topbanner.gif
Login
Username

Password




Not a member yet?
Click here to register.

Forgotten your password?
Request a new one here.
Shoutbox
You must login to post a message.

renatoa
02/04/2023 1:40 PM
Welcome, ediblemanager

allenb
02/02/2023 4:22 PM
bcoffeedrinker Welcome

renatoa
01/31/2023 1:17 AM
pouringZabbaskeema

renatoa
01/29/2023 4:55 AM
Welcome, drygrounds and CarlHaberfeld,

renatoa
01/28/2023 5:42 AM
ramsamorrow, VirTERM and Columbia, coffee drink

In Memory Of Ginny
Donations

Latest Donations
dmccallum - 10.00
JackH - 25.00
snwcmpr - 10.00
Anonymous - 2.00
Anonymous - 5.00
Users Online
Guests Online: 12

Members Online: 0

Total Members: 7,788
Newest Member: ediblemanager

View Thread

Who is here? 1 guest(s)
 Print Thread
Experience with a 1/3kg popper
eric
My first post here, was lurking back 3 1/2 years ago when I built my first coffee roaster based upon a common popper. It was intended to be a learning prototype but it worked so well that I have been running it since then, doing a roast every ~5 days. It was written up in detail on another coffee forum which has since gone off the air. I am back now as the second generation machine is taking shape, which was prompted by the apparent imminent demise of the popper - false alarm! A quick overview (refer to attached pic):

The popper is a Breville Crazy Popper with a Auber ramp soak fuzzy PID controller on the heater and a manual variable DC supply on the fan. The popper roast chamber is extended to nearly 600mm by 4 stacking soup tins (they just clip straight onto the popper RC) - the last 2 just so that I can use max fan for cooling. An inverted dog bowl and SS sieve form the chaff collector - simple and easy to maintain as the sieve is held in place by a couple of clips. The top 2 tins and DB lift off as one assembly for bean load and unload. The lean on the popper is what I use when roasting.

Here in Oz with 240V mains the poppers have 24V fan motors - I pushed an old bench power supply into service, replacing the dead regs with a 3 terminal 3A reg chip. The max fan voltage is set to 25.5V and that voltage is used often. Very clean DC minimises stress on the motor. Dissipation is around 80W into the air stream. I am lucky that line voltage is high here - 253V O/C and 250VRMS at the roaster on an extension at max power. Shorting out the heater tap for the fan I am getting 1500 watts total into the popper. Thus the 1/3kg capacity - worked up to this load gradually and decided I liked the results so kept with it. Heavy insulation is also part of the recipe, the popper casing and paint tin are stuffed with fiberglass. This is important so that heat is not wasted and keeps MET to acceptable levels and reduces microprofile variations during roasting. Sorry no pretty pictures of beans flying... now I just use smell to trigger the cutoff at end of roast, usually to within 5-10 secs. There is a 20W halogen in the RC, but I don't use that except to check bean flow if roasting late.

For BT there is a type T 1.5mm sheathed probe coming into the RC fairly high up and dropping down to within 25mm of the base of the chamber, about 13mm away from the side, and a type K in the airflow just outside the RC - position carefully adjusted to read a good average of the ET, close to what it is after high speed mixing upon entering the RC through the slots. The BT probe is fairly close to the incoming air so that BT PID control is stable. It is quite representative of BT as I once turned the heat and fan off at the end of the roast and waited for 1/2 a minute and the temp just dipped 1C quite rapidly then stayed constant. This was the only time I have had to take the roaster appart as the bi-metalic cut-out tripped and would not reset. So I am quite happy that my measurement reflects BT, not air. Running a probe around the RC during roasting showed less than 2C variation throughout the beans. Turnover time is 30-60 secs, quite slow.

Profile notes:
I am always roasting for espresso. I start my profiles at 120C, nothing happens before then IMHO. With 1/3kg it takes ~90 secs to get there under full heat and air. By 120C the beans are always flowing properly, then drying phase to 150C in 3 min, ramp to before first at 197C in another 3 min then a controversial slow down to allow the insides of the bean to catch up with the surface - 1 min to 198C then a final ramp to 338C in 5 min, which is past my cutoff point, which is usually in the range 332C to 336C, well before SC. Normal FC is at 207C, but with the stress relief of the rest before, often is minimal. These final temps may be a bit high - I blame the crappy Auber controller not well calibrated for type T probes. My MET is usually ~250C, measured on another old controller with a type K extension wire junction. Today's roast was just 245C MET for a 335C finish. It is important that ET is monotonically increasing for the final ramp - often I gradually wind the fan back manually to keep the PV tracking 2C behind SV while keeping the power on continuously to the heater. This does seem to produce the best results.

Cooling with full load on warm day (~28C): 30 secs down to 180C, then another 30secs to 130C, pretty sure all chemical reactions have stopped by then. Bottle up at 50C.

I include these numbers here so that others with similar setups can compare - I stress every roaster is different! It is all about results and personal preference. I do not vary my profile all that much, except the end point, (good quality beans do not benefit from slowing before 1st, but then they are not harmed either IMHO) and scale everything back 5C or so for decaf as these beans have been weakened internally by water processing. My preference and results are a very uniform bean colour, no oil at any time after roasting, must be a bit on the nutty side rather than toffee, hence the extra time just after the Maillard zone. Surprisingly with this load and resulting long microprofile and lower air/coffee ratio I need rest times often 4-6 days which is unusual for a popper, more like a drum. All to do with the load. I get no rest required with a 150g load - minimal microprofile with fast turnover time. Is this why drums seem to be preferred to air?

BTW the base crate was just there - could not find an instrument case big enough for everything and hey the holes in its base were exactly 1/16 DIN for the controllers... I like having one piece of kit for roasting, just pick up carry outside and turn on, roast, then pour the beans directly into the jars I use for storage - tall 750g Dolmio jars that take the 275g typical yield exactly and slide into the wine cabinet, same diameter as a wine bottle. I don't get much out gassing, not sure why.

I have to admit that it was an upgrade to a BDB machine that triggered a resurgence in attention to roasting as I started getting more detail out of my roasts than I was previously with the PIDed lower end DeLonghi machine I was using. Then the fan started to bind and I thought it was over for the popper... top bearing on the fan that is inaccessible even after disassembly, then WD40 on the armature and leave the roaster upsidown for a week and all is running smoothly now. The front panel on the Auber is falling apart and I want better than 1 min resolution on profiles so the time has come...

Thanks to Ginny for keeping this forum going, thanks to all contributors for hints to help fine tune the direction. This forum has come a long way in 3+ years. I will write up the new roaster soon. Have just done my first test flight (fully manual).
eric attached the following image:
popperroaster.jpg
 
greencardigan
Hi Eric and welcome back :)

I started off with that exact same popper but went with a DIY PID controller and variable DC laptop power supply. The sad thing is mine got chucked in the bin when I cleaned up the garage a few weeks back as it hadn't been used for years!

Those final temps do sound too high though the FC temp is close to what I get in my current air roasters.

Looking forward to the seeing the new roaster! Can I ask where abouts in AU you are?

Brad
 
yamhill
Wow, that is some popper. I have a quite robust wearever 72000, but it only manages 130 grams or so.
 
eric
Hi Brad,

Ooops got those temps wrong of course - 245C MET for 235C finish - still high but not outrageous! (can't see edit button?)

My new roaster uses exactly the same heat gun ($20 @ Bunnings) as your 500g roaster. Plenty of headroom for 600g.

Located in Sydney. Will PM.

Anyone with some ideas on microprofiling and its effects?
Eric
 
seedlings

Quote

eric wrote:

Anyone with some ideas on microprofiling and its effects?


What do you mean by microprofiling?

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
eric
To me microprofile is what an individual bean sees as it goes through the roasting process. How often it touches ET, how much/long of a hit it gets and how long it then transfers heat to other beans around and into its insides and cools marginally. Changing the batch size is the only way of changing this in a given roaster, for most roasters - and there is a very definite effect here. If there is a lot of truly chaotic motion then microprofiles are randomised and the effect appears diminished. It has been noted that better results are obtained by having a definite cycling of individual bean temp during a roast - a high velocity air roaster has little (eg light load in a popper) and there is less flavor development - at least that is what I get reading between the lines on several forums. Just wonder if anyone has noticed this effect? Building a new roaster gives me another sample point.
Eric
 
allenb

Quote

eric wrote:

To me microprofile is what an individual bean sees as it goes through the roasting process. How often it touches ET, how much/long of a hit it gets and how long it then transfers heat to other beans around and into its insides and cools marginally. Changing the batch size is the only way of changing this in a given roaster, for most roasters - and there is a very definite effect here. If there is a lot of truly chaotic motion then microprofiles are randomised and the effect appears diminished. It has been noted that better results are obtained by having a definite cycling of individual bean temp during a roast - a high velocity air roaster has little (eg light load in a popper) and there is less flavor development - at least that is what I get reading between the lines on several forums. Just wonder if anyone has noticed this effect? Building a new roaster gives me another sample point.


Very interesting topic. A few of us have been pondering this for a while but haven't seen any real testing to nail down whether on heat/off heat cycling versus always on really comes out different in the cup. The assumption for many of us has been that it does have a positive affect. Some studies have shown that overly high air velocities can have a negative affect due to loss of volatiles (stripping) but possibly could it be that it's really a result of not having this on/off cycling of the beans in and out of the heat source?

Have you found any studies related to this you can post links to?

If yes, or if you just want to get a discussion going on the subject please post about it in our "Roasting Coffee" forum.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
JETROASTER
Nothing scientific, but I have come to prefer a disciplined sprout, high density bed.
I (try to) maintain the lowest velocity necessary to fluidize and adjust heat to maintain my desired input temp.

Whenever I'm lazy on adjusting the bed 'down', I wind up with a flatter cup.
Thanks for posting Eric! -Scott
 
seedlings
Roast 60 beans one-at-a-time with a lighter or candle. That will give you about 1 cup of brew!!! !! !!!!!!

HA!

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
eric
Just follow up on temps to confirm now that I am using TC4 + typeK am getting more reasonable numbers - 203C FC and 228C finish for my preference before SC.

@Allen
Yes I will collect together my ideas, I have been just soaking up anything I read, however have not kept links. I think it needs more attention - never seen it a design consideration on all the roasters here.

Quote

freshbeans wrote:

Nothing scientific, but I have come to prefer a disciplined sprout, high density bed.
I (try to) maintain the lowest velocity necessary to fluidize and adjust heat to maintain my desired input temp.

Whenever I'm lazy on adjusting the bed 'down', I wind up with a flatter cup.
Thanks for posting Eric! -Scott

More confirmation, though separating microprofiling from stripping is going to be difficult.

With my new roaster I am having a go at doing your thing automatically - putting a paddle on a load cell and using that in a feedback loop on fan speed. Not going yet.

@Chad That's just forum noise!
Eric
 
Jump to Forum:

Similar Threads

Thread Forum Replies Last Post
ESP32 TC4 Popcorn Popper Dataloggers/Controllers/Rate of Rise Meters 1 01/28/2023 11:13 PM
Air Popper Heater Popcorn Popper roasting 39 08/29/2022 2:50 PM
Popper gets really hot after only a few seconds of heater on Dataloggers/Controllers/Rate of Rise Meters 22 01/08/2022 5:57 AM
Modifying Sweet Mary’s Nostalgia air popper for dummies Popcorn Popper roasting 4 09/02/2021 9:51 AM
Cleaning an oily, stained popper drum Popcorn Popper roasting 4 08/15/2021 3:05 PM
Homeroasters Association Logo, and all Content, Images, and Icons © 2005-2016 Homeroasters Association - Logos are the property of their respective owners.
Powered by PHP-Fusion Copyright © 2023 PHP-Fusion Inc
Released as free software without warranties under GNU Affero GPL v3
Designed with by NetriX
Hosted by skpacman