500g in a Hottop

[gregpullman]

Following on from Sink Cuts 300g in a Hottop question in http://coffeesnobs.com.au/YaBB.pl?num=1220868024 which led to the Hottop being pushed to 350g and then 400g, the torture chamber was re-opened tonight and the hungry Hottop B loaded with 500g of green beans - double its nominal capacity! Am I stupid??! No, I just like to see how far things can go before the cracks in design start to show!

This time I used 500g of Peru Grace Villa Estate and things went like this:

Time Temperature Adjustments
23 75
22 66
21 78
20 94
19 109
18 123
17 136     Fan 1, 80%
16 145
15 153
14 160     Fan 2
13 165
12 171
11 176
10 181
9 185
8 188     100%
7 192
6 196
5 200         Fan 3
4 204     Fan 4, 70%
3 208
2 212     40%
1 215
0

The 400g roast log showed the temperature slowed in the latter half of the roast (2 deg/minute) which was good and is normally what I aim for, but because of the extra bean mass it dragged the roast on too long. That roast went for nearly 24 minutes, and considering a Hottop wont go any longer than 25 minutes I didnt want to waste that much good quality coffee and have it miss SC! So I made the unusual decision to increase heater power back to 100% about 2/3 into the roast. At 80% power the increase had dropped to 3 deg/min and chances were it would have dropped down to 1-2 if itd stayed at 80%. By this stage the beans were a nice light brown and fairly dry so there was minimal chance of tipping as there could have been if itd been done earlier. This allowed the roast to push along at 4 deg/min for the rest of the roast.

First crack came about 19 minutes and sounded like fireworks, very similar to the Mexican Vera Cruz organic. Power was then pulled back to 70% and then 40% to prevent hitting the auto-dump point of 220C. The beans and the device had enough heat to basically complete roasting themselves by this point. FC continued and ran pretty well straight into SC which started with about 22:30 and again was very marked and aggressive once it started. Roast was dumped just shy of 23 minutes.

The roasted result was actually better than the 400g one. No divots, a more even colour and very little chaff in the roast. This is more a product of the bean than the roaster of course, but it was a surprisingly positive result. A couple of dozen beans overflowed the cooling tray but it wasnt as full as I expected, although its effectiveness in cooling was noticeably worse - after the 5 minute cooling cycle the beans were still warm, though not hot by any means. The final weight was 422g at about CS9-10. Very impressed indeed both with the roasted result and that the Hottop can perform so well at 200% load. Of course this may not be unique to the Hottop, its just the unit I use but I might fire up the Gene and see how it goes with the same challenge! Mwahahaha!

600g anyone??

Greg

[Dimal]

Re: 500g in a Hottop

Pretty impressive stuff Greg... 8-)

I wonder how long the HotTop would stand up to prolonged roasting of batches this size? What a pity they dont actually make one that is rated for duty at this batch size; would be a lot more popular in our neck of the woods I think. Would suit me if I only had to roast a couple of batches each week....

Mal.

[TC]

Re: 500g in a Hottop

Pretty impressive stuff Greg... 8-)

I wonder how long the HotTop would stand up to prolonged roasting of batches this size? What a pity they dont actually make one that is rated for duty at this batch size; would be a lot more popular in our neck of the woods I think. Would suit me if I only had to roast a couple of batches each week....

Mal.

Agreed, Interesting stuff Greg...

I have had a few goes with the Gene at 400g and it can do it as well. Probably wouldnt try it with Malabar though ;D

[Dennis]

Re: 500g in a Hottop

Interesting to see this can be done.

I have concerns that as the equipment isnt rated for such loads, and overloading may have an adverse affect on life expectancy, let alone void warranty. Maybe this isnt the case as Greg has thrown out a challenge? :-/

Dont worry Dudley - I wouldnt do it to you.

[Randy_G.]

Re: 500g in a Hottop

500 grams is a lot of grams for a Hottop. Right off, the length of the roast in total time is just too long. So whether or not the roaster can manage to finish a roast of that mass is, IMO, a moot point. That long of a roast was one of the negatives I mentioned in the original reviews of the KN-8828 and KN-8828D. It also becomes a matter of whether enough heat energy can be generated early in the roast to properly remove the necessary amounts of moisture early on so that at the end of the roast the beans can be developed without having to use too much heat energy from the heating element.

There is also the matter of the amount of chaff produced and the resulting increased hazard of it catching fire. Probably only a minor safety issue, but it could be a problem with the resulting taste that could get transferred to the beans. Same can be said for the machines ability to clear the increased amount of humidity and smoke during the roast, and the effect that might have on the electronics in the rear areas of the machine. The increased load will also press against the ejection door with more force, and if a bean gets lodged int here a lot of coffee can suffer from premature ejected... I said EJECTED... ;D

With that amount of beans, the wear and tear will mostly be to the drum motor and its gear box, and also to the agitation arm motor having to agitate a much greater load. The KN-8828xs are amazingly robust. Over the years many of the parts have been upgraded and updated as there were reports of problems. The bean cooling fan was updated as was the gearbox and drum motor. I think the biggest problem when roasting this size of a load is going to be a coffee with a lower quality taste than could otherwise have been created.

[farmroast]

Re: 500g in a Hottop

the biggest issue is the time between about 150c and first crack really dogged and will eat up the sweetness and add woodiness.  Should be under 6mins for this phase to produce an acceptable roast. Reminds me of trying to put 5 in my old VW beetle and did ok until we hit the steep hill  :-/
farm

[gregpullman]

Re: 500g in a Hottop

Its really just an experiment. As I mentioned in the 300g thread, Im not suggesting it should be done, Im sure over time the components would wear prematurely as Randy and Dennis both suggested and by overloading a unit you would certainly void warranties. But since this is my own unit Im prepared to see how it performs under higher loads for experimental purposes at my own risk, as we all recognise when we intelligently push things beyond their rated limits. Nothing wrong with a bit of experimenting though... next thing well be loading 20g of coffee into 14g baskets and trying to roast with heat guns! ;D

Like a lot of things, I think nominal ratings are often there to deal with the worst case scenarios, but if you understand the factors that can cause a problem and minimise those, you can often go beyond those ratings. The chaff as Randy suggested is one such point. This was certainly a concern of mine in the 400g Indian Tiger Mountain A roast but the Peru in this roast was much lower on chaff. You wouldnt try to push the limits on a very chaffy bean such as the Yemen Bani Ismail, for example. It reminds me of my old VL Calais Turbo (from way back!) - they all ran 6psi boost stock but provided you used good quality fuel they could handle 11psi with no mods, and up to 17psi with an intercooler, all without having to strengthen the motor at all (pistons, conrods etc). The 6psi would cater for all situations, but with appropriate precautions (such as not running too high boost on a hot day) you could go well beyond that.

Also, as a supplier of these devices Im interested to see how they perform beyond their rated limits as a guide to how well engineered they are (or arent). Just as for years Holden sponsored those Commodores at the Show where theyd fly them through the air and drive them round the track on two wheels. Good at showing off their engineering, but theyd never recommend Commodore owners to try this at home!

Maybe Im not an espresso afficionado, but the 400g one was one of the best roasts Ive done so far - definitely not lacking in sweetness - but if the 500g one tastes like seasoned Jarrah Ill know what I did wrong FR! ;D

One interesting outcome is to consider that this is a 750W element able to roast 500g of green beans in 23 minutes, and thus is only using just over 30% of the nominally rated power from a standard GPO. If you were to roughly double the size of the drum (and engineer the rest of the unit appropriately) and add a second (or third) heating element, you should be able to provide more than enough heat to achieve a 500g+ roast without any of the compromises.

Greg

[Dimal]

Re: 500g in a Hottop

If you were to roughly double the size of the drum (and engineer the rest of the unit appropriately) and add a second (or third) heating element, you should be able to provide more than enough heat to achieve a 500g+ roast without any of the compromises.

Greg

If only Greg..... :

Mal.

[farmroast]

Re: 500g in a Hottop

One interesting outcome is to consider that this is a 750W element able to roast 500g of green beans in 23 minutes, and thus is only using just over 30% of the nominally rated power from a standard GPO. If you were to roughly double the size of the drum (and engineer the rest of the unit appropriately) and add a second (or third) heating element, you should be able to provide more than enough heat to achieve a 500g+ roast without any of the compromises.

Greg

I agree, but my guess is the reason commercially produced homeroasters have a 1/2 lb or 250gr max is about the amount of smoke production with larger batches, especially if one was to dark roast. Plus more chaff and fire potential and liability. I have no trouble roasting a hard bean batch with up to 900grams and a good profile using 1600watts 120v in US with some convection for better heat transfer.
farm
ps Greg I like your tapers, do you have anyone offering them in the US?

[gregpullman]

Re: 500g in a Hottop

I think youve summed that up well FR (perhaps what I was trying to say, but in different words). 250g is the capacity at which you can roast anything. However if you know what youre doing you can go beyond that (well beyond it in your case! ) but you have to pick your bean and conditions carefully and of course be aware of the extra load placed on the device.

No US retailers at this stage - I dont actively push for retailers, I let people come to me who feel their store has the right qualities for my tampers. Being a more expensive unit than some others, they dont appeal to the masses as much so its up to the retailer concerned to see a potential and approach me about it. However Id be more than happy to help out if you want to order one directly.

Greg