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Homeroasters - Home Roasting Coffee Community » BUILDING A ROASTER » Turbo Oven Roasters

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KKTO build questions*FOR SALE*
Alaroast	#1 Posted on 02/05/2020 2:50 PM
Newbie Posts: 43 Joined: February 04, 2020	I'm really interested in the KKTO-design roaster build. Coming from a SC/TO design with the chaff-ejector ring, I'm curious about the air flow in a relatively closed design of the KKTO roaster. My SC/TO has free flow of air and chaff exiting from the ejector ring. Does the turbo oven really have that much induced air flow into the roast area? As air is pulled in and heated and circulated around in the KKTO, where does it exit especially with the silicone tubing providing a relatively tight seal at gaps? Maybe I'm just getting wrapped around the axle for nothing especially since this is a tried and true design. Thoughts? Edited by Alaroast on 10/31/2020 1:38 PM Fiorenzato Bricoletta Espresso Machine, Obel EB Grinder, USRC 3kg roaster


JackH	#2 Posted on 02/05/2020 2:56 PM
Administrator Posts: 1809 Joined: May 10, 2011	My turbo oven has sort of a dual fan setup running off the same motor. Lower fan for the convention and upper fan for exhaust. 90% of the chaff falls between the holes of the roast chamber and sits in the bottom of the pot. ---Jack KKTO Roaster.


renatoa	#3 Posted on 02/05/2020 3:22 PM
Administrator Posts: 3005 Joined: September 30, 2016	There is no free flow in a TO oven having a cylinder shape, whatever is the internal division into a roast chamber and other sections. The air movement starts with the lid fan sucking a central air column, that is thrown sideways centrifugally by the fan blades/leafs. The centrifuged air wraps the lamp, becoming hot, then reach the lid circumference and hitting the walls goes down, not straight vertically, but following a helical path, to the bottom of the pot, where is absorbed in the center to repeat the cycle described above. So the best place to catch chaff for my exhaust cyclone was on the bottom corner, using a pipe placed with the opening in the direction of the chaff descending path. The exhaust is not passive, not enough airflow to exhaust chaff effectively, there is an additional external fan, at the cyclone exit. Whatever is the internal layout of another roast chamber inside such oven, the hot air path is forced to find its way to the center, because there is vacuum, due to the lid fan suction.


JackH	#4 Posted on 02/05/2020 4:37 PM
Administrator Posts: 1809 Joined: May 10, 2011	How am I smelling/seeing roasting smoke in a vacuum? There has to be exhaust somewhere! ---Jack KKTO Roaster.


renatoa	#5 Posted on 02/06/2020 5:02 AM
Administrator Posts: 3005 Joined: September 30, 2016	Is not perfect vacuum, the lid to pot connection is not perfect. And the lid itself is exhausting some air, by design. If you ever dismounted completely a lid for maintenance, you know what I mean. For those who didn't, a short description of the internal lid build follows. There are some holes/places where hot air leaks can occur from a TO lid: around the fan shaft, the bulb wires exit hole, and the thermostat air trap, if lid is not electronic. Also, the metal plate below the lamp, where are the three mounting clamps of the bulb, become a lot hot, being at 1 cm from a +500C heat source, as is the halogen. In order to isolate this hot air, to not melt the plastics of the lid, there is an intermediate cooling compartiment, just above the bulb plate, consisting of a second fan, identical with the visible lid fan, that exhaust centrifugally the hot air leaked from inside oven, through a circle of slots located in the tin ring just above the glass. Check here, at 4:50 time, to see them, the second cooling fan and the slots: https://youtu.be/...ubAQ?t=290 Those slots are the main exit path of smells and vapors from the oven. Not a good path for chaff fortunately, else would have a mess in the room. Edited by renatoa on 02/06/2020 8:21 AM


Alaroast	#6 Posted on 02/06/2020 6:51 AM
Newbie Posts: 43 Joined: February 04, 2020	renatoa, thanks for the great explanation of operation. I've never disassembled my TO and not given much thought to how it operates beyond heat source and limited air induction. So let's go one step further. On a SC/TO setup, the smoke produced when roasting has an easy path for escape through the opening for chaff ejection and is further helped by the cyclonic action of the fan. What is the path for smoke exhaust in a KKTO other than the small cracks and holes by design? Fiorenzato Bricoletta Espresso Machine, Obel EB Grinder, USRC 3kg roaster


renatoa	#7 Posted on 02/06/2020 8:20 AM
Administrator Posts: 3005 Joined: September 30, 2016	Maybe a genuine KKTO builder will reply here, no idea, because my machine is not an exact copy of KK design, one of the additions being an external cyclone separator, which also is path for smoke to exhaust. But I think the lid slots are enough for smoke evacuation, imo. Is the same path for flavour in a normal usage of a TO, allowing you to smell a meat roast or a cake... and estimate it is done or not. Edited by renatoa on 02/07/2020 1:19 AM


Koffee Kosmo	#8 Posted on 02/06/2020 11:43 PM
Administrator Posts: 1620 Joined: December 31, 2008	Quote Alaroast wrote: I'm really interested in the KKTO-design roaster build. Coming from a SC/TO design with the chaff-ejector ring, I'm curious about the air flow in a relatively closed design of the KKTO roaster. My SC/TO has free flow of air and chaff exiting from the ejector ring. Does the turbo oven really have that much induced air flow into the roast area? As air is pulled in and heated and circulated around in the KKTO, where does it exit especially with the silicone tubing providing a relatively tight seal at gaps? Maybe I'm just getting wrapped around the axle for nothing especially since this is a tried and true design. Thoughts? Re - chaff Have a look at the build thread or the blogspot for the shorter version https://koffeekosm...ogspot.com/ Re - How does airflow in a turbo oven work ( simple version) Around the circumference of the unit it has many fresh air entry point slits. The air is sucked in by the spinning fan and over the heating element As the air now heated is compressed by more incoming air the older air is ejected via an exhaust point So it?s not a closed system If you want a faster exhaust you can leave a gap in the top silicone tube KK I home roast and I like it. Designer of the KKTO Roaster Build information https://homeroast...ad_id=1142 https://docs.goog...lide=id.i0 Blog - http://koffeekosm...gspot.com/ Bezzera Strega, Mazzer Robur Grinder, Pullman Tamper Convex, (KKTO) Turbo Oven Home Roaster.
	Web

Alaroast	#9 Posted on 02/07/2020 6:55 AM
Newbie Posts: 43 Joined: February 04, 2020	Thanks for the replies. I'm getting closer to the point of gathering the needed parts to build a KKTO but just wanted to wrap my mind around all the pros and cons before I started. What I am planning on purchasing is the pot and motor in the pictures. The pot is an 8 qt pasta pot with insert and the motor is a window motor for an Infinity. What I liked about this motor is that it already has a square shaft which should make it easier to attach a socket extension to without any modifications. I will source the 12V power supply from a thrift store and will also likely find materials at the thrift store for making a false bottom. I'll find silicone tubing and insulating materials online somewhere. I'm thinking of mounting the motor to the bottom of my roast station table and drilling a hole through table for the shaft to protrude through. I'll then need to figure out the best way to center and secure pot to table while roasting similar to KK's circular wood pedestal but more permanently mounted to table. Thoughts on motor and pot and mounting ideas? Alaroast attached the following images: Fiorenzato Bricoletta Espresso Machine, Obel EB Grinder, USRC 3kg roaster


renatoa	#10 Posted on 02/07/2020 7:25 AM
Administrator Posts: 3005 Joined: September 30, 2016	What are the RPM of motor ? It has way too much torque for what you need, imo, could be noisy (at least the wiper motors that I know), the gears could wear, they are from plastic. I am using KTYZ motors for all my builds. RPM range broad enough to choose: 30, 60, 80, 110, power 10, 14, 28, 40 watts, and no need for a power supply, as they are 220 AC. Silent and vibration free, metal gears. What is the volume of external pot ? If insert is 8 qt, be aware the pot/oven to not exceed 10-12 litres. The diameter is also important, for a gapless match with the lid. You could consider also a chaffing dish based setup, as I suggested here: https://forum.hom...post_69291 Such approach offer at the bottom an excellent base plate to mount the motor, replying to one of your questions. Unfortunately, the top lid diameter is 286 mm, need a funnel for TO lid diameter reduction, potential air and heat leaks. I would rather abandon the glass lid, and mount the heater in the chaffing dish provided SS lid. Anyway, you asked for ideas


Alaroast	#11 Posted on 02/07/2020 10:40 AM
Newbie Posts: 43 Joined: February 04, 2020	No idea on the RPM, was going by what others have suggested for KKTO builds;, either wiper or window motors. I'm in the US so all AC is 110V. I did see that chafing dish idea but was rather pricey for me. Fiorenzato Bricoletta Espresso Machine, Obel EB Grinder, USRC 3kg roaster


renatoa	#12 Posted on 02/07/2020 1:04 PM
Administrator Posts: 3005 Joined: September 30, 2016	https://www.amazo...B07J65VVFS Here that chafing dish is about $30, in the same range as cheap pasta pots. There is pasta equipment five times more expensive than the chafing dish


Alaroast	#13 Posted on 02/07/2020 4:33 PM
Newbie Posts: 43 Joined: February 04, 2020	That's a nice motor on Amazon Renatoa, I was thinking of making a run to the thrift store to see if they had any bread machines to get the motor from but that is cheap and like the idea of shaft with the hole drilled in it. Edited by Alaroast on 02/07/2020 9:56 PM Fiorenzato Bricoletta Espresso Machine, Obel EB Grinder, USRC 3kg roaster


Koffee Kosmo	#14 Posted on 02/07/2020 5:45 PM
Administrator Posts: 1620 Joined: December 31, 2008	Quote Alaroast wrote: No idea on the RPM, was going by what others have suggested for KKTO builds;, either wiper or window motors. I'm in the US so all AC is 110V. I did see that chafing dish idea but was rather pricey for me. Of the 2 KKTO designs The design of the agitator and size of insert determines the drive motor speed Design 1 Uses a smaller perforated insert and needs an agitator speed of 40 to 45 RPM Design 2 Uses an agitator speed of 70 to 75 RPM - This is the model you are building with the larger perforated insert Having said that If you use a lower speed agitator you will need to be creative with the agitator design with extra blades ?TIP? When looking at pots sets it?s best to use pot sets with welded handles KK I home roast and I like it. Designer of the KKTO Roaster Build information https://homeroast...ad_id=1142 https://docs.goog...lide=id.i0 Blog - http://koffeekosm...gspot.com/ Bezzera Strega, Mazzer Robur Grinder, Pullman Tamper Convex, (KKTO) Turbo Oven Home Roaster.
	Web

Alaroast	#15 Posted on 02/07/2020 8:19 PM
Newbie Posts: 43 Joined: February 04, 2020	So I have sourced a cheap bread machine for the motor. I tried running to motor by itself connecting various combinations of the 3 wires together but nothing. I then unsoldered the capacitor from the board and wired it up to motor and now motor spins like a fan (way too fast). I'm no electrician but what do I need to do to slow this motor down? It's running on 120V. Edited by Alaroast on 02/07/2020 9:11 PM Fiorenzato Bricoletta Espresso Machine, Obel EB Grinder, USRC 3kg roaster


Alaroast	#16 Posted on 02/08/2020 10:50 AM
Newbie Posts: 43 Joined: February 04, 2020	So I did some more research of using a bread machine motor for agitation/stirring and came up on this old thread where Zevadiah ( almost 8 years ago) was trying to do the same thing I was attempting and failed: https://forum.hom...ad_id=2632 Bread machine motors are okay I guess as long as you are using both the motor and the belt and pulley system to drive the shaft because the larger pulley turns slower than the RPM's of the motor. Now I've got to figure out another use for this heavy duty motor that likely spins over 300 RPM. Edited by Alaroast on 02/08/2020 9:00 PM


renatoa	#17 Posted on 02/08/2020 11:09 AM
Administrator Posts: 3005 Joined: September 30, 2016	Centrifugal roaster ... match made in heaven with the TO lid All you need is a wok style roasting pan, it's mandatory to have a gradient that make possible gravitational return to center of beans.


Alaroast	#18 Posted on 02/08/2020 8:53 PM
Newbie Posts: 43 Joined: February 04, 2020	Soooo, too much idle time on my hands today so I decided to give this motor a go anyways by using the belt and pulley mounted in the inside bread machine frame. Instead of using the motor shaft end for my agitator I am now using the shaft end that normally drives the bread maker agitator. This thread was started as a KKTO build but now morphed into an improved SCTO with motor replacement. If I like that speed using the motor in the stir crazy platform, I may switch over to the pasta pot idea. I unsoldered the capacitor from board and soldered the motor wires to it and mounted it to the frame with zip ties for now. Works great and is a very strong motor. Pics soon Fiorenzato Bricoletta Espresso Machine, Obel EB Grinder, USRC 3kg roaster


renatoa	#19 Posted on 02/09/2020 1:09 AM
Administrator Posts: 3005 Joined: September 30, 2016	A typical bread machine has about 200 rpm at the dough agitator shaft. Still too much for a flat bottom, is far from the still crazy movement, the beans will be thrown peripheral, unless you have a very smart agitator layout making them distribute evenly in the pan. As I wrote above, the best you need is a curved pan, like a wok, to make beans returning alone in the middle, where will be thrown outside by centrifugal force. Check Probat Saturn centrifugal roaster, for a better image.


Alaroast	#20 Posted on 02/09/2020 4:25 PM
Newbie Posts: 43 Joined: February 04, 2020	You are right my friend. The RPM's were reduced some but I did an estimate and they look to be about 350 which is way too much. It looked slower than that until I attached some makeshift stirring arms and counted (bummer). I looked at the Probat centrifugal idea and that is pretty cool. Back to the drawing board and out with the BM motor. Fiorenzato Bricoletta Espresso Machine, Obel EB Grinder, USRC 3kg roaster


mkane	#21 Posted on 02/09/2020 7:51 PM
1/4 Pounder Posts: 151 Joined: October 23, 2017	following your thread, hoping to build one soon, very soon. Always learning


JackH	#22 Posted on 02/10/2020 8:37 AM
Administrator Posts: 1809 Joined: May 10, 2011	@Alaroast If you look through the Turbo roaster build posts here, you will see what works and what does not. I went through the same process 10 years ago starting with the Stir Crazy and ending up with a KKTO style roaster. Tried many motors including windshield wiper. One of the issues for me in addition to speed was heat transfer from the agitator shaft to the motor. I wound up using a surplus continuous duty gear motor. This has worked for hundreds of roasts. With the perforated inner pot of the KKTO design, most of the chaff falls through the inner pot holes to the bottom, away from contact with the beans. ---Jack KKTO Roaster.


Alaroast	#23 Posted on 02/10/2020 11:04 AM
Newbie Posts: 43 Joined: February 04, 2020	Jack, thanks for the feedback and info. Yes the KKTO design seems to be a well thought out design and has not undergone much change over the years with many happy users that needed more capacity than the SC/TO roasters. That's what brought me to this site. I have toyed around with either modifying by current SCTO roaster with a better motor which is still an option or ditching the SC base and going with the whole KKTO design which I'd probably be much happier with in the long run. I'm still unsettled though on the motor. I thought I read where a 60 RPM motor was preferred but some have used 30 RPM's or less. Some have used 12V DC while others have used AC. Thoughts on this motor? https://www.ebay....2813390381 Edited by JackH on 02/10/2020 11:50 AM Fiorenzato Bricoletta Espresso Machine, Obel EB Grinder, USRC 3kg roaster


JackH	#24 Posted on 02/10/2020 12:13 PM
Administrator Posts: 1809 Joined: May 10, 2011	It looks good if 60RPM works for your setup. Worth a try. Mine was a surplus motor made by Oriental, 110V running about 40RPM which worked for me. Probably too much motor for the use but it was cheap. JackH attached the following image: ---Jack KKTO Roaster.


renatoa	#25 Posted on 02/10/2020 1:39 PM
Administrator Posts: 3005 Joined: September 30, 2016	Quote Alaroast wrote: Thoughts on this motor? Is a KTYZ as those I recommended in the post #10. Used many in various builds for three years, no failure so far.

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