Hi all. *What is the optimum shot temp for the 6900? *Mine is 55-56 C. *(I do a manual purge of the group before using to heat it up. *PF is also heated before filling). *Also, my extraction seems inconsistent. *Same beans/grind (Sunbeam 480), auto tamp etc. *Grinder is set at 6. *Took it to 5 - not a good move *;) *One shot will be under, the next will be mid, next over. *Hmmm. * Thanks for any tips. *Cheers, CJ
Optimum shot temperature depends on the blend that you are using, not on the machine. 55C is way, way too low ... not even in the ballpark (I brew most shots between 198 and 204F, with odd exceptions). How are you measuring this? If its with a bead thermocouple sitting on top of a packed coffee puck (or another method that appropriately restricts the flow rate), your results would be very worrying. If its just a thermometer under the water running from the group, or in a styrofoam cup, your results are probably about right. The latter methods are only really suitable for boiler machines.
Temperature has nothing to do with volume/time. Some variation at the same grind level and dose should be expected throughout the day, as the humidity changes. To give you an idea, at work we probably make 20 miniscule adjustments to the grind per day ... but thats with mazzer grinders that have a very sensitive adjustment mechanism. From what Ive heard, the sunbeam grinder has a woefully inadequate adjustment mechanism ... Alan Frews review confirmed your observations that one notch makes a HUGE difference. This means that you have to be really, really spot on with your dosing, which I suspect is the cause of your problems. There are a variety of different dosing techniques, but what works for me is to fill the basket level to the top and rap the portafilter on the bench to settle the grounds. You can then add more. My standard procedure would be to then dose and level off again, but if your grind adjustment is too coarse - like with the sunbeam and, to a lesser extent, my rocky - you can control the pour at this second stage by dosing a tiny bit more or less. You might find a different method that works better for you. Perhaps the best thing that you can do is to roast yourself 250g of beans just to practice with and burn through them all in a row to improve your consistency.
Hope that helps,