Ambex Users

[munkee]

Is there any more to discuss regarding the Ambex?

I just read this thread and would love to hear more discussion.

[peter]

A very good looking YM2K sold on fleabay this week; $4100, included some ductwork and a 100lb. propane tank.  The main thing that kept me from winning it was that it was an 8-hour drive both ways to pick it up.  But I truly see a roaster like this in my future.

[munkee]

I watched and bid on that YM-2.

He was going to allow an equipment carrier to pick it up if I won the auction, but the freight pushed it beyond what i wanted to spend.

[milowebailey]

Since I've had my Ambex the temperature readings never seemed right to me.

1st crack beginning was almost always between 385 - 390 degrees F
2nd crack beginning was at 412 - 416

These readings were very consistent.  However, the issue I see with this is there is only a measured maximum difference of 31 degrees between the beginning of 1st and the beginning of 2nd.  So it's very difficult to judge if If I was at C+ vs FC except for looking at the beans.  I wasn't happy with the minor inconsistencies I've been getting and assumed I was actually measuring the environment temperature near the top of the bean mass (possibly an occasional bean or two coming in contact with the probe)

Back in my sonofresco days I had a temperature probe and measured temperatures closer to:

1st crack (which I could hear) started at about 400 - 415
and I'd cool at about 438 - 450 depending on the bean

George Steinert's Degree of Roast/Temperature chart:
      
Degree of Roast    Temp    
Green Unroasted    75    
Starting to pale    270    
Early yellow    327    
Yellow-Tan    345    
Light Brown    370    
Brown    393    
1st Crack Begins    401    
1st Crack Under Way    415    
City Roast    426    
City+    435    
Full City    446    
Full City+    454    
Vienna (Light French)    465    
Full French    474    
Fully Carbonized    486    
Immanent Fire    497

So at Coffee Fest I spoke to Terry from Ambex about it and he said I should be reading a higher temperature and he recommended replacing the thermocouple, making sure I get the probe into the bean mass.

I replaced it with the 4" probe Ambex sells and got the probe placed a low as I could.  My readings went up about 2 degrees.  I still wasn't happy so I started doing some research on probe placement and looking at it more from an engineering standpoint.  I came across a good article...... on the Ambex site



In trying to estimate how deep the beans would be in my drum I determined that a 4" probe is not long enough to get through the compression fitting in the wall of the roaster, plus the bend radius and the down near the stir veins as per the above image.  In fact with the new probe I was a good 2" above the stir veins.  So I found (in my goodie box) a 6" probe.  I installed it and got the probe tip approximately 1/2" above the stir veins, checked for interference and then roasted a batch.  The results were what I'd hoped for.

1st Crack began 401
2nd Crack began 437

I may try to get the probe even closer so I can get more consistent readings with only 1 lb of beans in the drum.  The 6" probe gives me much more flexibility in probe placement.

You don't need to buy the probe from Ambex.  Any J or K or T type, 1/8" diameter probe will work.  Just make sure you change the PID if you change from a J type to a K or a T type.

I'll post photos in the next week or so, I didn't get around to taking any last night.

[FinerGrind]

Great info Larry. I know my bean probe is too short, no more than 2"; I think it must have broken off but the end of the probe is smooth and round so I don't know for sure but I need to replace it.

[Ringo]

Looks like I have some work to do, my 1c comes in at 367 with a small load and 385 with a full load.  Thanks for the info.

[seldomseensmith]

I hit 1C 385-390, 2C 430-435

I have a 6" probe that is just left of center when you open the door, and maybe 3/8" off the drum floor.

[danetrainer]

With 1kg of beans in my YM2 I see temps that are in what I feel is a "correct range" for the bean, typically
375-385 for 1C and 2C doesn't happen until upper 430, 440 depending on the bean type.

1lb batch is a complete different story and I'm sure correlates to Larry's probe placement discussion here. I generally stick with 1kg minimum load. My roaster was manufactured in 2009, I will have to look inside to determine what length of probe is in it.

[danetrainer]

Interesting...my probe is 2" and there is no bend to it inside the roaster to come closer to the drum wall. It is mounted on the inboard side of the site glass window, It would be 1 3/8" closer to the drum if the glass mounting were merely rotated 180 degrees...hmmm

[Ringo]

I moved my probe before I roasted yesterday, I think it was a good thing.  1st crack came in around 385 to 389 degs.  This is better, and small loads and large loads seem the same.  This will really help with controlling the roaster.  One strange thing now is when I am in the 340 to 350 degs range now bean temp is higher than environmental temp.  Bean temp continue to rise but environmental drops as I try to slow the roast before it gets into 1st crack.  I am guessing the heat is coming off the drum during this stage, I did not change how I am roasting so this has been going on before I just did not know.  I will have to do some testing with a little higher airflow and see if the cup improves.

[milowebailey]

I have decided to add a separate fan for my bean cooling.  This is something I spoke to Terry at coffee fest.  I've never liked that it take 6 -8 minutes to cool the beans in the Ambex.  Seems the airflow is underpowered for cooling and I can't start another roast until the beans are cool.... I ordered a high temperature blower and some duct parts.  I plan to use one of the cooling tray cleanout panels as the exhaust port.

I may also add a chaff collector as part of the new exhaust design.  Pictures, parts list and drawings coming soon.

[FinerGrind]

I have decided to add a separate fan for my bean cooling.  This is something I spoke to Terry at coffee fest.  I've never liked that it take 6 -8 minutes to cool the beans in the Ambex.  Seems the airflow is underpowered for cooling and I can't start another roast until the beans are cool.... I ordered a high temperature blower and some duct parts.  I plan to use one of the cooling tray cleanout panels as the exhaust port.

I may also add a chaff collector as part of the new exhaust design.  Pictures, parts list and drawings coming soon.

Larry, I have a supplemental fan for the cooling tray. I don't know if mine is high temp. blower or not, because it's external, in a (not so well designed) sheet metal box with an intake and outflow. The vent pipe coming out of the cooling tray is long enough that by the time the air gets to the fan, it's cooled somewhat and when it travels through the outflow pipe (a standard dryer metal hose) it's cool to the touch. The extra fan really does the trick - the beans are cool to the touch around 3-4 mins., and without it takes about what you listed above. It also lets me roast back-to-back so I can control the airflow through the drum if I want too. I'm curious how the US Roasters and Probat handle cooling tray airflow - I worked on both during a roaster maintenance class and for the life of me, I don't remember if they have internal supplemental cooling fans or not...

[milowebailey]

Here is a photo of my 6" probe.  I've only done 1 roast with it.... kinda roasted 25 lbs with the one Ambex sent me before I put this one in.  Tomorrow I'll roast a few batches and will report on the consistancy... I'm going to try 1 1/2 lbs and see how it reads.

[milowebailey]

I got the duct fittings in the mail yesterday for the blower.  I had to build an adapter place from a 2 1/2" x 3 1/4" rectangular hole to a 4" round hole.  Had company tonight so didn't get to finish cutting the hole in the steel.

As soon as I finish the install I'll post photos.

[FinerGrind]

Here is a photo of my 6" probe.  I've only done 1 roast with it.... kinda roasted 25 lbs with the one Ambex sent me before I put this one in.  Tomorrow I'll roast a few batches and will report on the consistancy... I'm going to try 1 1/2 lbs and see how it reads.

Larry, where did you source your 6" probe? I'm pretty sure my YM-5 doesn't have one that long and my YM-15 is a stubbie. I know my temps are off because it doesn't reach as far into the bean mass as it should.