D-Roast

[Geronimo]

This roast is not quite comparable as it's 110g and another bean an Indonesian Tana Toraja. It's made with D-roast. DTR 24%. At 1 min the temp is 106.7 deg and after 2 min 113.9 deg. Much lower temp than the previous NT roast the first 2 min. It doesn't follow the profile after 8 min.

If not already worked out yourself, you have run out of power. Many of us trying D-Roast profile and have non-perfect voltage (perfect being 240 volts and both Steve and Damian have this) have tweaked the later part of the fan profile curve to reduce power. For myself I'm using Damians D-Roast fan profile with the variation of it tapering off at 10 minutes. Everyone will vary slightly on where the safe cut off is to start throttling the fan back. But as a suggestion, don't mess with fan speeds thru first crack maybe, keep that constant by all accounts. I'm sure I will be corrected on this if I've put you wrong, but have yet to see any obvious crash/flick in the curves.

[nrdlnd]

quote=Geronimo post_id=1251 time=1595128245 user_id=177]

If not already worked out yourself, you have run out of power. Many of us trying D-Roast profile and have non-perfect voltage (perfect being 240 volts and both Steve and Damian have this) have tweaked the later part of the fan profile curve to reduce power.

Thank you Geronimo for your kind support! My machine is specially made for 220V and I have 230V on the power line. It should suffice.

I did edit my post and I published one more log later (and you maybe missed that) but now with a 100g batch and with a modified fan profile (DarkSide). Now the roast follows the profile to the end. So this is not the problem.

The observation I've made is the comparable low temperature during the first two minutes with these profiles that have a high fan speed in the beginning of the roast. With NinjaTurtle I get a temp of 122.4 at 1 min and 127.7 at 2 min. With D-roast and a modified fan speed I get after 1 min 106.6 and after 2 min 114.1. The difference is around 15 degrees during the first two minutes. How does that difference affect the roast as a whole? Scott Rao writes about the importance of having a high Delta T (dfference in temperature between outer and inner bean) in the beginning of the roast. I think the Delta T is higher with the NinjaTurtle. The initial fan speed of NinjaTurtle is 1470 rpm and a preheat of 1100W. D-Roast has 1570 rpm and 1000W and modified D-Roast 1530 rpm and 1000W. The NinjaTurtle has a higher preheat setting and a lower fan speed than the other two. Both these settings contribute to a higher heat in the beginning of the roast. The temperature of the air blowing around the beans rises with a slower fan speed at the same heat setting. I think this is important to understand. Could it be that high fan speeds in the beginning of the roast suits lower density beans like Brazilian better to avoid tipping or scorching?

[Steve]

quote=Geronimo post_id=1251 time=1595128245 user_id=177]

If not already worked out yourself, you have run out of power. Many of us trying D-Roast profile and have non-perfect voltage (perfect being 240 volts and both Steve and Damian have this) have tweaked the later part of the fan profile curve to reduce power.

The observation I've made is the comparable low temperature during the first two minutes with these profiles that have a high fan speed in the beginning of the roast. With NinjaTurtle I get a temp of 122.4 at 1 min and 127.7 at 2 min. With D-roast and a modified fan speed I get after 1 min 106.6 and after 2 min 114.1. The difference is around 15 degrees during the first two minutes. How does that difference affect the roast as a whole? Scott Rao writes about the importance of having a high Delta T (dfference in temperature between outer and inner bean) in the beginning of the roast. I think the Delta T is higher with the NinjaTurtle. The initial fan speed of NinjaTurtle is 1470 rpm and a preheat of 1100W. D-Roast has 1570 rpm and 1000W and modified D-Roast 1530 rpm and 1000W. The NinjaTurtle has a higher preheat setting and a lower fan speed than the other two. Both these settings contribute to a higher heat in the beginning of the roast. The temperature of the air blowing around the beans rises with a slower fan speed at the same heat setting. I think this is important to understand.

Its worth thinking about the context of Scotts comments in that they are based on a lot of data / experience he has collected over the years using traditional style ventilated drum roasters and as far as I know has zero experience on the KL. That being said ive found a declining ROR to produce the best roasts with no roast defects using a drum roaster and the KL.

The advantage of a well designed ventilated drum roaster and RPM in the correct range for its size, it already has proper agitation and good airflow from the start without forced air. All that is needed is a gentle exhaust just enough to remove chaff and gases and this is not a lot at all.

When Scott is talking about establishing a high Delta T at the start, its based on dropping cold mass beans into a properly heated large metal drum and giving it enough gas at the start to establish momentum producing this differential which builds pressure inside the seed.

With the KL higher heat at the start with poor agitation may actually be less efficient than a lower heat and good agitation?

Anyway, the best solution is for people to do their own blind cupping and come to their own conclusions or not and just dont worry about it.
For me anything that uses the stock Classic fan profile suffers from various roast defects depending on what the roast profile does.

[Geronimo]

quote=Geronimo post_id=1251 time=1595128245 user_id=177]

If not already worked out yourself, you have run out of power. Many of us trying D-Roast profile and have non-perfect voltage (perfect being 240 volts and both Steve and Damian have this) have tweaked the later part of the fan profile curve to reduce power.

Thank you Geronimo for your kind support! My machine is specially made for 220V and I have 230V on the power line. It should suffice.

I understand what your saying. With respect to the D-Roast only roast, have a look at this video link below, and around the 4 minute mark. It discusses flat line situations and causes. Other than power supply voltage, the use of a long power extension cord can result in a reduction of available power also. Things to consider for future if it happens again.

https://vimeo.com/415693480

[nrdlnd]

@Geronimo: Thank you for pointing at this "flatline" phenomenon where there isn't enough available power at the end of the roast.

I have looked at a couple of logs where this happened at the end of the roast. Both was with profiles with high fan speeds.

The first was with Damians D-Roast. "Flatline" power demand was 1.452 kW. My available power was 1.489 kW.
The second was with Steves DarkSide. Flatline power demand was 1.438 kW. My available power was 1.489 kW.

A third example was when I made a 100g roast with DarkSide and a Brazil Yellow Bourbon that came out as a very tasty sweet espresso. This time it was really "borderline". The powerline flattened at the end but the power was still enough so the temperature could follow the profile. Why this happened I think is because this bean is less dense (natural processed and lower altitude) compared to the former example where I had a bigger and more dense wet processed bean.

I have a hypothesis that if the beans get more heat in the beginning of the roast (higher preheat and maybe also lower fan speed but still good motion) then the power demand becomes lower later in the roast? I may try that with the second example above and do some changes in the very beginning of DarkSide and see what happens.

[nrdlnd]

Now I have made two more roasts with the Indian Kalladavarapura bean that couldn't follow the profile at the end of the roast because there were not enough power available. I used DarkSide but this profile also has very high fan speeds but not as high as D-Roast has at the end of the roast. This is of course also applicable to D-Roast why I publish it in this thread.

First is the original roast where I found out about the lack of power in the last part of the roast.

200716_Indien_Kalledavarapura.png (62.46 KiB) Viewed 9455 times

Second I have raised the preheat from 1050W to 1150W. This has of course effect of the temp in the beginning of the roast for good or bad. It does not effect the last part of the roast very much as the power requirement is still very high with the unaltered high fan speed. There is not much difference at the end..

200720_Kalladevadapura_preheat.png (62.7 KiB) Viewed 9455 times

Third I have kept the higher preheat but also modified the fan speed in the beginning from 1530 rpm to a little over 1500 rpm. This is not very much and maybe I should have reduced it more. It has a clear effect on the temp in the beginning of the roast but maybe a small effect at the end of the roast. I didn't change the fan speed of the original DarkSide at the end of the roast.

Kaladevapura_heat_fan.png (64.25 KiB) Viewed 9455 times

There may be an indication that more preheat could reduce the need for power later in the roast. The preheat is to short in time to show it clearly. These profiles with very high fan speeds may work if you are lucky to have 240V on your power line! I don't see the need for this. We have a lot of profiles now that don't stress the roaster especially now when we have got the 12 core profiles in version 1. I'm sure they will be developed further when we have got more experience with them. I will try them out and make my own adjustments if needed. The fan speed in the beginning of the roast is 1470 rpm on these profiles and I think that is sufficient to get a good movement of the beans. I will though always check the movement to avoid burning defects such as tipping and scorching. Disclaimer: I am hearing impaired so I have difficulties hearing 1C so it may not be correct. All DTR seems to be between 20-25% though.

[nrdlnd]

As a comparison I just made a roast with the same bean but with one of the new core profiles. The bean Indian Kalledavarapura is grown up to 1400m and is fully washed. This time the roaster didn't have to struggle with the power. There is a good movement of the beans. The profile is the 1200-1500m Rest. This profile has a preheat 1200W and the fan speed begins at 1470 rpm. L is the default 3. The end result has about the same roast degree as the other three roasts. The beans get more heat in the beginning with this profile. I did record 1C a little early but I think DTR was about 24%.

Kalledavarapura_1200-1500_Rest.png (59.51 KiB) Viewed 9416 times

[nrdlnd]

I have cut three roasted beans to see how they look inside if they are evenly roasted. The first is DarkSide with extra preheat, the second is DarkSide with extra preheat and lower initial fan speed and the third is 1200-1500 Rest. I've tried to take a photo but had to change light and contrast to be able to see the differences. 1 and 2 are about the same but 3 is more even in colour and seems to be more evenly roasted. I don't know if it's possible to see on the net.

Kalledavarapura_1_2_3.JPG (101.8 KiB) Viewed 9416 times

[theiguanaoz]

Damian, on roasts that have a noticeable crash/flick, can you pickup that they are baked? Cheers

Yes, you can taste it in cupping.
If you've never tasted defect-free roasted coffee, you're unlikely to know, and often people are so used to it, they prefer some baked defects when comparing.
Where it really makes a difference is in Espresso, particularly at higher brew temperature, higher pressure extractions.
Prevent roast defects and you will never get that astringent bitter taste that is so common.

I've been revisiting some of the older beans I had written off as pretty ordinary prior to getting my Kafelogic roaster, and am blown away by how good they are when roasted without defects.

In particular
An India Elephant Hills bean, tasting so close to a Columbian Geisha and at less than 1/10 the price.
A Panama bean in milk that is so much like black tea, you can't even call it coffee.

This is also me now I’ve got my KL! I’ve been drinking way too much espresso these past few days because I’m roasting, trying and enjoying my collection of beans and tasting things I’ve never tasted before and at levels of roast I once wrote off. For the life of me, I struggle to drink some boutique roasted coffee unless it’s a little darker - and I thought light-medium wasn’t for me. But these past few days I’ve been getting really balanced espressos even at light-medium levels using various profiles.

Good info re the Brazilian coffees someone posted - might explain why my natural tastes a bit charred at 3.2 using the classic profile?

Looking forward to trying D-roast this weekend. Downloaded and ready to go!

[Geronimo]

Looking forward to trying D-roast this weekend. Downloaded and ready to go!

Hi Mr Iguana

You may have noticed in the thread on Damians D-Roast profile that it requires a good power supply nearer to 240 volts. If you don’t have good power supply it may flat line at the end of the roast with respect to power (depending on the roast level).

For myself with rubbish voltage I’ve had to taper off the fan speed profile slightly at around 10 minutes.

Hopefully you have a good supply and none of what I mentioned is an issue.

Cheers