Feedback sought: New corretto/KKTO build
I've been using a heavily modified Breville BB290 (with insulated sides, cover, chaff vent) on it's dough program in conjunction with an Ozito heatgun for the past couple of years. ~400-450g per batch.
Anyway as chance would have it the Roasting Gods must of gotten a tad displeased with me last week as the corretto nearly caught fire (silly mistake after some rags I'd been using as insulation down the gaps either side of the vertical pan were accidently pushed to the wrong spot & started smoking....a LOT!!!) - thus it got me thinking to totally redo my home roaster design.
Now I'm kind of stuck deciding on between the KKTO design (full credit and a tip of my hat to Koffee Kosmo for this gem of design!) (which is based around the fitting pot-colander design, classically with the heat coming from a Halogen/Turbo oven) vs a breadmaker corretto using a heatgun. Or a hybrid of each.
Now luckily or complicating my choice (depending on your view) I've got quite a lot of the parts for either roaster path already on hand. Including:
- I gutted/dismantled the Breville BB290 and have removed it's motor keeping it's connections to the control buttons etc and power supply (so worst case scenario if I can't rewire it etc I could use it on the same 'dough' program - though I'd suspect it'd be easier to remove this extra bits and just connect a 12v(?) power source into the motor. I also removed the fanbelt/gearing on the motor as I assumed it might be simpler to use in a 'direct drive' style up directly to the agitator.)
IMG_0083 by NG, on Flickr
- I also happened to have pretty much the identical Arcosteel pasta pot set thats the foundation of the KKTO
- an Ozito variable temp heat gun (unsure how this compares as a heat source vs a Halogen/Turbo oven? Any pro's or cons of each?)
- I've also got another two breadmakers (one of them a very similar Breville BB270 and the other I'd prefer not to use a newer Sunbeam BM7800)
So I like the simplicity &versatility of the KKTO design - though I'm a bit worried about being able to cobble together an adequate drive shaft & agitator. I downloaded the basicish plans that KK had kindly put up and they give you an idea of where to go with the design so thats quite handy.
Alas I've not been able to find any cheap Halogen ovens here locally, was considering the KKTO design but with a heatgun as the heat source via an inlet in an insulated roof- not sure how that would compare.
Very much like the KKTO design, especially as I have the very sought after pots already on hand.....however the driveshaft, making a suitable agitator and modifying the electric motor I have onhand (if viable) are the current obstacles I'm weighing up vs whats essentially a almost ready to go option via one of the other breadmakers.
Would welcome any feedback etc from other members with experience in this area.
Thank you in advance, Nick
PS. I should also note that I've got the extreme luxury of knowing a person who owns one of the ACTUAL made by KK KKTO's. So if I went that path I'd be able to essentially compare and take notes from the real McCoy item, which is a huge advantage as the basic design path.
Now you have the designer answering your question
If you want a
1) Clean roaster that collects the chaff internally
2) Large capacity
3) Single unit roasting
4) Safe with electricity
5) Reliable & Modifiable roaster
6) It can be used with a heat gun for its heat source
Then a Koffee Kosmo roaster is a good choice as you have the preferred Arcosteel Pot Set
How reliable is the KKTO roaster you ask - I would be close to 3000 or so roasts on the same roaster - with a couple of TO changes in that time
This design has remained the same but as parts have depleted I have made design changes to suit
The drive section is available
Turbo ovens can be purchased from Deals Direct or Aldi and other outlets for $50 or less
Good luck with your build choice
ALDI have a halogen turbo oven at $35 at present, I just got one to replace my original unit. They went on sale about 3 weeks ago, but I've seen a number in several stores while I made up my mind to get one.
How are you mate?
Im doing fine Mal
Back working long hours again
Last edited by Koffee_Kosmo; 6th August 2015 at 05:30 AM.
Good to hear my friend...
Don't work too hard mate, you know what they say about time and roses....
Thanks for the replies chaps - special thanks to KK for taking the time to give his feedback.
Yes, I think using the KKTO as the design basework is a bit of a no-brainer. It's proven to work VERY WELL and it adaptable in multiple ways. haha thankfully we very seldom use the pasta pot set, so I won't have to worry about blowback on that one - another major reason the universe is telling me to make a KKTO.
So I have downloaded KK's excellent 36 page PDF designs for the KKTO (again my sincere thanks for being such an amazing individual to not only come up with this concept but share and assist people in making one as well!).
I also stumbled across this thread at another US coffee forum, which deals with how to rewire/simplify the electrical internals of most breadmaker's motors:
Homeroasters.org - Discussion Forum: Modifying a Bread Machine 2 - Re-Wiring
This is the pasta/pot set I very fortuitously had and it's bang on 24cm in diameter:
It appears to be a lot smaller than the initial one KK uses in the designs - however it's essentially identical to the 3 section one he details on page 32. I'M unsure if I'd use the larger inner colander or the smaller one as my roast chamber - I'd always tend to do around 400-500g batches as thats what we drink in a week-10 days and doing more just lends itself to stale beans. I like the idea of using the smaller chamber up at the top of it - as that would be closer to the radiant heat of the TO, and also obviously heat rises so makes sense that you'd have to put less heat in to get said results. And then the larger colander would be as KK has stated primarily be a chaff catcher.
One of the advantages of the smaller container is that I won't have to put the insulated false bottom in place to reduce the overall air volume - so thats a major plus.
However I do suspect chaff would find it hard to escape out of the colander as it is - dunno if that might be an issue - I don't mind just shaking it off later anyway but I'd also have to be careful that the agitator isn't too fast and this spinning the beans all over the place - might have to consider putting that gearing back on or getting a window winder motor instead i it spins too fast - will test that out in a while.
Also I found several suitable ebay listings for whats essentially,"8mm High Temperature Heat Insulation Fire Flame 10KV Protection Tubing Sleeve 1M" to place around the lips of the containers so they get a nice tight seal.
Says it's safe up to 260 (so knowing Chinese product claims prolly catches fire at 120 but anyway) - I assume this is the type of thing that KK uses? Just wondering what diameter you found suitable?
Again not sure if anyone knows of the pros vs cons of a Turbo oven as the heat source vs a heat gun? I would assume the TO might be more likely to get better results as it uses radiant heat over a wider spread - whereas the HG uses a small tight and very strong projection of hot air. The latter I would imagine tends to dry the beans out more and thus add an extra element thats somewhat undesired to roasts.
I'd figure the HG might have the advantage in the reliability stakes - as often even the Ozito ones come with 3yr warranties (which has bailed me out atleast once) but anyway alas I think I've missed out on all the Aldi ones in my area (which amazed me as they seemed like they'd never sell but sure enough as soon as I'm interested they're all gone!)
Anyway I'll have a hunt around - and also pull the scrap breadmaker body metal out of the bin as I will try to follow KK's design and fashion the agitator from that.
Much thanks, Nick
I checked the "air-off" temperature on my original turbo oven, admittedly not a halogen, and at the top of the pot it was more like 360 degrees IIRC. Anyway it singed the insulation on my thermocouple. I have been using tubing rated at 250 deg and it has slowly darkened over the years. Just recently replaced my original tubing (I had a double length), but when that goes I will look for something with a higher temperature rating.
Hey dudes, I've been looking into the hoses for my own build. You're not likely to find hoses over 250 degrees in silicone in my anecdotal experience - I'm not sure that car spec would need it higher than that?! But if you come across any let me know! I looked up KKs recommended inner and outer diameters and found the relevant tubing on evilbay (bunch of UK stores have it cheap with good shipping too)
@russellb, handy info - good to know.
@readeral, any chance you can post up or msg the links to the tubing you're considering? As it's not coffee related or anything sold by the sponsors I don't think it'll irk anyone. Thanks in advance.
FWIW just ordered an inline on/off power switch to mod the breadmaker motor. Also found a very cheap 19cm diameter steel baking sieve to use to make an improved bean cooler (I currently use a large sink colander/strainer with a large fan blowing on it - so the extraction fan style via bucket will be far more effective) - ~$AUD3.40 delivered from China.....crazy prices!
Anyway FWIW the dimensions of my potset (which isn't the Arcosteel one BUT is very close is)
MAIN POT (to be used as exterior)
Height to lip: 14cm
Internal diameter: 21.5cm
Nice thick and stable base around 3mm thick, all stainless steel, spotwelded handles (which I know KK insists on!)
By my calculation even if this was used as was it would have a volume of around 5.7L - so well within KK's recommendations and definitely NOT needing a false bottom etc.
LARGE INTERNAL INSERT/COLANDER
Height to lip: 14cm
Internal diameter: ~21cm
Again reasonably solid SS construction, has a lip around 6cm down from the top of it that allows it to 'sit' in the outer/exterior solid pot. All the holes are 5mm in diameter, which should be small enough to allow most of the chaff through but no beans (will test out just to make sure but optimistic).
SMALL INTERNAL INSERT/COLANDER
Height to lip: 6.5cm
Internal diameter: ~20cm
Same quality of materials, 2 wire steel handles (handy but would have to put lil extensions/holders out so they wouldn't fall down when in use and snag on the agitator). The holes in this are smaller, ~3mm.
Last edited by nikko.the.scorpio; 6th August 2015 at 03:33 PM.
Both KKTO roaster designs have a false floor or insert to adjust the chamber volume to the ideal I have set
Version 1 was a large pot with a floating insert - This design was changed to the two pot system for burn safety reasons
The hoses that I use are high temp vacuum type that are used in racing or high performance cars
OD top hose is 12 mm , OD lower hose is 8mm
Much thanks KK, I've been enjoying your posts over at Coffee Forum as well - so much wisdom but you've got to search out the best stuff - oh well makes it more rewarding!
Originally Posted by Koffee_Kosmo
I suspect my pots are quite a bit smaller than yours and unless I was using the small internal colander alone (without the larger one in as well) I'd actually not have much room for a false bottom inside the main pot. My larger pot is only 14.5cm or so in total height (vs the one in your plans being 16.5cm). By my calculations with the large insert in there's around a 4cm gap between it's base and that of the external pot.
Therefore with a total height with this on of 18cm that gives an internal volume of ~6800cm3. Which is around the ballpark of what you recommended.
Therefore I'm unsure if the false floor would provide any benefit as my concern is that it makes the already small-ish internal volume even smaller. As if I did say a 3cm total false floor and then had only 1cm clearance between the large insert and the false bottom it'd take ~1100cm3 off - I'm unsure if this is of much real benefit given the already small size - but would greatly welcome your feedback if you feel it's still essential or very recommended (even in this smaller pot/s).
Thanks again, Nick
PS. Much thanks for the confirmation of the tubing used and the diameters. :-)
So this is the hose for the seal between lower pot and roasting chamber (8mm hose, 4mm inner, 2mm wall) hose 1 or hose 2
And this is the hose for between the turbo-oven and the rim of your roasting chamber. You'll have to slit it to slide it over the edge of the pot (11mm hose, 6mm inner, 2.5mm wall) hose 3 or hose 4
Unfortunately somewhat mis-matched colour wise if you wanted anything other than blue or black, but it didn't matter too much to me.
All those links state they have a working temperature of 260°C - dunno how true that is, but the best you can do is take their word for it!
I've been thinking about the KKTO build for about a month now. The beta testers thread will give you a whole bunch of context into why KK has done what he's done in terms of design - the false floor seems invaluable.
Looks like you're all over it when it comes to searching through the forums Nick! Where you based?
Ah I wouldn't say that but hey it's worth doing right and KK has done all the hard work so tracking down a few posts (and those of other KKTO builds) isn't too hard. :-)
Originally Posted by readeral
I'm in Coffs Harbour. :-)
Oh and much thanks for those links to the silicone hoses. FWIW I don't think that silicone hose or any type of hose for the lower pot & large roasting chamber insert is actually going to be viable. Mine has a sort of a recessed lip inwards and thats what the internal insert sort of sits on. So I'd actually be better off making a sort of a gasket by sticking a thin strip of heat resistant material (silicone again seems a reasonable choice) around either the internal join point of the external pot or on the exterior same point on the roasting chamber.
To be honest it's already a pretty good seal I cannot imagine that much heat will escape from it. I might actually try and make a gasket to give a tighter 'seal/fit' by doubling up/folding some aluminium foil around the join point for the internal chamber. That might be all hard to picture haha and it's pretty much only specific to my pots but I don't think anything but some really BIG tubing/hose would work on that joint/seal. e.g 15mm
The top joint between the pot-roasting chamber and the TO however is very much perfect for the tubing you suggested and I'd say the smaller ones would be the best solution as I've got a rolled rim thats around 3mm in diameter. So as long as it's a nice even fit all the way around smaller would actually give a better seal than say a 8mm one , where there'd be a lot of play/room to move around etc.
Yes, I think the Chinese sellers have picked 260degrees as their temp mark - not sure how true that is but in theory it's ok and am happy enough to run with it & replace down the track.
Thanks again for your help, very handy as I did not see those at all!
PS Ordered the 5mm internal hose in lime green! Should fit easy and seemed the good value point. 75cm diameter so will do the top -> TO joint nicely.
Last edited by nikko.the.scorpio; 6th August 2015 at 05:45 PM.
The join between the two pots do seal when water is boiling and the steam forms a seal
However dry heat does escape especialy when it's also fan forced - Do not allow your roaster to leak or radiate heat away from the roasting chamber
To your pots - it looks like they are a mismatch
Looks like you have the right perforated insert and the lower pot is fron another set ?
It's a bummer you're in Coffs (I'm in Syd) - would have been good to have someone to tweak KKTOs alongside!
Re: KKs suggestion that the pots are mismatched - if that's the case, and you're keen to go along with a different set (or for anyone else watching in on this thread!) I recommend getting in touch with this seller in Vic on gumtree link removed as per site posting policy of the right pot set - they might post. Would be $20 for the pots, $20 for the postage (given the known parameters about this pot set).
Or if you're gonna pursue the pots you do have - I'm with KK on that one - any extra airflow is just gonna suck the heat right out. Like when your car window is open slightly but doesn't look it, just enough for the seal to break.. you feel that draught. Well I do anyway! You'll have to seal it somehow and the silicone might do the trick. There were some comments in a thread somewhere about picking the right silicone, or allowing it to season properly or something - so just be aware of that. I can't point you in the direction of what I read, but IIRC the resulting experience was a wasted batch of beans. [I've read WAY too many threads about this... shame the wiki is no longer online, would've saved a hellava lot of time]
Last edited by Javaphile; 7th August 2015 at 04:30 AM.
Reason: Gumtree link removed
Sigh... I knew it'd get removed, just hoped I'd be helping someone out.. given no one sells pots... If anyone is still interested, search 'Arcosteel stainless steel steamer' and find the ad based in Eltham.
KK, point taken regarding dry heat and the fan forcing - as stated I'll try it out as is and if needed make a gasket of silicone on steel via a layer of silicon around the inside at the joint section of the pot. The tubing just wouldn't work there for me as the 'joint' section where the two pots meet is too far from the lip.
Originally Posted by Koffee_Kosmo
The pots may look like a mismatch but I can assure you they are a completely matched - I'm the original purchaser from a retail sale so no dodgy imposters. ;-) They actually fit each other VERY well, as mentioned I'm not really sure if using the top smaller insert would be TOO close to the TO - I suppose it could be at a lower temp to adjust which in theory might be a positive.
On the TO, I drive across to the next nearest Aldi store today - which is Toormina - a bit of an outer suburb of Coffs Harbour. Anyway the Coffs Aldi had none but when I arrived I found that Toormina has around 30 or so of them left! $30 a pop.
Hence grabbed one. Also grabbed one of the full metal encased thermocouple probe's - the same one that KK has used in several of his builds with the quite thick robust probe. I already had the digital thermometer that accepts a K-type thermocouple so that was all fine. I also grabbed one of the screw-in short headed probe attachments, just in case that style of probe suited the design better. At $3 and $1 a pop it was no big risk.
I've a load of fire blankets and will use one of the spare ones as the innermost layer of insulation on the outside of the outer pot.
@readeral, thanks for the suggestion but as stated rest assured the posts are a a complete set and fit very well. Yes, it'd be quite handy to have another person to do the KKTO build with - haha but surely you can find someone down there! I reckon loads would be sitting on the fence about it.
Yes, bit of a bummer the link was removed - I always assumed the Ebay/Gumtree listing ban was to protect sponsors from competing sales but perhaps it's also to stop spammers etc - still I always find blanket rules are often inefficient and selective application of the rule (given that it wasn't something sponsors sell, and clearly not a spammer either) but it's others call and not mine - credit to you for trying to share your find with others.
Cheers and thanks, Nick
Ha, I went green too. So nice!
Originally Posted by nikko.the.scorpio
Which and where did you get your thermocouples from?
Originally Posted by nikko.the.scorpio
haha well obviously great minds think alike!
Originally Posted by readeral
Beanbay does actually sell thermocouples so out of respect for them I won't post the link but search for item number: 391159090362
Like I said, appears to be the same one KK used in a few builds and nice bit of kit for only a dollar or so more than a naked thermocouple lead.
I figure the driveshaft won't be too hard as socket extender bars are the well documented and easy choice. The agitator might be a tad trickier, I know if I keep it simple the stiff wire/coat hanger bent into a look seems a popular choice. KK uses one on his thats just dead sexy....haha alas having seen that I now want to do something the same. I've a bit of pressed metal on hand from the breadmaker and will see if I can cut and bend something out of that , with the wire loops as a fall back position.
Also need to test out the breadmaker motor to make sure it's not going to spin WAAAAY too fast...but most stuff is pretty much sorted. I figure I might go for the inverted box type stand that a lot of folks go for - putting the motor & cabling etc in there. Seems a smart choice and ideally I can find one premade, otherwise will knock one up with some MDF or similar.
On a sidenote I did find a thread over at another forum where KK and another member compared using a HG instead of the TO as the heat source for the KK roaster. It seems that atleast one of them thought the HG was considerably superior (noted towards the end of the thread - which is interesting and actually a little surprising - though it should be noted he was using a very expensive HG!
Anyway that does provide some thought that if you can't get access to a decent TO or already have a HG onhand, it's a VERY viable replacement.
Also.....have you given any thought to insulation or atleast reflective material on the glass perimeter of the TO's lid? As I mentioned earlier I'm lucky enough to have a friend who has an actual KK made KKTO and when it's in use the halogen bulb is absolutely BLINDING! It'll almost blind you if you look at it too much.
You also end up losing around 40% of heat via the top (assuming the %'s that apply to houses are similar to the KKTO) and so a lil insulation could make a big difference. If nothing else I was definitely going to put some aluminium foil on it - heat siliconed in place if need be. That'll block the blinding glare (as apparently looking in via the glass to get an idea of how it's going ISN'T that helpful as the halogen makes the colours appear all wrong) - so you're kind of best to go by what your thermocouple tells you and listen for first crack or life lid quickly to peek in.
I also noticed in a couple of threads KK had cut big holes in the halogen oven's metal heat diffuser screen. Would it possibly be viable to remove this all together and just use on a lower heat setting? Or is that a bridge too far?
Thanks again. :-)
PS. FWIW using the breadmakers motor without the fanbelt and gears is definitely NOT an option. Rigged it up and attached a clothes peg to the drive shaft so I had a more accurate idea of how fast it was spinning and was an absolute blur! Atleast 300rpm or so I'd say and thats many times the 70rpm that KK said to aim for.
So either have to find an adjustable resistor type option for it or just go grab a scrap window motor like most others tend to. :-)
Last edited by nikko.the.scorpio; 7th August 2015 at 02:10 PM.
Go to this thread and print out the pot size drawing and compare to your set
Next - Heat guard increased airflow mod - Yes it's worthwhile but don't remove it completely - for safety to the glass encased element reasons
Insulation on the glass - Yes that will also work but leave a gap for viewing
But in doing the glass insulation be mindful not to block the air intake slits / holes on the TO
KK, thank you for your reply.
In comparison to those drawings my exterior pot is 215mm (interior top), 205mm (base), total height is 145mm (though around 10mm on the top is lip & 3mm at the bottom a thickened base).
The larger interior colander/insert has a total height of 145mm, it's 'lip' that rests on the exterior pot 42mm below it's top. The height of it below the lip that actually goes into the larger pot is 90mm. Diameter is 205mm.
When they're inserted into each other you're looking at bang on 180mm in height.
So overall it's a fair bit smaller than those drawings, particularly on the height front (45mm less in total height and 25-30mm in diameter).
RE: Heat guard - thank you for confirming. I've seen a few of the mods of this you and others have done. - So the main idea seems to be to leave enough metal to kind of protect the fragile bulb/element from possible breakage BUT allow as much of the light/heat and airflow to get out? If the item being cooked was static/held in the one position then I could imagine the heat diffuser would need to stay in place otherwise the lap would scorch those things directly below it but as the beans will be constantly in motion the more of the lamp that can hit them the better.
RE: Insulation on the glass - thats a good idea to leave a small slit etc to view. Definitely will not block any of the air vents but excellent point.
I'd been wondering about the insulation of the glass as well. The options I can come up with are using foil insulation, or again going the silicone route, dropping a silicone mat (260°C safe) over the TO. Either option with a hole in the middle for the TO proper, and trimmed to sit neatly on the glass lid. Think like a poncho but for turbo ovens.
The foil would probably have to stay put (? I'm not sure.. how rigid is this stuff?), but a silicone mat could be lifted to look inside. Downside to silicone is further sound deadening, which is obviously unhelpful, upside is being able to stretch it over into place for a snug fit once on.
Bummer about the breadmaker motor - going the geared route might end up with a more reliable mixing speed under variable batch sizes?
Re: the HG option, I was curious as well, but not instead of but in addition to TO. It'd be great to have the option to funnel in heat from the bottom/side (diffused somehow) in order to better manage the ramp speeds for various beans. Unlike the proven 2-heat source version with the element in the base providing a constant stable bed of heat, the HG would be able to much more rapidly adjust the available heat - it's benefit would be it's instability - controlled by a Arduino+TC4 even? But with this thought experiment also comes the realisation that many KKTO owners do satisfactory roasts with just the TO.... over-engineering brings it's own problems. Maybe a retrofit to do once I move back to (currently 7°C) Hobart
Foil is definitely the easiest option. Shiny side down and you could either place just a single layer on either the inside or outside of the glass or 2 of them if you wanted.
Originally Posted by readeral
The foil is going to be essentially acting as a reflector to the IR/radiant heat. I know being inside the glass would be the most effective for this BUT it'll also wind up putting chaff/dust etc all over the foil and as it's not the toughest stuff you might have to periodically replace - I figure as you're not worrying about the edges of the rim it's probably easiest to keep it simple and apply a new layer every couple of roasts as needed. By using 4-5 straight pieces of foil and crinkling them to fold them over/around the lid's lip you should get something pretty sturdy that'll work in the most effective spot - inside the lid.
You're right that another insulation layer, like silicon, applied to the OUTSIDE of the lid would be very effective in slowing down the heat that would otherwise pass through the foil and glass. There's atleast one Aussie ebay seller who sells sheets of heat resistant silicon ranging in 1.5mm up. Even a very thin layer would be pretty effective. The roof is where the vast majority of the heat is lost (apparently 40%+) so probably worth doing in some capacity - as that means less heat has to be put in, which is always better for results. As long as it can be stuck in place (not causing issues with the TO's vents etc), is heat resistant (though being on the outside it'd not have to be as resistant on stuff used inside) it's an option - so several materials definitely viable to use.
Yeah the breadmaker motor I'm pretty sure is not viable ......if I use it with the gearing/fanbelt it turns at pretty much the perfect speed BUT at this stage I'm very unsure how I'd incorporate this kinda cumbersome piece underneath any build! Im order to maintain the existing drive shaft mount I trimmed the very bottom of the breadmaker's baking tray out but the whole thing is as you can see a real PITA to potentially use when you compare it to a direct drive, standalone 12v motor like KK advocates. So thats why I'm pretty sure I'll trash this and source out a low RPM 12v engine somewhere instead:
Originally Posted by readeral
IMG_0088 by NG
I think you've summed that up quite well - it's nice in theory but prolly brings a number of new issues to the table and there's defiitely as you say a LOT (I'd dare say the vast majority of KKTO users) getting great roasts without use of a HG.
Originally Posted by readeral
I think the combination of modding the heat diffuser screen/shield on the TO, properly insulating the exterior sides of the pot (using a fire blanket with old towel around it), several layers of foil on the exposed glass of the TO lid and possible silicon layer on part of the exterior of the TO's glass lid - combined with a preheat of the entire unit (as advocated by KK) would allow the roasts to be done easily.
Well I had an interesting and active last 24hrs with the KKTO project.
Firstly last night I applied some al-foil to the lid's glass sections. Pretty easy to go, just had to use a half dozen or so strips that by crinkling in the right spots would basically hold themselves in place. Also applied some very small dabs of heat resistant silicone (which by a minor miracle I also happened to have onhand) to secure them. Wasn't trying to make it a beauty contest entrant, just effective and so 15mins later this was the result:
I was sure to leave a small gap for viewing in (which was shown to be absolutely essential!).
I then realised that the handles on the larger insert tilted upwards and when the TO was placed on the top of it the downward curve of it's lid hit the handles leaving a 2cm or so gap! I tried bending the handles down but that wasn't sufficient - hence out came the angle grinder and 10mins later the top insert's handles were no more!
Also made a quick and painfree al-foil gasket for the large insert's lip/joint with the outer pot.
All these were done to allow me to roast some more coffee today, so the al-foil gasket although it worked very well and a very effective seal might be replaced with something superior in the long term - though I think the ease & effectiveness of it will possibly mean I'll keep it as using silicone on my pot's lip design is a PITA for the lower joint.
Anyway - I also very slightly tweaked the TO by wedging some screwed up bits of al-foil in the holes that the leads/cables that connect on either end of the halogen bulb some out from the body from. My rationale was they were around the size of a 10c piece and I could see chaff etc getting up into the electrics, hence easy to do and reverse if I need to. I left the heat shield/diffuser as was.
I folded a fire blanket a bunch of times and wrapped it around the sides of the outer pot. Fortune was smiling on me and the ties for it lined up JUST RIGHT so I could tie it firmly in place!
I used 400g of beans (60% Mexico Atoyac(?), 30% Ethiopian Gambella Naturals, 10% Sumatra Mandheling Jade) - preheated at 200c for 5mins, added the beans.
Now you're probably thinking how did you stir them etc????? Well this was always going to have to be a manual agitation job, so with some thick gloves on I gave held the edge of the lid to the lower handles (which kept a nice tight seal) and every 10 sec or so gave it a couple of swirls and a slight flick of the wrist, as you might flipping a pancake (but more subtle) to try and roll the beans over from top to bottom.
first crack came on at about 12min. second crack hit around 4min later. I continued on about a minute after this and dumped and cooled. I didn't even need to increase the temp from 200c to achieve all this!
Now I wanted to roast a little darker than I generally do (as I've still been erring on roasting lighter than one should for espresso consumption as opposed to my last many years of roasting for a french press!) though this still went a tad darker than I'd have like4d - prolly should have pulled 1min earlier. Here's the result - around a CS11......and I had perhaps 15 or so beans that were a CS16!!!!! aka charcoal!
So what did I learn from this first very rough and ready effort:
1. 400g is too small a batch in this smaller roaster, I'd say 600g or so might be the sweet point - either that or I need to roast on a lower temp.
2. The al-foil is very effective. It had no issues in coming off - despite me holding it on the outside to move the entire roaster around. Pretty easy to clean off too, being reflective in it's insulation abilities it really needs to be kept clean to work well - so we'll see how that goes longer term - but if you were happy to replace every few goes I don't even think you'd have to glue it in place (and I only used a few very small spots of glue)
3. The TO and the KKTO design is far more effective at getting heat into the beans than the HG/corretto ever was. Like I said I kept it at 200c and it was at first crack quicker than I'd have hoped, I'll try and stretch this out next time but it's very good at getting the job done. I was very impressed.
3a. You absolutely, positively need to have a motor and agitator which turns the beans evenly. I gave it a fair bit of tossing etc and like i said 15-20 of the beans were really badly burnt (I discarded them) - so if anyone was thinking of doing a low tech build and agitating themselves DO NOT, it's far more hassle to flip around etc and doesn't work that well.
4. Upon removing the large insert/roasting chamber I was greeted by the beautiful sight of a huge pile of chaff at the bottom of the outer pot! So that worked really well without any slits or anything else cut. From my tossing the beans around a bit of chaff got incinterated on the heat diffuser but otherwise it was really no issue at all and none left on the beans at all!
5. Any thoughts to removing or modding the heat screen/diffuser will be put on hold as it was VERY effective left as is and it does seem a very handy thing to protect the bulb from chaff and possible knocks. Like I said if anything my roaster was far too hot, hence not a priority at all.
6. The al-foil gasket around the outer/inner pot worked really well, I ran my hand around the outside whilst it was in use and could not notice any air getting out at all. The top of the pot to the TO's lip was pretty good (when it was moving I was holding it flush and tight) but with the silicone tubing coming this will be greatly improved.
7. The window (section left without al-foil) was essential - seems obvious but it gave me essential feedback on how the beans were going. I wore sunglasses when roasting and did outside, no issues at all.
Anyway I'm not a member of the KKTO club yet but this very rough trial was more than enough to show me what a wonderful design it is. I just need to come up with a platform, drive shaft, motor and agitator for it and we'll be in business. :-)
On this thread, a bloke managed to mount a breadmaker motor with some brackets - might be worth trying to rig up before you ditch it? http://coffeesnobs.com.au/roasters/3...nsys-kkto.html
Originally Posted by nikko.the.scorpio
Sounds like you made it too efficient Nick!
I haven't read anywhere about internal foil insulation, let alone foil + modding the heat diffuser - so doubt you'd need to touch it as you say.. You could experiment with only foiling half the glass - might back it off just a little to give you a little more room to move? Or do you think you're happy with it's efficiency and you'll just play with the green volumes?
Keeping it at 200 C is pretty impressive - would be interested to know once you have your thermocouple what your ramp is like at 200.
Are you just using regular home foil - or some of the more heavyweight stuff? Might be more durable if using stronger foil? - I'm thinking of getting some of the foil insulation from bunnings (not alfoil) and making a sleeve for outside the glass - hopefully it might manage a bit of reflection even through the glass - and I'll top it with a sheet of silicone - see how that goes. But I'll give it a run without insulating the glass at all first and see if it's satisfactory as it is.
I've got a bunch of my stuff arriving in the next fortnight, so hopefully I'll have a build pretty soon to show off as well! Did you end up getting and ALDI TO?
If you go to evilbay you will find 6/12volt dc geared motors suitable for use. KK should be able to recommend RPM .There are models the same as origonals
KK does have motors available too. I've just purchased one (and a drive shaft) from him.
Thanks as always to everyone for the excellent replies!
Ah I didn't do much myself - just a very good design by KK and the main thing is that my pots are smaller than those most folks seem to use. It's definitely a GOOD problem to have as a lot of folks seem to be asking about more powerful TO's, chopping up the heat screen etc and well this worked too well and did so without all kinds of insulation, lid being kept tightly down etc.
Originally Posted by readeral
IMHO foiling the glass is a good thing - if for no other reason it cuts down the VERY harsh glare of the halogen bulb - I accidently looked at it when it was on while I was roasting and my eyes hurt for 5mins! Hence I put the sunnies on.
Originally Posted by readeral
I'm all about finding the 'smart point' of tweaking/modding stuff - so I know you could do all kinds of lil tweaks/mods etc and squeeze every drop of efficiency out of whats already an excellent design by KK but I want to do the easy, cheap and simple stuff first - assuming it works well (and it ALREADY does) thats enough for me!
So yes, I'm very happy with the efficiency already - I figure I'll prolly increase the green bean volume slightly and also know to decrease the heat used, atleast initially in the roast as I want to try and drag first crack out until later (I believe the recommended roast profiles for espresso coffees (I know this is being massively simplisitic to lump all in together but anyway) is first crack at around 17min - second crack 7min after or so.
With the corretto/HG you often had the opposite probelm - in that you'd have trouble getting enough heat in and would have to really turn the HG up, resulting in tipping and scorching on the beans.
Yes, from the number of other KKTO threads I've read, and thats quite a few I was pleasantly surprised that getting the required heat in wasn't a challenge.
Originally Posted by readeral
Yes, just regular aluminium foil. FWIW if you wanted to be smarter I came up with a better solution (that I might switch over to myself!). The problem with the foil is it's very delicate and easy to rip etc. Also after a few roasts a layer of dark residue will build up on it and this will (I would expect) massively decrease it's efficiency as an insulation. Cleaning it might be hard due to it being so delicate.
So what you do is you buy one of the disposable foil cooking trays - you know the ones meant for BBQs etc? I was in Woolies this morning and they sell what appeared to be a near perfect one for ~$3.50. It was round and almost has a template on it for where to cut so you get this perfect piece of much thicker foil to place on the underside of the TO's lid. Being that it's round it should be a lot easier to fit to the curved lid than using multiple rectangular strips.
I've used this material in my previous corretto and it's strong enough that you can wipe it off and can't easily damage or rip it. One nice big piece, instead of my 7 or 8 - and put a lil window in it and you're done. You could always be a real smarty and have the window with a cover on the outside to maximise heat retention. Super simple - anyway if I was doing again I'd do THAT instead of the multiple layers of foil - is a much better solution and only $3-4. Just a few dabs of heat silicone and I suspect it's very close to the perfect size!!!
Dunno about the insulating foils at Bunnings - a lot of the ones I saw has a plastic or asphalt backing to them that made them unsuitable. Technically the foil on the inside of the lid would be the most effective (otherwise the glass absorbs a lot of the heat first) but I suspect we're splitting hairs here as any foil as all will be very effective - and on the outside you don't have to worry about it's performance diminishing over time (do have to clean inside of lid though!).
The silicone or another layer would definitely take it to another level - no argument there but for me I think the foil (specifically using the round disposable foil pan cut out) is the minimal effort/maximum benefit sweet spot. But thats just me. :-)
Cool, oh well I really look forward to your thread and updates. Yes, the TO is the current Aldi Lumina one.
Originally Posted by readeral
@bcspark, thanks for that I'll have a look - though that thread link by @readeral does make me think perhaps I could use the existing motor (which does the perfect speed) with minimal hassle. But good suggestion!
@readeral, oh I didn't know he still sold stuff, he's so modest that while many others would shove/force buying from them down your throat it wasn't even mentioned. Thank you for highlighting this!
Last edited by nikko.the.scorpio; 10th August 2015 at 01:13 PM.
Well after @readeral's advice I'm going to stick with using the breadmaker's motor for the KKTO and will mount/house it in a similar manner to the 'Burnsy's KKTO' thread. Thank you very much for this.
The speed of the breadmaker motor at full speed is very similar to the ~70rpm that KK advocates. It should be no more difficult mount/house this than a direct drive motor such as KK sells and it saves me the potential minor long term hassle of heat coming down the driveshaft and affecting the motor. That it's the perfect speed and onhand is the deal clinchers.
So it's just a matter of coming up with the drive shaft (which essentially allows a fair bit of flexibility - as long as it's stainless steel and around the right gauge). I'll then just have to figure out how to most effectively join/connect it to the breadmaker's connection/paddle mounting point. It'll likely either be through a couple of old sockets (possibly adapted in some manner) or some spare/scrap metal bits I locate around the house.
Thanks to @readeral for reminding me of that thread (as I had seen it before but completely forgot).
I know of 2 other builds that use the smaller pots and they work just fine
RPM is important but more important is the agitation and mixing result
Have a look at the videos I have posted with the red bean mixing tests and try to replicate it on your roaster
Enjoying watching your experimenting and problem solving with your kkto.
Sorry to jump in on this thread, feel free to shift this and tar/feather me if it bugs anyone.
Has anyone noticed any issue with roast times when using an extension cord with a multi box coming off it. My roaster is set up in a remote part of my workshop and the nearest power point is about 10m away, initial testing I was plugged directly into power socket but since then I've used the extension. Coming off the multi box I have the turbo oven, a 12v battery charger (runs my datsun wiper motor for stirring) plus the bread maker element (2nd heat source).
In my opinion it must rob a fair bit of power from the one socket?
Yeah this might not be the thread so much for that question right now. In a month or two we might have answers, but you're more likely to be able to answer the question for us at the moment!!
260zman, @readeral's points are valid - however, FWIW I'd expect there to be more than ample electricity from a conventional power point to easily supply all those devices you detailed. If you're hypothesising that changing roasting/heat results are due to the extension cord/power board being used I'd strongly suggest that it is far more likely to be other variables that have influenced your results and not there being less power to go around the devices. But thats very much a laypersons opinion and I would suggest either conducting further experiments yourself, popping a thread up to ask but I'd be amazed if that made any real and discernable difference at all - the TO, breadmaker (even with element on) and battery charger would use very little juice compared to a whole range of other devices that still run quite happily on domestic power supplies. :-)
Originally Posted by 260zman
Cheer guys, and yeah sorry about that, I just thought of it as I was reading through each post.
I'll do some testing and get back to you via a new thread. I have a feeling that the length of extension lead does make a difference (especially if it's a cheap, low amperage one).
OK let's start the ABCs of electricity
Originally Posted by 260zman
A home can have one line from the board to an outlet but that is rare
Most homes have several outlets per line and is calculated that if all outlets are used they should not exceed 2400 watts total or the breaker will trip
To your question - If only your TO and motor is connected to an outlet without other electrical appliances draining the power you should get full power
However for long extension cords my understanding is that you should use 15amp internal cable as im sure the long length will have a small power draining affect when thinner cable is used
( Electrician required to verify )
Hi guys, I don't visit here all that often anymore but have been following this thread with interest, great work.
Anyway back on the discussion of a KKTO-esque roaster build - I had a good catch up with a nearby friend who has a real, ridgy didge KKTO. He was gracious enough to allow me to look it over thoroughly and take a whole load of close up pictures of it's bits and pieces - with a view to having them to compliment the already great info and plans that KK has been ridiculously generous and shared with the world.
Cut a long story short I thought I'd have a bit of a hunt around for a similar spec'd electric motor to the one KK uses in his builds. Evidently his was a special on made via a custom order - and as such I was very realistic in knowing that the gearbox & motor combo would almost certainly NOT be the same likely perfect pairing that KK sourced. Neither would it have the socketed connection point (though that shouldn't be a huge issue).
Anyway after much hunting around I came across two likely options - one was 12v 70rpm, claimed 7kg/cm of torque but relatively generic makers. The other was the same maker as KK's motor, Zheng - 60rpm - claimed 6.5kg/cm of torque. Chose the latter as seemed superior build quality, for the curious the item number is 131458749952 ( the other one I didn't buy is 311359199279).
Both motors were ~$AUD11 delivered. Like I said am certain they're NOT as good as KK's ones but are very similar physical size/weight and known specs (KK's combo does 69rpm/min).
I think the breadmaker motor might have had a bit much 'play'/wiggle in it's shaft by the time the multiple bits were cobbled together - this alternative option should be a tad more stable, guess we'll see. :-)
That'd be a bunch easier to wrangle - did you order a mounting bracket for it as well, or you'll wait till it arrives before hunting for one of those? I guess the benefit with the KK motor is it's fairly robust mounting points built into the unit's casing. But, great find!
I just reread your post on the TO test run, and realised how you 'stirred' the beans. That's commitment! I assumed you had meant you'd put in an agitator and shaft and just used your hand to twist it manually. So, re. the shaft, will you go with the socket extension bar as you mentioned above? I assume you can convert from D shaft to the square socket extension with a coupler of some sort... Otherwise would a D shaft suffice? The gauge of the shaft that KK has sent me today looks about 10mm, maybe 12mm. Very sturdy! Also has a piece in the middle to stop the shaft collecting beans in the middle that won't then agitate.
It's great to see you're pulling bits together!
The genius part of using the socket extension bar as drive shaft would be rigging it somehow that you can build a second agitator to fit on the top of the original, with a hole drilled in an (even smaller) insert for small batches - the original pot set comes with a pasta insert, and a steamer insert that would be perfect. This wouldn't be at all worth doing in your instance though given you're using a smaller pot set anyway! Also I guess there's the risk that the TO would be too close to the beans... but interesting thought experiment.
I didn't buy a mounting bracket as it seems to have screw holes in the top of it that you could use to affix it directly to your enclosure/base section. Worst case it'd be easy enough to cut a piece of metal and then drill holes for mounting but I'll have to see when it arrives and I've a better idea of the drive shaft option thats been used.
Originally Posted by readeral
Thanks but I really didn't have a lot of other options and it really wasn't either that hard or overly effective! But the roast was vaguely as desired, though I think my experiement with going well past second crack will see me had back on the otherside of it so more bean characteristics come out and not so much roast characteristics. :-)
Originally Posted by readeral
I'm not really sure to be honest. The socket extension bars obviously have the handy benefit of having premade connectors at either end of them BUT the length is also critical and sure I can cut one off if needed but I'll have to weigh that up vs using some plain steel rod and then modding extenders/connections onto either end of it. Whichever way is easier & ultimately more effective I'll go with.
Originally Posted by readeral
The trick is to have something that allows you to take the top section (roasting insert with beans, agitator etc) and easily lift it up to tip the beans out and into your cooler. Thats one of the many little genius features of the KK design. If you have something thats difficult or tricky to get out you run the risk of having a PITA when it comes to do that quick dump at the end of the roast.
The only alternative option that could be a good work-in with this is if your bean cooler has a workshop vacuum or similar partially driving it and you can run the tube direct from the top of the cooler and literally vacuum the beans into it - there's a design on here that was done in this manner.
Anyway a lot of options.....it's not something I'm rushing to get together so we'll see how it evolves as I meander along. Cheers and thanks again for your suggestions and feedback.
Last edited by nikko.the.scorpio; 14th August 2015 at 06:06 AM.
An update on my build -
Today I received from KK a motor with screws and washers, aluminium drive shaft (with washers to keep it attached to the roast chamber), agitator wires, some insulation, and an aluminium false floor.
Next week I'll have my pots and will try to drill them next weekend (I've found a workshop attached to a small community organisation that had a press drill that I could use! Huzzah!) and then will be able to put all the mechanical bits together.
I've got an old 12v 2.5A power supply from an old external hard drive - so I've just got to get a hold of the right female socket for that, and wire it all up to the motor, and then build a base for the pot-set out of MDF and mount the motor the right depth for the drive shaft to fit perfectly, and I'll basically be done!
I'm tempted to use a wooden IKEA stool as my roaster base, rather than MDF, but that would mean that the whole roaster would take up more space in storage - and the extra height would give it a higher centre of gravity... Choices choices.
Once I've got the pots drilled I'll upload some more details.
So the KK design is all once piece - and where it disconnects for dumping is actually pulling out of the motor - so for you, you could use the socket extender and just yank it from your coupler instead (which is firmly fixed to the motor). So when you go to dump it, your agitator stays in place - but so does the whole shaft (in that it is connected to the roasting chamber). Then - in a sense it wouldn't matter what length the socket extender was - as long as it's long enough - and you're able to fix it to your roast chamber somehow (drill two small holes in the socket extender, slide it into the base of the roasting chamber, fit some washers and then drop in a split pin to each hole either side of the roasting chamber base). A la this image. Then you'd have to further modify the socket extender to hold an agitator, but you'd have to do that with any sort of rod anyway.
Originally Posted by nikko.the.scorpio
I dunno... heaps of options as you say!
I'd been thinking about the whole bean cooler thing, and trying to work out if it's possible to suck the beans without using a vacuum. A bloke in a thread I started reckoned that maybe the extractor fan design would have enough air speed (with care given to restricting the airflow to increase it's speed) to manage drawing the beans out - so I'll be testing this next week - and if it doesn't work - working out another way that enough draw can be made without a vacuum cleaner (I don't want another appliance dragged outside - already will be a TO, the motor PS, and the cooling fan). My first step is to find a clean hose somewhere :-/
I've used the coupling from a breadmaker fitted into the bottom of my insert so that I can remove it all to dump the beans in the cooler. The windscreen wiper motor shaft was very similar to the original bm shaft. So only required minor mods to fit the coupling. Combine this with using the bm element and I often do a full kg roast batch.
Nick - Regarding the motor speed - the drive motor speed ratings manufactures put on there motors is free spinning, they all go slower up to 30% with weight to push
The higher weight push rating the better the motor will be able to push at the rated free spinning speed
ReaderAl - I have sent you plans of two bean coolers, one with an exhaust fan, one with a vacuum
Not sure if this is helpfull but on my current build i am using a car wiper motor powered by a modded computer transformer. I screwed a nut to the shaft of the WM, a socket sits on that held there by silicone [high temp] then KK's agitator shaft fits in the 1/4 drive hole. That allows me to pull the colonder and dump the beans into the cooler
Ok completely backflipped on my design to using the breadmaker motor, bummer I've already ordered the other motor but no big deal. Reason for the flip is I think I've come up with a design that will be a lot simpler and require less connections etc using the breadmaker motor as the basis for it.
Hard to describe but essentially I've cut the bottom out of the breadmaker's baking tin (as shown in post #25 of this thread), this just sits in it's slot and can be lifted out very easily - it's driven by the motor connecting to the flywheel below it - this has the D-shaft spindle that the paddle used to mount onto. So I've ordered a 8mm to 10mm Coupler - now these are specifically designed to allow easy and efficient connecting of different drive shafts/connections. So one of these will be screwed on to the D-shaft of the breadmaker's paddle mount and I then just have to find suitable 10mm drive shaft to put the agitator etc on.
The real beauty of doing it this way is that I plan to actually glue/screw etc the entire piece of breadmaker tray base to the bottom of the exterior pot - worst case I could just use high temp silicone glue and then add a few small screws for extra strength. A hole is drilled in the base of the pot to allow the d-shaft to come up into the pots. I then use the Coupler to connect this to the drive shaft. So this is going to be all one connected and contained unit that can very easily be lifted off the old mounting point (and in some karmic luck it fits next to the exposed electric motor with around 10mm gap between them - which will be enough to make some kind of insulating cover/top for the motor to keep it out of the way etc.
But the Coupler's really are a VERY handy thing to get - I didn't know what they were called and went to Jaycar as another person on here used something from there to act as one (though I think it was an audio cable joiner) - but this is the real thing that is specifically for motor drive shafts etc. Very easy to find on Ebay, my 8mm to 10mm one was ~$3.
Also ordered a packet of copper washers, both for spacing/raising and also to ensure steel isn't rubbing on steel or aluminium etc. Around $4.50 for 20. 12mm internal diameter ones.
I'll try and bung up a KK-special drawing of what I'm envisaging a tad later as I'm sure the above ramble comes across as clear as mud. ;-)
Sounds pretty good. You're not worried about the BM motor fittings shifting due to constant exposure to heat/accounting for flex of the bottom pot? The motor itself should manage the heat right, given it was inside the bread maker...
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