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

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First build failure..
jedovaty	#61 Posted on 01/09/2012 12:40 PM
1/2 Pounder Posts: 225 Joined: October 31, 2011	Jim - if the full manual flip-on-off works, then I will consider this route as the benefit is that it'll reduce all the cables and weight and stuff to move around. It has many drawbacks for my situation, though: 1. I still don't understand it despite your time and efforts via pm 2. would have to take apart the roaster again 3. cost would be about the same, used variac will be $25-100 4. variac is just plug-n-play


JimG	#62 Posted on 01/09/2012 2:45 PM
1 1/2 Pounder Posts: 834 Joined: October 23, 2008	Gotcha. But just so you know, a potentiometer and SSR should cost less than $20. And if you use aCatuai you would also get a record of heater output levels in the log file and on the graph. Jim
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jedovaty	#63 Posted on 01/10/2012 10:00 PM
1/2 Pounder Posts: 225 Joined: October 31, 2011	Just confirmed the router control unit is not faulty. Same guat hunapu 400g, with the heating element plugged directly into the wall and no router control, manually flipping on/off switch to keep ET temp around 475. It's not until I get over 480 that I can get the BT into increasing rate and out of the stall. I learned I wasn't hitting SC in a couple of the prior roasts, the noise was the sound of the chaff. I theorize any one or more of the following will help, in order of simplicity: 1. become convinced it's okay to let ET go up to 500F 2. smaller batch 3. move beans closer to heat source 4. add another heat source (deni not strong enough at 1300W) #1: well, input? I have read conflicting info :) #2: tough, as it leads to an uneven roast for me #3: it'll be a minor pain but can be accomplished #4: fun idea, but a little dangerous. I have that nichrome element from the stir crazy, just wire it in by the TO's element, but then I may be drawing more amps than my circuit can handle... yikes! The results look clean, no tipping. A bit darker than I like. shrug


farmroast	#64 Posted on 01/11/2012 9:03 AM
1/2 Pounder Posts: 295 Joined: December 20, 2006	If you look at the traditional BT graph line it looks quite good during first crack. Having BT RoR puts it under the magnifying glass. It really shows the moisture exhaustion during the strongest part of the cracking. This release adds a cooler temp surrounding the beans as the temp inside will always lag by a few degree behind the surface reading. My theory on the level of drop in RoR has mostly to do with agitation. Getting the cooler moisture/air recirculated. The reason I say "agitation is important like grinder". I have variable speed on my agitation. If I slow the agitation during this part of 1st crack I get a more dramatic change than if I adjust the temp. If you look inside a commercial drum roaster the beans are flying around like a stirred up bee hive. All this being said I don't think the drop in RoR shown above is actually damaging the roast much if at all. Adding too much extra heat to over come this is more damaging IMO. Ed B. DreamRoast 1kg roaster, Levers, Hand Mills http://coffee-roa...gspot.com/


jedovaty	#65 Posted on 01/11/2012 10:34 AM
1/2 Pounder Posts: 225 Joined: October 31, 2011	Ed: Makes sense -- moisture being released is like the ice cube melting in a glass of water. The stall being experienced does lead to a very even roast. Why wouldn't it be damaging to the roast? Popular opinion seems to believe stalling is bad.. The dramatic change during first crack with a slower agitation -- dramatic in what direction, reduced or greater ROR? Would bringing the beans closer to the heat source be the same as adding more heat? Edited by jedovaty on 01/11/2012 10:36 AM


farmroast	#66 Posted on 01/11/2012 11:35 AM
1/2 Pounder Posts: 295 Joined: December 20, 2006	Increased agitation will benefit getting that moisture/air recirculating and increase RoR significantly. Lowering the top or increasing heat will get tricky by possibly overheating the exposed surface but not necessarily getting the trapped moisture/air recirculating. A balance in trade offs must be considered. Lowering batch size can be a work around only if stirring/churning is not diminished by doing so. Ed B. DreamRoast 1kg roaster, Levers, Hand Mills http://coffee-roa...gspot.com/


jedovaty	#67 Posted on 01/11/2012 12:55 PM
1/2 Pounder Posts: 225 Joined: October 31, 2011	Okay, since I can't increase the speed of my motor without replacing it, I'll add another stirring arm across to make "4" and see what that does. Ran out of Hunapu, but have 10lb Yirg so that should get me by. I cupped that most recent roast this morning, and thus far it's the most "normal" tasting, least amount of burnt/ash or grass flavor. By increasing heat, I don't mean increasing temp, but more along the lines of intensity. The idea is to get just a few more watts, and the benefit would be maybe I could do slightly larger roasts, too. But path of least resistance, first :)


farmroast	#68 Posted on 01/11/2012 2:17 PM
1/2 Pounder Posts: 295 Joined: December 20, 2006	Anything that can increase the convection without increasing the MET will help. TO tops put out enough btu's, it's getting the best heat transfer to the beans that will determine roast speeds and batch size. Edited by farmroast on 01/11/2012 2:44 PM Ed B. DreamRoast 1kg roaster, Levers, Hand Mills http://coffee-roa...gspot.com/


JimG	#69 Posted on 01/13/2012 4:27 PM
1 1/2 Pounder Posts: 834 Joined: October 23, 2008	Quote JimG wrote:And if you use aCatuai you would also get a record of heater output levels in the log file and on the graph. This graph is posted as a follow up to our PM's. The orange line shows the heater output level, 0 to 100%. The cyan line is a plot of the output signal to the fan motor, again 0 to 100%. This plot was made using aCataui and pBourbon with my Hottop. Jim PS - this turned out to be a really nice roast. Wish I knew why ...... JimG attached the following image: Edited by JimG on 01/13/2012 4:28 PM
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jedovaty	#70 Posted on 01/25/2012 10:26 PM
1/2 Pounder Posts: 225 Joined: October 31, 2011	Success, I think! :) Took me a while to get there, got the flu real bad this year, finally recovered. The issue is that my TO does not have enough heat. One way to solve it is by adding more, but as much as I wanted to do that, it would require major surgery, more wires and I'd be very close to needing a 220V outlet. So instead, I added two more stirring arms to make 4 per revolution, and went back to using the smaller colander, which puts the beans much closer to the heat source. It was dark so I couldn't get a good video of the beans roasting, next time if there's interest. Below's the resulting graph.. sorry it's kind of messy, I accidentally hit spacebar and couldn't figure out how to get back to stuff. Preheated the chamber (the dips you early on was me playing with the router speed control) for about 5.5 minutes, then added the beans. To 300F in 4.5 minutes. The first snap of FC occured about 8'40", then rolling first crack around 9'20" (relative to when beans were added). Because there was continued "popping" until about 12 minutes I got confused whether that was indeed second crack so I pulled it, but as you can see, the roast did not stall at FC this time and I could keep ET maxed around 475F! The ROR did dip more than what I've seen for others (see the leveling out at the higher BT), and I will attribute this to the 1300W TO, however, I think I'm finally in the ballpark for getting some good roasts :) This is an ethiopian yirg.. I know, you're supposed to take it only just past FC, but I ran out of the guatemalan last time, and wanted to see if I could overcome the prior stalling. Yeah!!


Koffee Kosmo	#71 Posted on 01/26/2012 4:17 AM
Administrator Posts: 1618 Joined: December 31, 2008	Quote The issue is that my TO does not have enough heat. I have designed for the KKTO roaster to work easily from a Turbo Oven with a 1300W - 1400W heat element However you have to observe strictly the volumes required for it to work 7 litres for a 1300W 8 to 9 litres for 1400w in overall volume There is a little over 1 litre in the glass dome of the TO One more very important thing is, and it goes hand in hand with the volume is heat retention Every bit of heat that is prevented from escaping is utilised for roasting KK Edited by Koffee Kosmo on 01/26/2012 4:19 AM 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.
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jedovaty	#72 Posted on 01/26/2012 10:04 AM
1/2 Pounder Posts: 225 Joined: October 31, 2011	KK: I was just around 7L volume with the large colander, including my extra piece for the raised floor but it was still too much for my TO, even with insulation (silicone mat and two towels). I could prevent the stall, but that meant I had to go to at least 500F ET, which was presumably causing the ashy taste. I guess I've effectively reduced the volume by bringing the beans closer to the heat source, since the smaller colander in my pasta pot set doesn't have as many holes and it's acting more like a SCTO/KKTO hybrid. The nice thing about the stall: it would make the beans quite even in roast color, but 7 days out the flavor was pretty lousy. With this reverted setup, I'm still a bit lost as to when second crack occurs, I think I'm going to have to burn a sacrificial roast. Theory: The bubbling/popping sounds are caused by steam from condensation boiling against my false bottom, and the sound gets amplified as my motor housing unit / base is an old speaker. Pfffft. Cupping the roast from last night yielded something decent, nothing epic, balanced, and consistent in flavor through the cooling. I guess that's what happens with a 2nd-crack yirgacheffe.


dja	#73 Posted on 01/27/2012 8:52 AM
1 1/2 Pounder Posts: 701 Joined: November 07, 2008	Quote With this reverted setup, I'm still a bit lost as to when second crack occurs, I think I'm going to have to burn a sacrificial roast. Theory: The bubbling/popping sounds are caused by steam from condensation boiling against my false bottom, and the sound gets amplified as my motor housing unit / base is an old speaker. Pfffft. put some foam inside to muffle the sound of the motor. get some beans that you don't like that are really cheap and got from green to almost flames and you will learn a few things about your roaster I bet you don't know. I pour Iron and roast Coffee Beans If life seems normal your not going fast enough Mario Andrette


JimG	#74 Posted on 01/31/2012 7:45 AM
1 1/2 Pounder Posts: 834 Joined: October 23, 2008	Quote jedovaty wrote:... Below's the resulting graph.. sorry it's kind of messy, I accidentally hit spacebar and couldn't figure out how to get back to stuff.... Jedo and I have communicated already via PM. But for the benefit of others reading this thread: after you press the space bar while logging with pBourbon, you have an opportunity to type a note that gets written to the log file. The note text appears overlaid on the graph as you type. To save the note and exit the text entry mode, press ENTER. This also restores the function of the other hot buttons (B, F, S, E). Jim
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jedovaty	#75 Posted on 02/06/2012 10:20 AM
1/2 Pounder Posts: 225 Joined: October 31, 2011	Hi, with the increased agitation and the more-or-less consistent results I'm finally getting with the beans closer to the heat source, I tried two new beans, one after the other (my roaster cools down between roasts). The first was a sumatra mandheling, second was a columbian. My goal was to get both to just the verge of second crack so I could compare flavors. The results? Got there, but the sumatra was unbelievably weird.. I got what looks like a stalled roast which I couldn't get out of unless I raised the ET higher to 490 (this is old behavior before my changes)? Can different beans with the same batch size have such different results? Almost days post roast the sumatra tastes very strange (bitter, burnt, fruity, sour) and I was forewarned that it would look weird: indeed, half the beans look scorched and the other half look okay, and there are a few very light ones. A local roaster has this bean sometimes, and it both tastes better and looks more uniform (granted on a deidrich machine). The columbian was the second roast, and it did what looks like an almost desired beginner's profile. In the cup it tastes like.. well.. decent coffee :) Sumatra: Columbian:


jedovaty	#76 Posted on 02/18/2012 4:41 PM
1/2 Pounder Posts: 225 Joined: October 31, 2011	Hi, everyone, all issues figured out :) My TO is too weak in the setup, dropping my batch size to 350g yields an even roast, let's me get straight through FC without stalling and without the need to break 475F. Now to figure out how to slow down the roast a little, the columbian is still kind of sharp and I think a slightly longer run to FC would be good. Thanks again for the help, this build is now a success! Edited by jedovaty on 02/18/2012 4:42 PM


jedovaty	#77 Posted on 02/25/2012 6:02 PM
1/2 Pounder Posts: 225 Joined: October 31, 2011	Pictures of the stirring arms. I cut up the "tongs" that came with the TO set and then wedged them between stainless steel washers and jam nuts. Here's a link to a movie, dunno if my server can handle the load, if its slow be patient.. it does move the mass around, but the beans do flip. I'll try a red colored bean when I get a chance. http://jano.porta...ngarms.mov Edited by jedovaty on 02/25/2012 6:05 PM


Koffee Kosmo	#78 Posted on 02/26/2012 12:43 AM
Administrator Posts: 1618 Joined: December 31, 2008	That looks like a good agitation As noted - I also would like a red coloured bean or 2 to view the movement of the bean mass 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.
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jedovaty	#79 Posted on 03/11/2012 5:42 PM
1/2 Pounder Posts: 225 Joined: October 31, 2011	I thought I had everything figured out but now I'm about to throw this POS into the trash. The last several roasts have been completely censored up, what's downright maddening is that I haven't changed a thing - the beans are the same, the temps are the same, only difference is position of the moon. Most recent roast, bean temps began to drop like a rock during first crack and I had to compensate by taking my env temps over 500F, which resulted in a horridly uneven roast that tastes like burnt rubber. With this goes my fun scheduled day of cupping with friends. Like the pirates say, aaarrrrrrggghhhh. :@ Is there a roaster for home that can safely do up to a pound without scorching the beans and allow me to control the speed? I give up. Waaay too much time and money wasted, time to stop fooling myself and realize I'm not a DIYer. Looks like I'm SOL, the quest, hottop, gene, and behmor don't fit the bill, batches are too small. The larger machines do too much (2kg is way more than I need), are far too large, and are too expensive at this time. Am I missing anything?


JackH	#80 Posted on 03/11/2012 6:21 PM
Administrator Posts: 1809 Joined: May 10, 2011	Any chance that you are on the same AC circuit as another appliance that may be bogging down the power at times? Probably best to have it on it's own circuit. You were doing well for a while, Something has changed. One thing I noticed with my turbo oven is that the fan motor bearings get gunked up by smoke/oil residue and the it takes quite a while to get to full speed. This is after over 8 months of roasting. You should check inside the turbo oven, I was surprised at the residue inside my oven blocking the vents etc. If the Turbo oven fan slows down, it will really effect the roast. Worth a check.


jedovaty	#81 Posted on 03/12/2012 9:33 AM
1/2 Pounder Posts: 225 Joined: October 31, 2011	Jack - good point on the other appliances, I did make sure of that the last few times. Fan wearing down is certainly a plausible theory, that could explain why the BT goes down without a very strong ET, as well as the more uneven roasts. Would this also explain the inconsistent temps, where historically FC would occur between 392 and 400, and now all of a sudden it happens at 370 to 380? The only other explanation for this, I noticed my BT thermocouple has become quite a bit frayed, it's probably touching something metal. Hrrrm.


BenGeldreich	#82 Posted on 03/12/2012 2:25 PM
1/4 Pounder Posts: 76 Joined: January 20, 2011	Jano, Keep your head up!!! Coffee roasting isn't easy. I've failed more than I've succeeded. I've probably roasted 40 lbs of coffee and only 7 of the 40 were outstanding. 17.5 % success rate isn't something to write home about but the success out way the 33 lbs of mishaps or failed roasts. I know you were tinkering with running a Variac and am not sure how you are powering your TO. Can you fill us in on your current electrical setup. Ben -------- Ben Turbo Oven Roaster w/ Variac, TC4Cw/ Bourbon \| Bezzera Strega \| Baratza Vario Grinder \| Yama 5 Cup Syphon \| Aeropress
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Lawnmowerman	#83 Posted on 03/15/2012 1:39 AM
Pounder Posts: 546 Joined: March 14, 2012	Has anyone besides me noticed what appear to be internal heat leaks in a turbo oven between the element and thermostat sections? I have a 1200 watt flavor wave that shines light from the element up thru the holes that the elements themselves are mounted on into the thermostat area! This can cause serious temp swings i think, and i will be plugging these when i install a bypass switch. Still working the roaster. Bad coffee prevails when good coffee roasters stand by and do nothing.


Koffee Kosmo	#84 Posted on 03/15/2012 7:53 AM
Administrator Posts: 1618 Joined: December 31, 2008	Quote Lawnmowerman wrote: Has anyone besides me noticed what appear to be internal heat leaks in a turbo oven between the element and thermostat sections? I have a 1200 watt flavor wave that shines light from the element up thru the holes that the elements themselves are mounted on into the thermostat area! This can cause serious temp swings i think, and i will be plugging these when i install a bypass switch. Still working the roaster. The design needs to be like this' as it draws in air for the fan to blow in to the chamber If there is no expelling and the chamber is sealed it will create pressure and it will blow Thats my take on it B) 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.
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Lawnmowerman	#85 Posted on 03/15/2012 9:34 AM
Pounder Posts: 546 Joined: March 14, 2012	Air is drawn into the top section of the co thru a cencentric vent. And there is a vent on top. I thought co systems use forced air. What i am seeing appears to be a design flaw. The plate that the element mounts to has 3 die cut holes in it to accept clips that hold the element. These appear to be causing heat leaks out of the r c area. Bad coffee prevails when good coffee roasters stand by and do nothing.

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