Posted Wed Jun 1, 2005, 9:09am Subject: Just some interesting Rocky observations...
Have been having problems getting any consistent shot timing with Silvia/Rocky - and usually not near 25s (usually closer to 15). I also could not even come close to stalling Silvia - this really started to concern me after reading the Rocky thread where most Rocky users were commenting they were about 8-12 clicks above zero....I was about 3.
So, I ordered a new set of burrs and installed them yesterday...WOW! What a difference. Started out about 8 clicks above the NEW zero point (which is now at about -20 on the tape - I can't even see any numbers), and Silvia huffed and puffed and dribbled out 1/4 ounce in 25 seconds. Up to 12 clicks....and out oozed a nice 25s shot.
Funny thing is, the old burrs (which are not very old - maybe 20lbs through them) and the new burrs feel exactly the same in terms of sharpness etc. I can shred finger nail similarly on both. I can't visually see any difference. The old ones still feel razor sharp.
Also funny, is that from the factory (I assume), that the zero point on the old burrs is not even REMOTELY close to the zero point on the new burrs. They are half way around the hopper different.
I would have probably caught this a lot earlier except that I used to have a Saeco pressurized machine, and so shot timing etc. never really worked out so I never really realized I had a problem until Silvia appeared on the scene.
Reading all the threads on the defective carriers etc, I was starting to think that was my problem, but is there any chance there is a batch of defective burrs out there?
Posted Wed Jun 1, 2005, 9:17am Subject: Re: Just some interesting Rocky observations...
any chance it could have been a calibration problem with the old burrs, that's fixed now, since you installed the new burrs properly?
Now that you are all happy you probably don't want to go back to the old burrs, but if they really look the same to you, and you put them back in, they might work too?
Posted Wed Jun 1, 2005, 9:24am Subject: Re: Just some interesting Rocky observations...
GrantT Said:
Reading all the threads on the defective carriers etc, I was starting to think that was my problem, but is there any chance there is a batch of defective burrs out there? Grant
What's the age of your Rocky? If you're at any setting on the grinding dial (doesn't matter where), try pushing at the top of the bean hopper back & forth & see/tell me please if there is any appreciable play/movement that you can feel/see.
Any chance you have access to a vernier caliper or a micrometer to measure the thickness of the 4 burrs, both the old & new? There may very well be a difference in tolerances.
Posted Wed Jun 1, 2005, 9:44am Subject: Re: Just some interesting Rocky observations...
wogaut Said:
any chance it could have been a calibration problem with the old burrs, that's fixed now, since you installed the new burrs properly?
Now that you are all happy you probably don't want to go back to the old burrs, but if they really look the same to you, and you put them back in, they might work too?
I have removed/installed the old burrs a couple times for a total Rocky cleaning, and both times, the zero point remained almost exactly the same upon re-installation. At about -1 on the dial. Things have moved a LOT with the new burrs.
CraigA Said:
Hi Grant,
What's the age of your Rocky? If you're at any setting on the grinding dial (doesn't matter where), try pushing at the top of the bean hopper back & forth & see/tell me please if there is any appreciable play/movement that you can feel/see.
Any chance you have access to a vernier caliper or a micrometer to measure the thickness of the 4 burrs, both the old & new? There may very well be a difference in tolerances.
Unit is about 1 year old. There is definately some play in the unit....ie. if you apply a little pressure to the hopper, you can feel some movement. I have had some teflon tape in there for some time to remove the slop/play in the threads.
I could probably manage to get some calipers....even if I just bring my burrs to the local store to "test" drive some. Hmm...but this is a great new excuse to buy another new cool tool for the toolbox!
Posted Wed Jun 1, 2005, 9:57am Subject: Re: Just some interesting Rocky observations...
Grant, What I mean, & I wanted to provide 2 pics., is the overall height/thickness between the flat outer area of the burr & the underside bottom ridge of the burr. Ignore that this pic is from the bottom burr carrier, it was the only & best pic I had to show the difference between the top & bottom of a OEM Rancilio 50mm burr.
You never know there could be a .005 - .010 variance/diff, though I don't really see it happening.. It depends on what the manufacturing tolerances are.
Posted Wed Jun 1, 2005, 10:14am Subject: Re: Just some interesting Rocky observations...
My Rocky DL, which I bought pre-owned (and painstakingly, lovingly maintained by our own Stash), seems to have its zero point at 0. Depending on humidity, bean type, age, and degree of roast, I grind anywhere from 4 to 8. I get gushers if I go too coarse, and near-stalls if I go too fine. In other words, it works exactly as conceived and intended. Guess I'm just lucky.
I have also found I don't have to do my suggested "bass-ackward" mod of taping the front switch"on" and using the side (master) switch instead for adjusting grind while grinding. (The tape only holds temporarily because of the heavy spring-loading of the switch). I find if I remove the lid and firmly grip the rim of the hopper with my right fingers, I can simultaneously hit the adjustment button with my thumb while activating the on-off switch with my left hand. I can then move the hopper a little in both directions without it spinning out of control, especially if I apply some pressure on the hopper's edge with the upper portion of my palm. I have small hands and short fingers, so it should be easier for most people.
Sandy www.sandyandina.com ------------------- Life's too short to drink lousy coffee, play crummy guitars and write with ballpoint pens.
Posted Wed Jun 1, 2005, 10:40am Subject: Re: Just some interesting Rocky observations...
Some facts & figures on thread pitch, differences in shot timing between 1 click on a Rocky versus Mazzer Mini, etc. That 0.0125 mm = 0.0032" (thousands of an inch) & with the Mini you could go as low as ¼ of a line division, so accuracy would be approx 0.0008". That's 8/10,000" or eight tenths of one thousand's of an inch! {:-)
P.S. I just did a test last night Thurs June 2nd, with this brand new Magnetic Base with Deflection Gauge that I purchased the same night. I tore apart my May 2001 Rocky for a through cleaning & re-assembled without the teflon tape to measure the deflection/play in the thread pitch of the upper burr carrier to receiver housing. The play was .010" or 10 thousands of an inch, & that's equivalent to 3 1/8th clicks!! {:-O on the Rocky., so you can see the extreme inconsistency that this play allows!
If your running dynamic zero point is +2 say, & you're grinding for your double shot @ a +7., there's only room for +5 clicks. With a play of +3 1/8th clicks, you can see the problem!! If you're grinding @ +5 or lower, even worse. The teflon tape mod will definitely & temporarily help & restore accuracy & efficiency of your grind.
puffink Senior Member Joined: 18 Apr 2005 Posts: 33 Location: Traverse city mi Expertise: I live coffee
Espresso: Electra A3 Grinder: super jolly / doserless
Posted Wed Jun 1, 2005, 3:48pm Subject: Re: Just some interesting Rocky observations...
Hi grant, For what its worth, I took some thin plastic pastry sheeting and cut three pieces 1in / 3in and installed them between the canster and the housing, this reduced the variation and you may go stepless if you like, if you get it snug enough.
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