StirCrazy CopyCat

[Mdub]

Re: StirCrazy CopyCat

Mal,

Firstly the wave mixing bit, was an article explaining the problem with the even mixing of emulsions, and explained that to be truly efficient a stirrer must be designed so the each of the stirring fins, moves through un-stirred liquid.

It was a fairly short article, which I can no longer find (googled about a fair bit, before finding it and only printed it at work), but Ill keep searching.

I too, toyed with the idea of fitting angled fins on the arms of my stirrer rods, but I could make it work. I hope you have better luck.

I think my motor actually turns too slow and therefore there is a natural tendancy for the beans to crowd against a fin, and this does not allow the beans to be stirred effectively.

Unfortunately it seems that the motor cant be adapted to go any faster, so I will need to look around at another motor or adding a pulley or chain drive, or making the fins more efficient.

Your comment "I would never have thought that as little as only twelve months ago that I would now be contemplating all these small projects in an attempt to achieve the best a bean can offer " is right on the money.

If I go into a shop somewhere Im always thinking of what products can be adapted to use as a roaster.

This is becoming an all consuming passion.

Cheers,

Mdub

[Dimal]

Re: StirCrazy CopyCat

Wow!,

Very technical Mdub. I cant admit to knowing very much about Wave Theory, but is the intent to gradually move beans radially as well as circumferentially to ensure that the bulk of the beans are moved as much as possible per rotation?

Maybe you could provide a link to the website that goes into the theory, looks very interesting. I guess the proof of the design will only be known after you actually put it to the test. Would be interested to hear how it goes.

I guess with my thoughts on design, I was really trying to think of a way to remove everything other than the actual stirring component of the mechanism from the bean load. It was my intention to stagger the stirring arms(4 arms in total) such that each alternative arm moved the beans in the same radial direction and the other arm moved the beans in the opposite direction. So, looking from the top it would appear like this (very roughly):-

/\/
|
/\/
|
--/--/----/--/--
|
/\/
|
/\/
(For some reason I cant get the Vertical arm to remain on the centre of the Horizontal arm in this pseudo sketch. Youll have to use your imagination Im afraid.)

The main drive shaft would stop about 50mm above the deck of the frying pan/pizza tray and the two horizontal arms would screw into this, with a key to prevent slipping probably, and then the actual stirrers would drop down from the horizontal arms in more or less the configuration shown above. The oblique lines represent the stirrers and the straight lines the main arms.

I dont think that this would be terribly hard to knock up. Ive pretty well got everything I need in a couple of old dot matrix printer carcasses. I imagined that I would make the stirrers from some piano wire that I have left over from my radio controlled aircraft building days.

My thinking on the layout of the stirrers was based on the precept that by moving the beans in three directions, radially out, radially in and circumferentially... this should minimise the tendency for any beans to get stuck or remain in the same orientation for more than a couple of seconds at a time. Each stirrer would be sized such that there would be a small overlap in the paths swept by the stirrers ensuring that the whole frying pan/pizza tray base would be swept without the likelyhood of "blind" spots.

I know it all sounds fine in theory as well and the proof of this line of thinking will have to wait until I build it too, but at least it keeps me of the streets and it is all a bit of fun. Probably wont start building it for a couple of weeks yet but when I do, will keep a picture record of the progress I make and post up here for all to review and comment on.

I tell you one thing though, I would never have thought that as little as only twelve months ago that I would now be contemplating all these small projects in an attempt to achieve the best a bean can offer. Must be crazy ,eh? Anyway, must head off and start sketching out some of the details. Bye for now,

Cheers,
Mal.

[Mdub]

Re: StirCrazy CopyCat

Mal,

I have actually spent some time desiging some new stirrer fins.

The design uses some basic "wave theory" which I got off a website.

The premise is that each find only moves some of the beans, and places the beans in a spot which is swept by the following fin.

For what it is worth, here are the fin shapes.



Let me know what you think.

Mdub

[Dimal]

Re: StirCrazy CopyCat

Anyway back to the topic.....

I have found a place in QLD called Small parts & Bearings which has a lot of interesting bits & pieces, including teflon balls (yes balls) and motor shaft collars.

At the risk of being admonished by the Admins the URL for Small parts & Bearings is:
http://www.minibearings.com.au/cgi-bin/product.pl

I have ordered a collar for the motor, which will allow me to hold down the new stirrer and take it off easily.
http://www.minibearings.com.au/cgi-b...phafile=C=post

Hope this helps,

Mdub

Hi again Mdub,

Great info. Thanks for your help.

I was just having a bit of a think about the stirring issue and wondered if a better stirring action might be achieved by using a longer stirrer shaft, a horizontal arm on top of this and then drop-down L shaped wire stirrers attached to the horizontal arm.

What do you think... have a chance of working? I thought it might be better to try and get the horizontal section of the stirrer mechanism up out of the bean load and just use appropriately sized and shaped wire droppers to stir the beans around. Should stop the dam effect created by having the arm submerged under the bean load. Anyway, I thought I might give this a try and see how it goes.

All the best,
Mal.

[KopiO]

Re: StirCrazy CopyCat

Mdub,
Have you tried using only one blade to stir? I did encounter the same problem when I was building my first wok stirrer similar to yours. It just move the beans along in a bunch rather than stiring them.
Now I just use one lower blade for small batches and the upper blade comes into play when the
batch size increases.
As my first unit also uses a motor similar to yours, the problem I have encountered batch size limitation and stir speed. It tend to stall when stirring more than 300g of beans.
Hence the stepper motor. Hope you have as much fun building your machine as I did with mine.

KopiO

[mycle]

Re: StirCrazy CopyCat

The next question is a risky one but Ill ask anyway...
Has anyone ever tried using a microwave to roas (nuce) beens? If yes, what were the results like?

Theres a local roaster in Wollongong that (to quote their website) "Roast using a combination of both traditional and leading edge heating technologies that minimises aroma and flavour degradation that occurs during the roasting process. In an industry that hasnt significantly advanced roasting mechanisms for centuries, we are producing a uniquely roasted coffee that will set the standard for the new millennium."

The guy that seems to run the place has his day job working at the University fiddling with things microwave so I guess there is some aspect of that being applied here but theres no details given.

their sites at www.baristasbrew.com - its pretty basic so far.

mycle.

[B.o.r.i.s]

Re: StirCrazy CopyCat

Not sure if this ios the best place to ask but here it goes

Can a turbo oven be used on its side, upside down or anywhere in between?

The next question is a risky one but Ill ask anyway...
Has anyone ever tried using a microwave to roas (nuce) beens?  If yes, what were the results like?

Im thinking a little "outside the bean"   ;D

[Mdub]

Re: StirCrazy CopyCat

Mal,

It just so happens that the shaft size of the motor matches the inside diameter of a mudgard washer.
When I attached the blades to the washers (one each side of the blade) I made sure to grind a flat section on the rounded end of the 15cm SS rule which sits against the flat of the shaft.

Once the blades were riveted in the whole thing was tightly fixed to the shaft (its still a bugger to get off)

Unfortunately I am disapointed with the stirring action of the rules, as they tend to bunch the beans up at the leading edge, and there is significantly less bean agitation when this happens.

I have found a source of special wire (read coathanger wire)which when bent into a specific shape (more on this later) stirs the beans more evenly.

Anyway back to the topic.....

I have found a place in QLD called Small parts & Bearings which has a lot of interesting bits & pieces, including teflon balls (yes balls) and motor shaft collars.

At the risk of being admonished by the Admins the URL for Small parts & Bearings is:
http://www.minibearings.com.au/cgi-bin/product.pl

I have ordered a collar for the motor, which will allow me to hold down the new stirrer and take it off easily.
http://www.minibearings.com.au/cgi-b...phafile=C=post


Hope this helps,

Mdub

[Dimal]

Re: StirCrazy CopyCat

Hi Mdub,

Out of interest, how did you couple the output shaft of the motor/gearbox to the shaft of the Stirer? Did you machine up something for the job or adapt something else for the task?

Cheers,
Mal.

[Mdub]

Re: StirCrazy CopyCat

Bruce,

The motor has two male spade connectors which are well insulated from the motor body. I have attached the wires from a 3 pin 240 v plug and cable to a set of insulated female spade sockets.

I have also attached an earth wire to one of the mouting lugs on the bottom of the motor.

I have temporarily mounted the motor directly to the Pizza Tray, however I will need to use a brass offset to further insulate the motor from the direct heat from the tray itself.



I suspect that I will further develop the stirrer blades before replacing the pizza tray with a SS frypan (or similar)

Hope this helps

Mdub

[Bruce]

Re: StirCrazy CopyCat

Hi Mdub. Can I ask how the motor is shielded, both electrically and physically? Is the motor and electrics contained somehow or just improvised for now?
Cheers...
Bruce...

[tim]

Re: StirCrazy CopyCat

YT,

I bent my wires up in a bit of a "V" (an obtuse angle of about 150deg) shape before adding the brass connectors. Very sucessful and no beans jamming. This wire is stiff but can be bent to your preferred config.
Tim

[poundy]

Re: StirCrazy CopyCat

MDub, you da man! thats great ingeneuity, cant wait to see it in action and taste the results!

[yankeetrader]

Re: StirCrazy CopyCat

Mdub,
I just tried another mod on my Stir Crazy and have gone back to the factory default which is just a piece of SS wire (quite stiff) which runs along the bottom of the pan. It is held off from rubbing on most of the bottom by a small ridge which rises off the bottom about 20 mm in from the outside edge.
The wire(1 wire, 2 arms) rides on this. For all I know the real purpose of the ridge is to keep popping oil contained. Even this wire can ride up on a coffee bean and jamb and reverse the motor. All it takes is a coffee bean laying on its flat face. The wire hits the rounded back of the bean and sometimes goes right up on it and jambs. I seam to get less jambs the factory way. I have tried many mods, but always get more jamming. This little motor of mine is really not very strong.
I have thought of making a small "Tent" out of sheet metal for stirring. It would look something like ^ and have to experiment with the angles. I would start with some sheet metal maybe 10-12 mil wide and as long as my stirring arms. Bend it in the middle and lay it over the Stir crazy wire. Like making a tent with a blanket over a rope. Probably a bend of around 40 Deg or so. Probably silver solder it to the wire. Any compatibility between the SS and the tent as far as silver soldering it goes and I’ll just replace the SS wire with a coat hanger or whatever.
Since this tent would literally scrape right along the bottom it should be impossible (?) for it to ride up on a bean And it would do the same in reverse. Naturally in the Stir crazy you would loose the Teflon finish (not needed anyway and I would remove the finish rather than have it mix with my coffee) and the leading edges of the tent legs would get very sharp.
I won’t be able to get to this project for awhile and am most keen to learn what you eventually come up with.
Happy roasting, YT

[Mdub]

Re: StirCrazy CopyCat

YT,

The motors have a 7mm shaft, metal shaft, metal gearing & a flat on the shaft (for driving)

The motor is designed to withstand up to 260c (microwave / convection oven temps

I have modified the stirrer so it consists of 2 short and two long rods (coathanger wire) which seems to move the beans around a lot better.

Ill give it a go this afternoon, and post the results.

Mdub