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Homeroasters.org » BUILDING A ROASTER » Fluidbed Roaster
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My 1kg Electric Air Roaster build
greencardigan
Well, I have to admit I'm now addicted to coffee roaster building. Shock

My PID popper has served me well but like most, I grew tired of the small roast sizes. I've done 1 roast with my new breadmaker and heatgun but am already looking ahead to a bigger air roaster.

So this will be my build thread for my 1kg electric air roaster.

Here's what I've been dreaming of.

- Capable of at least 500g roasts. Preferably 1kg.
- Electric heating
- Changable perforated plate
- Portable
- In roaster cooling
- Automatic roast controller to follow preset profile
- Data logger

And now a few dodgey sketches of my initial thoughts.

I'll probably use the square RC idea. I have minimal tools and need to keep it simple.
www.greencardigan.com/misc/air_roaster_build/air_roaster_concept1.jpg

Possible electrical configuration. I plan to use 2 x 240v circuits for a total of 4800W of heating.
www.greencardigan.com/misc/air_roaster_build/circuit_concept1.jpg

Thanks to all the other air roaster builders for the inspiration and tips. ThumbsUp
 
seedlings
Sounds familiar! Couple of things while you're in the planning stages- how will you unload the beans, how will you deal with lots of chaff, and if your hopper is steel it will retain heat, making cooling slower.

Oh, and the roast profile control you're looking for will need to control air flow, not heat- a good solution hasn't come up yet...

CHAD
Edited by seedlings on 11-30-2010 03:31
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
greencardigan
Regarding unloading the beans, I like the idea mentioned in another build thread where a bottom hinged door opens into the RC. The beans get blown over the door and slide out.

Roasting will most likely be done outside where the neighbours will have to deal with the chaff. However, I did my 1st 'big' roast (500g) the other day and was amazed at the amount of chaff. So I can see how 1kg would make a mess.

I'm thinking an aluminium RC as it'll be easier to work with?? Any reasons an aluminium RC is not good?

Hmm, I dont have a solution yet either for automated blower speed control. But I have a few ideas up my sleeve. ;)

I'd really like the an oversized heater to do the temperature control and the blower controlled automatically based on bean movement or bean temp (this is what I do with my popper).

BUT, I'm going away for 3 weeks from this weekend so this project will have to go on hold before it starts. :@
Edited by greencardigan on 11-30-2010 14:02
 
SteveN
An oversized heater for 1kg is likely a bit bigger than what you are planning.

My setup isn't optimal as I've got a lot of volume before the RC but I'm using 5500W and roasting 1kg requires max heat all the way through.

Your best bet is likely to get the right blower; something with low cfms and high pressure to make sure you can loft 1kg and still maintain a good temp. As Chad mentioned, you'll need good control over the blower if you want to do a range of loads.
 
greencardigan
Hmm, ok. I'm planning now for 4800W of heating. Yes, I can see how good air control is critical.

I think I better start off with manual control and think about automation later.
 
dja
my dimes worth,
1 would use two seperate circuits, reason is that when that heater turns on your going to have one heck of a drag on the line which will pull the V/C motor down. does mine anyway.
2. try to keep your air flow in a stright line, reason is air hits something it slows down.

I made my heat chamber out of steel 4.5" OD tubing inside is like 4.250 give your air some room to expand and slow down to pick up heat before it hits the outlet were it will pick the pressure back up that your going to need to circulate the beans. if you have a little skinny heat tube the air is going to be screaming thru it, if your outlet is no bigger than the inlet of your V/C motor you will not loose any pressure.

first thing to design is a handle on the roast chamber, mines pyrex and at 550 degrees its no fun if you forget you mitts, might be ok during the cold days of roasting have to check that out maybe today when I gt back from the Doc have to see.

make sure you have pleanty of plugs on your control box, easier to factor in a couple extra than you think you will need, like for that cooling fan that has to get juice from somewhere.

Fuses, or pushbutton circuit breakers, your choice or what you can find at work. Still on my to buy list for C/B.

V/C motor inlet air filter, sometype, I opened my roaster to show my brother the insides, thing had a bunch of chaff inside it that got cough up in the inlet air stream is my only guess, so it gets a throwaway computer filter attached somehow, or some type of H/A throw away fiber filter ever couple of roast toss it.

Chad hasn't said anything about his roaster, mine will diffinately try to blow the roast chamber off the bottom half when I cut the heat. So I need to workup some type of quick release catches for it, but that may just be the reaction of the triac speed control when I cut the heat, a variac which I plan to use may not have this effect.

Thats my 10 cents worth.

get ready for lots of fun and chaff.

David
Edited by dja on 12-01-2010 02:34
I pour Iron and roast Coffee BeansThumbsUp
If life seems normal your not going fast enough Mario Andrette
 
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greencardigan
Thanks for to advice David.

Are there any details here about your triac speed controller?
Edited by greencardigan on 12-01-2010 03:01
 
seedlings
greencardigan wrote:
Are there any details here about your triac speed controller?


http://www.harbor...43060.html
www.harborfreight.com/media/catalog/product/cache/1/image/370x/9df78eab33525d08d6e5fb8d27136e95/i/m/image_1025.jpg

I use this to control my blower - I soldered to the inputs and used my own fuse, though. I'm not sure what triac it used, but it may be able to take 220V - DON'T quote me on that, though!

David, my roast chamber will not blow off - empty or full.... Well, I've never had reason to turn the blower all the way up just to see, but suffice to say at any usable airflow amount the hopper rests fine.

CHAD
Edited by seedlings on 12-01-2010 04:33
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
dja
it may just be something with the way that same controller acts when I unplug the heating coil, it won't do it at start up as I normally have the beans in it when I turn the air on, plus when I plug the controller in I have the knob all the way to max but before flipping the switch I turn it down to the low side of the green....like I said it might be the redneck sunlight we have around here that affects things electrical...

happy roasting.


I pour Iron and roast Coffee BeansThumbsUp
If life seems normal your not going fast enough Mario Andrette
 
SteveN
I haven't had any issues with my RC blowing off or surging when I turn off the element. The surging could be from resistance on the wiring; my main wiring is oversized (can handle about 40A on a draw of about 25A).
 
dja
I think its just the way that the router speed controller is acting, I turn it to max before pluging it in with the switch in the off positon then turn it almost all the way down before turning the V/C motor on, then while the roaster is running I am getting a lot of surging up and down in the speed. and when I plug the heating element in the speed drops way down and I have to increase the speed setting, then when I unplug the heating coil (no Switch yet) the speed surges way up.
It doesn't bother me too much as when I build a control panel to use with other items that keep the nebighors on their toes I plan on a variac for the speed control on the roaster and furnace blowers.

It may be nothing more that the fridge kicking on and causing the surges or the line that feeds the nebighorhood could be doing it, who know's
I pour Iron and roast Coffee BeansThumbsUp
If life seems normal your not going fast enough Mario Andrette
 
greencardigan
I've had a look around in Aus and there doesn't seem to be any similar 'router controllers' available here. Quite frustrating. I know what I want but can never seem to find it locally. However I noticed the user manual for the Harbour Freight controller says can handle 250VDC? 15A. I wonder what shipping to Aus costs.

http://manuals.ha.../43060.PDF

I did find this motor controller kit but it's a bit expensive.

http://www.jaycar...rm=KEYWORD


I was wondering if I could replace the control potentiometer with a digital potentiometer like this to allow automated blower control? Any thought on this?

http://www.maxim-...vp/id/2402
Edited by greencardigan on 12-01-2010 12:26
 
dja
if your handy with a soldering iron a peice of breadboard and a few componetes you could knock one together, the circuits not rocket science.

thing weights about a pound so postage can't be much.

dump the cord and box your looking at maybe 4 ozs
Edited by dja on 12-01-2010 13:00
I pour Iron and roast Coffee BeansThumbsUp
If life seems normal your not going fast enough Mario Andrette
 
RoasterRob
Get a 1kw dimmer or build your own. I have built several of these. http://www.epanor...ml#1kw230v

Just need a good heat sink on the triac.

Rob vL
NZ
VBM Minimax 2gp, 1gp Reneka Techno, 2 gp la Pavoni Pub, la Cimbali M28, SJ Maz, FB 6kg HM roaster and other stuff
 
greencardigan
Thanks heaps Rob. I'll have a read through that site. I have been thinking about building my own controller but thought it might be a bit beyond me.
 
RoasterRob
Nay, just be careful and earth your case etc. I bought a kitset universal motor controllet from DSE here in NZ. It was a piece of junk, the motor pulsed badly.
This 1kw light dimmer circuit works well can be turned down very low. When I get a chance will tell you the right triac etc to use. The one listed I believe is obsolete.

Rob

Rob
VBM Minimax 2gp, 1gp Reneka Techno, 2 gp la Pavoni Pub, la Cimbali M28, SJ Maz, FB 6kg HM roaster and other stuff
 
greencardigan
Hmm, it says it's "designed to operate with non-inductive loads."

Are you using a vacuum cleaner motor?
 
seedlings
greencardigan wrote:
Are you using a vacuum cleaner motor?


Don't want to speak for Rob, but: http://homeroaste...ad_id=1709

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
RoasterRob
greencardigan wrote:
Hmm, it says it's "designed to operate with non-inductive loads."

Are you using a vacuum cleaner motor?


Yup. A universal motor as used by 99% of VCs are not as such an inductive load. If you dismantle any (variable speed) VC you will find a triac based controller. Actually exactly the same triacs are used in VCs as I have used.
I have done somewhere between 1000 and 2000 roasts on my roasters. The controller hasn't missed a beat and causes no interference.

Triac to use is BTA12 600B. Which is 600V 12amp - with insulated tab. All the other components are are off the shelf (which the triac should be too).

Rob vL
NZ
VBM Minimax 2gp, 1gp Reneka Techno, 2 gp la Pavoni Pub, la Cimbali M28, SJ Maz, FB 6kg HM roaster and other stuff
 
greencardigan
I found a source for the BTA12 600B triac and the BR100-03 diac.

I'm a bit confused about the filtering coil I need. Is this what I'm after?

LINK TO 100uF 5A inductor

img-asia.electrocomponents.com/images/RD308874-01.jpg
Edited by greencardigan on 12-02-2010 13:49
 
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