Coffee Roasting     Roasts are taking too long on MCR-6

2023-02-03 14:25

Roasts are taking too long on MCR-6

Hi all,

I've been having a challenge getting my roast time down. After attending class last week and taking some insight back with me, I am still stumped. I increased both drum speed and air speed and I'm still getting roast times in the 17 -19 minute range.

Are there settings I can change? My max pressure is 3.1kPa and I'm on propane.

When I increased the fan speed, I was getting a good number of beans leaving the drum into the exhaust. Yesterday I adjusted the drum gap and still had the same problem. I was at 4mm and moved it to 3mm and that didn't work, so I just made an adjustment to 2.5 mm. I haven't tried that gap setting, yet.

Regardless, even if we solve the beans leaving the drum, I'm still left with long roast times. Speeding up the drum seemed to help the look of the exterior of the beans at during the initial minutes of the roast. What RPM should I be targeting with a full batch on the MCR-6? After checking my drum speed again, it looks like the Hz measurement corresponds with RPMs, i.e., 60 Hz equals 60 RPM.

Any thoughts are appreciated.

My charge temp was 465.

https://portal.roastpath.com/roasts/share/1393204490400030223

https://portal.roastpath.com/roasts/share/3965867252220010223

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2023-02-06 14:22

Hey Doug,

Higher air is pulling your beans out of the drum with the faster drum speed. I would bring air back down between a range of 20-23-26 to eliminate beans getting sucked out and maintain your drum speed at that max 60hz for 60RPM for the time being.

Drum gap would not contribute to beans getting sucked out, but it could let beans fall under the burners, so let's make sure to set that in a good spot where you have no bean loss.

Try profiling a coffee at a 4kg for batch size. Taste that and see how you're liking the results. If the experience is positive, then move up to 5kg for batch size and see if you can get similar results (profile will elongate as you scale up). You will ultimately decide if it's more beneficial to do 4-5kg batches faster or 6kg longer. It will help to know how much faster those two batch sizes move.

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