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CoffeeAir II Roaster Build
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| Ringo |
Posted on 09/06/2010 04:33
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1/2 Pounder
Posts: 281
Joined: 01/14/2010 05:17
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I ask this question when I built my roaster becouse I wanted to make my own TC from TC wire. The wire is very cheap. I was told they had too be welded together. He had a set up made to weld his own. I could not find the post, I really do not remember the board it was on. Sorry. Learn how to do it you could make TC's for a few cents.
All you need in life is ignorance and confidence, and then success is sure. Mark Twain
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| allenb |
Posted on 09/06/2010 07:44
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Super Admin
Fix It Man
Posts: 1473
Joined: 02/23/2010 19:51
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Ringo wrote:
I ask this question when I built my roaster becouse I wanted to make my own TC from TC wire. The wire is very cheap. I was told they had too be welded together. He had a set up made to weld his own. I could not find the post, I really do not remember the board it was on. Sorry. Learn how to do it you could make TC's for a few cents.
Here's a few reasons why it should be a welded bead at the tip:
-Less thermal mass than a quarter inch of twist (reacts quicker)
-Can't build up insulating debris between the two wires.
-Can't loosen contact due to expansion and contraction.
I've seen the post for using a 12 volt car battery as well but can't remember exactly where it was.
Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
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| allenb |
Posted on 09/06/2010 08:55
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Super Admin
Fix It Man
Posts: 1473
Joined: 02/23/2010 19:51
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On the other hand, some who seem to know what they're talking about say the twisting method is just fine. I also just read where silver soldering with a very small solder bead works fine too. After soldering you snip all but the last twist. Supposedly, the reduction in accuracy using silver solder is negligible. I'm guessing you'd need a real hot flame to do silver soldering?
Here's some informative stuff on DIY TC's from HB
http://www.home-b...t2460.html
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
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| seedlings |
Posted on 09/06/2010 17:41
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Administrator EMERITUS
Posts: 4295
Joined: 06/27/2007 11:39
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Allen, you were on the right track!
I decided to remove the entire sensor tip... and what did I find? Underneath were twisted-together TC wires - appeared to make no contact whatsoever to the stainless screw-terminal tip. On further inspection the very end of the wires looked to be soldered/welded, however I made the executive decision to tightly twist the last 1/8" together. The PID reacts much faster now!
So, I high-temp silicone caulked the pyrex viewing glass to the hopper. (Temporarily used electrical tape which was beginning to fail after several tests).
While that is drying, I'm going to figure out how to program this PID.
CHAD
Edited by seedlings on 09/06/2010 17:43
Don't put the cart before the horse. Put the horse in the cart and listen to him say "weeeee" all the way down the hill.
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| Unta |
Posted on 09/06/2010 18:06
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Moderator
Posts: 802
Joined: 01/26/2010 17:44
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.....pictures?
sean
Sean Harrington
educate.
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| seedlings |
Posted on 09/06/2010 18:54
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Administrator EMERITUS
Posts: 4295
Joined: 06/27/2007 11:39
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Sean:
The twisted wire used to be inside the tip (on the right). The tip was crimped [rather loosely] to the SS mesh sleeve.
I twisted the wires much tighter than they were originally.
CHAD
Edited by seedlings on 09/06/2010 18:55
Don't put the cart before the horse. Put the horse in the cart and listen to him say "weeeee" all the way down the hill.
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| seedlings |
Posted on 09/08/2010 10:04
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Administrator EMERITUS
Posts: 4295
Joined: 06/27/2007 11:39
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I need PID help. For some reason these menus skip right over the ramp-soak setpoints.
Specifically I have a Fuji PXV3
Here's the manual:
http://www.instru...manual.pdf
It's like I need to 'turn on' the ramp-soak feature..?
CHAD
Don't put the cart before the horse. Put the horse in the cart and listen to him say "weeeee" all the way down the hill.
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| seedlings |
Posted on 09/08/2010 10:50
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Administrator EMERITUS
Posts: 4295
Joined: 06/27/2007 11:39
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Nevermind. Turns out the display was configured to hide a bunch of options...,
Now - waiting for time to do a test roast with PID!
CHAD
Don't put the cart before the horse. Put the horse in the cart and listen to him say "weeeee" all the way down the hill.
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| seedlings |
Posted on 09/09/2010 13:29
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Administrator EMERITUS
Posts: 4295
Joined: 06/27/2007 11:39
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The first PID roast was ... <drumroll> ... 'completed'.
The temperature showing on the PID from the bare TC shown above 'stalled out' in the 340s. However, this was not accurate because the other TC I threw in the top topped out at 487F with beans. Roasted 1.25# of Robusta into the snaps of second crack in 14 minutes. First crack came about 10:00. I switched the heat off and turned the fan up and the temp came down to 150 in a minute or so, but the steel hopper was still very hot. I used an oven mitt to dump the beans to my cooler, but the beans were just barely warm to the touch.
I had the PID set to:
Ramp to 325F in 3 minutes
____hold 325F for 1 minute
ramp to 440F in 3 minutes
____hold 440F for 1 minute
ramp to 460F in 3 minutes
____hold 460F for 3 minutes
ramp to 50F in 0.0 minutes
____hold 50F for 3 minutes
The first ramp to 325F went perfect, but since the temp never rose above ~345F, none of the other ramp/soak points really mattered.
CHAD
Don't put the cart before the horse. Put the horse in the cart and listen to him say "weeeee" all the way down the hill.
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| freshbeans |
Posted on 09/09/2010 13:56
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Super Admin
Reasonable
Posts: 1400
Joined: 03/06/2010 11:10
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Sounds like progress to me! Congrats!! -Scott |
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| allenb |
Posted on 09/09/2010 17:09
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Super Admin
Fix It Man
Posts: 1473
Joined: 02/23/2010 19:51
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Chad,
Is the ET TC tip just barely below the roast chamber inlet plate where it would be getting a good air flow past it or well below this position?
Either a bad TC or location is bad.
Can you verify with a second TC somewhere near the mounted one?
Allen
Edited by allenb on 09/09/2010 17:10
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
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| dja |
Posted on 09/09/2010 18:18
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1 1/2 Pounder
Posts: 734
Joined: 11/07/2008 09:34
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if you can get the twisted end of your TC in the air stream directly over the heating element that I see in the photo, it will make a differance in the way that it reads, you will have to maybe move it a couple times to find the sweet spot for it. hope you get it working so I can break mine out of the closet again for my roaster.
I pour Iron and roast Coffee Beans 
If life seems normal your not going fast enough Mario Andrette |
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| allenb |
Posted on 09/09/2010 18:48
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Super Admin
Fix It Man
Posts: 1473
Joined: 02/23/2010 19:51
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dja wrote:
if you can get the twisted end of your TC in the air stream directly over the heating element that I see in the photo, it will make a differance in the way that it reads, you will have to maybe move it a couple times to find the sweet spot for it. hope you get it working so I can break mine out of the closet again for my roaster.
I think David is spot-on. Even getting only one of the two elements for a read will work fine since they both should be pretty close to the same discharge temp.
Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
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| seedlings |
Posted on 09/10/2010 11:25
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Administrator EMERITUS
Posts: 4295
Joined: 06/27/2007 11:39
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These projects are learning experiences.
Lesson #1:
I think the problem with my TC was that the end was soldered together, which introduced foreign metal and caused error. I snipped the very end off then re-twisted two tight twists. Finally the TC measured very close to my other medical temperature probe up to around 400F.
Lesson #2:
I drilled a small hole in the hopper to insert the second thermometer to measure bean temp. With my new overconfidence I loaded 2 pounds of the Ethiopian beans and started the ramp-soak program. 'YES!' The TC measurement climbed steadily to 325F, the programmed set point, in 3 minutes. Held there for 1 minute, then climbed to 440F in another 4 minutes. Problem: By this time (8 minutes into the roast) the bean temp was only at 230F. I took evasive action and raised the setpoint to 500F only to watch the bean probe climb ever-so-slowly. I raised the setpoint up to 600F, and the beans still climbed slowly. After about 20 minutes of goofing around with temperatures the beans were hovering around 370F! BAH! I raised the setpoint up to 799F, and the beans finally started to climb in temperature up to 415F, when my program time ended... No first crack - surely the coffee was far too overdried. I'm left with baked beans. Under-baked beans.
It seems as though I need exceptionally high air temperatures to roast beans - but what about scorching and tipping... or is the TC still reading off (but now high instead of low??)
I dunno.
CHAD
Don't put the cart before the horse. Put the horse in the cart and listen to him say "weeeee" all the way down the hill.
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| dja |
Posted on 09/10/2010 11:35
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1 1/2 Pounder
Posts: 734
Joined: 11/07/2008 09:34
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I think Jim Shuleman I think I spelled his last name correctly, was one of the first to do this with a popper, you might check the post at coffee geek is where I saw his post on what he did.
your thermall couple are not going to be that far off with just twisted wires on the end instead of a welded bead, I have run a lot of thermal couple like that till I could get replacements for them.
have you tried putting your thermal couple into the very bottom of the bean mass with the ET probe in the very top of the beans as they agitate? just a thought.
I pour Iron and roast Coffee Beans
If life seems normal your not going fast enough Mario Andrette |
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| Unta |
Posted on 09/10/2010 11:53
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Moderator
Posts: 802
Joined: 01/26/2010 17:44
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so your running the PID program from the air temp TC or the bean temp TC? Seems to me that you should be running the PID from the Bean temp TC.That is of course if i am understanding how the PID unit works..
When I am reducing air or adding heat into my machine its based off of the bean temp probe readings. which can be dangerous. If my placement is off I could be moving faster than I want to be.
sean
Sean Harrington
educate.
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| Unta |
Posted on 09/10/2010 11:56
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Moderator
Posts: 802
Joined: 01/26/2010 17:44
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Another test I ran with my two TC's ,was just boiling water.. put them both in in close proximity to each other. If its rolling boil and they are not reading around 212, you have a problem.
sean
Sean Harrington
educate.
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| seedlings |
Posted on 09/10/2010 12:07
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Administrator EMERITUS
Posts: 4295
Joined: 06/27/2007 11:39
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David, with a longer TC wire I could try different positions.
Sean, my PID TC is now measuring the same as the reliable TC/thermometer/SS probe that I've been roasting with for over a year. I'm interested in accuracy from 350F and up, but might try the 212F test just to have a baseline.
CHAD
Don't put the cart before the horse. Put the horse in the cart and listen to him say "weeeee" all the way down the hill.
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| seedlings |
Posted on 09/11/2010 10:25
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Administrator EMERITUS
Posts: 4295
Joined: 06/27/2007 11:39
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Just roasted some Brazil Decaf. I didn't use the ramp/soak, just a simple set temperature.
550g (1# 3.4oz) start weight
minute bean temp air temp
01______171F______600F
02______255_______ slowly
03______291_______ climbing
04______331_______ to
05______355_______ the
06______374_______ set
07______387_______750F temperature
08______394 (first crack)
09______399
10______406
11______419
12______430 (Heat Off, Blower High to Cool)
13______316
14______183
15______129 (dump beans)
I'm going to do another slightly larger batch of Ethiopian.
CHAD
Don't put the cart before the horse. Put the horse in the cart and listen to him say "weeeee" all the way down the hill.
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| seedlings |
Posted on 09/13/2010 12:26
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Administrator EMERITUS
Posts: 4295
Joined: 06/27/2007 11:39
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There should be a video here:
Direct url = http://www.youtub...k5wjpC904w
CHAD
Edited by seedlings on 09/14/2010 11:29
Don't put the cart before the horse. Put the horse in the cart and listen to him say "weeeee" all the way down the hill.
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