Alaroast wrote:I've found a good source of greens at Green Coffee Buying Club. Been buying from there for over a year and there is always a decent variety at good prices.

Thanks for the heads up, Alaroast. Will check out their offerings and prices.

you must roast its a blast and the satisfaction is unequalled

I've roasted three batches now. First was just past 2 crack and the taste was a bit dark for the nice Ethiopian Harrar dry processed coffee that it was.

The second batch, I attempted to reduce the heat as first crack started and drop before 2nd crack. Unfortunately, I think I may have stalled the roast and while it was a brighter drinkable coffee, it was ashy with no visible signs of tipping or scorching.

The third, I think I added too much heat during drying, ramped quick quickly and got a good rolling first crack. But like the first roast, the development time was very quick and I think I heard second crack starting. Only 8 minute roast time. Overall, this third roast tasted quite good. A little dark, but nice brightness that came through. Another plus was the addition of two thermocouples. One aluminum taped to the bottom of the dog bowl. The second was a 1/8" probe, which I added a small thin aluminum plate to the end which was used to stir the beans. I bought a Amprobe logger to record what I did. I plotted the data afterwards and interestingly the probe on the bottom of the dogbowl did a better job of measuring bean temp than the stir probe. The bottom probe showed tanning at 300F and first crack around 390F. The stir probe was consistently hotter and may be a good measure of environment temp. If so, at least I know what the stir probes should read with the next roast (a bit cooler).

I'm going to try roasting 2-3 batches this weekend in succession. I'll likely have this bean a a very good spot by the end of this weekend (fingers crossed). If not, I should have a pound of these same beans left for more roasting the following weekend.

Looks like I need to get some new greens on order or visit my local roasted again. I'm going to be out of this Ethiopian pretty quickly with three batches at a time. I think I will shop for some washed Guatemalan or maybe something from Brazil. This will likely bring on a new roasting experience.

So how do you like being able to control your own roast and experiment with them
Bill

I did two roasts this weekend. One with a stretched drying time and another with a shorter dry time. Both were charged with a bowl temperature of 250F and I dumped them at 418F, which is before second crack. It was significantly colder in my bulkhead this weekend. Ambient temperature was 30-35F. The first roast wound up with a stretched drying likely due to this colder condition and the second roast, I likely over compensated. Both roasts are resting, but I pulled espressos for both. While both are similar in brightness (too bright for espresso or at least not to my liking), I can taste the difference in mouth feel and body as expected. Next roast, I will attempt to ramp somewhere between these two and dump at higher temperature. Todays espresso tastes like it needs less brightness and more caramel flavors and I believe a deeper roast will accomplish this.

What I am discovering is that controlling these ramp times is quite difficult with a heat gun / dog bowl. Simply noting the nozzle distance to beans and gun settings gets me in the ball park, but not likely close enough for fine control of development phase. My ET or MET is all over the map sort to speak. And my varying atmosphere is not helping. I suppose this is why DIY roasters have merged to enclosed bread machines.

This said, my temperature logging shows me where I have been and my stir probe, I believe is close to being an ET probe, so it provides some feedback. But fine control is likely not possible. My last roast, I believe I had a decent declining RoR during development, but with all the temperature fluctuations, I'd be surprised if it made a difference in taste. First crack seemed to last about 1 minute and I dumped 30 seconds after that. I likely will repeat my technique, heat gun setting and distance to beans, agitation and such. With previous roasts, I attempted to stretch the development times, but believe I stalled the roasts. So, my control may be limiting my ability to do much stretching during development. But I am not certain. I find it difficult to sharply determine start and end of first crack with these dry processed Ethiopian Harar beans. And if I stall, it is quite hard to tell. The one roast that I am almost certain I stalled had a strong ashy taste and yet no visible signs of scorching or tipping. I don't know the moisture content of these beans and been reading that storage should be RH of 60-70%, which mine is likely 40%. SO, am I getting poor FC rolling due to low moisture?? Perhaps. My very stretched out roast #2 had very little cracking at all. The quick ramp had more, but nothing I would consider rolling FC.

All good. All coffee is drinkable. More beans on the way. I ordered some SM Colombian La Plata Diomedes, Kenya Nyen Kiawamururu and Altiplano blend. I think this is a good mix of very different coffees. With these, I should know a bit more about roasting different beans and continue to learn my roaster.

Just a suggestion
If your control is hard to do have you installed a gas flow meter?
I had the same problem so I calculated scfm using a Dayton flow meter with a ball in it
Here is a site to calculate scfm gas to btu

http://inspectapedia.com/plumbing/Gas_BTUs_Volumes.php

Take a look here is a clip of my Franken roaster that I made, now it's 6 years old over 3000# thru it

http://www.youtube.com/watch?v=uECZ_4oBPPg

Hope this helps
Bill

moreshots wrote:If your control is hard to do have you installed a gas flow meter?
I had the same problem so I calculated scfm using a Dayton flow meter with a ball in it

Bill, thanks for the tips and very nice roaster! However, my heat source is a heat gun with no gas aiding help. Just yesterday my Master Appliance VariTemp heat gun arrived. It has a knob for controlling the heat source and more cfm of air flow. If I add to this my KiloWatt watt meter, I likely could get very nice control over heat being sourced. However, I am still losing a lot of heat to the environment that is constantly changing. I'm thinking now that I must consider an alternative to the dog bowl or providing some sort of cover to minimize mixture of cold ambient air with heat gun air. I am also getting a lot of chaff blowing up into the heat gun inlet causing reduced air flow. Mr. Spiderman24-7's heat gun/sifter setup is looking better all the time!

But, significant updates to my dog bowl arrangement are in the future after quite a few more roasts. I seriously need to experiment more with different roasts right now. I'm confident I can do better than what I have produced to date with no significant updates.

That's great
Very inventive, I never would have thought of a heat gun
Let me know how it works out for you

Ok, so it is time for an update. I've now roasted 9 7oz batches and my 3lbs of Ethiopian Harrar is about done. Quite a journey and I am certain I did not master the bean. The main reason is the instability of my roaster. While a dog bowl and heat gun allows for some good, cheap method to roast, I was too impatient to add some methods of data collection. I added a couple of thermocouples and a Amprobe logger. Then I switched heat guns. Now, I added motorized agitation and something to hold the heavy heat gun (cause a Master heat gun is too heavy to wand over coffee for 15 minutes). Finally, I added a canning funnel to the heat gun to help heat the beans and shield from the ambient cold. This weekend, once again, I learned the value of roasting by your senses as I fired up this new DIY roaster.




I roasted two Ethiopian Harrar batches. I took a shot at the proper MET temperatures (dialed in the heat gun setting to obtain) and was WAY off. I knew early in the roast because how long it took to yellow and tan. But little additions of heat wasn't done fast enough. I figured a longer roast is better than a scorched roast. But it took 22min and I dropped at 410F BT, which turned out to be a Full City+. SO, my BT has quite an offset compared to my other dog bowl. I compensated for the second roast of the same bean, which is the best coffee of this entire 3lbs of Ethiopian Harrar. I dropped at 405F in 15minutes, which was a nice Full City. The last roast was a freshly opened bag of SM Altiplano Blend. I attempted to run a slightly faster profile, but this bean took more energy to warm and ended up with almost the same profile as the previous batch. Today is day 1 and my esspresso was quite nice with an attractive aroma and pleasant acidity and mouthfeel. The shot finished with chocolate flavors. I think my roaster is a winner for me at this stage of experience.



This roaster is now very similar to a bread machine roaster, but still a dog bowl and heat gun. The benefits other than the obvious motor and holding the gun is the captive heat chamber created by the canning funnel. I think this helps a lot to hold the heat in and therefor I can reduce the scorching heat of the gun. I may add more insulation at a later date since my MET probe did hit 600F. Cons are ability to see the beans very good. I do have a crack where they are visible, but nowhere near as good as an open dog bowl. Another deficiency is controls of air. I may change the heat shield to be a chaff collector with aid of another blower. This may allow me to create low pressure inside the chamber an increase of airflow. Another date for sure . . . .

Meanwhile, I have 2lbs of three types of SM beans waiting. This weekend I hope to do a few more roasts. Cannot wait !!

Nice mods!
I had the same trouble with open air roasting and gave up. Years later now trying out the Turbo Crazy variant and much more stable. Perhaps you can mitigate some of the losses from a viewing/chaff door by adding insulation?
Happy roasting!