StirCrazy CopyCat

[Mdub]

Re: StirCrazy CopyCat

Mycle,

Congrats on getting a Prima. The stirrer bit is not as easy as first appears, as you need to get a few things in place first.

My experience with the microwave motors and the pizza tray leads me to beleive that,

1. You need to get a base (frypan etc) with high sides , at least as high as the collar provided with the Prima. The base should have decent thermal efficiency, ie to keep the heat in.

Whilst the pizza tray is good (read cheap) it is subject to changing temperatures, but it does not conduct a lot of heat to the motor, leading to longer motor life.

The Microwave motors I have turn at 6 RPM and I suspect the best speed is somewhere berween 30RPM and 45 RPM to ensure that the beans are stirred well.

Ideally you could get a motor with a speed controller, like an electric ceiling fan (yes I have my eye on one) which could be a likely candidate.

All in all Mycle its great fun, and even better when you finally sit down and have a cup of coffee, and realise that youve also done something worthwhile.

Mdub

[CM]

Re: StirCrazy CopyCat

I have been lurking around here for some time trying to learn and have found this a great site. I still dont have my machine and grinder (hopefully by weeks end) but am really interested in putting together a roaster (no money left after machine and grinder ).

After reading just about every post here and on coffeegeek in the roaster sections  I am thinking of using a convection oven and frypan with a stirer built in, simmilar to the stircrazy.  The main reason is I have to use my sight and hearing to do this as my sence of smell is almost non existent due to allergy problems. I have the majority of components to put together the motor / stirer lying about in the shed so no issues there.

I just wanted to ask before I start construction has anyone reached a point where they are happy with the design of the stirer arms used in their roaster? The main issues as I see them are RPM of motor.
Number of arms.
Shape of arms.
Do the arms have to just move the beans or is it better to rotate them during roasting (more agressive stirring)

I have copied some arm profiles from Coffeegeek and one photo from Java (in another thread on this forum) as possible design choices.

I am open to all suggestions as I really would like to get this right 1st time.
Thanks for any advice.

Craig

P.S Can some advise how to post the photos....after trying for several minutes with no luck I guess I shoud ask how its done.

[mycle]

Re: StirCrazy CopyCat

The main issues as I see them are RPM of motor.
Number of arms.
Shape of arms.
Do the arms have to just move the beans or is it better to rotate them during roasting (more agressive stirring)

Im still experimenting with mine. Ive been using an old rotisserie motor from my dads bbq which is about 30RPM and a two arm stirrer made from a coathanger. Ive found that the beans have to move a fair bit to get an even roast - just shuffling them about with a wire going under them doesnt seem to do enough so the coathanger is doubled over so there is one wire on the base of the pan and another about 15mm above it. This works OK for 600g of greens so far but theres still more experimenting to be done - the pan Im using isnt the best so Im looking into options there.

hth
mycle.

[Javaphile]

Re: StirCrazy CopyCat

P.S Can some advise how to post the photos....after trying for several minutes with no luck I guess I shoud ask how its done.

Hey Craig,

If you want to post just one picture click on the grey "Browse..." button below the box where you type in your post and select the picture you want off of your local hard drive.

If you want to include more than one picture per post youll have to put the pictures on a picture hosting website somewhere and then while composing your post here click on the 3rd button from the left in the top row above the text box where youre typing (the one with a little picture on it) and then put the path to the picture on the website between the tags. Repeat as necessary.

Java "Hmm...Pictures!" phile

[CM]

Re: StirCrazy CopyCat

Well I tried the browse button last night when posting. I can upload the path from my hard drive to the box but the photo is not transferring to the message when hitting preview??

[nunu]

Re: StirCrazy CopyCat

It should work if you just post it, as it never shows using preview for some reason.

[CM]

Re: StirCrazy CopyCat

Ok here goes again, These are the pusher arms I have been looking at

[CM]

Re: StirCrazy CopyCat

Posted by Java

[nunu]

Re: StirCrazy CopyCat

A bit more aggressive stirring would be best. Otherwise the beans stay mainly in the same place, instead of going everywhere within the roasting chamber. Simply attaching an upward pointing vane to the stirring arm should do the trick. Even making the stirring arm a bit better by bending it into an up and down s-curve will be sufficient, but the length of the stirring arm will be compromised.

[AndyCJ]

Re: StirCrazy CopyCat

I just use a hunk of angle iron... but I can tilt the pot while roasting, so the beans get scooped on one rotation, and pushed on the other.

Very even roasts so far, cept when I use the Mao Horse, which is so irregular that you always get a few tiny little suckers that underroast a bit!!

[nunu]

Re: StirCrazy CopyCat

Andy brings up a point that I thought of when I went to bed. Let gravity help you do some of the work. Even a slight tilt will help move the beans around better than on a completely level surface.

The speed of the agitation also has an impact. If the beans get tossed around a bit, it might also be beneficial. Im not talking about lawnmower blade speed, but even 10 more rpm. Thats another thought, rather than trying to modify too much, simply up the speed a little.

[Javaphile]

Re: StirCrazy CopyCat

Hey Nunu,

Are the Columbian Supremo beans really as dark as the picture makes them look? Looking at them here they appear to be well beyond the optimum roast level.

Generally Columbian beans dont like to come anywhere near 2nd crack and reach peak flavor shortly after first crack. The Columbian beans are the lightest roast I do with their flavor degrading very rapidly by the halfway point between 1st and 2nd crack.

The Columbian Mesa de los Santos is one of my all-time favorite beans when taken to a light roast but by the halfway point between 1st and 2nd crack theyve lost almost all of that great flavor.

Java "Loves the Columbians" phile

[nunu]

Re: StirCrazy CopyCat

That picture was back in September sometime. Looking back, I found that batch was average at best. Most of my roasts are in the neighbourhood of Full City - Light French. It keeps a bit of the origin characteristics, and combines it with the roast characteristics. For most of the coffees Ive roasted, this seems to be near the mark from my taste perspective. I dont have a huge stock of beans on hand to do a whole lot of testing, so I enjoy everything I roast.