Hi fellow baristas!

I bought a brand new Rocket Cellini espresso machine and Rancilio Rocky Grinder setup. Great machine but I am having two key issues in getting my shots dialed in correctly:

1. Shots run too quickly and bitter
I have Rocky grinder set at 12 out of 50

2. Shots run too slow over 35 seconds like hang condition and taste sour!
I have Rocky grinder set at 5-7 setting
The espresso feels like powder.

Any ideas? I have the dosing correct and tamp fairly well. I did not receive a user guide from Rancilio. Unfortunately the reviews are bad for Rocky and I would have bought a better grinder like a Rocket mini Mazzer had I known better.

The Rocky often gets a "bad rap". To me it is an example of a basically well designed device with a few badly designed and sometimes badly produced and assembled parts. There also seem to be "lemons". There is one thing that has been discussed several times on HB is the so called "Teflon tape mod". This involves wrapping the thin (blue, not yellow) variety of teflon tape around the burr carrier. If you have a well made Rocky 1 turn of the tape will make it adjust smoothly, and cause it to grind dramatically better, because the burr carrier no longer can vibrate during use. Some apparently require more turns of tape. You will find with the modification it will adjust like a fine camera lens made before the era of electronic focus! The grind will be more even, and you will find the burrs need to be set farther apart to achieve a given grind.

Buy a scale with 1/10th gram accuracy. Weigh out 15 gram doses for your Rocket in the basket supplied. Grind fine enough so the shot blonds at around 30 seconds.

The Rocky is a good grinder for lower doses and finer grinds; not so great for higher doses or coarser grinds. If you prefer to fill the basket up, you should buy a VST-18 or Stada or basket, which dose at 18 grams with a fine grind.

Thanks I'll do that. I had to unscrew the dose part to clean out the old stuck ground beans what a royal PITA but I don't want stale coffee left in the grinder. I ran a new test with following results:

Test #1: set to 8 the double espresso shot took over 30 seconds very slow pull and bitter.

Test #2:
At setting 12 the double espresso shot took between 15-25 seconds with good crema and smooth taste not bitter.

Questions

Why do I have to use such a high course grinder setting on the Rocky to get a decent espresso shot with my new Rocket Cellini?

Should I take it back for exchange to get a better grinder with doser like Rocket mini Mazzer?
I just bought it few days ago.

I don't like having to unclog the grinder opening each time I use it. With that said the Rocket Cellini is a wonderful espresso machine especially mine which has the PID that can be programmed. Here is some latte art that I created today on the second test latte.



The steam nozzle on the Rocket Cellini is amazing! Very fast and powerful for quickly created perfect milk for latte art.

cellinirocketman wrote:Thanks I'll do that. I had to unscrew the dose part to clean out the old stuck ground beans what a royal PITA but I don't want stale coffee left in the grinder. I ran a new test with following results:

Test #1: set to 8 the double espresso shot took over 30 seconds very slow pull and bitter.

Test #2:
At setting 12 the double espresso shot took between 15-25 seconds with good crema and smooth taste not bitter.

Questions

Why do I have to use such a high course grinder setting on the Rocky to get a decent espresso shot with my new Rocket Cellini?

Should I take it back for exchange to get a better grinder with doser like Rocket mini Mazzer?
I just bought it few days ago.

I don't like having to unclog the grinder opening each time I use it. With that said the Rocket Cellini is a wonderful espresso machine especially mine which has the PID that can be programmed. Here is some latte art that I created today on the second test latte.

Did you test using setting 9, 10 and 11?
The numbers are there for reference and will vary from grinder to grinder. I am guessing you are using the doserless model and like all doserless grinders, the Rocky DL retains grinds up in the chute that are difficult to get at. I would return the rocky and exchange it for a better grinder. I replaced my rocky with the Macap M4 stepless grinder with doser. It was a big improvement in several ways.
1. The 58mm burrs of the M4 are faster than the 50 mm burrs of the rocky.
2. The M4 has infinite grind adjustment controlled by a simple worm gear.
3. The M4 has never gotten clogged due to oily beans.
4. There M4 has zero grinds retention in that the doser design gives the user easy access to the area where the grinds exit the burrs.
5. There is no clumping with the M4.
6. There are no static issues with the M4.
I still use the Rocky when brewing pour over with a Hario or Chemex. It is not a bad grinder. The Macap M4 is much better suited for espresso duties and a lot less frustrating.

Ed

You do understand that grinding for espresso needs fine adjustments ?
One mark on the dial can be the difference between a good shot and a disaster.!
Moving 2 marks on the dial could be the difference between a 15 sec shot , and a choke shot !
Hence the Teflon tape mod to allow part step adjustments
If your grinder is constantly blocking up, I would try a different roast !
There are better grinders, but with care and practice the Rocky can work well....as it has for many other users.

I tried two different high quality local beans.
At this point I'll return it for a better grinder
like the mini Mazzer made by Rocket espresso.

I modded my friends Rocky to be step-less, it was still a barely mediocre grinder for espresso and he quickly got another grinder, way too many other better grinders today, a Vario will curb stomp it as well as plenty of others. What are you looking for, and any reason you want the Mazzer Mini E? Again there are much better grinders even for cheaper, the E is overpriced and outperformed by others.

So what would you recommend instead of the Mazzer Mini for a better grinder?

Note that this thread was started by the OP:
Need recommendations better than Rancilio Rocky grinder