# Gene Café - Chaff blocking chamber outlet



## mathof (Mar 24, 2012)

The temperature indicator on my Gene roaster won't rise beyond 217C after 17 minutes. This is with 225g of washed Columbia green beans from Rave. It's even worse with 225g of Kona beans, also washed that I have, where the temp only gets to 206C in 20 minutes.

When I tested the heating with no beans in the chamber, the temp rose to 230C in 3' 24".

The problem seems to be that chaff quickly blocks the chamber outlet, rather than exiting. Here is a photo of what it looks like:









Any ideas would be appreciated.

Matt


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## Coffeejon (Oct 10, 2014)

Don't over fill it. Go down in bean amount until it doesn't block. I had this problem with a Brazilian.


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## DavecUK (Aug 6, 2013)

Ensure the slits are not bent and all straight and level. Ensure you clean it really well and that the chaff clapper runs true across the vent to clear it. If the chaff clapper doesn't scrape properly, it will quickly block. you're only roasting 225g, so not exactly overloading it at all.

Also ensure the chaff collector box isn't blocked as reduced airflow may make it harder to clear the chamber chaff and also lead to overheating.


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## johnealey (May 19, 2014)

Is the scraper actually operating by flapping back and forth? If it is could be the little coils that hold it in place (ish) might have got a bit stretched thus not sweeping correctly across? Claudette at Bella barista had some last time the sweeper became less efficient after I scrubbed the central divider with a pan scourer and it stretched the coil, throwing the sweep out ( they can also supply a whole new central divider with new scraper etc if required).

May be off the mark but above made a difference when switching beans seemed not to cure it.

John


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## mathof (Mar 24, 2012)

Thank you for your replies. I don't think the scraper is doing much of anything. I wondered whether it is supposed to keep the vent clean. I think I may have knocked it out of position some time ago when I was cleaning the chamber. Here is a video I made today that might help diagnose what is (not) going on:











Matt


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## DavecUK (Aug 6, 2013)

Watched the Video...do you tube charge by the second now and is it extra if you zoom in?

I say this because it's very hard to tell, but it looks as if you got something the wrong way round and the chaff clapper is not even scraping over the vent, but scraping over the opposite side of the chamber?? If this is the case, then it will cause the problem you have and you can go back to 250/275g of coffee after correcting it.

Perhaps a few photos of how the clapper moves in your chamber would help.


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## mathof (Mar 24, 2012)

That diagnosis was exactly right. Thank you. I had taken the central divider out for cleaning and put it back with the chaff clapper facing backwards. I fixed it and roasted 250g of Columbia El Bosque. (Ambient 26C) The measured temperature reached 230C in 9' 53", and after holding it there for a minute, I set a new target of 240C which it reached at 13' 0". First crack came shortly after that, and after about 40" I set the target temp at 235C. A minute later it looked dark enough to hit the Cool Down switch. The end result is a rich chocolate colour and relatively (for me) evenly roasted beans.

Matt


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## johnealey (May 19, 2014)

Result!

John


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