Category: Roasting Guide

Roasting Guide

Roasting Guide

Never roasted before?  No problem!  We’ll teach you how!  You’ll be an expert in about 5 roasts!  After your purchase, for your first roast, we’ll walk you through the entire first roast so that you get the hang of it quick!  If you have any questions afterwards, we’ll be around to help you out there.  Your roasts should always be simply spectacular, the best coffee you have ever tasted, if for some reason it isn’t that way, then let’s talk about it and we’ll offer some suggestions to get people knocking down your door to get at your coffee!  For a good start read the guide below, or feel free to call or email.
Take a look at the video tutorials on the RK Roast process that should give you a great idea on how to roast providing as many visual cues as we can show you.  This will document the roast process from start to finish and will show you how we do it.

Coffee roasting really is simply an art form.  Nothing is more true of this than when you roast on the RK.  The reason for this is that you don’t have any computer controls or any automation to roast for you.  With this form of roasting, you will become a true expert of the trade very quickly as we roast entirely with sights, smells, sounds, temperatures and times.  What I will document here is what works for us and what seems to work really well for most of our customers.  Undoubtedly there will be someone who will say that roasting should be done this way or that and you’ll get better roasts if you do this or that.
That is simply the beauty of coffee roasting.  Every coffee roasts differently, has an ideal roast temperature, and even a roast time.  The quality of the coffee you choose will determine the ultimate perfection of a coffee.  Conversely, you can ruin a near perfect green coffee by roasting it incorrectly.
A Colombian coffee may have an optimum roast at Full City and a particular Salvadoran coffee may not be too great at Full City, but begins to really shine at Full City +.
So if you truly wish to master the art of coffee roasting, then you really should study each individual coffee that you buy, and understand to what degree the coffee should be roasted in order to achieve maximum flavor in that given coffee.  Tom Owen at Sweetmarias.com has a database of coffees and what their ideal roast should be and should serve as an excellent reference as to what you should try for on your roasts.
I, personally, have only scratched the surface in obtaining excellence in coffee roasting.  And will always be learning. I once had a conversation with someone whom I consider an expert in coffee and he told me that even after 20 years, he is still learning new things about coffee every day…
I suppose I have a long way to go and a lot to learn even now.

Now I’m sure someone out there will want to burn me at the stake for taking this angle.  I suppose I am a bit of a practicalist and frankly have entirely more to do on a daily basis than what the average person should have.  I basically run 3 businesses and have a family too.  As much as I would like, I just don’t have the time in the day to be ultra-focused on the art of roasting like some folks do.  I’ll just settle for happy customers, repeat orders and real good coffee.  If you have the time to become a top-notch expert on roasting, then I am truly envious of your skill and dedication and sincerely, we need people like you to teach the rest of us how to roast better and to perfect the art and tradition of excellence in coffee roasting.
Personally, however, I find that just about no matter how I roast, or for that matter, what coffee I roast, my customers are just flat out obsessed with the coffee that I give them.
I suppose that is a testament to the excellence of Ron’s drum design.  It just works very well on any coffee, and roasts as well, or better, than the really expensive commercial roasters.
The reason that I tell you this, is that particularly if you are new to coffee roasting, then you simply don’t need to be afraid of roasting, or producing bad coffee.  The system is very forgiving and in my opinion, you actually have to work at it to make bad coffee.
In my experience, the vast majority of Americans are simply accustomed to drinking Folgers and other low quality brands.  They drink it because it is cheap.  Even the national brand that you see hocking $4 cups of coffee on every street corner in every major city nationwide is peddling terrible dark sludge in a cup that supposedly is the public standard for good coffee.
Quite simply, most Americans have no concept of what fresh roasted coffee is.  Even to the point of people saying “I don’t like coffee, it’s too bitter.”
People don’t know that good coffee simply isn’t bitter!
So for that reason my tips to the new roaster would be:

Don’t spend a whole lot of money on a Ultra High Quality coffee.-  My experience tells me that no matter what bottom-rung moderately fresh coffee I choose to roast, my customers are falling over themselves trying to get at it.  When you are starting out, your technique wont be perfected for some time, so start out with a cheap coffee, your customers will love it regardless.

Don’t obsess about perfection and micromanagement of your roasts-  You will find that very small fluctuations in roast temperature and time really won’t make that much of a difference in the end result.  Your customers are going to love it anyway if you follow some basic guidelines.  It’s not hard to win when you average customer is used to drinking a cup of dirt each morning.   🙂

Your average customer will never be able to tell the difference between the Nutty-Chocolaty Guatemalan and your Citrusy Colombian, but they will sure know good coffee when it hits them.

When you get the general hang of it, you can start learning more and take your skills to perfection.

Coffee is ideally 10%-14% water weight.  In my work in Green Coffee in Colombia, we would strive to ship coffee as high as 16% so that it would arrive at the customer at that magic 14% moisture mark.
During the roast process you can expect to lose up to 20% of the weight of the coffee due to moisture loss and burning of oils and other interior pergamino skins in the form of evaporation, smoke and chaff.
So for every pound of finished coffee that you require, add 3.2OZ or 20% extra coffee to your drum.  I found that this number works well for pulling the roast at second crack. So use this following table as a rough guide.  Every coffee is different so use this as only a rule of thumb.  If you roast well into 2nd crack, you will lose even more weight.  So, in general, the longer or darker you roast, the more and more coffee you will have to provide to complete the volume (12OZ or 16OZ) that you intend to sell.
To restate, a vienna/french roast will take more or less 1/3 more beans to make 1 pound of coffee as compared to a full city.   Plus, it will cost you more gas to get you to that point.  So, in order to reduce cost per pound keep your roast times shorter and less dark if you have the choice.

Finished Roast Volume

Green Load

1Lb

1Lb 3.2 OZ

2Lb

2Lb 6.4 OZ

3Lb

3Lb 9.6 OZ

4Lb

4Lb 12.8 OZ

5Lb

6Lb

6Lb

7Lb 3.2 OZ

7Lb

8Lb 6.4 OZ

8Lb

9Lb 9.6 OZ

While were on the subject of green loads, the 4, 6, 8 and 12 pound drums are best rated for 4, 6, 8 and 12 pounds of green coffee, not finished coffee.  That said, I have, the drums have been rated with a MAX load, that you can attempt if you have extra heat. With this method you will get decent, albeit possiblyslightly uneven roasts by adding a few degrees of temperature to my standard roast profile.  
***PLEASE NOTE THAT THESE SHOULD BE CONSIDERED ROUGH RULES OF THUMB, EVERY GRILL, COFFEE, AND PERSON WILL ROAST DIFFERENTLY.  USE THESE NUMBERS AS A STARTING POINT AND LEARN WHAT BEST WORKS FOR YOU AND YOUR COFFEE.***

It is important to understand that each of the RK Drums (4, 6, 8 and 12) will roast with approximately the same results at a given % volume for a given temperature.  So, a 4, 6, 8 and 12 pound drum will roast the same at its 100% rated volume.  To clarify, a 4Lb Drum with 4Lbs of coffee at a given temperature will roast the same as a 8Lb drum with 8Lbs of coffee at the same temperature.
While each drum can roast more than its rated green volume, be aware that these tables may show green loads in excess of the rated load, and can be done, but will need higher than normal temperature to accommodate the extra amount of bean mass.  Beware however, that your roast uniformity may suffer slightly.
The following table works for us with most coffees and should be used as a starting point. The numbers aren’t exact, and you won’t be exactly on these numbers no matter how hard you try, but you should likely be able to hit these numbers give or take 1 minute with these temperatures and get excellent coffee.  They seem to work for most grills, and probably yours.  But if the times aren’t working out based on the scheduled temperature, you will need to adjust the heat up or down to accelerate or decelerate the roast.
To clarify, this is a starting point.  There could be other variables in setting up your roaster.  Your probe could sit higher or lower to the flames than the model used to generate the below numbers.  Your heat flow could be different and thus register higher or lower, thus it is important to understand that we must find a starting point, a profile that works on your grill/setup.  These numbers are where we start.
If you take a 4LB drum example below, roasting 4LB green.  You should be able to arrive at 1st and 2nd crack on time based upon 550-600 degrees according to the chart.  On your grill you may find that in actuality, because of the aforementioned variables that your grill is only able to deliver 1st and 2nd crack on time at at 650 degrees.  Or it could happen at a lower heat setting as well.  Our time on the first roast will be the key if we have injected enough heat into the system or not enough.
So understand that the first roasts we do on a new setup, are more like calibration roasts.  We won’t ruin any coffee, but it may not be perfect either.  We are trying to get a feel for the grill and the process.  You must learn to target a timely arrival of 1st and 2nd crack by adjusting the amount of heat you put into the system.
Please consider this article mandatory reading:
Roasting Techniques:  Roasting to target your time, not your temperature
With this understood, lets start roasting using the following charts as a starting point and then adjust the heat up or down so that we can time the arrival of 1st and 2nd accordingly.
2LB DRUM

Finished Roast Volume

Green Load

%Load

Temp

Est. 1st Crack

Est. 2nd Crack

1/2LB

9.6 OZ

25%

470

6 mins

10 mins

1Lb

1Lb 3.2 OZ

50%

500-525

9 mins

12 mins

1.5Lb

1Lb 4.8 OZ

75%

525-550

14 mins

16 mins

2Lb

2Lb 6.4 OZ

100%

550-600

16 mins

18 mins

4LB DRUM

Finished Roast Volume

Green Load

%Load

Temp

Est. 1st Crack

Est. 2nd Crack

1Lb

1Lb 3.2 OZ

25%

470

8 mins

12 mins

2Lb

2Lb 6.4 OZ

50%

500-525

11 mins

14 mins

3Lb

3Lb 9.6 OZ

75%

525-550

16 mins

18 mins

4Lb

4Lb 12.8 OZ

100%

550-600

18 mins

20 – 21 mins

6LB DRUM

Finished Roast Volume

Green Load

%Load

Temp

Est. 1st Crack

Est. 2nd Crack

1Lb

1Lb 3.2 OZ

16.6%

450-470

8 mins

10 mins

2Lb

2Lb 6.4 OZ

33.3%

470-500

12 mins

14 mins

3Lb

3Lb 9.6 OZ

50%

500-525

14 mins

16 mins

4Lb

4Lb 12.8 OZ

66.6%

525-550

16 mins

18 mins

5Lb

6Lb

83.3%

550-575

18 mins

19 mins

6Lb

7Lb 3.2 OZ

100%

575-625

19 mins

21 mins

8LB DRUM

Finished Roast Volume

Green Load

%Load

Temp

Est. 1st Crack

Est. 2nd Crack

1Lb

1Lb 3.2 OZ

12.5%

450-470

8 mins

10 mins

2Lb

2Lb 6.4 OZ

25%

470-480

10 mins

12 mins

3Lb

3Lb 9.6 OZ

37.5%

490-500

12 mins

14 mins

4Lb

4Lb 12.8 OZ

50%

500-525

14 mins

15.5 mins

5Lb

6Lb

62.5%

525-535

16 mins

17.5 mins

6Lb

7Lb 3.2 OZ

75%
535-565
17 mins

19 mins

7Lb

8Lb 6.4 OZ

87.5%
565-585
19 mins

20.5 mins

8Lb

9Lb 9.6 OZ

100%

600-625

19 mins

21 mins

12LB DRUM

Finished Roast Volume

Green Load

%Load

Temp

Est. 1st Crack

Est. 2nd Crack

1Lb

1Lb 3.2 OZ

8.3%

450-470

8 mins

10 mins

2Lb

2Lb 6.4 OZ

17%

470-480

9 mins

11 mins

3Lb

3Lb 9.6 OZ

25%

490-500

9 mins

11 mins

4Lb

4Lb 12.8 OZ

33%

500-525

10 mins

12 mins

5Lb

6Lb

42%

525-535

12 mins

14 mins

6Lb

7Lb 3.2 OZ

50%

535-565

12 mins

14 mins

7Lb

8Lb 6.4 OZ

58.3%

565-585

16 mins

17.5 mins

8Lb

9Lb 9.6 OZ

66%

600-625

16 mins

17.5 mins

9LB

10LB 12.8 OZ

75%

625-650

17 min

19 min

10LB

12LB

83%

625-650

17 min

19 min

11LB

13Lb 3.2 OZ

92%

650-675

19 min

21 min

12LB

14Lb

100%

650-675

19 min

21 min

First thing you want to do is clean your grill if you haven’t already, get the chaff and other material out of the bottom of the grill.  Take your green coffee load (I love the 5 gallon square buckets from the hardware store as you can use the corner as a pour spout to load the drum.)
Let’s pre-heat the drum and the grill.  Light your burners and set to MAX temp.  Put the drum in the grill, close the lid and close the latch.  Turn on the motor so the drum heats evenly and wait until the temperature rises close to your target temperature for the green load of your choosing.
When the temp gets close to the target temperature, turn off the motor and put on your protective glove on your unfavored hand (the hand that grabs the spit rod), open the lid, remove the drum and set the handle end on the ground and prop the coupler end up against the grill.
Close the grill lid to keep the heat in.
BE CAREFUL THE DRUM IS SUPER HOT AND WILL BURN YOU INSTANTLY.  YES IT WILL LEAVE A SCAR!

With your protected hand, pull the pin and open the drum.  I like to set the lid at a 45 degree angle and  use it as a bit of a funnel to pour the coffee into the drum.
After you have all the coffee in, close the lid and latch.  
Grab the rod by the coupler with your protected hand and grab the handle with the other hand and insert into the coupler and drop the handle side onto the bearing and close the lid on the grill and turn on the switch.

Your Roast has now begun.  Start your stopwatch or wristwatch and monitor your time.  Your temperature will have dropped after opening the lid, this is fine, but you will want to see the grill come back to your target temperature within about 3 minutes.  If you see that you are not coming back up in temperature, then give it more gas to boost it up to temperature.
What you need to do is set your burners up or down to maintain your target temperature.  So adjust as necessary.
You won’t see, or hear much during the first 6 minutes even in the smallest roasts.
What we are going to begin doing at this point is hold our temperature all the way to 1st crack, then we will adjust as necessary.
1st Crack has been said to sound a bit like the popping of popcorn.  This is where the bean is releasing a large amount of its moisture.  As 1st crack approaches, if you stand near the rear of the grill you will begin to smell a rather pungent odor that kind of burns your nose and eyes.  When you start smelling this, we are getting close to 1st.  Light white smoke will gradually increase more and more until the onset of first.  Use this smoke and the pungent odor to help you time the arrival of first crack.
You will want to do your best to time the arrival of first crack, more or less to the numbers in the tables on the previous page.  Let’s look at an example.
Lets take the example of the 4Lb Drum with a 2Lb load.  Here is the data from our table:
4LB DRUM

Finished Roast Volume

Green Load

%Load

Temp

Est. 1st Crack

Est. 2nd Crack

1Lb

1Lb 3.2 OZ

25%

470

8 mins

12 mins

2Lb

2Lb 6.4 OZ

50%

500-525

11 mins

14 mins

3Lb

3Lb 9.6 OZ

75%

525-550

16 mins

18 mins

4Lb

4Lb 12.8 OZ

100%

550-600

18 mins

20 – 21 mins

We are going to run about 500F right up till 1st crack.  We estimate 1st crack at 11 minutes.  If we use the smoke as a gauge, you will start to see the smoke about 1-2 minutes before 1st.  So to clarify, we should be seeing smoke by about 9 to 10 minutes or so.  If we are seeing no smoke at all by say 10:30, we now know we are getting behind schedule as there is usually a minute or two of smoke before 1st.  Let’s crank the heat up a bit to get us back on our schedule.  We are shooting to end the roast at 14 mins in this example so we don’t want to drag the roast out any longer than necessary.  To do so dulls the roast and you loose some of your brightness in the coffee the longer you go past the recommended time.
Conversely, if 1st crack starts at 9 minutes and the interval between the pops is very rapid (like machine gun fire) then you are roasting too hot and you need to back off your temps by 20 degrees or so.
You will initially hear one pop, then two, then a few more and then all the beans will start to go, similar to the way microwave popcorn pops in the bag.
As 1st crack reaches its rolling stage, where it rolls forward seemingly unstoppable, the smoke will be at its most intense.  At this point lets reduce the temperature by 10 to 25 degrees.  Use more of a drop for the larger the roast.  8 Pounds, lets drop 25 degrees.  2-4 pounds lets drop 10 and what we want to do is just reduce the temperature and let the roast coast on its own heat.  The popping will begin to subside and the smoke will taper off.  Now the beans are exothermic and begin to generate their own heat.  Heat is sustained in the bean mass and they sort of cook themselves.  For this reason, we back off on the heat a bit and it also serves to improve the roast.

As 1st crack subsides, the coffee will slowly cease to pop, the smoke will all but completely subside and the only thing you will hear is the swishing of the coffee in the drum.  At this point the coffee is still very hard and really not useable for anything.  The coffee is still semi-green and will have a strong grassy flavor if you try to drink it now.  We need to keep going a bit.
Lets monitor our temperature and ride it out.  We still should be 10 to 25 degrees below our initial temp depending upon the green load.  (see above).
In our 2Lb example in the 4Lb drum, we are looking for 2nd crack to occur at around 14 minutes.  As we approach second crack, the coffee will increase in temperature automatically without you raising the heat.  Not a lot but it will slowly begin to creep up.  Maintain your temperature and start watching for the white smoke again.
This is the final release of moisture and oils.  We should start seeing the smoke again, a minute or two before the second crack actually starts.
2nd crack sounds more like rice crispies, having a higher frequency of a pop than 1st.  The smoke is also thicker and heavier.  In the same fashion we should start seeing smoke by say, 12 or 13 minutes.  If we are seeing no smoke by say 13:30, we know that we are not anywhere close to 2nd.  Lets push the heat up by 20 degrees just to shove our roast over the top and try to finish on time.
Lets go ahead and get your glove on as we’re about to pull the coffee, also turn on your cooling fan and get your cooling device setup.
The smoke thickens and you will slowly start to begin the higher pitch cracking.  This is the physical fracturing of the bean itself.  If you look around the edges of the bean, you will see these fine cracks at the end of the roast.
The cracks will begin to increase in frequency and the smoke will grow more intense to the point where the cracks are continuous and non-stop.
This is described as rolling second crack.
Now we need to examine here this very important moment.  The minute before the start of 2nd and the minute after the start of 2nd are perhaps the most important moments of the roast and argurably where the roast will be a success or a failure.
Personally I will recommend that for a light roast you stop the roast an estimate 1 minute before 2nd and for a dark roast, 30 secs to 1 minute after the begin of 2nd.
All of the finishing of the coffee exists really in these last 2 minutes and during the cooling process.
In most cases, I will personally stop the roast right as soon as 2nd crack is established.  When I am sure that the majority of the beans are starting to crack.  This, for me represents the average balanced coffee.  I’m sure I’ll get emails about that, like I said before, every roast, and roast master is different and prefers different things.  In my opinion, 1 minute before 2nd crack, you will start to lose all of the grassy origin flavors, and even possibly some of the uniqueness of the coffee.  At about rolling 2nd crack and forward, the coffee will noticeably begin to take on a darker, heavier, possibly more bitter and increasingly burned flavor (Sort of like Starbucks coffee).
I’ll recommend that you should almost never go past about 1 minute after 2nd crack as it results in a very dark coffee.  Approaching 2-3 minutes post 2nd crack it is likely that the internal oils of the coffee will actually ignite and catch fire.  Yep, that’s bad.  It happens to just about everyone at least once!
So in this example, as soon as you can tell that most of the beans are cracking let’s stop the roast.

THE DRUM IS SUPER HOT, WEAR PROTECTION
As 2nd crack is fully established, lets pull the coffee (You can pull it earlier or later around this point depending on your coffee or preference.)
Lower your burners to the lowest setting.
Open the lid of the grill, watch the door and pin, stop the motor when the motor is moving to the top position, rotate the drum with your hand as necessary.  While the drum is sitting here on the bracket, lets go ahead and open the latch and hold the door closed with the thumb of your gloved hand.
Use your other 3 or 4 gloved fingers to wrap under the spit rod.  Note that the coffee will be smoking and still cooking in its own heat.
Lift the drum and coffee off the motor and bearing and close the lid of the grill to hold your heat in if you intend to do another roast, otherwise turn off your burners in the step before.  If it helps, quickly set the handle on the ground and prop the drum up against the grill so you can close the grill lid.  Sometimes you may find it easier to just leave the lid open as you will likely be short on hands, that’s fine, it will just cost you more gas to heat it back up.  Not a big deal if you can’t get to it though.
Next, pick up the drum, and carry it over to your cooling device.  Using your gloved thumb, open the door and dump your coffee into the cooling tray.  Note that the coffee is still cooking and it is important to cool the coffee as quickly as possible to preserve the quality of the roast.  You may even want to anticipate your intended stop point of the roast by 15 or 20 seconds as this is the time it will take you to stop the roast and get the coffee in the cooler.
After the drum is empty prop it back up against the grill, with the door open to begin your next roast.
You will get some chaff (a sort of paper like material that comes off the roasted coffee) that will blow away.  You may even choose to pour the coffee slowly into your cooler allowing the wind to blow the chaff out of the coffee, or you can use a large spoon, wooden or stainless to stir the coffee, aid chaff removal and cooling.
While the coffee is cooling down, go back to your drum and load your next batch of green beans and repeat the process and get the next roast going.
After about 90 seconds, the coffee should be cool enough to touch.  I usually offload the coffee into a bucket so I can go and bag later for sale.
So, that’s the end of the roast tutorial.  I am by no means a roast expert, now with 13 and counting,  years under my belt,  as compared to some of the great people out there.  I welcome any comments and corrections.  This however, should reliably get you good reproduceable, coffee and plenty of customers that are in love with it.
-Happy Roasting!-

2LB DRUM

Finished Roast Volume
Green Load
%Load
Temp
Est. 1st Crack
Est. 2nd Crack

1/2LB
9.6 OZ
25%
470
6 mins
10 mins

1Lb
1Lb 3.2 OZ
50%
500-525
9 mins
12 mins

1.5Lb
1Lb 12.8 OZ
75%
525-550
14 mins
16 mins

2Lb
2Lb 6.4 OZ
100%
550-600
16 mins
18 mins

4LB DRUM

Finished Roast Volume
Green Load
%Load
Temp
Est. 1st Crack
Est. 2nd Crack

1Lb
1Lb 3.2 OZ
25%
470
8 mins
12 mins

2Lb
2Lb 6.4 OZ
50%
500-525
11 mins
14 mins

3Lb
3Lb 9.6 OZ
75%
525-550
16 mins
18 mins

4Lb
4Lb 12.8 OZ
100%
550-600
18 mins
20 – 21 mins

6LB DRUM

Finished Roast Volume
Green Load
%Load
Temp
Est. 1st Crack
Est. 2nd Crack

1Lb
1Lb 3.2 OZ
16.6%
450-470
8 mins
10 mins

2Lb
2Lb 6.4 OZ
33.3%
470-500
12 mins
14 mins

3Lb
3Lb 9.6 OZ
50%
500-525
14 mins
16 mins

4Lb
4Lb 12.8 OZ
66.6%
525-550
16 mins
18 mins

5Lb
6Lb
83.3%
550-575
18 mins
19 mins

6Lb
7Lb 3.2 OZ
100%
575-625
19 mins
21 mins

8LB DRUM

Finished Roast Volume
Green Load
%Load
Temp
Est. 1st Crack
Est. 2nd Crack

1Lb
1Lb 3.2 OZ
12.5%
450-470
8 mins
10 mins

2Lb
2Lb 6.4 OZ
25%
470-480
10 mins
12 mins

3Lb
3Lb 9.6 OZ
37.5%
490-500
12 mins
14 mins

4Lb
4Lb 12.8 OZ
50%
500-525
14 mins
15.5 mins

5Lb
6Lb
62.5%
525-535
16 mins
17.5 mins

6Lb
7Lb 3.2 OZ
75%
535-565
17 mins
19 mins

7Lb
8Lb 6.4 OZ
87.5%
565-585
19 mins
20.5 mins

8Lb
9Lb 9.6 OZ
100%
600-625
19 mins
21 mins

12LB DRUM

Finished Roast Volume
Green Load
%Load
Temp
Est. 1st Crack
Est. 2nd Crack

1Lb
1Lb 3.2 OZ
8.3%
450-470
8 mins
10 mins

2Lb
2Lb 6.4 OZ
17%
470-480
9 mins
11 mins

3Lb
3Lb 9.6 OZ
25%
490-500
9 mins
11 mins

4Lb
4Lb 12.8 OZ
33%
500-525
10 mins
12 mins

5Lb
6Lb
42%
525-535
12 mins
14 mins

6Lb
7Lb 3.2 OZ
50%
535-565
12 mins
14 mins

7Lb
8Lb 6.4 OZ
58.3%
565-585
16 mins
17.5 mins

8Lb
9Lb 9.6 OZ
66%
600-625
16 mins
17.5 mins

9LB
10LB 12.8 OZ
75%
625-650
17 min
19 min

10LB
12LB
83%
625-650
17 min
19 min

11LB
13Lb 3.2 OZ
92%
650-675
19 min
21 min

12LB
14Lb
100%
650-675
19 min
21 min

FAQ & Troubleshooting

Troubleshooting Q&A

What are your recommendations for a grill and rotisserie set up?Any grill that is at least 30K btu rated and is big enough to accept a drum that measures 8” X 12”. If you roast in cold weather you will need a grill with 36K to 45K btu. I like the rotisserie kit that is sold by Char-Broil, and can be bought at Home Depot. Char-Broil Premium Electric Rotisserie kit $33, I have had success with B04 charbroil 30K, and the one I really like is the Fiesta 30K.

How much would it cost me to go from scratch?
It would cost approximately $500, this includes a Grill, a rotisserie, a thermometer, a fan, and a cooling tray, and of course a RK Drum.

Do I need a cooling tray?
Yes, you will need a cooling tray and a fan, I use a 20” box fan, and a 3” X 16” sifter. The sifter can be bought at any restaurant supply store.  You may also opt for an RK Cooler here

Do I need a timer?
No, but I do recommend that you use one. It is easier to duplicate roast when you use a timer.

Will I need a pair of thermal gloves?
YES, these are a must, the grill, drum and spit rod get extremely hot, and will burn you in a second. I suggest that you get a glove that will with stand 500+ degrees for 30 seconds or more. They make a knitted mitt that works nicely, and can be bought at Walgreens. I use one glove, and the wooden handle on the spit rod. I recommend this Glove made from Nomex and Kevlar, goes by the name of The Ove” Glove

Can I roast indoors?
NO, all gas, propane or charcoal grill should be use outdoors.

Can I roast with the standard rotisserie motor.
Yes, and No.  It depends on the speed of the standard motor.  A few years ago, the standard motor was around 6 RPM.  It seems these days the standard is 1.5-2 RPM  The 6 RPM does a great job from ¼ to 2lbs. It will do 3 to 4 lbs but it labors the standard 6 rpm motor. Also the Webber motor only rotates at 3 rpm and a little slow for a good mix.  So in short, less than 3RPM and the coffee does not mix well and you will get uneven roasts.  This includes the standard motor that comes with the New Charbroil Rotisserie.

What is the advantage of a 50 or higher speed motor.
It will produce a nice even roast, in about 2 to 3 minutes less time, or will allow you roast at a lower temperature due to the increase hot air flow through the drum. It will out last a standard slow rpm motor, and is more suited for heavier batch weights.

Will I need special tools to mount the motor assembly and/or the drum? Yes you will need some tools, but not special tools.  You will need and adjustable wrench or ½ “ wrench to attach the motor assembly if you buy one. It would be nice to have a screwdriver, both straight and Phillips, a set of hex key, the ones that fold up into their holder will do.

Roast Troubleshooting Q&A

What can I do if I am getting uneven roasts on a drum (Specifically the 8LB/12LB Drum)

The following is an article on improving roast consistency on the RK Drum with focus on the 8LB drum.

In some grills you may have difficulty, particularly with the 8LB Drum and very minimally present on the 6LB Drum with uneven roasts.  This is a result of trying to roast coffee evenly over an 18″ or 24″ span over varying heat sources.  Specifically, your burners may not be distributing heat evenly across the entire length of the drum.  This is particularly present on 8LB Drums and on grills that don’t have adequate burner diffusion.

To clarify, off of each burner you have a column of heat rising up off of the burner directly, which is controlled by your burner knob.  It can be difficult to tell exactly how hot that flame is.  Just because your knob on burner 1 is set to 75% and burner 2 is set to 75% and burner 3 is set to 75% does NOT mean that each burner is actually producing the same amount of heat.  The valves in the burner knobs on these grills are just not manufactured with fine tolerances, and may have slightly different gas flows depending on their internal structure.  Furthermore, your burners themselves may have slightly differing hole sizes which translates to more or less gas getting through and thus more or less heat.

The longer a drum gets, the more pronounced this becomes as you are stretching the coffee out over 24″ (in the case of the 8LB) and it is quite easy to get the right side feeling hotter then the left, or to have cold spots here or there (relatively speaking).  This is almost invisible in the 4LB 12″ drum as the coffee is compacted into such a concise area.

 

So, to solve this, some experimentation is necessary.  The objective we are trying to achieve here is to even out the heat that the drum “feels” across its entire length.

So how can we even out the heat?  Here are a few approaches. Please apply these points in order as the first suggestions will be the most likely and easiest solutions.

 

 

  • Leveling the Drum: Keep in mind, that your drum must be level when roasting.  Use a level to see that the drum is completely level to the ground.  This will prevent coffee from piling up more in one end than the other.  If this happens then you will get  a larger bean mass on one side vs. the other and that heavier side will roast slower than the lighter side.  This will cause unevenness.  Try this as a first approach.

 

  • Heat or Rotational Speed: The final reason that could explain uneven roasts is rotational speed.  If you are roasting at less than 6RPM’s you will probably get uneven roasts.  The closer your approach to 40-60 RPM’s the more even your roasts will be.   Finally you may not be roasting hot enough.  If you have done all these things and still getting uneven roasts, you may not be getting enough heat penetration.  Try increasing your heat by 25 degrees and see how the roast turns out.

 

 

  • Burner Balancing:  Adjust your burners up or down to achieve equal heating on all burners.  This is a bit tricky and may involve some raw roast time.  You may notice that coffee in one end of the drum is darker than the other.  This should indicate to you that burners on that side are running a hair too high.  They can only be 10 degrees off and that 10 degree difference over a 20 minute roast can cause the coffee on one side to be predominantly darker to give an example.  So backing that burner down to a lower setting for the entire roast may be a solution.  I have heard of some people getting to know their grill so well, they know what each burner needs to be set at to  get an even roast.  An infrared thermometer may help here.  You can take the laser pointer of the infrared thermometer and hold it on the bottom of the drum to see what areas of the drum are hotter than others and then adjust it accordingly.

  • Burner Diffusion: Another approach and possibly a better approach in my opinion is simply to diffuse or blend the heat coming from all the burners into one heat source.  The basic way to do this is to install a piece of metal over the burners.  It is true that most grills do indeed come with a heat diffuser over the burners.  However, if you look at some of these diffusers (particularly in grills whose burners run front to back) you will see that the diffuser only covers the burner tube itself in a sort of upside down “V” profile and then allows the heat to boil straight up.  You can see that this really does very little to break up that heat column coming up off of the burner.  The idea here is to keep the drum from feeling the direct heat off the burner and blend all the heat together.  Some grills have a great diffuser plate which rather covers the majority of the bottom of the grill thereby blending the heat very well.  Some of the new infrared grills are better at this as they use an entire plate to actually separate the heat column from the coffee.  (Be careful to watch BTU requirements on the infrared grills).    So what you need to do is look at your diffuser and decide if the diffuser is doing a good job of breaking up and blending the heat rising off the burners.  If not, throw out the diffuser you have and install a piece of aluminum or steel.  Usually 1/16″ steel works well.  The piece should be big enough to fit in the entire bottom of the grill leaving only 1 and 1/2″ of clearance between the edge of the plate and the wall of the grill on all sides.  So what we want is for the burners to heat the plate, and then for the plate to radiate heat towards your coffee and secondly for the heat to collect under the plate and then boil up around the edges of the plate to fill the space in the grill where the drum sits.  (So you should have heat rising up around the edges of your square plate on all four sides of the rectangular plate).  Some people have drilled holes in this plate to allow for more heat to trickle up through the holes.  Lastly, please understand that your heat up and cool down timeframes will be extended as the majority of your heat will go towards heating the plate initially extending your heat up time, but conversely the plate will hold heat between roasts reducing your heat up time for roast #2.  Remember steel retains heat longer than aluminum so keep that in mind.  It doesn’t matter either way however.  See the two images for further clarification

 

K. Test Firing & First Run

General Information


Wash your drum in hot water and detergent before using. A 5 gallon bucket works great, wash the outside, but not the inside, not much room and you could cut yourself, just slosh it up and down in the bucket.  You may also use dish detergent and rinse it off in the tub.   After washing you will need to do a burn in.

Burn in is the process of burning out anything unsavory (machine oils) etc that could be in the drum from manufacture.  So, burn in is putting the whole thing together the first time, empty, and run it at high temperature. (600F) or thereabouts.. for about 30-45 minutes.  This will temper the metal, burn any contaminants out, and begin to “season” the drum for coffee.  The metal will start turning a golden bronze color (this is what we want) and then after it cools down, go back through the whole roaster and tighten everything one last time, since the heat and warping will loosen things up.  Now you’re ready to roast.


The drum will go through some changes for about 5 heat cycles. The door may get a bit tight, or loose. The drum should stabilize after 5 heat cycles and will stay put after that.  It’s called tempering, and stress relieving. The drum should turn a nice bronze color; this is normal, and actually quite nice.

The roasts will improve as the drum and your grill normalize. The more you roast the better it will get. Practice, Practice, Practice.


1. The drum is all stainless steel, not a high polished stainless, but durable.

2. The drum will turn a bronze color when heated. This is normal, so don’t be
alarmed.

3. All grills are different and you will have to adjust the profile to suit your grill, but the profiles provided are a good starting point.

4. Placing the drum as low as possible in the grill is preferred.

5. Thermometer placement in the grill will affect the profile temps. Locate your thermometer in the center of lid and dead center of the drums length and diameter if possible. The profile was developed in our grill, yours may be different, and so you will have to adjust the profile temps to suit your grill.

6. If your thermometer is near the top and off to the side, like a Weber grill. You will have to go higher then the profile because the top of the grill is cooler then at the bottom, all heat goes to the top, and cools as it raises.

7. It is not hard to relocate or install a new thermometer near center and pointed to the center of the drum. It will be nearer the bean temps. Refer to the pictures on the web page.

8. CAUTION: Wear protective equipment when handling the hot drum. Gloves
should be able to withstand 500 degrees, or more for at least 30 sec.

9. The drum will take 3 to 5 roasts to season; the coffee will improve in taste as the drum seasons.


10. If your rod becomes loose in the sq. tubing, and you begin to hear a thumping noise while roasting. You can tighten it by removing the spit rod and putting a slight bow in your spit rod. Just bow it a bit over your knee or thigh and insert back in the drum. Allow it to cool before doing this.  Another option is to very slightly “V” in the square tubing to tighten the fit on the rod.  You may also shim it with strips of metal or wire, just inside the square tube.

K.  TEST FIRING & FIRST RUN

(Figure 168)

Here is our thermometer cold, on our first test firing. (Figure 168)

 

(Figure 169)

Light’er up.  Make sure you turn on the motor thereby turning the drum.  It allows for even heating, expansion and burns off the protective oils, and the residuals oils that are impossible to get out.  These other residuals oils were used for cooling the stainless metal during the welding process.  It gets inside the drum and you can only burn it out.  You will also smell the paint fumes and other strange odors during the first firing.  This will absorb into your coffee.  I recommend running the roaster at 550-600F for 40 mins to 1 hour before putting coffee in it.  We want to burn it ALL out.  (Figure 169)

(Figure 170)

The bearing may squeak initially and from time to time.  A little 3-in-one oil or motor oil will clear it up.  Avoid spraying aerosol based oils (WD40 and similar) as it could flame up being close to the flames.(Figure 170)

 

(Figure 171)

I have made additional metal inserts that I can use to simply wedge under the sheet metal.  This closes off the rear vent.  Particularly useful for max efficiency, cold weather, windy weather and high-heat roasts. (Figure 171)

(Figure 172)

Lets do this first burn-in, empty and let it run at 600F for 1 hour. (Figure 172)

(Figure 173)

Right on my numbers.  If you have built it efficiently, then you should be able to hold this temp at a relatively low gas setting. (Figure 173)

(Figure 174)

All three burners set between 40%-50% and holding 600.  Not bad, that means 550F should land at about 1/3 gas.  That’s great!   (Figure 174)

 

——(This below section is for Pre-2008 Drums and does not apply to the new assemblies with the latch.)—————————-

(Figure 175)

Some people have mentioned that when the drum is hot (right after a roast) the door is very hard to open, and impossible to close again until cool.  This is a result of thermal expansion and is incredibly hard to predict, or fix from the shop side without firing the drum.  This was the case with this new drum as well.  Inspect the lid and pin where the lid closes to see where you have overlap.  Take a drill bit and just insert the bit into the hole in the lid and hold it at the side of the hole that is interfering.  Not a lot, do it slowly little by little until the drum closes and opens semi-easily while hot.  As time goes on, it will loosen up, so you don’t want it to fall open either. 

——————————————————–END section on Pre-2008 drums—————————————

Once this is set, you are ready to roast your first batch and you can roast back to back without waiting for it to cool.  For how to roast, please see the roast profiles section for assistance in this area. (Figure 175)

One last suggestion, keep your roaster garaged, and don’t cook meat in it after it becomes your roaster, unless you like meaty flavored coffee!!!!!!

Keep the ash and chaff vacuumed out every few roasts, and your roaster will last you absolutely many years.

 

Tips for Gear Drive Motors


1. Mount your motor as far away from the grill as possible, 6”
minimum.

2. Make a heat deflector to go between your grill and Motor to
mount in front of your Coupling. It can be made with flashing or
light sheet metal that can be bought at any hardware outlet. Use
bushings or washers to have it stand off the grills hood about ½ to
1” cut a slot with beveled edges to go over your spit rod when you
close the hood. This will help protect the motor and rubber driver
in between the couplings from the extreme heat created during a
roast session.

3. The motor is not weather proof. Do not leave your motor exposed
to the weather. Cover it with a grill cover, tarp, or keep it inside a
building.

4. You will have to lubricate the non motor end, where the solid
bearing rides in the support bracket. Use some High temp white
lithium grease. Dupont makes a spay can that works quite well,
alternatives are Slick 50 oil additive, or good synthetic motor oil.
The Dupont lithium grease is best.

5. You will encounter more noise using a fast rpm motor, not from
the motor, but from the beans moving against the drum. After a
few roast you should not have a problem distinguishing the bean
movement noise from the cracks of 1 st and 2 nd crack.

6. If you do have trouble, use this as a guide. Smoke will start to
appear as first crack gets going. It will slow or stop at the end of
first crack, and will begin again 15 or so seconds before 2 nd crack
begins.

That’s it, I hope you found this guide helpful.  Happy Roasting!-Shane

 

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