Weight loss

[gonzob]

No, this is about coffee.

I decided to weigh the beans after roasting. 306g of cold EGS reduces to 252g after second crack at 223C.

Normal?

Gonzo

[Steve82]

Around the start of rolling second crack I would expect around 18% loss. So you are looking pretty good.

[evelynr]

The first line was really needed as I thought it is something about weight loss through coffee

[Yelta]

Around the start of rolling second crack I would expect around 18% loss. So you are looking pretty good.

Second crack around 16%, rolling second crack! never been there so cant comment.

[gonzob]

Thanks for the replies.

The reason I asked was that my Roast-Pi runs the heat gun fan flat out all the time, and PWM adjusts the heating coils. I was wondering if I would be better off ramping the fan speed as well, so as to "cook" rather than "dry". It sounds as if I am in the right ball-park, so I don't think I'll bother.

Gonzo

[Dimal]

G'day Gonzo...

If you wanted to do anything with the fan output, would probably be better to pulse the output from a low of say 50% to a high of 80-90% (only guessing) during the latter stages of the roast and then leave on high between 1st and 2nd-Crack. Experimentation would would confirm what the optimum duty cycle would be. This would allow you better control of moisture retention whilst still allowing for the exhausting of chaff.

Some of the up-market pro roasters (equipment) allow for it to be done this way, so might be worth thinking about...

Mal.

[MrJack]

You could always control the airflow the old fashioned way - with some kind of slide/louvre/butterfly valve. You could even actuate it with a stepper motor controlled by the pi.

[Dimal]

I think Gonzo loves the idea of automation, just the impression I get...

Mal.

[Yelta]

No good talking to me then, I'm a control freak, no machine is going to make decisions for me, hands on all the way.

[Barry O'Speedwagon]

You manually switch the boiler on and off Yelta? I'm impressed.

[Yelta]

You manually switch the boiler on and off Yelta? I'm impressed.

Was under the impression we were discussing roasting Barry.

[gonzob]

G'day Gonzo...

If you wanted to do anything with the fan output, would probably be better to pulse the output from a low of say 50% to a high of 80-90% (only guessing) during the latter stages of the roast and then leave on high between 1st and 2nd-Crack. Experimentation would would confirm what the optimum duty cycle would be. This would allow you better control of moisture retention whilst still allowing for the exhausting of chaff.

Some of the up-market pro roasters (equipment) allow for it to be done this way, so might be worth thinking about...

Mal.

Ooooo... "up-market pro roasters". Sounds like a challenge. I like the idea of 50%+

And yes, I like automation.

A bit.

Well, no, a lot.

Gonzo.

[MrJack]

What, an actuated valve isn't automated enough?

[gonzob]

Well, after spending the afternoon farting around with PWM on the Raspberry-Pi, I got the variable fan speed working, however I discovered that the fan motor was overheating my servo driver, and slowing the fan down even a bit really made the heating coils glow red.

I decided to leave well enough alone.

Gonzo

[MrJack]

You could find a way to redirect some of the flow between the heating element and the roast chamber. Could aim to maintain approximately the same total flow (so no change in air temperature).