Jan. 3, 2020
Heat guns and flour sifters are becoming a popular building blocks for homemade coffee roasters for a while and we are starting to see even more of our creative customers use them. Recently, Sweet Maria's customer Thomas Meeks sent us photos and a description of his creation that he attached to a rolling cart.
"A little over 3.5 yrs ago I decided to devise/build a heat gun/sifter roaster. Leading up to this I'd tried 2 different air poppers as well as a 'slow feed' stainless bowl/heat gun method and all produced satisfactory results, but I wanted something more involved to maximize the coffees I choose to roast specifically for espresso. My V1 (as I refer to it) was built on a small wood frame (totally safe I might add) and utilized a stainless 8 cup sifter, a Master VT-750C heat gun and a cordless screwdriver for agitation. Of course I measured everything many times over, then made my cuts, pieced everything together and it worked great from day 1. The V1 setup ran strong for about 3 yrs then I had to replace a few parts due to typical wear. At this point I had done over 500 batches (200 grams each). Kept roasting away and around the 575-600 batch point I decided to really tear it down and revise it. Bought a new heat gun, the new/improved Master VT-751D and I will honestly say that for anybody interested in this type of roasting there couldn't be any better heat gun than the Master VT (Variable Temp) series as they perform 100% day after day, year after year with very consistent results and offer very accurate fine tuning instead of being stuck with preset heat levels cheaper heat guns have. I also replaced the cordless screwdriver (as I had worn it out) with a Milwaukee right angle drill and a few other upgrades. I will add that my V1 setup only had an analog grill hood thermometer to give readings of heat hitting the sifter screen. At that time I was going pretty much by 1/2C sound to determine development and that worked really well for me. Problem is about 15 months ago I contracted an illness that destroyed my hearing in both ears, so I had to come up with a way to continue roasting with this likely permanent issue. I started focusing solely on bean appearance as well as aroma, then decided to add 2 high quality stainless temp probes and a FieldPiece ST4 dual temp meter. One probe reads temp coming out of the heat gun nozzle and the second one reads bean mass temp."
"This has really given me great feedback to go along with my visual outlook on the roasting process. Even though my V2 revised roaster is based on my initial V1 arrangement, I decided to install all parts on the stainless cart I initially used simply as a way of moving it inside/out as I roast outdoors year round. I will add the fact that the way I designed this (no insulation needed) I have roasted in temps as cold as 15 degrees F with a 10-15 mph wind and had no problem keeping things dialed in/consistent. Biggest issue I see with most sifter setups is the bottom of the screen is exposed, but from day 1 I decided to use a stainless canning funnel to prevent ambient temp air from being sucked up into the sifter which could lead to stalling. I also have an inverted/hinged stainless strainer mounted on the top rim as this prevents coffee from popcorning out when I increase RPM to get rid of chaff, it helps retain heat while allowing the heat gun to breathe and it prevents cold wind from funneling down into the sifter. All parts that come in contact with heat are stainless to be as safe as possible."
"For roasting I always start at ambient temp as it heats quickly, so no need to preheat. I pour 200 grams of green into the sifter, get my agitation speed set to around 80 RPM and start the process. I start at a lower heat for the first 4 mins, then go to a medium range for the next 4 mins. At the 8 min point I go to a higher heat level to get to the point I run things at until 1C, which I reach around the 11:30 mark. Bean temp probe is in the 380s F at this point. Once I give 1C about 1:30 to finish I go down on the heat a bit and keep things on a consistent coasting range until I hit what I consider the full city range around the 16:30 mark, sometimes a bit longer. Bean temp probe is reading in the low 440s F at this point and the bean color is what I'd consider a rich mahogany brown and satin finish. From what I remember from the past when I could hear this was right at the slightest beginning of 2C, then I kill the heat and cool rapidly. With the strainer lid closed I use an electric leaf blower to drastically drop the bean temp and once it's cool enough to handle I transfer the coffee to a colander, then place over an indoor fan 4-5 mins and it's down to room temp at this point. I then transfer to a Mason jar with the lid loose for 24 hrs., then snug down and let it rest for 7 days or so. The way I roast/rotate my jars each batch is 7-8 days post roast when used so consistency is always spot on. For those interested I will gladly provide temperature settings on the heat gun and readings from the temp probes throughout the process. Just didn't want to use up so much space unless necessary and of course every setup/environment will be different. In the past I've tried roasting a bit hotter/faster, but found most coffees were lacking the rich flavor/heavy body that I shoot for with espresso, so I slowed things down a bit between 1/2C and it immediately gave me the increased flavor/body I was searching for."
"I've attached pics of how I currently have V2 setup and it's working so well I seriously doubt I'll ever need to change anything. At this point I've roasted well over 600 batches (200 grams) since starting and the end result is just outstanding. I'm often asked how heavy of a batch this will handle and honestly I don't know. 200 grams has worked so well from the beginning and perfectly fills the jars I use for storage that I haven't seen a need to change things. I will gladly say I do not miss buying roasted coffee one bit. The coffee in the colander pic is a recent batch of Brazil Pedra Branca Lot 1, which I find righteous for a SO." - Thomas Meeks
All photos by Thomas Meeks.