Ambex Users

[milowebailey]

Larry

The only number I could find on the Honeywell Valve was SV9501.   The valve is ahead of the control unit which is a Maxtrol M420RH.  Hope that helps. 

Could you snap a photo or two for me too?

[H-D Rider]

Does this show what you need?

[milowebailey]

Yes I believe it does...

Thank you!!!

[Ringo]

I have a question for the drum heads.  I built my roaster, big steel drum, propain powered.   I have three termocouples installed. #1 Is in the beans as they roast  #2 is at 12 oclock on the drum for environmental temp  #3 is in the hot gas stream just before it is pulled through the drum.  The relationship between the three temps is based on the air flow.  Very high air flow through the drum Bt is the highest, I think this is becouse I am heating the big steel drum up too much and the radient heat is in charge, coffee roasted this way is flat. So I started turning back the air alot as I roast, flame set to med high.  This is a better flavor but I think it shoud be better.  With very low air in the drum at 1c Bt will be 375, Et will be 380 , Firebox temp will be 430.
  Now the question- Does this firebox temp seem too high? With an ET at 380 and a FB temp of 430 I would think I am heating the drum up too much?   Coffee roasted this way is not bad, but I think it has room for improvment.  I will hit 300 deg around 5:30 min, 1c around 9 min, end the roast around 12:30 Bt around 390 for a City+ roast.
   Question #2  I am really having a hard time getting a handle on drop temps, Every time I drop the turnaround is different.  One time I drop at 280 deg and turnaround will be 168 deg, the next roast I may drop at 280 deg and turn around may be 198 deg.  In my mind I did the same thing but got really different results, any hints for me to try?   What I am doing now is after a roast, I kill the gas, open air to full after a few min when BT gets under Drop temp I turn on the gass low set air to med, BT slowly rises.  When it hits Drop Temp I drop the beans.
As soon as I drop I set air to min and flame to med-high.   After all this now question #2  How shoud I guage the heat stored in the drum better. Sorry for the long guestion.

[gotnoname19]

I dont understand why you turn temps are varying so much? Are you doing several batches consecutively? Are the batches the same size, of the same bean? I have learned that 8.8 lbs is the sweet spot for my machine. When I first start roasting, I drop at around 315, and turn at 150. As the drum heats up, I lower my drop temp a couple degrees each roast, and my turn remains at 150. I don't what would explain the dramatic differences in turn if you are using the same amount of the same kind of beans?

Oh, and when I say that my "sweet spot" is 8.8 lbs, I mean that I can drop that amount in the roaster with full gas / full air, and reach 341 between 7-8 minutes.

[Ringo]

I have been roasting 1 pound batches, This gives me more roast to work out best roasting practices but my roaster does better with 2.5 pound batches.    Thats just too much coffee for me, I do not sell.  I just give it to friends and family.  I like to have 3 or 4 different kinds roasted variety is a good thing. :)The problem does seem to get worse the more batches I roast but I am not sure, maybe I should think of a lower and lower drop as I roast more batches.

[milowebailey]

How long do you let the roaster warm up before your 1st batch?  It may be that the early roasts the roaster is not really "hot" yet.  As you roast more batches it gets "hot".  If I remember you made it with a pretty thick walled pipe.  That could take a while to stabilize.  Thus you think the drop temp needs to go down, maybe as you roast more your drum is hotter than earlier.  Also it may take a while for your drum to get back down to the environmental temp.

for the Air flow.  it's about convection vs conduction.  I'm no expert on the affect of each on the favor, I just know that Air is yet another variable.... overall it sounds like you are learning your roaster.  They each are different.

[gratefulroast]

I think Milo's hit it on the head. i remember reading a post from you previously about the thickness of the drum, and speaking from experience, the first batch (no matter how long a charge time) is always the prime batch, and will roast 'cooler' than the rest. I can imagine that the drum walls are really heating up during the first batch, pulling heat from the beans as much as to. Thus the following roasts will absorb more heat from the drum than the first, higher turn temp and faster to 1c - end roast, etc.

Once you master that thick walled drum, you're giong to be able to roast a batch of beans with more air-flow control than heat control.

[Ringo]

I think the next roast I will let everything cool off longer between batches, It has some logic the more I think about it.  On warm up I have to run the flame on med to get the roaster up to drop temp, but on second and third roast the flame is at its very min to reach drop temp.  I should have seen this-but thanks for the help.  One more guestion.  Do you go by Bean Temp or Evironmental Temp when you drop beans into the roaster.   They are only a few inches apart but hardly ever match.  I believe the BT is seeing the radient heat off the drum becouse its close to the drum. Does that make sense?  I have switched positions of the probes and nothing changes.

[gratefulroast]

Drop temp is based for me on environment. Also that point is dependent on ambient temp. When it's ball shattering cold, the drop is around 420 and when it's warm, hot or ball blistering hot, the temp is going to be between 395 and 375.

As you said, you're roasting for just you, so I don't know how aplicable this will be, but my first batch is going to be either a decaf or the lightest roast I'm running that night, as as my roaster heats up, my roasts are lined up to go from lighter to darker.. that is to say, as the drum heats up (and it continues to heat up for a few roasts), my roasting 'heats' up too.

[gotnoname19]

I think the next roast I will let everything cool off longer between batches, It has some logic the more I think about it.  On warm up I have to run the flame on med to get the roaster up to drop temp, but on second and third roast the flame is at its very min to reach drop temp.  I should have seen this-but thanks for the help.  One more guestion.  Do you go by Bean Temp or Evironmental Temp when you drop beans into the roaster.   They are only a few inches apart but hardly ever match.  I believe the BT is seeing the radient heat off the drum becouse its close to the drum. Does that make sense?  I have switched positions of the probes and nothing changes.

My drop temp is based on bean probe; I drop around 315. Whatever you do, its gonna be specific to you and your machine. Notice how different Gratefulroast's and my numbers are, but I'd imagine that we both turn around 150 bean temp, at around 1:20.

[Ringo]

I did some roasting this weekend and had a lot better control of the turnaround.  With the help of people here I realized that the residual heat was the problem.  After a roast I would blow the shop vac under the drum while I was packing the beans and weighing out the next batch, untill all temps were under 200 deg.  I used a very low flame with adjust to the air to get Bean Temp and ET very close to each other at the drop temp , this seemed to really help.   I was roasting small batches and dropping at 230 deg turn around was 175 to 185 deg.  The roast was easier to control with a more consistant turnaround.  I saw no sign of scorching, Should I try higher drop temp?

Thanks for the Help!!!

Ringo

[gratefulroast]

I shoot for an eq / turn temp of under 170 with a fast ramp to just before 1st (360ish or smell).. I open air wide at around 250 and keep the heat on blast to ramp up as fast/slow (makes sence to me!) as possible ... just before 1st I ease off the heat and try and almost coast through the crack. Depending on the bean and the roast degree, I either leave the heat on low and ride the roast till drop or bring up the heat to medium / high just after first is done till the bean goes exothermic .. then it's a no heat coast till it drops. Air flow is either 100% open or close for me.. but I'm still a noob, so it's all open to progression.

Where are you at during 1st? 2nd? I'm reading environmental temps with the probe at about 10:45.

[Ringo]

1st for me is between 365 and 375 deg.  I do not roast into 2nd so not sure were that would come in at.  I will pull a roast 385 to 400 on the BT.  I look for a smooth skin after 1st, and try roast 3 min after a good 1C.  I am really changing things around a lot right now trying find the best way to roast.   To be honest I think I built too much into this roaster, too much heat, too much air, too much steel and too many temp probes.  An old time drum roaster would like to have too much, he would only use what he needs.  For a nubbie the leaning curve is slow.  I am getting better, this drop temp was a "BIG" help. I think the DP Ethiopians are better in the drum than the Behmor now, The Hard wet process beans seem a little flat.

[milowebailey]

  For a nubbie the leaning curve is slow. 

I think for any new roaster the learning curve can be slow.  Think about how much you are learning.  There is both science and art to coffee.... neither can be left out and both have to be learned.