Ambex Users

[H-D Rider]

OK since I got my Ambex YM-2 I have been struggling to get good roasts.  I know there is a learning curve and I don't expect to become a Roast God overnight but I'm sitting here at work tonight with a fresh cup of Ethiopian Hope Project, roasted 72 hrs ago and it's better than the local fuel stop swill but I have no fruit.  Many of my roasts since I got the Ambex are good tasting but not what I was getting from my Hottop.  I know it's my fault but I'm ruining good beans.  They're a good drinkable beverage but not at all what they should be.   I've tried #3 roasts down to 1# roasts.  I have times that I would think are very respectable as far as time to 300 and yellow, time to 1st and a nice coast (3-4 min) to end of roast, but they aren't really successful in taste quality.

Here's what I have done in general.  Drop temps vary with size but my attempt is to bottom out in 45 sec-1min.  Recover to drop temp in another minute.  Steady rate of climb to 300 within 5 min.  4-5 min to 1C.  coast to end of roast 3-4 min.   Lighter roasts(just out of 1c 3-3 1/5 min) Darker roasts just this side or very slightly into 2c, 4 min.    Roasts are normally 12 to 14 1/2 min total and consistant with batch size.  I've been able to get the #3 roasts to profile very similar to a #1 batch but obviously my profile is not working and I'm stuck.

I'm at work and don't have my temp records with me to post right now.  I leave the air on full throughout. I read somewhere that was Ambex's technique.  Perhaps that's where I need to adjust.

I was hoping one of you old experienced Ambex users might shed some light and keep me from squandering away any more good beans as mediocre coffee.  Just a generic profile perhaps or a normal rate of climb between the phases?  Air adjustment maybe?

If not I'll have to start my Christmas roasting way earlier than planned 'cause the Hottop only does about 1/2lb batch.

Thanks Guys/Gals
HD

[peter]

I can only wish I had an Ambex.

Your ramp from 300 to 1C does not allow enough time in the 350F range to caramelize the sugars and develop sweetness that the fruits need.  I always let my roast hover in the 350-360 range for a few minutes.

That's my shot in the dark.

[cfsheridan]

HD--what's your temperature reading at the equilibrium point?  (bottom out).  I trained a bit on a YM-2 with the roaster who worked with Ambex to develop their automated profile tool.  She recommended that your equilibrium point not be above 150°F.  We tested this with the Alta Mogiana Brazil, and there was a BIG difference between above and below ~ 150°F.  The higher equilibrium temp gave an ashy taste to the beans.

Ambex does not recommend modifying the air profile within roasts, but I don't recall if the recommendation was full air or slightly off that.  Your times are not far off what we found successful with that Brazil, but we didn't do much profiling with other beans in that class, and I'm sad to say I have no YM-2 here.

[milowebailey]

I've found that 3# or more produces the best results.  A couple of questions

1) what is your drop temp for 3#
2) what are you roasting (high altitude grown beans roast differently)  Ethiopians are pretty high grown normally.
3) Time from bottom temp to 300
4) Time from 300 to 1st crack
5) time from 1st to 2nd

I'm fairly new to the Ambex too but have had some pretty good roasts out of it.. similar or better than the hottop.

If you are missing the fruit Peter is right.  You may be getting to 1st crack too soon.  Remember that stage is where the water evaporates out of the bean and if you get there too soon the water in the center of the bean doesn't get out.  I've been dropping at 300 with 3# and bottom out at 145 or so, then back to 300 in about 5 minutes and hover there for a bit then on to 1st crack in about 10 minutes hovering at 350 for a bit then off I go to second crack in 3 minutes after 1st has stopped.  

[nimbus]

I've never used an ambex, so I'm pretty useless here as far a specific temps. But for a lot of DP's I like to reduce the heat a minute or so before first crack. Then I shoot for three minutes between cracks. Depending on what darkness I'm going for, I'd drop it right before second crack or right at second crack, or possibly ten or fifteen seconds in.

I like to pull beans during the late stages and observe them, and even taste them. I notice the fruitiness can go away pretty fast if you wait too long. And there is also a body consideration of course.

I think a lot of it is trial and error. That's why beans come in such big bags! I rarely roast less than 15 pounds, so I try to figure it out as quickly as possible..

Cheers...and happy roasting! Keep us posted on your results.

[milowebailey]

........ That's why beans come in such big bags! 

I've always wondered why.... makes sense now!

[Shannon22]

I can only wish I had an Ambex.

Your ramp from 300 to 1C does not allow enough time in the 350F range to caramelize the sugars and develop sweetness that the fruits need.  I always let my roast hover in the 350-360 range for a few minutes.

That's my shot in the dark.

Peter, for you, is the 350-360 range right before the first crack usually?

[peter]

I can only wish I had an Ambex.

Your ramp from 300 to 1C does not allow enough time in the 350F range to caramelize the sugars and develop sweetness that the fruits need.  I always let my roast hover in the 350-360 range for a few minutes.

That's my shot in the dark.

Peter, for you, is the 350-360 range right before the first crack usually?

No sir, 1st varies, but is generally beginning ~400, lasting 'til ~415-420.  2nd crack is generally beginning ~430 in my setup, a SC/TO.



Speaking of a pro-roaster, this is the time of year I wish I had one; I roasted 7 hours yesterday, netting 30#.  Today's the same gig.   

[Stubbie]

On my USRC 18K machine - 1st crack starts around 340-350 on smaller batches, and 360-370 when fully loaded.

2c will start right around 395-410 depending on batch size.

-Stubbie

[milowebailey]

Speaking of a pro-roaster, this is the time of year I wish I had one; I roasted 7 hours yesterday, netting 30#.  Today's the same gig.   

You could almost had flown here, roasted your 30 lbs and flown home..

[milowebailey]

On my USRC 18K machine - 1st crack starts around 340-350 on smaller batches, and 360-370 when fully loaded.

2c will start right around 395-410 depending on batch size.

-Stubbie

Why is that?  My Ambex is close to those #'s and for the life of me I can't figure out why other than my thermocouple must not be accurately measuring bean temperature...

[Stubbie]

On my USRC 18K machine - 1st crack starts around 340-350 on smaller batches, and 360-370 when fully loaded.

2c will start right around 395-410 depending on batch size.

-Stubbie

Why is that?  My Ambex is close to those #'s and for the life of me I can't figure out why other than my thermocouple must not be accurately measuring bean temperature...

Why the differentiation in temps on crack times?

I have always assumed it was due the amount of thermal mass inside the drum.

On airflow, I usually go low (10-25%) at the beginning, 50% 5-6 mins in, 75% at the onset of 1c and 100% during the ramp up to 2c, with the burners turned back down low.

-Stubbie

[peter]

On my USRC 18K machine - 1st crack starts around 340-350 on smaller batches, and 360-370 when fully loaded.

2c will start right around 395-410 depending on batch size.

-Stubbie

Why is that?  My Ambex is close to those #'s and for the life of me I can't figure out why other than my thermocouple must not be accurately measuring bean temperature...

Why the differentiation in temps on crack times?

I have always assumed it was due the amount of thermal mass inside the drum.

On airflow, I usually go low (10-25%) at the beginning, 50% 5-6 mins in, 75% at the onset of 1c and 100% during the ramp up to 2c, with the burners turned back down low.

-Stubbie

I think Larry was asking about the low temps for the two cracks.  If he wasn't, I am.  It seems odd that 1C would be starting around 340-350.

[Stubbie]

That low of temps is on 5-6# batches as compared to 30-35# fully loaded.

Each bean is different too, as are therm probes and their locations I'm sure.  Mine is located right below the sight glass on the left middle side of the drum.

When I fire up the machine, the temp always reads accurately to the temp in the room.

-Stubbie

[Shannon22]

My USRC 5-kilo is in the range of Stubbie's, maybe a bit higher. First is usually 345-370 and second starts around 410-420.  From my understanding, the main difference is thermal couple placement.

Peter, generally speaking on a timeline, what's your total roast time? Time fo 350-360? Time at first & second crack?  Time that your second crack ends?