Feedback sought: New corretto/KKTO build

[Koffee_Kosmo]

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 ?

KK

[readeral]

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]

[readeral]

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.

[nikko.the.scorpio]

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 ?

KK

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.

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

[readeral]

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.

Ha, I went green too. So nice!

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.

Which and where did you get your thermocouples from?

[nikko.the.scorpio]

Ha, I went green too. So nice!

Which and where did you get your thermocouples from?

haha well obviously great minds think alike!

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 1C 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. :-)

[Koffee_Kosmo]

Nick
Go to this thread and print out the pot size drawing and compare to your set

http://coffeesnobs.com.au/roasters/2...ns-ok-lot.html

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

[nikko.the.scorpio]

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.

Much thanks.

[readeral]

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

[nikko.the.scorpio]

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.

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.

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.

Bummer about the breadmaker motor - going the geared route might end up with a more reliable mixing speed under variable batch sizes?

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:
IMG_0088 by NG

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

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.

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.

[nikko.the.scorpio]

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:
IMG_0089 by

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.

1C came on at about 12min. 2C 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!
IMG_0090 by

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 1c 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. :-)

[readeral]

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

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

[readeral]

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?

Al

[bcspark]

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

[readeral]

KK does have motors available too. I've just purchased one (and a drive shaft) from him.