Posted Sat Mar 8, 2014, 9:08am Subject: SC while FC is still happening ?
I have a bone stock Poppery 1. I've roasted 5 small (90g ea) batches of beans so far. I extremely happy with the taste in the cup with my Brazil and Kaffa beans so far. My Kaffa was actually way better than another I've had that was professionally roasted. Is it possible to have beans still in FC while others are starting SC? I guess my beans are a bit inconsistent. I've been stopping the roasts 30-sec to a min after the end of first crack but I'm definitely getting some beans that are Full City +. Is this common with the Poppery? FC seems to last about 2- 2 1/2 minutes. I know a BT probe would help determine what is happening. Any thoughts or ideas?
Posted Sat Mar 8, 2014, 11:13am Subject: Re: SC while FC is still happening ?
Your FC time seems a little longish. My usual time from beginning to end of FC is about a minute and a half.
Note that some beans roast unevenly, as a product of processing. I have roasted Yemeni brans that I have had to cull about 5% for under roasting.
My best guess with an unmodified Poppery is that you've got inadequate agitation. The way the heating system is designed in this machine, there are some parts of the chamber that has air entering at 40-50 degrees F hotter than others. If you've also got beans that are sitting too long in those areas they will be over-roasted relative to the beans that are agitating in other areas.
That is one reason I installed a mesh false bottom in my roasting chamber - it allows for mixing of the air coming into the chamber to eliminate beans in contact with super-heated air. It helped with tipping and scorching for example. See this post.
With an unmodified Poppery, make sure the agitation is sufficient to ensure that the beans are moving around VERY freely starting at the beginning.
Dana Leighton - Espresso hack and CoffeeGeek moderator
Posted Sat Mar 8, 2014, 5:49pm Subject: Re: SC while FC is still happening ?
The false bottom sounds like a fantastic idea. I will try this out maybe tomorrow. Hopefully Home Depot has some ss screen? I saw in the linked post that your using a considerably larger batch size than I am. Do you think I should try increasing my batch size? ? Right now at 90g's I get a pretty good rotation on the beans (probably not enough though). I'm going to try manually stirring the beans as well to see if it helps. One other thing I probably should have added is my total time for the roasts. I'm at about 8-9 mins. I was told 4/4/4 is a good start to shoot for. I'm pretty close. ( I just have my poppery plugged into a loaded outlet which I believe is slowing my roasts a bit)
Posted Sat Mar 8, 2014, 10:29pm Subject: Re: SC while FC is still happening ?
The screen Dana mentioned is a good idea (I use it, as referenced in the thread), but I would suggest you get a thermometer to measure what your temperature gradient actually is across the vents (and to know what temp your beans are roasting too.) All roasters have temperature gradients across the bean mass and it is a good idea to minimize them as much as possible; the less the better. Getting good mixing of the beans is as important to lower temperature gradients in the bean mass too. Putting the screen in has a negative effect on the air stirring the beans and will require more manual stirring on your part.
You can up your batch size to 150grams on the poppery 1, but this lowers air flow and increases air temperatures. Most who run batches this large use some form of heater control. (150 grams is my batch size)
Doubt it. It's really a specialty item. I had to mail order.
I saw in the linked post that your using a considerably larger batch size than I am. Do you think I should try increasing my batch size? ? Right now at 90g's I get a pretty good rotation on the beans (probably not enough though).
On an unmodified Poppery that sounds about right. I was using temperature control so the batch size is not comparable. I think I also might have had a boost transformer on the fan to increase the airflow.
Dana Leighton - Espresso hack and CoffeeGeek moderator
Posted Sun Mar 9, 2014, 2:10pm Subject: Re: SC while FC is still happening ?
Forgot to mention;
I used the stainless steel screen for a drain catch, you may find the right size at a hardware store. Flattened the screen to a nub in the middle, below, then with a brass plumbing flange around this in the middle to act as a support post... Improvise.
Posted Mon Mar 10, 2014, 11:07am Subject: Re: SC while FC is still happening ?
Not saying this is the problem here, but FYI...
Even in roasters which heat very evenly, overlapping or nearly-overlapping 1stCe (1st Crack end) and 2dCs (2d Crack start) are not uncommon when the beans haven't been sorted for size -- certainly not unusual with African coffees.
Posted Mon Mar 10, 2014, 12:13pm Subject: Re: SC while FC is still happening ?
Keeping MET below temperatures that start second crack will avoid going into second crack altogether.
I didn't want to speculate, ....but 2.5 minutes of first crack and entering second crack without pause sounds like an uneven roast running fast and hot. If first crack is pacing slow enough to last 2+ minutes, this should leave some time before second crack starts. Knowing temperatures and what the beans look like would help to explain, but enough reasons an untempered poppery 1 would usually run (too) hot through the finish.
Posted Mon Mar 10, 2014, 5:54pm Subject: Re: SC while FC is still happening ?
Frost- I never would have thought of a sink strainer...I will get a couple sizes and see what I can make work. I ended up doing another roast the other day of some Guatemalan beans. I tried manually stirring them about every 10 seconds or so. One other thing I did was turn off the other load on the circuit right before FC. (I know I need a router speed controller lol) Anyways, the roast seemed slightly more consistent. I guess I need to do a couple mods to this thing.
Rich- That's really interesting. Is it a common practice to sort beans for size before roasting?
Sorting by size is part of the drying and bagging process. It's something growers should do, but not all of them actually do it. It can be a factor of region, grade, individual growers, particular crops -- and/or other things as well. Bean size disparity is common in Ethiopian coffees, even "A" lots.
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