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Homeroasters.org » BUILDING A ROASTER » Fluidbed Roaster
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Fluidbed Bake-A-Round Build
jbenson4
Hi everyone, just a quick intro and then I'll jump into my build. This is my first roaster. I read through many of the build threads on here and was inspired by few people. Fransg has his cheap tiny fluidbed build https://forum.hom...ad_id=5054 that I took most of my inspiration from with a heavy dose coming from oldgearhead and keving.

So I'm using the most powerful air pump I found on Amazon (I believe the same one renetoa is using) and the HAS-043K element for the base components. The pump is rated for 39 cfm, whether that's true or not is another thing. The roast chamber is a standard Bake-A-Round and cocktail shaker lid, cutting through some frying pans, just like keving, all held together with threaded rod with a sleeve of stainless tubing to look pretty. The heating element is sitting in a chromed brass sink extension tube. I have the whole setup from Jim (TC4, ZCD, and LCDapter) controlling the fan and heater. I am reusing some cherry wood from an old high school shop project for the case. This roaster is being used on a dedicated 20 amp circuit.

I am able to use it functionally, but I'd rather finish up what I have left before diving in to roasting back to back batches. I need to sound deaden the box so it's not so noisy, first crack is tough to hear (plus I live in an apartment). I am a bit cramped in my lower compartment so I'm not sure if what little foam or insulation I could fit in there would make any noise difference other than increase the amount of heat. Speaking of heat, I have to run the fan with the box closed up so I can see if the fan temp gets too high. If so, I may need to put in a fan and cut some holes.

I am planning on recirculating the exhaust up to the PVC limit, but that will come later. I am fine playing around with 250g loads for now. I had tried 300g for my first trial batch and heat was an issue.

I will keep updating this thread as I add things here and there. Living in an apartment with little to no access to tools has stretched this build way longer than I wanted.

Thanks for looking!
Edited by JackH on Oct 16, 2017 04:01 PM
 
oldgearhead
With a 043K and a two-stage vacuum cleaner motor my roaster draws 19 amps. Therefore, I have heavier wire in the wall and a 30 amp breaker. However, my roaster does not throw the 'hot' air out the top. A good portion is re-claimed at 150°F. With the top open I, like you, only roast 350 grams.
Our favorite roasts are 'full city 440 gram' at 12 minutes, but it will do 500 grams with ease until the ambient temperature gets below 25°F. I do adjust the blower speed at times to profile a bit. However, most of the 'profile' is in the design of the roaster.
No oil on my beans...
 
jbenson4
So due to Photobucket not working, I'll attach some pictures to this post instead.

1. Roast chamber atop it all
2. Perforated steel sheet for looks (still need to cut and bend 3 more)
3. Upper roaster section which houses the insulated heat tube (not pictured)
4. Inlet air tubing, still needs to be sealed and TC installed
5. Roaster innards
jbenson4 attached the following images:
20171015_165746.jpg 20171016_124404.jpg 20171015_165645.jpg 20171015_165457.jpg 20171015_165054.jpg
 
jbenson4
oldgearhead wrote:

With a 043K and a two-stage vacuum cleaner motor my roaster draws 19 amps. Therefore, I have heavier wire in the wall and a 30 amp breaker. However, my roaster does not throw the 'hot' air out the top. A good portion is re-claimed at 150°F. With the top open I, like you, only roast 350 grams.
Our favorite roasts are 'full city 440 gram' at 12 minutes, but it will do 500 grams with ease until the ambient temperature gets below 25°F. I do adjust the blower speed at times to profile a bit. However, most of the 'profile' is in the design of the roaster.

My blower pulls less than 2 amps, so I am at the threshold of 20 amps minus 20%. The outlet I use also has a GFCI, which did not trip when I tested the roaster.

I plan to emulate your air recycling with the exhaust tube flowing into a mixing box with a sliding panel to temper the heat with ambient air. My inlet TC will let me know how much to have the panel open.

I'm hoping to be able to roast around 400g, with moisture loss and a cupping sample that will put me around 3/4 pound. Friends and family will be getting a lot of coffee at cost, giving me a lot of experience with roasting.
 
oldgearhead
For $3.00 less money for 5 pounds of, say, a fair grade of Costa Rica Tarrazu green coffee shipped to your door you will get 170 grams more coffee than 'Sam's Choice Costa Rica Tarrazu Whole Bean' coffee?
I doubt if you will see very much savings. I haven't saved any money after 7 years of roasting and Sam's Choice is ALMOST as good. However, you will get better and fresher coffee. Just remember the main rules:
__Coffee should be roasted within 15 months of harvest.
__Coffee should be ground 4-15 days after roasting.
__Coffee should be brewed within 15 minutes of grinding.

Sam's Choice or any other commercial company can NOT beat your home roast.
Edited by oldgearhead on Oct 18, 2017 09:53 AM
No oil on my beans...
 
jbenson4
So I seem to be having heating issues...

When I first tested the blower and heater, I was getting temps up to 500*F for ET. That was 100% heater, 90% fan, a 3mm TC in the uninsulated heat tube with no roast chamber on top.


Now, with an insulated heat tube, roast chamber (with a restricted exit for backpressure), and heat at 100%, fan 50%, I can barely rise to 375*F. I have the 3mm TC, along with longer pointed 3mm TC and a 1/4-20 mounted TC all in the same place with 2 being the same and one being 60*F higher. (Forgive the numbers, I switched to Celsius mode on Artisan)

For the first test, I had set up Artisan and the TC4 before Brad put out his incredibly helpful videos. I had scoured HRO looking how to setup everything and had setup in a slightly different way than Brad. I then switched to Brad's settings for the subsequent tests. I don't recall the previous settings...

I believe the older version of aArtisan I uploaded had defaulted to 50Hz in the user.h sketch (I didn't know how to edit it :( ), but I have since corrected it to 60Hz. I'm pretty sure there are no other issues with my user.h sketch. I can't seem to figure out why I can't get the temps up higher.

Does anyone have any ideas on why my roaster is literally struggling with about half the heat as my first test run?

(Please also forgive picture of the screen, I was unaware of how to save the screenshots at that time)
Attachments:
1. latest test with an empty roast chamber (BT is long pointed tip TC)
2. TC placement, 3rd TC 1/4-20 installed at top of heat tube (all at the same height)
3. 1st test setup, no roast chamber and no insulation
4. first test artisan graph

EDIT: I believe in my previous setup, I had used IO3 instead of either OT1 or 2 in the slider menu.
jbenson4 attached the following images:
heatissue.png 20171101_160424.jpg 20170929_140138_hdr.jpg 20170929_140445.jpg

Edited by jbenson4 on Nov 01, 2017 01:51 PM
 
chaff
That first graph seems to show the fan affecting the measured BT. Assuming heater and fan connections are not incorrectly swapped then, for a fixed heater power at 100%, the BT rate
increases each time the fan power is reduced. There's no part of the graph with Fan==0% and Heater==100% so it's not possible to see the effect of heater alone. Maybe after the first test adding the roast chamber increased the effectiveness of the fan ?
Maybe drive the heater directly off line supply to ensure 100% heat and retry with roast chamber in place and fan at minimum ?
 
oldgearhead
I would not bother with 'empty' roast chamber tests. Test with beans 90& heat and only enough air to keep the load of beans circulating. You should notice the beans will become lighter as the roast progresses. You should tun down the blower more at that point. Remember it is the inverse more air equals less heat and less air equals more heat. Be very careful and don't run the heater without the blower or you will burn out the heater. On my heat reclaiming roaster I usually run 70% heat (depends on ambie or the beansnt temperature) set the initial blower speed to just spout a bit and turn on the heater. Depending on the profile I desire. I turn down the blower at different times. My usual turn down T+3 minutes, T+6 minutes, and maybe turn down at T+9 minutes (depends om first crack). Even though I'm a retired PLC programmer and do have a SLC-500 around here someplace. I see no need for any control other than %on time for the heater and a knob for the blower speed. I usually roast 440 gram load for 12 minutes. I prefer the variable auto-transformer over my built in single board DC drive. It pulls a bit less current and is smoother. Heck I don't even use a TC in the beans anymore. I use only a Raytek to check the reclaim temperature once in a while....
Edited by oldgearhead on Nov 02, 2017 03:55 AM
No oil on my beans...
 
jbenson4
Again, I am wondering why from test to test (both empty) I have nearly half the heat output. We have very similar builds (same element in a sink tube, Bake-a-round, cocktail shaker, etc) yet I can barely get a roast of 250g to FC. I tried a smaller 225g load today, similar issues.

I did have a 2nd BT probe which read 10-15*C higher and I presume more accurate. Before starting another batch, I removed TC1 and swapped it with the one I had as TC4, but now all my TC inputs are reading the exact same temperature and not increasing or decreasing. I tried reuploading a fresh sketch, but it is still the same. Not sure what this issue is caused by.
jbenson4 attached the following image:
guatemala_003_17-11-02.png
 
oldgearhead
Okay, what is the SCFM air flow, with beans slow in motion and no beans?
If the 043 element is rated at 1000°F at 8 SCFM you need 16-18 SCFM to have 500°F. The more flow past the heater the cooler the temp.
The only advantage empty roast chamber tests told me was there was some blower self-heating going on so I poked some holes between the blower and heater to increase blower RPM a bit. Hot air reclaiming makes a lot of difference. I can roast 500 gram loads with it and only 350 grams without it. Recirculating 150°F air also makes the unit less sensitive to low ambient temperatures...
No oil on my beans...
 
jbenson4
My fan is rated for 35cfm. I'm sure the cfm to output percentage isn't linear, but turning my fan down into the 30s% I should be around or less than 16cfm. I'll add a hole or two before the heat tube and see what happens with that.

Now to get the thermocouples sorted... When I plug in the TC4, all the temps (AT, BT, ET) start the same at around 22*C and slowly over 10 minutes end up around 37*C. This is with no temperature change to any TC. When attempting to raise the temp of the TC with hot water, there is no change to the temp.

I only found one other instance of this issue (on the Huky forum) and it never got sorted. The person bought a Phidgets instead.

At least with my reduced output I could still roast coffee. Now without a temp reading, it's pretty much useless. It's doing my head in
 
btreichel
Did you try switching the TC wires in the terminals? It is possible to wire them backwards. Are they ungrounded?
 
oldgearhead
My roaster reads 18 Standard Feet per Minute to loft 440 grams of green wet processed beans. 'Standard'' is the key here it is compensated for Standand temperature and atmospheric pressure. Hot air will read much higher on a prop-type flow speed meter adjusted for tube diameter to calculate CFM...
No oil on my beans...
 
greencardigan
Some suggestions/questions.

Try your thermocouples in boiling water to confirm they are measuring close to 100C.

Was test 1 using 50 Hz and test 2 using 60Hz in user.h? Try using 50 Hz again? Confirm what frequency your power actually is?

Don't forget to save settings in Artisan when you get it working.

Can you reach first crack? Your chart is getting close to 200C which should be close to FC.

Can you measure the resistance across the element when unconnected.
 
jbenson4
greencardigan wrote:

Some suggestions/questions.

Try your thermocouples in boiling water to confirm they are measuring close to 100C.

I have no other method to test the TCs other than the TC4, and doing so nets no change in temp. Running the fan and heater to above 100*C temps still results in no change (27-36*C)

Was test 1 using 50 Hz and test 2 using 60Hz in user.h? Try using 50 Hz again? Confirm what frequency your power actually is?

Yes, that's correct. I had tried 50Hz again and I had the same results as test 2 but the fan ran rougher. My power is 60Hz, running the fan around 50% at 50Hz setting was rough and pulsed sporadically whereas 60Hz was smooth at 50% fan speed.

Don't forget to save settings in Artisan when you get it working.

Can you reach first crack? Your chart is getting close to 200C which should be close to FC.

I am able to reach first crack. On my last roast I accidentally tripped the GFCI by shorting my heater switch on a metal cocktail cup. In the silence of no fan I could hear first crack happening. I was going off a larger mass BT TC which was reading lower (below 200*C) than a smaller secondary TC I had in the RC. I plan on switching to the smaller TC which may solve a couple issues.
Can you measure the resistance across the element when unconnected.

Resistance across the element is 8.6 ohms, which puts me at nearly 1700W.

Sorry for the late response, I've been out of town and away from my roaster. Responses in bold within quote

As for TC direction and type, they are ungrounded (confirmed w/ multimeter) and I believe wire direction only inverts the temp reading.
 
JackH
There is a polarity for thermocouples. Omega uses red for - (minus) on their J and K type. Not sure what type or manufacturer you are using.

Reversing them will probably cause it to display the ambient temperature.
+ and - are marked on the TC4 board.
JackH attached the following image:
capture_57.jpg

Edited by JackH on Nov 13, 2017 02:17 PM
---Jack

KKTO Roaster.
 
greencardigan
jbenson4 wrote:
When I plug in the TC4, all the temps (AT, BT, ET) start the same at around 22*C and slowly over 10 minutes end up around 37*C. This is with no temperature change to any TC. When attempting to raise the temp of the TC with hot water, there is no change to the temp.


I have no other method to test the TCs other than the TC4, and doing so nets no change in temp. Running the fan and heater to above 100*C temps still results in no change (27-36*C)


Sounds like you're not getting any readings from the thermocouples at all. The TC4 has a temperature sensor on the board which does the cold junction compensation. The thermocouple essentially measures the temperature difference between the 'hot' and 'cold' ends. This difference is added to the actual cold junction temperature measured by the on board temperature sensor. The recorded temperature from the on board sensor does tend to increase slowly during a roast.

I guess you should double check you have the thermocouple securely connected to the TC4 and there are no damaged thermocouple leads etc.

Worst case your ADC chip on the TC4 is dead.
 
jbenson4
Thanks for the diagram Jack, my TCs are from Auber Instruments.

greencardigan wrote:

Sounds like you're not getting any readings from the thermocouples at all. The TC4 has a temperature sensor on the board which does the cold junction compensation. The thermocouple essentially measures the temperature difference between the 'hot' and 'cold' ends. This difference is added to the actual cold junction temperature measured by the on board temperature sensor. The recorded temperature from the on board sensor does tend to increase slowly during a roast.

I guess you should double check you have the thermocouple securely connected to the TC4 and there are no damaged thermocouple leads etc.

Worst case your ADC chip on the TC4 is dead.


TC leads look fine, and I checked with some light tugging that they were secure. I also reversed polarity, same result.

I noticed while checking with my multimeter that there is continuity between the -ive of TC1 and the +ive of TC2. Another point of continuity is between 5V and GRD. Resistance between pin 18/19 and 5V are not 4700 ohms, but open.

So I'm assuming my board is fried. I had read that Jim used to service boards in the past. I'd rather do that than buy a new one outright, but it seems that either option isn't really on the table since it's been quite difficult for others to reach him.
 
JackH
It does look like the board is bad.

You might want to try re-loading the TC4 sketch just in case something was scrambled. Are all four inputs acting the same?

Are you viewing the readings on the LCDapter board or from Artisan?
---Jack

KKTO Roaster.
 
jbenson4
I tried loading older versions of aArtisan and reloading a fresh 6.3 version and all versions acted the same. Also fresh installed Artisan, no change there either. The short only seems to affect the two TC terminals I listed, the others read high resistance between each other and ground.

Both the LCDapter and LCDs on Artisan read the same values.

Since I can still operate the fan and heater with the TC4 manually, I am going to order a Phidget and use that to monitor temps until I can get the TC4 fixed or order a new one.
 
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