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I thought there may be some interest in another variant on KoffeeKosmos design, using some recycled equipment to keep costs down. Of course being retired, so that the time involved in developing the unit is not "costing" helps. I suspect there is something over a full weeks work involved, but should anyone be sufficiently masochistic to take it on, this may save you some time.
I should make the point that I had almost a a metre of 1/4" stainless steel rod, and a sheet of SS about 1.2mm thick and a small block of aluminium about 6mm thick in my "stock." I also had access to a moderately good bench drill press, and a MIG welder - on which i am almost as much a novice as I am a coffee roaster.
Major recycled components were a 12v drill whose batteries had died and a computer power supply capable of delivering about 10 amps at 12v.
Heres the completed unit: Fig 1
The base is simply MDF supported on wooden legs to clear the motor, right angle drive box and power supply. Fig 2
The right angle drive consists of bevel gears for a model car, with a 2.3:1 reduction. Bearings are the thick aluminium sheet, doubled, and with about 8 roasts done thus far, seem to be holding up. The box itself is sheet galvanised iron, folded and welded, with the lid held by screws into T-nuts in the MDF.
After an initial foray into a bottom turning stirrer, I was attracted to the design shown in http://coffeesnobs.com.au/YaBB.pl?num=1228631426/176 with the arms on the top. Therefore I extended the vertical drive shaft and added the stirrer made of sheet SS put together with SS rivets. You can see the thermocouple end sticking up through the bottom of the pasta pot. Drive is simply a slot cut in the end of the shaft, and bracing on the stirrer to reduce "spreading" of the slot. Fig s 3 and 4
Variable speed control is achieved by turning the screw: Fig 5
The basics of converting a standard computer ATX power supply are at http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply. One thing I discovered to be necessary with my unit was to put a 3A diode in the positive line supplying the motor, otherwise the PSU would shut down.
Otherwise, a Tiffany oven, a pasta set I was given (on request) for my birthday and a disused fire blanket for use during roasting sessions.
You can see the edge of my cooler - aluminium flyscreen on a wooden frame with a 30cm fan blowing over it.
I havent done an exact costing, but probably about $200 before buying the datalogger would cover most of it. Of course if you had to buy the SS rod and sheet specifically, that would increase costs.
I hope it is of interest and perhaps helpful to someone.
Thanks to KoffeKosmo for the initial idea and encouragement along the way
Russell
I should make the point that I had almost a a metre of 1/4" stainless steel rod, and a sheet of SS about 1.2mm thick and a small block of aluminium about 6mm thick in my "stock." I also had access to a moderately good bench drill press, and a MIG welder - on which i am almost as much a novice as I am a coffee roaster.
Major recycled components were a 12v drill whose batteries had died and a computer power supply capable of delivering about 10 amps at 12v.
Heres the completed unit: Fig 1
The base is simply MDF supported on wooden legs to clear the motor, right angle drive box and power supply. Fig 2
The right angle drive consists of bevel gears for a model car, with a 2.3:1 reduction. Bearings are the thick aluminium sheet, doubled, and with about 8 roasts done thus far, seem to be holding up. The box itself is sheet galvanised iron, folded and welded, with the lid held by screws into T-nuts in the MDF.
After an initial foray into a bottom turning stirrer, I was attracted to the design shown in http://coffeesnobs.com.au/YaBB.pl?num=1228631426/176 with the arms on the top. Therefore I extended the vertical drive shaft and added the stirrer made of sheet SS put together with SS rivets. You can see the thermocouple end sticking up through the bottom of the pasta pot. Drive is simply a slot cut in the end of the shaft, and bracing on the stirrer to reduce "spreading" of the slot. Fig s 3 and 4
Variable speed control is achieved by turning the screw: Fig 5
The basics of converting a standard computer ATX power supply are at http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply. One thing I discovered to be necessary with my unit was to put a 3A diode in the positive line supplying the motor, otherwise the PSU would shut down.
Otherwise, a Tiffany oven, a pasta set I was given (on request) for my birthday and a disused fire blanket for use during roasting sessions.
You can see the edge of my cooler - aluminium flyscreen on a wooden frame with a 30cm fan blowing over it.
I havent done an exact costing, but probably about $200 before buying the datalogger would cover most of it. Of course if you had to buy the SS rod and sheet specifically, that would increase costs.
I hope it is of interest and perhaps helpful to someone.
Thanks to KoffeKosmo for the initial idea and encouragement along the way
Russell
. Well done again and enjoy the coffee that comes from it 
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