Popper Mods for a SB Cornelius...

[bennyb]

Hi all.

I just tried a roasting of this stuff in the popper today. I had just finished the pack of Zimbabwean which also came in my Starter Kit (newbie roster here), and it was great! But this stuff was a nightmare; No second pop, billows of smoke and jet black beans after only around 5:30 (the Zimbabwean was taking 6:30). Oh and oily as hell. I emptied them out onto paper towel in an effort to get some of the moisture off.

Do I need to somehow tone down my popper to get a good roast on this bean?

cheers

Ben

[Thundergod]

Re: Ethiopian Gambella Naturals

Which popper do you have?

[bennyb]

Re: Ethiopian Gambella Naturals

Which popper do you have?

Its the Sunbeam Cornelius.  It was a bugger to open, I had to drill out a security screw which had a weird triangular pattern!

Im thinking of splitting the fan off to a separate 24V supply then putting a nice beefy 6A rectifier in series with the heating element;  It should chop the AC wave in half effectively also halving the power.  I hope half-power heating (650W) still produces enough heat to roast a bean!  Maybe Ill mount a switch to turn the element on/off so I can cut the heat for longer roasts if needed.

[Thundergod]

Re: Ethiopian Gambella Naturals

I doubt there will be enough power to roast.

The way I increased roast times was to get more air in and to open the body up to let retained heat escape.

Have a read:
http://coffeesnobs.com.au/YaBB.pl?num=1221653644/9#9

[Bill]

Re: Ethiopian Gambella Naturals

I hope half-power heating (650W) still produces enough heat to roast a bean!

It wont be hot enough. Ive got a high-power dimmer on the heater circuit on mine, and need to adjust it to around 80% power to get to first crack.

[Dimal]

Re: Ethiopian Gambella Naturals

Gday Bennyb....

When you refer to a rectifier, do you mean a "Half Wave Rectifier (Diode)" in series? A better method to use, for something simple, would be to use a "Full Wave Rectifier" which will reduce the voltage output to the heating elements (in true RMS terms) by about 10%. This might be just enough to allow you sufficient control using only the fan speed for fine adjustments.... More air-flow for lowering the bean mass temp. and visa-versa to increase it.

Also, a 6A bridge is a little on the low side where youre talking a continuous load of roughly 1,200W. Id double that and then consider using a decent Heatsink as well. All the best mate,

Cheers,
Mal.
P.S.
Another thing to be wary of... Any switching to control the heating elements should be in the A.C. circuit, NOT the D.C. circuit.

[bennyb]

Re: Popper Mods for a SB Cornelius...

Thanks guys.  Good suggestions.

I drilled a heap of holes on either side of the popper today; Then pointed a little fan at it.  First pop kicked off at around 2 minutes so Ive still got a long way to go.  Wouldnt have helped with the air temp in Melbourne being 33+!

Mal, I was basing my diode current rating on P=VI so I = 1200/240 = ~5A.  Given power and voltage are both quoted as RMS, the current should stay the same if PMPO is substituted instead for both V and P terms right? But its been a heck of a long time since Ive done a calculation like this!

Im going the bread maker route now, already wasted too much time fiddling with this thing!  ;D  I wouldnt recommend the popper solution to anyone who has taken the time to register at Coffee Snobs, its just not worth the extra step towards a better roasting system.

[Thundergod]

Re: Popper Mods for a SB Cornelius...

Its actually a good first step up the learning ladder.

[Dimal]

Re: Popper Mods for a SB Cornelius...

Hard to go wrong with a Corretto Benny.... 8-)

Once you get the details sorted out for your particular setup, you will enjoy very good control. Important to think about acquiring a DMM with temperature function too, as this will help you to know exactly whats going on within the bean mass. Andy is in the middle of trialling one or more units to see if theyre suitable for listing in BeanBay but I dont know how far away this is. Might be worthwhile considering a "cheapy" from DSE or Jaycar in the mean time.

Referring back to the Diode(s).... Their power rating is very much influenced by both environment and junction temperature and it is this that will limit their maximum output before thermal runaway destroys the junction. Always safer to err on the side of caution and be very conservative when selecting suitable devices. If you understand the basics of electronic devices, then you could select suitable components by referring to their data sheets. As an aside, the RMS voltage output from a full wave bridge is close to 90% of the input A.C. voltage....

Cheers,
Mal.

[bennyb]

Re: Popper Mods for a SB Cornelius...

I managed to get a cheap little Panasonic BM off eBay. It only required a simple low-voltage mod to bypass the stop-start spin. I bought a heat gun from Bunnings and Zip-tied it to a folding chair then pointed it into the BM; Works a treat, only $80 total!

Ive just ordered 10kg of green beans.

[Thundergod]

Re: Popper Mods for a SB Cornelius...

I bought a heat gun from Bunnings and Zip-tied it to a folding chair then pointed it into the BM

A picture please.

[smokeydeck]

Re: Popper Mods for a SB Cornelius...

I managed to get a cheap little Panasonic BM off eBay.  It only required a simple low-voltage mod to bypass the stop-start spin.  I bought a heat gun from Bunnings and Zip-tied it to a folding chair then pointed it into the BM;  Works a treat, only $80 total!

Ive just ordered 10kg of green beans.

that sounds great! I also started with the cornelius. it only lasted a month till it started to die. i switched to a corretto and never went back. enjoy.