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Element Build
greencardigan
Hi all,

I'm planning ahead for a 0.5 - 1kg air roaster (after I finish my breadmaker roaster Grin).

I have a vacuum motor sorted but might build a custom heating element.

I want something that looks like Chad's element. Probably about 3000 - 4000 Watts. I have a 20A 240V circuit to work with.

i206.photobucket.com/albums/bb54/seedlings/13coffeeairii55.jpg

I'm having difficulty finding any ceramic insulators. Can I wrap the coiled nichrome around a piece of cement board?
dja
try here; http://www.infraredheaters.com/ they have the stuff you are looking for, or try your local heat and air dudes see if they have any burned out electric elements, or try thrift stores for elcheap electric heaters, or MacMaster Carr for Mica board which ain't cheap.

Small as that tunnel looks the element your sliding into it should work like it is. or do like I did and make it about 4.5 inches in diameter and length adjustable.
I pour Iron and roast Coffee BeansThumbsUp
If life seems normal your not going fast enough Mario Andrette
dja
nice element by the way if you don't mind me asking where'd you procure it from??????
I pour Iron and roast Coffee BeansThumbsUp
If life seems normal your not going fast enough Mario Andrette
greencardigan

Quote

dja wrote:
nice element by the way if you don't mind me asking where'd you procure it from??????

This happens to be one of the elements seedlings used in his CoffeeAir
II roaster. I just borrowed his pic to show what I'm after.

Also I'm in Australia so not sure how useful those stores will be.

Does any know if I can safely wrap the nichrome around cement board? That seems like a cheap and easy way to build an element.
dja
you can wrap the element around anything that will take the heat and is electrically safe.

I may have a picture of what I used for an element I will have to look.

The one I started with came out of a home central heat unit and was flat with three rows of ceramic insulators the insulators were mounted in pairs to make the three rows, the NiC made 6 passes thru the insulators.

anyway it was made from wire so I cut it up and welded the peice's to some hex bar that I had fitted to a rod with one end fixed and the other being adjustable which allow for changes in the NiC length while I was in the process of adjusting the length.

will look to see if I can find some pictures of what I talking about.

Mica board .125" will work great for what your wanting if you can find it in Aus cheap, it's pretty expensive here for the size peice that you get.
I pour Iron and roast Coffee BeansThumbsUp
If life seems normal your not going fast enough Mario Andrette
dja
if you know some one that does ceramic's you maybe able to con them into making you some ceramic insulators in that basic X or + shape with the promise of some freshly roasted beans.

make that basic cross shape but put little slits in the edges, or slits leading into small .125" diameter holes. once its fired it will take a lot more heat than the NiChrome will make. one thing about a doit yourself is you can make it to it your roaster instead of making your roaster fit the coil.

going to look for photos see if I can find the ones I think I took
David
I pour Iron and roast Coffee BeansThumbsUp
If life seems normal your not going fast enough Mario Andrette
dja
check this link it has some pictures of the coil that is in my roaster right now, may change at some time or it may stay the same if the coil holds up to the extreme heat that is created in that chamber, over 700 degrees checked with a thermal couple and PXR3 controller.

http://s1222.phot...e257/index

this is how my coil started out, its shorter now
i1222.photobucket.com/albums/dd484/Superdave257/furnace%20and%20roaster/Heating-Element-2.jpg
Edited by dja on 11/25/2010 4:17 PM
I pour Iron and roast Coffee BeansThumbsUp
If life seems normal your not going fast enough Mario Andrette
greencardigan
I found out that my 20A circuit is actually only 15A. :(

That gives me 3600W. Subtracting 900W for the VC motor leaves me with onlt 2700W for heating and control.

Now i'm wondering what weight of beans will be the limit with a 2700W element in a fluid bed roaster.

Or maybe I can use 2 circuits for a total of 25A. I dont really want to do this though.
dja
your on 220 in Aus aren't you?
and if I am correct from what someone else was saying most of the home circuits are 15 amps.

if you plan on roasting in the garage you might put in a circuit and breaker for a welder which would give you plenty of amperage.

I have my roaster running on 110 on a 30 amp breaker
Edited by dja on 11/25/2010 4:22 PM
I pour Iron and roast Coffee BeansThumbsUp
If life seems normal your not going fast enough Mario Andrette
greencardigan
Those elements look great! How many Watts are they? What gauge nichrome?

I do have a friend who teaches pottery classes. I'll have to think up some insulator designs. Probabbly shoud get he nichrome and heating tube sorted out first though.
greencardigan

Quote

dja wrote:
your on 220 in Aus aren't you?
and if I am correct from what someone else was saying most of the home circuits are 15 amps.

if you plan on roasting in the garage you might put in a circuit and breaker for a welder which would give you plenty of amperage.

I have my roaster running on 110 on a 30 amp breaker


Yes i'm in Aus. I thought our general circuits were 2400W. I already have a circuit in the garage for a welder. I'll have to recheck the breaker in it.

Of your 3300W, how much are you using for the heater and blower? And what weight of beans can you roast?
dja
I still have to check the amp draw on the coil, holiday here so i been being lazy.

I have had 1.5 pounds in it without any heat problems, the problem I was having was due to air flow into the beans and not having a damper in the top exit, I now have a damper in the top and changed the air entry from slanted slots to a flat plate with 3.16" holes in it.

The last roast I did was videoed and crummy as it is is on my thread Air Roaster, the roast lasted 9 minutes and was 1.25 pounds of beans, as Seedlings said in a post on his build the coil is full on and the temp is controlled by air flow, ie, slow air flow hotter air. I am seeing a problem in my roaster in the roast chamber not being large enough in diameter to handle much more than 1.5 pounds due to the amount of space the roasted beans take up. My V/C Motor has the power to move the beans I just don't have room for more than what I am roasting now, and I can only consume so much coffee in a day by myself, so no reason to roast more that what I do, and yes I would like to build one that would do 10 pounds but first there has to be a reason or a need.

The NiC I started with was originally suppose to be hooked to 220 VAC, it was six feet long, for it to work in my roaster I cut almost half of it off. with your 220 voltage it will depend on the size of the NiChrome that you use as to how much heat you will create, the site I dropped a link for earlier has some handy charts and formules you might find helpful.
I pour Iron and roast Coffee BeansThumbsUp
If life seems normal your not going fast enough Mario Andrette
seedlings
Here's THREE elements similar to what I used for sale right now on eBuy for $19.99 USD:

http://cgi.ebay.c...2eb037f247

thmb.inkfrog.com/thumbn/auctionfynder/010_013.JPG

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
endlesscycles
Sweet. Exactly what I needed (and had in my basket at Drillspot!). Thanks Chad!
-Marshall Hance
Asheville, NC
JETROASTER
Ready made, cheap. Any single element like those could handle a pound. I grabbed one after some heat gun testing. Dan posted a link to an element that is from a commercial heat-gun. Intended for industrial applications, it will deliver 750 at 40cfm. Not bad for 29.00$
I love to tinker, but on this stuff, why bother.
Chad is wise.....he must be old. -Scott
Edited by JETROASTER on 11/27/2010 3:41 PM
dja
yea after today almost finishing a roast in the beast, finding out that with the 20' long 14 gauge and a 100' long 16 gauge corads plugged together on a 10 amp breaker I'm sorry I didn't buy em last night.

DJA
I pour Iron and roast Coffee BeansThumbsUp
If life seems normal your not going fast enough Mario Andrette
greencardigan
I picked up a small 2400W blower heater for $2 at a garage sale yesterday.

Here's what the element looks like. It consists of 2 equal length pieces of nichrome. Any good for a roaster? Maybe if I straightened it out and put it into a tube?

What weight of coffee could I roast in an air roaster with approx 2400W of heating?

www.greencardigan.com/misc/air_roaster_build/blower_heater_element.jpg
Edited by greencardigan on 11/27/2010 11:37 PM
seedlings
I'd bet you can roast 500g with 2400W. If you straighten the elements out, be very careful not to short them!

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
allenb

Quote

greencardigan wrote:
I picked up a small 2400W blower heater for $2 at a garage sale yesterday.

Here's what the element looks like. It consists of 2 equal length pieces of nichrome. Any good for a roaster? Maybe if I straightened it out and put it into a tube?

What weight of coffee could I roast in an air roaster with approx 2400W of heating?

www.greencardigan.com/misc/air_roaster_build/blower_heater_element.jpg


Looks like an Eichenauer zig-zag radial.

http://www.eichen...l-fan.html

Those work pretty well as-is and if you try to straighten them they will loose their ability to hold a shape when they get to a red-hot state.

I would just block the central area and maybe bend the loops upward (both sections) to reduce the outside diameter. You'll need to jump out the high limit since it's set for space heating temps.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
greencardigan

Quote

seedlings wrote:
I'd bet you can roast 500g with 2400W. If you straighten the elements out, be very careful not to short them!

CHAD


Thats great. 500g was the minimum I wanted to be able to roast. And I could always add a bigger heater later if needed.
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