Why You’re Getting a Wavy Tamp on Your Breville Oracle (And How to Fix It)

Noticing a wavy or uneven tamp in your Breville Oracle, Jet or Oracle Touch? This issue is surprisingly common — especially if you're using the double shot basket. These machines use a spinning tamping fan to automatically press down your coffee, but several factors can cause the tamp to go wrong. Here's what might be happening — and how to fix it.

 

Grind Size Is Too Coarse

The number one reason for a wavy tamp is that your coffee grind is too coarse. If the grind is too loose, the tamping fan doesn’t encounter enough resistance to compress the puck properly. Instead of compacting and polishing the surface, the fan can just push the grounds around — leading to a lumpy, uneven tamp.

Fix:
Make sure you're using a fine espresso grind — similar to table salt or even finer. This provides the resistance needed for the tamping fan to do its job properly.

 

Coffee Grounds Spinning in the Basket

Even with a good grind, dry coffee grounds can spin in the portafilter basket during tamping — especially in Breville’s uncoated double baskets, which lack the non-slip surface found in their single baskets. This can cause the tamping fan to dig into the coffee and create a spiral or wave pattern.

Figure 1 - Single basket with abrasive coating.

Fix #1 (Easiest):
Lightly dampen the inside of the basket before dosing by running off half a shot. This adds a bit of surface tension and friction, helping the grounds stay in place during tamping.

Fix #2:
Roughen the inside of the basket with a bit of fine-grit sandpaper. Breville coats their single baskets to prevent spinning, but for some reason, this friction-enhancing coating is missing on their double baskets. By adding a light texture yourself, you can achieve a similar effect.

 

 

Incorrect Dose Amount

Breville’s tamping system is designed to work best with 19–22 grams of coffee. If you’re dosing below or above that range, the tamping fan might not engage properly — either tamping too shallow or too deep, resulting in an uneven or unstable puck.

Fix:
Weigh your dose to ensure it’s between 19–22g. If your machine is under- or overdosing automatically, you can calibrate the auto-dose setting by following this tutorial:
📺 How to Adjust Dose on the Breville Oracle Touch

 

 

Worn Tamping Fan

The tamping fan relies on a smooth chrome finish to polish the puck efficiently. Over time, this finish can wear down from friction or improper cleaning. When that happens, more drag is created and the fan will start dragging across the coffee bed.

Fix:
Inspect the fan visually. If the chrome looks dull or scratched, it may need replacing. A fresh fan glides more smoothly and applies even pressure.

Figure 2 - Old versus new chrome.

 

Shrunken or Damaged Rubber Seal

The tamping fan also relies on a rubber seal to stay aligned and glide smoothly during operation. Over time, this rubber can degrade. If it shrinks, hardens, or wears unevenly, it can cause the fan to drag as it spins — resulting in a wavy tamp or even damaging your coffee bed.

Fix:
If only one side has worn, you can easily pull these out and flip them; however, in most cases, you will need to replace the tamping fan.

Figure 3 - New versus old seal.

 

Summary: How to Fix Wavy Tamps

1. Grind finer — the most important step.
2. Dampen your basket before dosing to stop grounds from spinning.
3. Roughen the inside of your double basket with sandpaper for added friction.
4. Inspect the tamping fan for chrome wear.
5. Check the rubber seal and flip seals/replace the fan if needed.