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Homeroasters.org » ALL ABOUT ROASTERS » Popcorn Popper roasting
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Advice on Nostalgia APH200 first attempts
AMRoberts
Newbie with some sample green coffee and the APH200 from Sweet Maria's. I tried a couple of small roasts last Saturday to see what happens with the popper out-of-the-box, and hopefully learn what first and second crack events sound like. Note that I plan to modify this unit, if nothing else to have separate fan control so I can do some cool-down inside the popper.

Coffee was Colombia Caicedo Don Juan. Testing outdoors on the porch, cool rainy afternoon, 56F ambient at the start of my first attempt, had dropped to 52F ambient by my second test. Temperature measurement was with an Ryobi handheld IR (I've got a TC-based unit on the way). So ...

Question #1 - Trying to measure the temps seemed pretty inconsistent, is trying to use an IR handheld from above a popper even valid, or should I consider all of my measurements below suspect?

First test was 60g of beans. Almost no movement at power on, so I stirred until well into yellowing, when motion picked up. Yellowing seemed to happen fast, 2 minutes after start I was seeing a lot of color change. IR temps were: 380F @ 4:30,400F @ 6:40, 405F @ 8:40. I heard only a few popping/cracking noises somewhere between the 6:40 and 8:40 temperature checks, but no sustained period of cracking. Definitely nothing remotely like air-popping popcorn. To be fair, I have 58-year-old, recreational target shooter's hearing, and the popper makes a lot of fan noise.

Question #2 - Using a popcorn popper, do you really expect to hear sustained first and second crack sounds over the fan noise?

Past the 8:40 mark, things slowed down a lot. I only reached 420F @ 19:00, and seemed to plateau at 426F @ 24:00 and beyond. Gave up and dumped the beans for cool-down at 28:00. Never heard anything I would call a second crack noise.

Reduced second batch size to 55g of beans for my second test. This charge produced a good amount of movement from initial power up, so I didn't have to stir. Yellowing was still substantial at the 2 minute mark; afterwards I had somewhat lower temps (387F @ 6:00, 394F @ 8:20, 400F @ 10:00). Once again only heard a few cracking sounds over the fan noise. Temperature seemed to plateau even lower, 409F @ 19:00, 210F @ 22:00, and a drop to 407F @ 24:00, where I dumped the beans.

I've attached pictures of the cooled beans from each attempt. The lack of very dark color or any oil on the surface makes me wonder if I even reached second crack.

Question #3 - Am I experiencing stalled roasts? Given that I can see two rivet heads on the interior of the popper chamber, I am assuming a thermostat on the wall. I probably need to bypass this when I modify the popper to separate fan control?

Any advice and suggestions would be greatly appreciated,

Alan
AMRoberts attached the following images:
img_20180324_160331985.jpg img_20180324_152114618.jpg

Edited by AMRoberts on 03-26-2018 12:55
 
chaff
I checked my model No. I have the same. That's a thermostat on the side, self-resetting. There's also a thermal fuse inside by the main heater that doesn't reset. The wires on the side thermostat can be connected either to a switch ( mouser sells the same type as the On-Off) or even to an SSR to control the main heater. The other heater is in series with the fan to drop the fan's voltage.
I usually do 120grams at a time and continuously stir with a paint paddle, 150C at 4min and FC around 8-10 min. Sometimes the crack is less obvious, depending on the bean, but usually easy to hear so I'd suspect the thermostat is interrupting the heater too much.
Edit: With more means in the load you may well get higher temps / faster rise with the downside you'll have to stir well, I find anything above 80% heat can tend to singe the beans early on. The beans look good: for me, oily right out of the gate is too much, maybe a 'sheen' with a little oil a few days later.
Edited by chaff on 03-26-2018 11:36
 
AMRoberts
chaff wrote:

... I usually do 120grams at a time and continuously stir with a paint paddle, ...

With that large a batch am I correct in assuming that it never reaches the point where airflow alone will stir, so you are hand stirring for the entire roast?


... I find anything above 80% heat can tend to singe the beans early on....

So at start of roast you are implementing a duty cycle on the (main) heating element, via the manual switch or SSR you mentioned?

Seems like it is time to open it up and do some mods, thanks!
 
chaff
Yes to both. I've messed around with the vents at the bottom of the chamber, enlarging them with a right-angled screwdriver, but with that load I need to stir. ( I don't have the cover on )
If you just bypass the thermostat and pour in beans until they barely swirl at the start of the roast there's probably a sweet spot where the beans come up to temp quickly and they move enough to prevent singeing.
I used the manual switch on the wires from the thermostat in a second-On seconds-Off for a while but now I drive an SSR, reading the temperature with a bare thermocouple clipped to the rim of the popper. Sophisticated .. not.
 
AMRoberts
Hi chaff, just wondering how your APH200 is holding up over time?

Earlier in the spring I felt like cool ambient temperatures and breezes on the porch were hindering my reaching desirable ET for the late part of the roast, so I set my popper up inside a big box to act as a windshield, and made a baffle to divert exhaust air back to a screened port into the box, towards the base of the popper.

Seemed helpful when it was cool, getting inlet air from 50-60F up to 90-100F pretty early in the roast.

Unfortunately, when I was trying yesterday for a dark roast, I didn't think through the fact that my ambient temperature was 90+F, and I left the exhaust baffle in place. ET got away from me on the 3rd roast of the afternoon, climbing into the 490s before I noticed and cranked more airflow back in to pull it back down. See the picture, the baffle seems to have contributed to a hot-spot at the exhaust.

How is yours holding up?
AMRoberts attached the following image:
toohotsmall.jpg
 
chaff
Hi ! No meltdowns so far, on the roaster at least. The main switch melted early on, once i bought a $12 backup popper from Walmart and a switch from Mouser the old unit has done well. The SSR will take a lot of wear away from the switch and I don't use any re-circulation.
Certainly my stirring hand gets heated enough that re-circulating somehow looks interesting.
 
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