This Imex is a tricky beast

[simonp]

I'm still struggling with roasting in the Imex I have no problems up to first crack, but after this the temp rise is just too slow, and it is so hard to reach second crack, my measured temp gets to 430F OK, but then it just takes ages to get higher. When I do finally reach 2nd, I just cannot hear it
Any tips, Imex users?

[MKSwing]

I'm still struggling with roasting in the Imex I have no problems up to first crack, but after this the temp rise is just too slow, and it is so hard to reach second crack, my measured temp gets to 430F OK, but then it just takes ages to get higher. When I do finally reach 2nd, I just cannot hear it
Any tips, Imex users?

Hi, I'd like we talk using Celsuis, it's more international and this is what I use for my imex. I've put a themocouple where the airflow goes out the machine and did a nice graph I hope we'll see soon in the articles part of TMC but let's go back to your problem

For me, the imex starts 1st crack at around 185°C and second at around 210/215°C. I agree with you, you have to listen very carefully around 210°C to hear the 2nd crack but you can totally hear it. Some use a cloth (is that the correct word ?) to isolate the chamber so the sound is clearer but seeing how good is a profile of a standard imex, I think it can only mess the process.

[simonp]

I use F as the profile graphs I have are from the US.

I find the Imex roasts fer too fast at the start of the roast, hence my heat controller to slow the first part.

I have the thermocouple through the exhaust and into the beans, first crack is at 210C, second I cannot hear, but is has definitely started by 226C. I'm seeing about 5 minutes from first crack finishing to second starting, too long.

[MKSwing]

I have the thermocouple through the exhaust and into the beans, first crack is at 210C, second I cannot hear, but is has definitely started by 226C. I'm seeing about 5 minutes from first crack finishing to second starting, too long.

WOW ! How much time does it get to go to 210°C ? I never saw mine going over 215°C. And my roast heating time is around 12 minutes.

[simonp]

I'm profiling so that first crack starts at around 10-11 minutes. I'm running the heat so that there is a 6 minute rise 10 to 145C, then 3 minutes to 195C, then try (not acheiving this) 6C rise per minute to the finish.

Your temperature at the exhaust will be way below the bean temperature, first crack is around 200C bean temp, I believe.

[simonp]

Some use a cloth (is that the correct word ?) to isolate the chamber so the sound is clearer

No, this doesn't work, yes it dampens the noise of the beans moving, but I still can't hear 2nd crack till it is WELL under way. I do have the Kitchen extractor running which may not help.
I roasted some Lintong this evening, and stopped it when I thought I heard some crackles. When I dumped the beans, there were lots of divots, so 2nd was well under way.

[Raf]

The problems that you described are exactly why I stopped roasting (having an excellent microroaster nearby also helps ) It was too hard to hear the second crack and the results were just too inconsistent. Someone wrote a great post about the problem on alt.coffee where he listed all the reasons for not homeroasting anymore.

[phil]

It looks as if it boils down to "don't home roast if you don't have a Hottop"!

Yeah I know I'm biased - but I've yet to hear of a Hottop owner that thinks homeroasting is too hard and the results not good enough. Seriously. They may exist - but I haven't heard of them.

One well known microroaster sent out to a national blind cupping test samples which had been roasted in a Hottop. I think only one person guessed (me), and that was only because there was some loose chaff in the roast. The taste was excellent.

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[tisri]

Even using a HotTop can be a tricky business. You have to decide how many times to hit the Plus button and judge whether your beans are very dark brown, extremely dark brown, practically black or totally blackened while fending off remarks about using soot from the chimney.

[simonp]

It looks as if it boils down to "don't home roast if you don't have a Hottop"!

Not so, I got excellent results using my modded popcorn machine, cracks are easy to hear. BUT you need to do it outside due to the chaff/smoke issue, and in winter it is cold to sit outside, and dark in the evenings.

[phil]

Hey, you didn't quote my laughing smiley!

[simonp]

I meant to, must have slipped with the mouse

I just have to defend the cheapskate's coffee corner!

[MKSwing]

I just have to defend the cheapskate's coffee corner!

I agree with you, the imex is doing really good, even without "hacking" it.
The only thing that would make me upgrade is the sound.
But there are 2 things I don't like about the hottop.
1. It costs too much.
2. Every 30 roast, you are charged for a filter. At this price, they could have come with a better idea.

I'd really like to know how the i-Roast is doing and how much noise it makes.

[phil]

The feedback on the i-Roast I see on a.c is significant sample variability, some reliability issues and it's noisy.

I agree that the Hottop's disposable filter is not ideal, but it is effective IMO. There are ways of extending the filter life, and unless you roast to destruction the cost is just not significant at all. It's just something people like to mention when they're looking for reasons not to like the Hottop.

Re the cost of the machine, it always surprises me that people think it's reasonable to spend the price of a small car on an espresso machine, but that a top quality roaster should be cheap for some reason. The Hottop is a premium product and vastly better than anything else on the market unless you go up in price towards professional territory. I know exactly how much the European distributor is paying per unit. The retail price is reasonable.

The Hottop may not be on its current pedestal for ever, but for the moment it's the machine to have unless you want to build stuff yourself like simonp and matts have.

I hear very mixed stories about the Imex too. You obviously love it Stephane, but Raf & Eward both had significant issues and problems with theirs when they each bought one in the first half of last year.

I love the Hottop so much because I just wanted something to roast coffee and do it well enough that I would no longer want to buy pre-roasted. I don't want to be messing around trying to build a better mousetrap - I have enough to do in life with a job, a family and a growing web site to run.

The Hottop does that for me. Totally. I just have to remember to roast the coffee. Job done.

[simonp]

I think that for lighter roasts, for non espresso brewing then the Imex is fine, even good. For espresso roasts where you are getting to or going in to 2nd crack then you hit issues with not enough heat input, and not hearing the cracks. I'm going to try the pattial blocking of the outlet to get more heat re-cycling to speed up the end of the roast.

I think that for most non fanatical coffee people the Imex is fine. For these people, just the fresh roast will be enough, but for geks like us who want profiles, and exact roasts it is maybe not the best. Horses for courses .

Me, I'd love a Hottop, but, no space, and too much money. I spent £200 on the used espresso machine, £30 on the used Rocky, so £500 for a roaster is just not one, even though it may well be worth £500. Plus being an engineer, I can't resist buolding a better mousetrap