StirCrazy CopyCat

[yankeetrader]

Re: StirCrazy CopyCat

Mdub
Good work. I agree that with your slower revolving shaft 4 blades would probably be in order. Does your motor have a plastic or metal shaft?? If/when my stir crazy dies Ill probably go your way.
YT

[Mdub]

Re: StirCrazy CopyCat

Here are some details & images of my version of the Stir Crazy base.

The Base is a Teflon coated Pizza Tray (33cms) with a hole drilled in the centre for the motor collar. The Pizza Tray ($6.85 KMART)

The motor is screwed to the base (at least for this version) however rivets have lower profiles, and I’ll use them on the next version, since I’m confident the motors will last a long time.

The Stirrer Base

The humble Pizza Tray

The Stirrer Base with Prima Collar


The collar fits entirely within the Pizza Tray, and is further secured by the weight of the Prima.

The whole shebang


The roaster in action


Only two blades were fitted for this test, but 4 blades will be required to keep the beans moving quickly enough to ensure an even roast throughout.

The finished roast


A few beans were a lot darker that the majority, as they got stuck under the hub, and under the blade. A redeign of the stirrer blades will fix this.

Good Points

Much less work required compared to popper and HG,
Fun to watch with a beer
No chaff to sweep up
Pizza Tray is cheap and so are the motors, so it may be possible to have several stirrers to even out the usage.

Bad Points

Stirrer mechanism can be improved
Thermostat is inaccurate
Pizza tray does not retain heat for a long period of timer and may affect roasting time and consistency (to be proven)

Roast Details

300gms Organic Dominican Solomon
1st Crack – 15 Minutes – 225 c
2nd Crack – 22 Minutes – 240 c

Conclusions

Encouraging 1st try with the Prima, better result will be forthcoming with stirrer changes, and the possible inclusion of an accurate thermostat.

Comments and suggestions are most welcome…

I’ll try the Solomon on Sunday night


Mdub

[tim]

Re: StirCrazy CopyCat

I saw a Tiffany when I went to get the Prima and the only reason I got the Prima was that it was a bit cheaper.
The Tiffany looked pretty good to me....... if anything a little bit better quality.
At that end of the market, I wouldnt be suprised if they are all re-badged from the same factory anyway...

Tim

[mycle]

Re: StirCrazy CopyCat

My local Goodguys is out of stock of the Prima ovens and said they have some on order but theyre Tiffanys not Prima. Has anyone had any experience with the Tiffany ovens? Is there any particular feature these things need to have for optimal performance?

thanks
michael.

[tim]

Re: StirCrazy CopyCat

YT,

Use the brass connectors that come out of the plastic strip connectors you can get from any electronics store. They just slide on and screw tight. You just need to demolish the plastic strip with snips to get them out.
I put three on each side, but I notice leopard uses four.
These move the beans about nicely.



Tim

[yankeetrader]

Re: StirCrazy CopyCat

Mdub
I had exactly the problem you described with a “fin” mod I tried on my Stir Crazy. It also has an auto reversing motor. I also tried a small piece of copper tubing on each arm ( full length of arm) which would roll along and push the beans ahead and tumble, but had a tendency to ride up on them and jamb or cause a reversal. There may be some joy in this however. I will experiment with some different sizes of tubes when I find some.
I looked up your motor at Oakleys and it looks basically identical to the one in the Stir Crazy. Mine is 4w vrs your 3 and my specs say 16 rpm at 50 Hz vrs your 5. If yours is geared down that much more it could indeed have more torque if it is not overidden by whatever it is that senses overtorque or whatever to reverse the motor.
The only problem that I can see in using mine is the plastic motor shaft. It would require an insulated extender of some sort.
Keep us posted. Im most curious to see what you come up with.
YT

[Mdub]

Re: StirCrazy CopyCat

Yankeetrader,

The motors are new and cost $4.00 each and are 240V AC and they auto reverse when they meet too much resistance. Ie frees up bean jams under the blade.
The motor also swap directions when powered off / on,I dont know how this is done given the size of the motor.

I got them from Oatley electronics part no MAC2(www.oatleyelectronics.com)

The stirrer design will need to be modified ie no 15deg angle on the blade as to prevent beans from becoming trapped under the high edge if the motor reverses.

I am going to use a pizza tray (32cm) as my base as the Primas collar fits into the outer edge of the tray.

Ill give it a go on the weekend, and take photos for a laugh

Mdub

I

[yankeetrader]

Re: StirCrazy CopyCat

Mdub...Excellent!
You have given me some Ideas. Very pro presentation and common sense selection of parts. Most excellent!
What did your motor cost if I may pry?
YT

[Mdub]

Re: StirCrazy CopyCat

Tim,

This is the design of the stirrer which I will be using, it uses common components from hardware and stationery suppliers, and might help.

I have ordered 4 microwave geared turntable motors which turn at 6RPM. I suspect that it will be able to stir 500gms, with little effort

My design will use a springform cake tin or frypan base, rather than the SC base, but essentially it should do the same thing.

Mdub.

[tim]

Re: StirCrazy CopyCat

Is 300g max capacity at the moment?
The turbo oven seems to fit perfectly. Is that just a happy coincidence?
On the capacity issue, is it just a case of adding an expansion collar, or is it an available heat problem?
What happens with the chaff and smoke ventilation?
Is it easy to hear the first and second crack?
I think that is all the questions I have... for the moment anyway.

Thanks Shark,
To answer your questions:
- Some people on CoffeeGeek claim you can do 1 pound in an SC.
This is 453 grams and too ambitious with my current config. The stirring arms are simply not big enough to handle the volume of beans. I intend adding some vanes and bending the wire arms upwards a bit more, then I also need to add the spacer that came with the Turbo oven, but to do that I need to add an adapter ring like Leopards. At the moment, Im pretty happy with 300 grams.
- The oven lid overlaps by about 7mm which doesnt cause a problem, nearly every photo I have seen of other projects shows a small overlap. Heres a photo I didnt put in before:


- at the moment the chaff/smoke mostly escapes through the gap, but if I add an adapter ring, I guess I will have to think of something else.

- The whole thing is very quiet and the cracks are easy to hear....much easier than they were with my air popper.

Tim

[Framey]

Re: StirCrazy CopyCat

Nice work

Is 300g max capacity at the moment?
The turbo oven seems to fit perfectly. Is that just a happy coincidence?
On the capacity issue, is it just a case of adding an expansion collar, or is it an available heat problem?
What happens with the chaff and smoke ventilation?
Is it easy to hear the first and second crack?
I think that is all the questions I have... for the moment anyway.

[yankeetrader]

Re: StirCrazy CopyCat

Well done Tim.
My Stir Crazy just arrived and havent had time to open the box yet. Youve probably saved me a kilo of coffee and a couple days roasting with your research. My cooler looks similar. Mines a ceiling exhaust fan wedged into the bucket about 1/2 way down. Have holes around the bottom of bucket for air intake and fan blows out through the beans.
YT

[tim]

I know this is not original but they say imitation is the sincerest form of flattery.........
My StirCrazy finally arrived last week and I set about quickly doing the necessary mods before roasting.
- disconnected the heater.
- replaced plastic nut with nut from 8mm dynabolt.
- covered nut/rod with alfoil, then a brass pipe-cap.

First roast (Friday night) was fast, hot and uneven with some beans oily, some light.
Roaster was too hot and I added too much coffee (400 Grams)
Pre-heated to 200 deg C, 1st crack was not happening, cranked to 250 after 14 minutes and everything happened way too fast after that. disappointed with the outcome but put it down to inexperience.


Second and Third roasts (this morning) look like a roaring success and I have posted the pictures here:
Coffee = Brazil Yellow Bourbon Pocos De Caldos
Quantity = 300 Grams (for each session).
Temperature = Pre-heat 5 mins to 220 deg C, crank to 230 deg C after 1st crack.
1st crack = 9 mins
Rolling 2nd crack started = 14 mins
Finish = 16 mins
This is the most uniform roast I have done thus far and I am able to do 3 times the volume in a single roast than I did with the air-popper.

The Beast awaits:



Time for Cooling


The Cooler


All done.