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Honey Badger 1k
bryce_wes
Thanks for the info. That is more than enough flexibility for what I am looking for. I will try to post a thread as I build the roaster.
jkoll42
Hi all - it's been a while. Work, family etc.

So after 6 years I had my first failure on the roaster. I was planning to roast some batches in single digit weather, dumped the beans and maybe 15 seconds later the stirrer seized.

As best as I can tell after probably 250 batches of heat cycles the long preheat got the aluminum fatigued enough that when a bean got jammed between the stirrer and the RC wall it bent the stirrer back and jammed it against the RC wall. They were pretty small Guats, not peaberry but small.

There aren't any cracks in the metal and that gear motor only puts out 4 in-lb of torque so that's my only thought.

Back to the shop tomorrow to make the most annoying to make part of the whole build out of steel. Let this be a warning to anyone making a stirring arm out of aluminum that's getting hit directly by a torch during preheat - you might only get 6 years out of it roar

Happy New Year all!
-Jon
Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3
jkoll42
Update on the stirring arm for anyone who might be looking to build something similar. Finally got around to fixing it. To make fabrication and future mods/repairs easier I kept the geometry the same but totally redesigned the assembly.

It is now a piece of 1" square aluminum stock for the spindle with mild steel bar attached for strength. The leading edge is thin flat stainless as it is much easier to profile it for height/curve of the RC. Where the set screws meet the shaft I ground flat spots on the shaft as a sort of keyway. All set screws/screws tapped at 10-24.
jkoll42 attached the following image:
img_20180226_080200.jpg

-Jon
Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3
JackH
Jon - Glad you got it back together and working again. How fast does that spin?
---Jack

KKTO Roaster.
jkoll42
iirc it's 200rpm
-Jon
Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3
homeroaster
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jkoll42
Quick update

Ever since I had to replace the stirring arm I've been having issues with roast evenness. The worst was an old batch of SM Monkey which had a finicky bean in the mix that was so light it roasted really fast. With the new set up I had some glowing red in the cooler and actually had a batch catch on fire on a very hot day this summer. I'm assuming the new stirrer changed the way the beans stirred and was no longer putting the main mass in front of the flame.

This is revision 2 of the fix done late at night so it's a little rough looking. Basically a flame baffle at the end. The end of the cap is drilled w/ 1/4" holes. I initially tried to just drill out the cap but basically turned the tube into a furnace that sounded like a misfiring pulse jet. When the copper started smoking a foot up the tube I figured I better cut the gas and redesign BBQ grill Side note if anyone is looking for a design for an overly complex and dangerous tube furnace hit me up.

Roasted a batch of Rwanda and it was completely even. Didn't have time to weigh out a batch of Monkey but will get to that this week to confirm it's finally working correctly.

The last thing is going to be to tweak the thermocouple location. Before the beans expand and lose water weight I'm still getting influence on the TC from RC air temp.


farm5.staticflickr.com/4816/45794496622_ce573cfed3_k.jpgIMG_20181112_074419 by J Koll, on Flickr
-Jon
Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3
DeepB
Hi,

This is an interesting build, and I am considering building something similar.

Do you have any experience on batch-range? Could you do 500g batches?

Would you do the same design again? Change anything?

Do you by any chance have more detailed pictures or a plan?

Thanks
Daniel
jkoll42
I just wanted to update the thread with a recent change to the bean mass TC. After fighting erratic reading with my standard twisted bare TC I decided to make a switch to a probe style. The response is still quite good but there is enough smoothing to also make the ROR readings more reliable.

It's a straightforward install - 1/8" NPT female cap w/ a hole drilled to allow passage of the probe. High temp gasket maker as a junction to the RC. The jam nut style setup threads into this which allows the probe to easily be slid in/out even while operating if necessary. The copper wire is just there as support since the probe length puts a fair amount of weight onto the joint. The RTV allows for some probe movement as the beans hit it which should make sure there is no chance to get a weird bean jam between the probe and stirring paddle. Standard twisted bare TC is up top for ambient RC temp readings.

First roast went perfect!

live.staticflickr.com/65535/50418166398_bc7e8e6460_k.jpgPXL_20201004_173450967 by J Koll, on Flickr
live.staticflickr.com/65535/50418166463_3b1519fe63_h.jpgPXL_20201004_173426090 by J Koll, on Flickr
-Jon
Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3
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