at 50Hz. Really, all that leaves then is the burrs or friction in the exit chute??? anything else??

Cheers, Chris

Hi again, I think it may be defective burrs. Look at the inconsistency in the coarse grinding area, at the tips. I am not sure what they are meant to look like, but I would think they should be consistent from tip to tip.



It would appear that there is metal to metal contact (or has been) high up in the coarser area. I wouldn't have thought that this should happen. It would explain (I think) the slower grind, as it would reduce the been grab rate high up.



Any thoughts anyone?

Nicholas, you are into photography? Any chance of a comparison photo or two from your machine?

Thanks, Chris

Chris, I took these this morning for something else. Not sure how much help they could be:


Link to full size via Flickr.


Link to full size via Flickr.

It's hard to say. You can see my Robur has some strange looking "defects" on the bean crushers (on the top), but they're not against the part that actually smashes the beans during rotation (and I don't have any speed/consistency/clumping issues).

Are you sure that both your burrs are mounted dead-center? It's unlikely, but possible they aren't aligned right. I think the best way to check is to defeat the interlock and run it while you watch it. Wobble is most apparent at the spin-down, for the bottom burr. Don't know how to check the top one.

another_jim wrote:Can you post a panned out pic of what you are showing up close; the context is missing, at least for me?

shadowfax wrote:Are you sure that both your burrs are mounted dead-center? It's unlikely, but possible they aren't aligned right. I think the best way to check is to defeat the interlock and run it while you watch it. Wobble is most apparent at the spin-down, for the bottom burr. Don't know how to check the top one.

No apparent wobble or vibration. I guess I have nothing to lose by taking them out fully though and reinstalling them.

Nicholas, I can't see enough detail on the flickr photos, could you possibly zoom on the original to show the 'teeth' on the upper burrs to see if they have the same inconsistent 'stamping' as on mine. Looks like the stamping should be there, but on the 3 bigger 'teeth' on mine, look at the third/bottom one is very different to the other two... wish I could figure out how to edit a photo other than zoom etc, just switched to a mac...

Cheers, Chris

OK, so I figured out how to get the large photo off Flickr. Below is Nicholas's ROBUR upper burr, with the areas circled that are of interest to me.



and here is mine...



and...



Looks like mine is poked. Not only is there an inconsistent 'stamping' pattern at the end of the larger teeth, but it appears that the burr edge to the right of each larger tooth is rough. I believe that its roughly this area that has been doing most of the grinder on my machine. Manufacturing error?

Anyway, one of these thing is not like the other.

Chris

Hi guys,

I dunno, I got a fresh pack of flat burrs from Owen a few months ago and I was surprised how uneven some of the surfaces were. Remember this is in the coarse area, so it shouldn't matter that much (or at all) in my opinion.

Are you sure that both your burrs are mounted dead-center? It's unlikely, but possible they aren't aligned right. I think the best way to check is to defeat the interlock and run it while you watch it. Wobble is most apparent at the spin-down, for the bottom burr. Don't know how to check the top one.

I wouldn't trust your eyes when it comes to wobble, few people on this forum thought their burrs were wobbling and in the end it turned out to be an optical illusion. Remember all that's needed for the burrs to look like their wobbling is a slightly off-centre lower burr locking nut/washer.

The grinder is still on warranty and I would just simply pack it up and send it back to where you bought it. Considering the price tag it should work well straight from the beginning.

Looking at that photo of the grinds stuck behind the grid it looks like they are being compacted quite hard and when pressed against the grid they fall out in blocks. Have you tried cleaning out the chute and running the grinder then? the first few seconds should show grinds shooting out from the burr chamber quite far away and hitting the wall of the funnel. After a few moments the 'throat' should get stuck with grinds and it won't shoot out anything any more (just stuff sliding down the funnel).

Regards,
dsc.

dsc wrote:Remember this is in the coarse area, so it shouldn't matter that much (or at all) in my opinion.

The trouble is, I think this is being used as the fine area since the corresponding shaved metal on the inner burr is in this area.

dsc wrote:The grinder is still on warranty and I would just simply pack it up and send it back to where you bought it.

Would in a flash, but it is in HK and it was bought from Europe. Got a price for 830USD to Fedex it back, so not really an option. Couldn't buy one locally so picked it up when I was in Europe, hand carried to aeroplane (heavy).

dsc wrote:Have you tried cleaning out the chute and running the grinder then?

About 10 times! Throws the beans out initially, but not continuously. I have had new flat burrs as well, but I really think there is a problem with these ones. I will reseat the burrs though to be sure.

Hi Chris,

Got a price for 830USD to Fedex it back,

Ouch! well that's not good.

I would take off the funnel, cut a cardboard cup in half (vertically) and stick that in front of the chute. Turn on the grinder, time it and weigh how much grinds it produces. If it's still very slow I'd try to re-seat the burrs.

Btw have you actually tested how the grinds behave in a machine? Do they produce good pours? maybe you're worried for nothing? I mean if it gives nice pours I would try using it for a month or so and see how it behaves afterwards.

Regards,
dsc.

Do you know if those two screws on the funnel are just screws, or do they have a washer behind them. Don't want to hear that 'tink' noise as a washer falls internally inside the machine!

It behaves differently. I did notice a reduction in bitterness immediately, but it was also noticeably blonder. I thought this must have been just the way it was. I did also immediately notice though that the crema produced a distinct line where it changed to liquid, instead of the normal sort of 'guiness' effect as it settled.

When feeling the grounds, they are substantially coarser than on the Mini for a similar pour time. I know it sounds a bit funny, but it just feels wrong - the grind, the speed, the lack of consistency. I've put through 10 pounds of coffee, so I feel I've given it a reasonable go at settling down - I'm no espresso savant, but I am certain something is not as it should be.

Cheers, Chris