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Hello, I’ve been roasting on a RK since 2018. Up till last year it was great and most roasts were very consistent to what I wanted. I’m using a nexgrill 5 burner with 55000 btu with rear vents mostly blocked, 6lb roaster. I moved from the Arizona Desert to Michigan and had to adjust the roasts with the climate. At first it was fine but I ran into some issues starting last summer. The main issue is that my roasts are inconsistent in color. It mainly impacts medium roasts and happens across bean varieties although natural/honey processed beans seem the most inconsistent, also lower batch sizing doesn’t help. At first I had a leveling issue, once I corrected that it improved but still wasn’t perfect. I started temp checking each burner with a laser thermometer. Temps tend to swing from burner to burner, sometimes quite a bit during the roast and I hate opening it every few minutes which allows in cold air (much of the year). I have added a piece of sheet metal over the heat shields which helps some. I also changed out each burner, and drilled the jets to try to even the heat. That didn’t do much positive. Everything looks and appears fine from a roast perspective until I pour the beans and generally have to pick out an ounce or two from each batch. I thought it was time for a new grill although I can’t find anything wrong with the current one. Upon getting it (same nexgrill) each burner will temp all over the place, pretty similarly to the older grill. I haven’t set it up yet with the drum but I don’t have confidence this will fix my issue. Any and all help appreciated.
Good Morning Nate!
First, I’d encourage you to give me a call as we can usually make faster work over the phone.
Let me run through everything that I’m aware of that can cause inconsistent roasts…
I’ll also toss in this article: https://www.rkdrums.com/articles/tips-to-improve-roast-consistency-and-uniformity-revisited/
-First you should check the drum leveling… put a bubble level on the drum itself at the place you roast. Just because you level the drum at one place doesn’t mean it will be level at another place.
-Second, make sure your roast speed is between 20 and 60RPM. If you’re using our motor, you should be fine.
-third, burner imbalance is the main cause for this, so make sure your piece of sheet metal below is fully covering the drum, when you look at it from above. Note that the piece of metal is acting as a heat shield to shield the whole drum from the heat blast rising up from the burners….
-Roast volume. If you overfill the drum you can also cause some unevenness. Drum is rated for 6LB green, but let’s do no more than 5LB green or less while we work on this issue.
-Do your roast normally and right after first crack, try and crack the hood and shoot the laser onto the bottom of the drum… check “what the drum is feeling” all along the bottom… we’re looking for hot spots
Just want to make sure your roast times are lining up with the roast profiles. Too long\too short\too hot\too cold can sometimes mess with evenness.
-Is it possible you have wind blowing in to the roast chamber through any of the holes? That can blow heat around and cool things off in certain places….
-Mixed dryness beans, also probably not your issue, but…if you have beans of mixed dryness from your supplier… meaning they mixed some old and new together to get rig of old stock… this could happen. Dry beans will always roast faster than wet beans.. a possibility?
-It’s a stretch… but… I have heard of cold propane tanks losing pressure and such… they make tank insulators\heaters to keep the temp up on the tank. Also, the way you hook up the propane tank can sometimes mess things up.
I don’t have the exact science on this, but I’ve run into it a bunch. I believe the tank regulator (thing on the hose) has some kind of safety mechanism in it that limits the propane flow, if for example, you hook up the tank and the valves are cracked open by accident. The idea being your tank would seep out to empty, and it could cause a safety hazard. Propane flow is low\off\wildly inconsistent.
The fix is to:
-ensure all valves are off
-Shut off the tank
-Unhook the hose from the grill.
-Hook the hose to the grill again
-open the tank
-Then open the gas valves and light it to see if it now flows more consistent.
(Probably not your problem, but just thought I’d mention)-We had one drum years back that we sent to SC and it always had inconsistent roasts. No matter what, from day 1. We found that a set of vanes was installed wrong from the shop. After inspection we found that all vanes were pushing the coffee to the ends of the drum regardless…. this doesn’t make sense for you though since you were fine in AZ… But we can look at it if we rule everything else out.\
-Send some pics of your whole set up to email above. Maybe I’ll spot something.
Get back with me on some of the above
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