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HG/BM Thermocouple placement/measurement?
Sherman
Heatgun? check.
Bread Machine? check.
Thermometer from eBay? check.
Type-J TC probe? check.
11/64 drill bit? check.

I've been getting relatively consistent results, but my readings seem to be more in line with what appear to be environmental temperatures, so I am posing a question to all of you HG/BM users: how and where are you mounting your probes?

As an example, tonight I roasted 340g of Sweet Maria's Espresso Monkey, with the following highlights:
Preheat to 400?F
Dump in beans
Slow ramp to 300?F at 5:45
Kick into HI
First pops of 1C ~ 9:45. 439?F
Last pops of 1C ~ 12:15. 440?F
slow ramp to 2C
First pops of 2C ~16:30. 458?F
slow ramp up, stopping roast at ~17:45. 470?F

Beans compare favorably to FC coloring on SM's website.

The only thing that seems to make sense is that the paddle is agitating the beans so much that I'm getting ET readings. FWIW, I've gotten similar results with SM's Basaltic Bourbon, and the shots are tasty, so I'm not as concerned about being way off base, just trying to figure out why these readings seem off.

Also, I've since flipped the lid so that it's inverted, getting the HG closer to bean mass.
TIA,
-s.
Sherman attached the following image:
hgbm_main1.jpg

Edited by Sherman on 04/29/2009 10:30 PM
 
Sherman
Here's a close up of the interior.
Sherman attached the following image:
hgbm_thermocouple_placement_closeup.jpg
 
Koffee Kosmo
Information gathered from BM/Corretto users is that its better to do a larger roast than a smaller one

The sweet spot appears to be 600grams

Also the probe should be immersed in the bean mass you can push it right in leaving some clearance for the agitator 1/2 inch should be enough

Do you use a fan to cool the heat gun

KK
Edited by Koffee Kosmo on 04/29/2009 11:31 PM
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.
 
seedlings
Sherman, your probe is getting beat way too much in that position and it won't last long. Try placing it in the corner like in the picture below. You can just leave the little hole in the side, that won't hurt anything.

Another benefit is that you should get readings closer to bean temps. I'd also recommend putting it about 1/2" above the bottom of the hopper.

Nice setup, by they way. Looks a lot like mine!

CHAD
seedlings attached the following image:
13hgbm_thermocouple_placement_closeup.jpg

Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
David

Quote

seedlings wrote: Try placing it in the corner

Yes, what CHAD said.

Three other things that help make sure that you are getting bean temps and not just heatgun blast.
1) I make sure that the HG is pointed towards the opposite corner from the thermocouple.
2) I also tilt the whole machine 10-15 degrees to make the bean mass deeper in the area of the probe.
3) I use lotsa beans (20 ounces), which helps to keep the probe well buried.

Breadmachines rule!
 
seedlings

Quote

David wrote:
2) I also tilt the whole machine 10-15 degrees to make the bean mass deeper in the area of the probe.


Oooh. I'm going to try that!

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
seehad
I have mine in the middle like sherman's. It is on the opposite side of where the heatgun is pointed and get first crack when it reads 400-405, depending on the bean. 440 is when second crack starts.

The other night when i popped the pan down i caught the probe in the gear for the motor. It ripped off the tip of my probe. For now, I've just twisted the two wires together but is there a way to repair that?
Edited by seehad on 04/30/2009 2:11 PM
 
seedlings
Seems like you have repaired it, seehad. Are the readings still the same? Otherwise, I bet some silver solder may work... unless it actually has to be welded.

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
Sherman

Quote

seedlings wrote:
Sherman, your probe is getting beat way too much in that position and it won't last long. Try placing it in the corner like in the picture below. You can just leave the little hole in the side, that won't hurt anything.

Another benefit is that you should get readings closer to bean temps. I'd also recommend putting it about 1/2" above the bottom of the hopper.


@CHAD:

Regarding the probe, it's a plastic handle with a steel sheath. The wire running out of the handle is about 36", and has a mini connector to the thermometer. I don't know if the wire is grounded or ungrounded, but it's definitely not exposed bare wire. Given this information, should I still be concerned about possible damage? I've been through about 30 roasts so far, and haven't noticed any issues, but if you think it's worth looking into, I'll definitely reevaluate the placement method.

Regarding placement, it is where it is because it was the first place I considered :|. I figured that the sheath would protect the probe from any dings, and that since it only sticks in about 0.5", it wouldn't be close enough to trap beans or get knocked around by the paddle.

To make the hole, I locked the basket in, then used the 11/64 bit first to punch through the outside, inner wall, and basket. Then I drilled through the outer/inner walls with a 1/2" bit. Finally, I put a rubber plug on the outer wall and punched a slit into it so that it would grip the TC sheath and prevent it from wiggling out during agitation.

Regarding depth, I've included a picture that shows depth of the hole relative to the bottom of the basket. It's as close to the bottom of the basket as I could get it, while still being able to present a perpendicular surface to the drill bit. I think it compares favorably to your recommended position in the corner, but the picture will tell the truth, and I welcome any further recommendations and corrections.

The HG is canted slightly away from the probe, so as to (hopefully) minimize direct heat-on-probe action, but I can't speak to the absolute efficiency of that method.

Thanks for the compliment, BTW. I modeled mine after what I saw in your videos. Imitation blah blah sincerest form of flattery blah blah :).

Also, this is the first BM that i tore into - the start capacitor for this one was NOT on the logic board, so I got lucky here. I'm still working on the 2nd one.

Regards,
-s.
Edited by Sherman on 04/30/2009 8:57 PM
 
Sherman
Closeup of TC probe hole, relative to bottom of basket.
Sherman attached the following image:
hgbm_tc_hole_closeup.jpg
 
Sherman
Basket - locked and loaded. Insulation is fiberglass high temperature sheeting from McMaster-Carr item 9356K11. $14.10 for a 1" thick sheet of 24x96.
Sherman attached the following image:
hgbm_basket_lockedin.jpg
 
Sherman
Assembled, no probe. The top is the original top from the bread machine. I stripped the plastic and removed the glass, and presto!
Sherman attached the following image:
hgbm_assembled_no_tc.jpg

Edited by Sherman on 04/30/2009 9:08 PM
 
Sherman
Drying colander is an Oxo fine-mesh colander and a wastebasket from your local Sheets & $#!+ that I had laying around. Added some 2" wide duct tape around the outer rim in an attempt to provide better seal for airflow.
Sherman attached the following image:
hgbm_drying_colander.jpg
 
Sherman
The metal hose is a 1.5" riser hose from an auto parts store, duct taped to the hose of a 2gal shop vac. I pressed the riser hose to the wastebasket, marked the diameter with a felt tip pen, then drilled a series of holes with my 11/64 bit and punched it out. More duct tape around the hose, and we have enough airflow to cool 282g of roasted beans to ~100?F within a minute.
Sherman attached the following image:
hgbm_drying_setup.jpg

Edited by Sherman on 04/30/2009 9:15 PM
 
Sherman

Quote

Koffee Kosmo wrote:
Information gathered from BM/Corretto users is that its better to do a larger roast than a smaller one

The sweet spot appears to be 600grams


I wonder if this just might be the issue. All this time, I've been limiting the size of my roasts because I wanted to learn, and figured that smaller roasts (and more of 'em) would provide me with more experience. I've been experimenting, with 340g (12oz.) being the heaviest. This was giving me 282-284g (10oz.) roasted, a nice amount for a few days' worth of shots and/or vacpot. Also, my hesitation at being new to roasting had me balking at the thought of tossing in 1lb+ per roast.


Quote

Koffee Kosmo wrote:
Do you use a fan to cool the heat gun

No, I use a colander/wastebasket/shopvac. I've attached some pics above that show the rig.

Regards,
-s.
 
Sherman

Quote

David wrote:
1) I make sure that the HG is pointed towards the opposite corner from the thermocouple.
2) I also tilt the whole machine 10-15 degrees to make the bean mass deeper in the area of the probe.
3) I use lotsa beans (20 ounces), which helps to keep the probe well buried.


1) Done, kinda. I've posted a pic that shows the assembled rig. There's a cant to the HG, but it's no more than 20? or so.

2) I wonder about this, and may try it. The only concern that I would have about this is the possibility of insufficient agitation and consequently, an uneven roast. Granted, in some beans unevenness may be more desirable with different roast levels adding to complexity in the cup, but I suppose that's another topic altogether. What are your results? What beans, and how are you brewing? Most importantly, how's it taste? Have you compared the raised-platform beans to flat-platform beans in the cup?

3) Point well taken. Time to start buying more green beans...

Thanks for the input, and I apologize in advance if my OCD is showing through. I'll have to put on a long sleeve shirt ;)

Regards,
-s.
 
Koffee Kosmo

Quote

Koffee Kosmo wrote:
Do you use a fan to cool the heat gun

No, I use a colander/wastebasket/shopvac. I've attached some pics above that show the rig.

Regards,
-s.


Sherman my remark was for a fan to cool the HG

It is important that the heat gun itself is cooled with a fan the reasons are

1) Prevent auto cut out form overheating (the fan may blow but element is out)
2) The air from the fan assists the HG to produce constant & reliable heat
3) Blows away chaff from the HG inlets

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.
 
seedlings
Sherman, you can pick up more beans all this month in the auction, PLUS support some needy kids. Win-win!

So, you have the metal TC... I have one of those too. Now that you've changed everything around (dang, I should've payed closer attention to the picture!)... My latest version has the entire SS probe inserted about 1" from the side and just high enough to clear the stirring paddle. I use 1.25 to 1.5 pound batches, and it works pretty well for me. If I get down to 1/2 pound batch the beans tend to fly out - but I see you have some insulation there.

CHAD
Edited by seedlings on 04/30/2009 9:45 PM
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
Sherman

Quote

Sherman wrote:

Quote

Koffee Kosmo wrote:
Do you use a fan to cool the heat gun

No, I use a colander/wastebasket/shopvac. I've attached some pics above that show the rig.

Regards,
-s.


Excuse me while I *FACEPALM*

Sorry Koffee Kosmo, I should've read your post more thoroughly. I don't use a fan to cool the HG during roast, but the lid arrangement results in minimal venting - there's a vent in the lid, but total airflow outbound from the roast chamber is pretty limited; I haven't observed any issues with HG heat.

A secondary benefit of the inverted lid is that most of the chaff is retained in the roast chamber, instead of floating around in the air and possibly getting sucked into the HG intake. I considered taking another page out of CHAD's book, and poking a larger hole through the outer/inner wall for venting, but decided that the current setup was sufficient. This may change when I start a fire in the roast chamber due to chaff buildup, though Shock

Perhaps an easier alternative for chaff management would be to enlarge the current vent on the lid and bend some chicken-wire to form a chaff collector. Hmm... I might try this next instead.

Also, the location of the rig is such that the HG intake is right next to an open window in my garage, so getting fresh, room-temperature air usually isn't too much of a problem.

Post-cooling, I do pull the riser tube out of the waste basket and stick the HG nozzle into it, to aid in cooling the heating element (in a possibly futile attempt to extend the life of the HG).


Regards,
-s.
 
David

Quote

Sherman wrote:

Quote

David wrote2) I also tilt the whole machine 10-15 degrees to make the bean mass deeper in the area of the probe.
2) I wonder about this, and may try it. The only concern that I would have about this is the possibility of insufficient agitation and consequently, an uneven roast.

Best by test.
One of my first modified breadmachines had a DIY stirrer which kept drifting upwards, leaving some beans unshuffled at the bottom of the roaster, never seeing the light/heat of day. Tilting the whole machine cured it completely. So, I have never gone back to the flat machine arrangement. The roasts are as even as imaginable.

Dude! Great stories about your modifications. You're definitely one of us! ThumbsUp
 
Sherman

Quote

seedlings wrote:
Sherman, you can pick up more beans all this month in the auction, PLUS support some needy kids. Win-win!

Well, I'll certainly bid on some more beans at the auction, but whether I can actually win the bid is more dependent on the fight between my wallet and that of the rest of HRO's membership Grin.

Quote

seedlings wrote:I use 1.25 to 1.5 pound batches, and it works pretty well for me. If I get down to 1/2 pound batch the beans tend to fly out - but I see you have some insulation there.


My rationale has been to roast the smallest amount of beans that my setup will tolerate while producing acceptable and consistent results, then break down the variables and try to modify one at a time. I don't know about you, but if I can get 7 roasts per 5 lb. bag (ok, 6.667, assuming a 12 oz. load) while I'm learning the idiosyncracies and gotchas of both the setup and the bean, I'll end up burning through fewer beans to get to the finish line of finding a roast profile that suits my preferred brew method for a given bean.

The fewer beans that I have to burn through to get to this point, the more beans I can enjoy!

Regards,
-s.
 
Sherman

Quote

David wrote:
Best by test.
One of my first modified breadmachines had a DIY stirrer which kept drifting upwards, leaving some beans unshuffled at the bottom of the roaster, never seeing the light/heat of day. Tilting the whole machine cured it completely. So, I have never gone back to the flat machine arrangement. The roasts are as even as imaginable.


I'm going to have to try this one out. I wonder if I can get more accurate bean mass temps with a smaller load by tilting the basket...

Thanks for the idea, David.

Regards,
-s.
Edited by Sherman on 05/01/2009 3:38 PM
 
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