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My Third Roaster
Koffee Kosmo
Top  #76 Print Post
Posted on 02/22/2012 7:34 PM

Quote

Inspecting the roasts I am still getting some tipping (no more scorching) but I'm currently playing with the volume of beans to see if I can find the sweet spot.


Regarding tipping
Its the amount of agitation your roaster set up is doing

I found that the mid level of the bean mass needs good agitation
So you may need to alter or add to your agitator arms so by its action, will agitate to both the lower and higher parts of the bean mass
You have seen my agitation test videos

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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BenGeldreich
Top  #77 Print Post
Posted on 02/22/2012 8:59 PM

Quote

Koffee Kosmo wrote:

Regarding tipping
Its the amount of agitation your roaster set up is doing

I found that the mid level of the bean mass needs good agitation
So you may need to alter or add to your agitator arms so by its action, will agitate to both the lower and higher parts of the bean mass
You have seen my agitation test videos

KK


Yes I have seen your agitation videos!

I am going to wait and see what difference this oil cap makes as my last roast had very little tipping. I have been roasting 455g batches and am going to try half of that working my way back up to 455 and see if it make any difference. I am also struggling with keeping ET below 500? which may also be the cause. My suspicion is the overall volume of my roaster is a little to high. But I'll keep playing with it cause I'm getting closer every roast!
Edited by BenGeldreich on 02/22/2012 9:03 PM
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Ben

Turbo Oven Roaster w/ Variac, TC4Cw/ Bourbon | Bezzera Strega | Baratza Vario Grinder | Yama 5 Cup Syphon | Aeropress
 
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jedovaty
Top  #78 Print Post
Posted on 02/22/2012 9:42 PM
Hi Ben, seeing as we've kind of been on similar build tracks, I'll chime in with what I've learned on my roaster.

When I keep my ET (measured slightly above the bean mass halfway between the center and side of the colander) below 500 (I shoot for max 475), I have no tipping or scorching - give that a shot if you can!

Changing batch size and increasing my agitation speed only led to a more even roast (my sweet spot is 350g and agitation speed increased by adding two more arms since I'm not sure how to overclock a window wiper motor).

I like the idea of the center cap, I'm going to work on adding one as well since I get a few straggler beans just getting pushed around the center. Thank you for sharing that! smile
Edited by jedovaty on 02/22/2012 9:45 PM
 
BenGeldreich
Top  #79 Print Post
Posted on 02/23/2012 3:03 PM

Quote

jedovaty wrote:
When I keep my ET (measured slightly above the bean mass halfway between the center and side of the colander) below 500 (I shoot for max 475), I have no tipping or scorching - give that a shot if you can!


Thanks for the advice! I am planning to use a beaded type thermocouple for ET on my next roast but I will try and get it right above the bean mass and see what my ET readings are like.

Quote

jedovaty wrote:
Changing batch size and increasing my agitation speed only led to a more even roast (my sweet spot is 350g and agitation speed increased by adding two more arms since I'm not sure how to overclock a window wiper motor).


I read that you had added two more arms and that you lowered your batch size which helped you find the sweet spot. I'm glad you shared that information it started me thinking about agitation and batch size. I don't recall you posting any photos of your new stirring arms on your thread.

Not sure if you seen these links but this is where i pulled all my info on wiper motor and wiring them.

http://www.scary-...wipmtr.htm
http://www.scary-...ipmtr2.htm

Quote

jedovaty wrote:
I like the idea of the center cap, I'm going to work on adding one as well since I get a few straggler beans just getting pushed around the center. Thank you for sharing that! smile


The centre cap really improved overall agitation in my roaster. I will say that cutting the cap to allow the arms to go through had to pretty precise to allow the cap to stay down without lifting up durning a roast. If it lifts off the insert, beans start getting trapped underneath. I measured three times and cut once to find my first attempt very accurate. I played around with some magnets as well but found it was to mush strain on the motor.
Edited by BenGeldreich on 02/23/2012 3:03 PM
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Ben

Turbo Oven Roaster w/ Variac, TC4Cw/ Bourbon | Bezzera Strega | Baratza Vario Grinder | Yama 5 Cup Syphon | Aeropress
 
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BenGeldreich
Top  #80 Print Post
Posted on 02/23/2012 10:41 PM

Quote

Koffee Kosmo wrote:

Quote

Inspecting the roasts I am still getting some tipping (no more scorching) but I'm currently playing with the volume of beans to see if I can find the sweet spot.


Regarding tipping
Its the amount of agitation your roaster set up is doing

I found that the mid level of the bean mass needs good agitation
So you may need to alter or add to your agitator arms so by its action, will agitate to both the lower and higher parts of the bean mass
You have seen my agitation test videos

KK


This is a video of my current agitation with the new centre cap. I added some red beans to see the agitation in action. Do you think it's enough or should I look into adding a few more arms.

Edited by BenGeldreich on 02/23/2012 11:06 PM
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Ben

Turbo Oven Roaster w/ Variac, TC4Cw/ Bourbon | Bezzera Strega | Baratza Vario Grinder | Yama 5 Cup Syphon | Aeropress
 
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Koffee Kosmo
Top  #81 Print Post
Posted on 02/23/2012 11:29 PM
What I see is the red beans in relatively one position, they appear to circumnavigate the pot & bob up and down like a cork on water

From experience I would recommend that the beans need a more through mixing

This is a quote form my blog

Quote

Q. Explain how the roaster agitates the beans?
A. I have spent countless hours fine tuning the agitator to have a complete mixing action rather than to push a mass of coffee beans around the roasting bowl
The main purpose of the agitator shape is to mix the beans in a specific way that is to move the beans from the centre out and back to the centre again
The action also cycles the beans from top to bottom in a helix pattern while also allowing the beans some intermittent rest time.


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.
 
Web
BenGeldreich
Top  #82 Print Post
Posted on 03/07/2012 4:16 PM
More updates!

I've added two new arms and modified my original spring arms to help with agitation. I added two pieces of steel strappings to agitate the middle / top of the bean mass, while the spring arms now act as bottom feeders.

The steel strapping is very easy to bend and manipulate so changing angles is easy but finding the perfect one has been more of a challenge. After a couple weeks of testing I think I found an angle that works well for a pound of beans. I have shaped the new strapping like a small smile or smirk. High point on both the inner and outer edges and low point in the centre. I angled the strapping in the centre slightly downwards so the beans squeeze out either side of the centre.

Here is a youtube video of the new arms and agitation.



On another note I have finally found a better solution then silicone to hold my BT in place. I was finding that after a couple roasts that I would have to re apply high temp silicone to my BT tube and wire to keep it from falling though. Looking through my hardware bin and came across a small collet for my Dremel tool.

farm8.staticflickr.com/7205/6816537622_dabb473dc4.jpg

I cut off the tapered end. Filed the freshly cut end down so the 4 pieces reach a point. This point acts as a compression fitting. I filed enough off as to not pinch to hard on the wire but enough so it won't fall through the tube. A light but firm compression. I put the wire through the collet and held the the BT wire in my desired position and then snapped the collet into the tube. The collet snaps into the tube because to the groves on the top.

farm8.staticflickr.com/7176/6798639892_c59c304e45.jpg
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Ben

Turbo Oven Roaster w/ Variac, TC4Cw/ Bourbon | Bezzera Strega | Baratza Vario Grinder | Yama 5 Cup Syphon | Aeropress
 
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Koffee Kosmo
Top  #83 Print Post
Posted on 03/07/2012 5:06 PM
Thats a great agitation action Ben

It should also equate to better more even roasts
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.
 
Web
BenGeldreich
Top  #84 Print Post
Posted on 03/07/2012 6:11 PM
And here is a shot of 434g of Rwanda that i just finished roasting.

farm8.staticflickr.com/7055/6816807910_87d64be409.jpg

No sign of tipping or scorching and the roast is very even.

Here is a copy of my pBourbon graph of the roast.

farm8.staticflickr.com/7058/6962972655_d68ec09dd8.jpg

Notice that I still went above 500?F. So my question now is if I increase the volume of beans to 500g or 600g should I see the ET lower? My methodology is the more beans = less air movement = bean mass retains heat better. Am I way off? IF so then I may need to make a false bottom to lower my overall volume of the roaster.
--------

Ben

Turbo Oven Roaster w/ Variac, TC4Cw/ Bourbon | Bezzera Strega | Baratza Vario Grinder | Yama 5 Cup Syphon | Aeropress
 
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Koffee Kosmo
Top  #85 Print Post
Posted on 03/07/2012 6:40 PM
Do you have a false bottom now ?

If not and you decide to install a false bottom, you should have by volume 7 to 9 litres for best results

This is also a good opportunity to add insulation for better heat stability
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.
 
Web
BenGeldreich
Top  #86 Print Post
Posted on 03/07/2012 7:45 PM

Quote

Koffee Kosmo wrote:
Do you have a false bottom now ?

If not and you decide to install a false bottom, you should have by volume 7 to 9 litres for best results

This is also a good opportunity to add insulation for better heat stability
KK


No I do not currently have a false bottom and I think I'm at 11 Litres using a Galloping Gourmet 1470 watt model.

Is the aluminium insert that you use on the KKTO for both volume restriction and insulation?
Edited by BenGeldreich on 03/07/2012 7:50 PM
--------

Ben

Turbo Oven Roaster w/ Variac, TC4Cw/ Bourbon | Bezzera Strega | Baratza Vario Grinder | Yama 5 Cup Syphon | Aeropress
 
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Koffee Kosmo
Top  #87 Print Post
Posted on 03/07/2012 8:09 PM

Quote

BenGeldreich wrote:

Quote

Koffee Kosmo wrote:
Do you have a false bottom now ?

If not and you decide to install a false bottom, you should have by volume 7 to 9 litres for best results

This is also a good opportunity to add insulation for better heat stability
KK


No I do not currently have a false bottom and I think I'm at 11 Litres using a Galloping Gourmet 1470 watt model.

Is the aluminium insert that you use on the KKTO for both volume restriction and insulation?


Yes it is
It sits on a mattress of insulation on the correct level to reduce the pot set to the optimum overall volume
The insert is also designed to have a small air gap on the side to retain even more heat (Works like double glazing)

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.
 
Web
BenGeldreich
Top  #88 Print Post
Posted on 03/07/2012 8:17 PM

Quote

Koffee Kosmo wrote:
Yes it is
It sits on a mattress of insulation on the correct level to reduce the pot set to the optimum overall volume
The insert is also designed to have a small air gap on the side to retain even more heat (Works like double glazing)

KK


Looking through my coffee left overs I found the original pot that the insert came in. Its made from a lighter gauge steel but is 6.69 litres and almost fits perfectly inside my outer pot. I would only need to take in my brackets about 1/4" which currently holds the insert. This would make the roaster 7.69 L with the TO and give me an air gap for extra insulation.

I'm curious what type of insulation you put as a mattress?
--------

Ben

Turbo Oven Roaster w/ Variac, TC4Cw/ Bourbon | Bezzera Strega | Baratza Vario Grinder | Yama 5 Cup Syphon | Aeropress
 
Web
Koffee Kosmo
Top  #89 Print Post
Posted on 03/07/2012 8:49 PM

Quote

BenGeldreich wrote:

Looking through my coffee left overs I found the original pot that the insert came in. Its made from a lighter gauge steel but is 6.69 litres and almost fits perfectly inside my outer pot. I would only need to take in my brackets about 1/4" which currently holds the insert. This would make the roaster 7.69 L with the TO and give me an air gap for extra insulation.

I'm curious what type of insulation you put as a mattress?


High temp - Needle/Felted fibreglass or ceramic insulation is best, comes in different thicknesses fabric rolls, It's then cut to size - but use gloves when handling

Something like this
www.firesleeveandtape.com/images/fiberglass_mats.jpg

Found at this site -
http://www.firesl...ation.html

KK
Edited by Koffee Kosmo on 03/07/2012 8:58 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.
 
Web
Lawnmowerman
Top  #90 Print Post
Posted on 03/15/2012 5:02 PM
T u 4 your insight regarding to. Yes it has a glass tube element. But im stuck w what ive got for 7.50 at s army. I will start a new thread to avoid hijacking another.
Bad coffee prevails when good coffee roasters stand by and do nothing.
 
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