readeral's KKTO

[nikko.the.scorpio]

I was also thinking re: the aluminium shielding. You really want to avoid any heat returning to the glass, as although the amount of glass in contact with the inside of the system is small, the remaining surface area of the glass with which to transmit that heat into the outside environment is still 500 square cm or so. With aluminium shield, the air trapped between the aluminium and the glass will act as an insulating force as well. Even if one gains 10% efficiency, that's 10% more beans you can get into the roaster with controllable results [/QUOTE
Fair point and as I've said from the get go it's not overly hard to put the tray in place (unless you're looking for aesthetic perfection) so should only take ~15mins (not including any gueing on the inside). Cost is also very low ~$3 so worth doing from several perspectives.

What beans have you got in your stash?

I've currently got a couple of kg of the following:
Ethiopian Gambella Sundried
Panama Jaramillo SHB
Peru Ceja de Selva AAA
Sumatran Mandheling Jade

Also around a 1/2 dozen <1kg scraps from previous bean buys. Try to go with 3-4 beans per roast along the rough KJM Blend type guidelines. Keep a very basic log of the batch but it's pretty spartan in detail. Don't mind that I don't ascertain much from it in this regard as I look at the varied combinations of beans as part of the fun of roasting - kind of a lucky dip but I've never had any be poor.

I've historically ordered the lower mid range beans as I didn't find the more pricey ones made much difference in the cup (or could just be the entry level ones were very good!) - IMHO blending is definitely the way to go rather than SO's. And blending is where an expert can turn a good coffee into an unbelievably fantastic coffee......I don't profess to have any great prowess but try to balance out using the KJM template. :-)

[readeral]

Yeah so my Kenya, Ethiopia aren't the cheapest on the shelf, but they were the cheapest africans in stock at the time :P Aside from the Brazil Daterra, the rest were all what came in a sample pack, and the Brazil was definitely worth its cost. Gonna be picking some more up asap as it's deliciously sweet, send some to my brother who "doesn't like coffee".. He'll like this one

I wouldn't necessarily buy a bean because it's valuable - I think you're right, you can be totally satisfied with the less costly beans. It's unlikely I'd get all the potential out of roasting expensive beans right now. But one thing I would happily pay a few dollars per kilo more for (but thankfully one doesn't always need to...) is good graded coffee. Well graded beans are the ones that have given me the best, most consistent results as an amateur.

I've done a little pre-blending in my popper, but had no idea what I was doing, so the result wasn't great. Also it was popper so the result wasn't great... :-/ I think at this point, my preference is for cupping each coffee individually, learning about its flavours, seeing if I can get some consistency from my roasts, and then from there start thinking about post-blending with various ratios till I find something I really enjoy. I'm totally happy to blow my own head off with SOs with high acidity, I've had many an african espresso in my time, and quite enjoy the ride.

[readeral]

So a very slight modification to my build.

I purchased from Andy a 3mm thermocouple, and have installed it exactly where I had the last one.

What I've done is purchased some 3mm fibreglass sheathing (rated to 450 degrees apparently) from Jaycar, and placed two layers of it over 95% of the thermocouple length. I pulled the spring from the top portion of the TC cable (came away easily) and so now the thickness of the cable will not inhibit the turbo oven. I've mounted the TC with a small plate behind so that the entire length sits away from the wall of the chamber. I've also ensured that it sits 5mm above the bottom of the chamber.

So the thermocouple is basically entirely isolated from the chamber itself because of the fibreglass, except for the point where the cable touches the lip of the pot.

The hope is that although the thermocouple will be subject to ET prior to beans being added, and so the length of the TC will still heat up, that it won't struggle to drop in temperature when beans come into the system like it might have if it was in direct contact to the preheated chamber. My previous 5mm thermocouple did not respond to temp drop sufficiently, bottoming out at 140 degrees, as the chamber itself retained a lot of heat (a good thing!!) but being in constant contact with it, I was fighting a losing battle. I'm also hoping the change will give me a little better accuracy in the bean temps as it climbs again, rather than chamber wall temps. Entirely granted BT is a combination of air temp, bean surface temp, airflow etc. (gosh imagine a tiny burn proof Bluetooth temp sensor. Give em 5 years.)

Here's a photo or two l

[readeral]

I'll need to work out a better way of mounting eventually, as this collection of bits and pieces will accumulate cruft.

[readeral]

Well as much as I might have a fancy looking KKTO, I absolutely haven't tamed the beast yet.

I'm feel like a total rookie, and without someone much more experienced roasting beside me and giving me feedback, it's definitely a frustrating experience. I think out of all my roasts, there has only been two that I've been totally happy with (ironaically my first two listed in this thread!), and some that have been 'fine'. I drink (almost) everything I roast though. The only exception was an especially old and dry brazil that I tried to roast I threw out cause it really wasn't suitable for roasting in the end.

Part of the trouble I think I'm having is because the turbo oven is just so sensitive to change, being fan forced AND a halogen element, that the pulsing of the element makes the temperatures hard to control. Preheating properly should help me mitigate this issue, but I don't feel like I've found the right pre-heat temperature yet.

It's also evidently remarkably hot at times I think. I'll end up with underdeveloped roasts that seem plenty dark enough - and sometimes also quite uneven, which is even worse. I think I need to start quite gentle, and then ramp up, and not be too scared to let the roasts exceed 20 minutes.

(The other thing I think that is impacting my roast is the spring that I added. I'll be removing that soon, because I suspect it is still pushing beans around a little bit, not helping with the unevenness)

I've been consistently trying to roast 600g - I'll be dropping down to 450 or 500g with my next efforts I think, to see if I can master the lower weights before trying to increase again. Any insight y'all can offer me (especially you Nick!) would be great!

[Shano592]

I have only done the one roast in mine so far, and it was about 400g.
I think the roast time was around 20 minutes, but I didn't really time it. I just watched it until it hit the right colour for me. I also didn't preheat it, but let it heat up from ambient with the beans.
2 days later, and the beans smell superb!
Don't give in. You will hit on a system that works for your taste, and once you have it, then you will be set.

[Dimal]

I think with a KKTO Roaster, even though it's not absolutely necessary, consistent roasts (and therefore results in the cup) benefit from preheating such that the internal temp is between 130C-150C and stable before you drop the beans in.

A significant portion of the roasting in a KKTO is achieved by conduction with the sides and bottom of the vessel as well as convection and radiation from the TO itself. You're basically looking for a Turning Point of between 60-80C, so adjusting the batch mass and the TO heat setting may need to be juggled to get this.

As mentioned at the beginning, there's no need to go to these lengths but it will help in getting full roast development of the bean, and consistency in the cup.

A lot of people, of course, choose to go the simple path and use the KKTO as a set and forget kind of roaster, which it can do quite well; some of nicest results in the cup I have enjoyed, have been from a KKTO used in this way. All in all, I think the KKTO offers the best of both worlds, depending on how far you want to get into coffee roasting at home.

Some TOs seem to have a wide dead-band temperature controller and it seems that you may have 'lucked' on to one of those "readeral", unfortunately. I do know of a few KKTO users out there who have modified their TOs with a better type of controller but can't remember the details. Maybe one or more of them will chime in with some advice....

Mal.

[bcspark]

I have a modded KKTO using a Steinel HG2300 heat gun fitted to a stainless steel top,shown in previous thread. By using 66% of available cyclonic airflow my main roast is 625grm of greens from ambient ,with full heat the roast takes 15-17 minutes to complete to CS9 @224deg.With my setup I have completed 1125 grm roast in the KKTO.My suggestion to you is to increase the batch size and let the beans roast them selves.Green beans will only use the heat they need to roast as Koffee Kosmo and I have agreed upon.

[readeral]

Don't give in. You will hit on a system that works for your taste, and once you have it, then you will be set.

Haha Shano, don't worry, I have absolutely no intention of giving in! Given I've nailed a few roasts, I know my built is capable so it's just a case (as you say) of getting the operator comfortable on a repeatable approach

I think with a KKTO Roaster, even though it's not absolutely necessary, consistent roasts (and therefore results in the cup) benefit from preheating such that the internal temp is between 130C-150C and stable before you drop the beans in.
...
A lot of people, of course, choose to go the simple path and use the KKTO as a set and forget kind of roaster, which it can do quite well; some of nicest results in the cup I have enjoyed, have been from a KKTO used in this way. All in all, I think the KKTO offers the best of both worlds, depending on how far you want to get into coffee roasting at home.

I think you're right here Mal. My best roasts have had a fairly high preheat (150-200 degrees) but I stopped preheating that high to try and avoid the tipping I was getting. But now I think about it, it was only the overly sensitive brazil green I had that was tipping with a preheat... possibly by lowering my preheat is causing more trouble than it solved.

I was thinking last night that possibly the element-style TO (remarkably hard to get now! Found one at JB-HiFi for more than I was willing to spend) is more desirable, despite their lag in responsiveness, given that the element remains hot while it's not receiving current. The glass halogen element can cool down almost instantaneously, so relying on circulating existing heat in the system - making paramount the importance of the pre-heat! I know this because the fluctuations I'm getting on my bean temp probe (one of Andy's, its definitely accurate - I test it often) can be pretty wild. So I think you're right on the dead-band comment too - will try a different model TO in the future.

A significant factor in my failed roast last night was that I tried roasting in Tasmania, not NSW, and my outdoor temperature dropped 10 degrees across the 20 minute roast. Learned my lesson - roast in the mid-morning/early-afternoon when in the south :P

I know a fair amount of roasting theory for a rookie, I have a bunch of friends that roast commercially and we talk about it often. Also, the internet is a wonderful place, and I _think_ I know enough to filter out the rubbish. Obviously the problem is that I need to better learn my roaster to apply that theory - and what I'm just not going to be able to achieve with it - and also how it responds to environmental changes. One can learn to make coffee quickly, as you're able to make 2-3 a day. Roasting takes a lot more time unless you're perfectly willing to roast up 5kg of beans that you'll likely not be able to drink.

I'm definitely not a set and forget fellow - I'm keen to roast to the benefit of getting the most from a bean, just need to work out how best to control this beast! So I think I'll return to my 175 degree 20 minute preheat, which usually gives me a turning point of around 60, and this will also reduce the number of step ups I'll need to take to increase my temperature across the roast - which will hopefully be a lot more consistent for me.

[Bosco_Lever]

Simplicity is the key.
Follow the teachings of KK.
Preheat at 250C for five minutes.
Tip in at least 650g of green beans.
Let the TO do its stuff at 250C. Tip at cusp of second crack, or slightly into it.
Perfect results.
Burping is only needed for SHB varieties. Once at first crack, and again, 2 minutes later. I only do this for Kenyans, Yemen and Costa Rican beans. All others including blends are left alone.
The trick is to work out the capacity of your roaster, and adjust your technique accordingly.
Playing around with temps is a waste of time.
I followed KK's advice and have had great success. The only bad roasts were due to me becoming distracted and not ending the roast earlier. Even then, the roast was very good, just with some roast flavours becoming prominant, but no ashy taste.
KISS is always the best approach.

[readeral]

Depends what you mean by "best" and "perfect results". I've followed such an approach and it hasn't yielded results that I'm entirely happy with. Probably in the 'fine' category for some beans, and some beans ended up with charring or very roasty flavours, so there are more variables than temperature and time to consider. Maybe you roast in a closed environment, I'm not sure, wasn't part of your KISS explanation. I don't like to roast as dark as the cusp of 2nd - even though that's the most popular depth around here, so I need to be more careful with my development phase and know when to pull.
At the moment I'm documenting everything. I'd sooner know how to tweak a roast to get the best out of a bean. But I'm still green to this game yet.

[Bosco_Lever]

I roast in the garage with the door open and adequate ventilation. I do not use a fire blanket. Ambient temp is 22 to 24C.

Your issue (putting it simply and diplomatically) is that you are complicating matters.
Choose one bean, say an Ethiopian, and follow the above method.
Start with 650g, then do the same with 700g, 750g, until you find the sweet spot.
Forget about the length of time of the roast. Just do it and taste.
You will find which load is best.
This is what KK recommends, and my experience concurs.
I do not get any charring or roasty flavours unless the roast goes into rolling second crack territory.
You need to maintain the temp at 250C, and adjust the weight of beans.
You went to the extreme when building your unit, to stop heat escaping, and can probably do 1kg roasts with no issue. Your problems stem from too small a load.

[Bosco_Lever]

At the moment I'm documenting everything. I'd sooner know how to tweak a roast to get the best out of a bean.

Before you can tweak a roast, the roast has to be drinkable. Tweaking it is by bean weight.
You are trying to run before you walk.
Concentrate on one bean, and learn what your roaster can do at different weights.
Once you have mastered this, you can tweak the roast.

[Koffee_Kosmo]

The KKTO roaster was designed to handle larger loads It's designed to roast loads of 650 grams to 750 grams and above ( roaster chamber volume setting dependent )
Yes it can roast smaller loads but heat control needs to be monitored carefully and check that agitation is also adequate for complete mixing

Also One mans profile using XYZ roaster will not result in the same roast on another roaster Only automation and control of heat source will get close

KK

[readeral]

Yeah so that's what I think I was pushing back against KK - I'm not convinced that (for example) my KKTO wants a 250 degree 5 minute preheat, cause my RoR after loading at that temp is upwards of 30 degrees/minute. My best experience has been a preheat to 150 degrees, but with the whole roaster stable at that temperature.

Absolute statements like "X approach is always best" gets my back up. I'm sure my roaster will behave differently to others.

I'm hearing you on the charge size Bosco, and I appreciate the suggestion - I'll increase the charge to 800g and I'm sure I'll get a much more evened out roast given what you've said - but I still want to know what's going on, and I wouldn't say that keeping records means I'm trying to run before walking. Incidentally, I'm still putting 600 grams in, it's not like these are disastrously small batches or anything. In my conversations with KK and then with other KKTO owners, 600 grams seemed a reasonable starting point, and my method was learned from the info I received from KK. KKs documentation recommended starting with 450g charge, and my starting point for method was as follows (verbatim):

Coffee Roasting Method 2 - Roast from hot start
A Digital Multi Meter can be used for accuracy if a specific drop in temperature is wanted


o Pre heat the roaster at 200 deg Celsius for 5 minutes or until all surfaces of the roaster are hot
o Start the roasters agitator
o Add green beans to hot roaster or a pre determined temperature
o Roast in set increments of temperature settings:
- Start at 200 deg Celsius on the dial for up to 2 minutes
- Increase heat to 220 deg Celsius up to 6 minutes
- Increase heat to 250 deg Celsius to first crack
o Only reduce heat after a rolling first crack and to facilitate a longer time to second crack
o Aim to reach second crack in the range of 6 to 8 minutes after first crack

This was a great start for me - I learned a lot about it's behaviour, and I guess my next step is to increase the charge weight.