Weird Artisan profiles on Hottop K2+ over the last 6 months or so

Discuss roast levels and profiles for espresso, equipment for roasting coffee.

#1: Post by DSNORD »

Over the last 6 months, my 2K+'s Artisan 1.something version roast profiles have gone from a generally smooth downward slope with occasional flick up close to First Crack to severely but irregularly sinusoidal along the entire curve with a repeating interval of about 30-45 seconds or so.

I've got about 270 roasts on the machine to date. I've settled on this standard Heat/Air program that I have tweaked over the years to get my best results with this particular unit: At Charge (ET400)-> Heat 100, Air 10. At DE-> Heat 90, Air 40. At FC-> Heat75, Air 80.

Regardless of my settings, the sinusoidal pattern persists with only small differences in period, even if I let the unit run at 100% Heat/Air. It doesn't really change whether the roast is the first or last of the day.

Fortunately I still get really good results regardless of what the Artisan curve is telling me, but I'd like help trouble shooting this issue. I use Sweet Maria's coffee exclusively, regular and SWP decaf at 225 grams per batch, but I jump up to 235 or so for the last roast from the bag so as to not throw any away.

Last year at the 200 or so roast point, I disassembled the unit to clean it since I was bored sitting inside in the winter and needed something to do. Hottop's tutorials were excellent. Everything worked well, but I'm wondering if the cleaning job somehow altered the probe sensitivities and have resulted in the present behavior.

Has anyone had a similar experience? The pictures show things nicely. Hottop customer service rep recommended I post online since he had no idea of what was going on short of electrical interference from motors running elsewhere on my home grid. The roaster is located in my main mechanical room that houses 3 HVAC units and a hot water boiler, but nothing has changed with there use over all the years to suddenly start causing this issue.

Thanks for any suggestions.



#2: Post by rmongiovi »

Those stair-steps in your graphs look really strange to me. Especially in the ET curve at the beginning of the roast. With the power at 100 I don't see how it's possible for the temperature to remain constant for what looks like up to 30 or 40 seconds (from 1:20 to 1:50 or so, for example).

I saw oscillations in my delta-BT graphs on my hottop 2k+ before I replaced the thermocouples with phidgets that return more than integer temperatures but that was towards the end of the roast when the temperature actually was remaining the same for seconds at a time (since the fractional degrees are truncated).

Since your roast is completing pretty quickly it doesn't seem like it's a problem with your heat. I'd suspect the thermocouples. I don't see how noise could create flat spots in the graph but someone who knows more about that than I should comment....

Supporter ❤

#3: Post by Milligan »

The ET graph has the steps as well so I doubt both TC's are malfunctioning at the same time. That would be a bit coincidental. You are using a laptop and it seems to be plugged into the wall while in use. If so try unplugging it while you roast. If that works then you likely need a USB isolator if you want it plugged in while in use. That would be my first step since it is easy.

For reference:
NOTE Unplug Your Laptop Before You Roast Note that for most people unless you have a USB isolator you need to unplug your computer when using Artisan or will get feedback loops that will create all sorts of crazy spikes in the graph. If you are using a desktop I guess you need to get an isolator. ... leshooting

User avatar

#4: Post by okmed »

Further to Milligan's response, this YouTuber (Jason Scott) shows how to test for idle noise and then references some USB isolators at 4:45 in the video.

DSNORD (original poster)

#5: Post by DSNORD (original poster) »

Thanks all for the excellent information. I use an old 2011 MacBook Pro that I have repurposed solely for roasting and beer recipe configuration, and it is alway plugged in because I haven't trusted the battery to not run out in the middle of a multi-roast session. It's on a surge suppressor along with my espresso machine and grinder (both usually off), a small LED light, an Apple USB phone charger, and a Sonos speaker (just have to have tunes while roasting, right?). Next session, I'll try running the computer unplugged to see if that changes things. If so, I'll pick up an isolator for peace of mind. I'll let you all know how things turn out. Thanks again.