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Heat Gun...Max Capability?
JETROASTER
What's the most coffee I could hope to roast with a heating gun element?
(under 12 minutes) -Scott
 
seedlings
With my breadmaker I can easily get 1.5# of coffee to the end of first crack in 12 minutes. 1.25# in 10 minutes or less.

I roast with the lid closed, so it should be fairly efficient (read: max).

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
JETROASTER
I'm thinking high density cylindrical fluid-bed. Similar to the Sivetz heat gun on steroids.
I cranked out 4oz thru the heat gun in about 4 minutes.
It was suprisingly tasty (Yirga). The blueberry was very pronounced.
Anyway, ...got me thinking the element could do more.
Is 1 lb crazy? (with a differant blower) -Scott
 
seedlings

Quote

freshbeans wrote:
I'm thinking high density cylindrical fluid-bed. Similar to the Sivetz heat gun on steroids.
I cranked out 4oz thru the heat gun in about 4 minutes.
It was suprisingly tasty (Yirga). The blueberry was very pronounced.
Anyway, ...got me thinking the element could do more.
Is 1 lb crazy? (with a differant blower) -Scott


Did you see my original air roaster (http://homeroaste...ead_id=552)? I used an auxiliary leaf blower and two heat guns to roast about 1.25# in a design pretty much identical in concept to what you want.

You will run into trouble when the airflow to loft the beans drops the heat from the heatgun down too low. With one heatgun I couldn't get the beans above 300F. VERY inefficient roaster compared to the breadmaker + 1 heatgun.

CHAD
Edited by seedlings on 08/07/2010 1:44 PM
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
JETROASTER
Hi Chad, I'll go back and have another look. Sounds like good news. It will likely be a matter of getting the RC right.
At least the heat source sounds like it's in the right neighborhood.
I think the leaf blowers have alot of CFM, but pressure may be more important for this one. -Scott
 
seedlings
If the center mesh hole is about 25%-30% of the area of the hopper, and funnels down, it will work for sure, especially at a 1# range. When you get up to Sivetz's 12 pounder, there may be some math to think about. Oh, and leaf blowers have plenty of pressure... they're essentially plastic vacuum cleaner motors in reverse.

CHAD
Edited by seedlings on 08/08/2010 5:10 PM
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
JETROASTER
I've already had some materiels picked out for a 1lb project....small and fun.. I've put aside the propane for this one, it seems electric will be a bit more accessible.
Anything over 2.5 I'd probably go back to gas.

Any favorites on heat-gun choices out there??
-Scott
 
seedlings
I choose cheap heatguns - mine was $9.99 from harborfreight. It's lasted almost a year now, but I did have to repair it once. The screw terminal between the power cord and the guts of the gun got hot and started to melt, so I just bypassed that terminal and soldered the wires together.

A more expensive heatgun isn't hotter, but might last longer? If you have cool air blowing on the gun, then it shouldn't overheat, but I'd still stay cheap for testing purposes.

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
JETROASTER
Is it feasible to dissect the coil and reshape it inside a different heat tube? (as long as it gets sufficient cooling)
-Scott
 
seedlings

Quote

freshbeans wrote:
Is it feasible to dissect the coil and reshape it inside a different heat tube? (as long as it gets sufficient cooling)
-Scott


Yep. The roaster I'm working on is based on two replacement elements. On some heatguns there are two coils, one to drop voltage to the fan (like most poppers), so the one with the lowest resistance is the one you want for heat.

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
JETROASTER
...As predicted by Chad. The Milwaukee-gun brought 3/4lb
up to 400 in good time. No mechanical agitation, no breadmaker. However, ...That was it.
I re-outfitted the gun with a small single stage blower(like a baby ametek) It will push 1lb nicely, but it's too much cfm for that coil. A little more heat is all I need.
The question; Does any one make a gun that will offer another 25% heat?
The other option is the candy store that Dan posted.

Ideas? -Scott


 
seedlings
Scott, you could perform open-heart surgery and remove some of the heatgun's nichrome, which would lower the resistance and draw more current, increasing the power. If you want 25% more heat you'll have to remove about 25% of the nichrome... If you have an 1800W gun, 120V, 8ohm element, then you'll need to reduce that element to 6.4 ohms to get a 25% increase in power.

P = (V*V / R)

1800W = 120V*120V / 8ohm

25% more power
1800W * 1.25 = 2250W

Now:
2250W = 120V*120V / 6.4ohm

CHAD
Edited by seedlings on 08/25/2010 10:07 AM
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
JETROASTER
Will this shorten the life of the coil? ...Not that it matters.
This is just a fun little experiment. Thanks,Scott
 
seedlings
My unscientific opinion is that since you have increased air flow, that counteracts the higher-temperature nichrome to equal a similar lifespan.

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
JETROASTER
Well, this is a pretty unscientific experiment. I'm going for the surgery. It may fry the switch, but that's a few more BTU's I can use.
If it works, I'll post it. If it ignites, I'll post video.
Thanks,Scott
 
Dan
I would look at the Master Appliance Heat Guns and Heat Blowers. You can buy replacement heating elements from Grainger. For instance, here is a Heat Blower Element I used on an industrial parts washer. It is 750? (with lots of air blowing over it), 120V, 16A, $38.

http://www.graing...Pid=search

images.grainger.com/B313_51/images/products/450x450/Heat-Blower-Element-1A505_AS01.JPG

 
John Despres

Quote

seedlings wrote:
Scott, you could perform open-heart surgery and remove some of the heatgun's nichrome, which would lower the resistance and draw more current, increasing the power. If you want 25% more heat you'll have to remove about 25% of the nichrome... If you have an 1800W gun, 120V, 8ohm element, then you'll need to reduce that element to 6.4 ohms to get a 25% increase in power.

P = (V*V / R)

1800W = 120V*120V / 8ohm

25% more power
1800W * 1.25 = 2250W

Now:
2250W = 120V*120V / 6.4ohm

CHAD


If you increase your power that much, be sure to run non a 20 amp breaker or it'll only work for a few seconds. My guess is that won't be enough time.

John
Respect the bean.
John Despres
Fresh Roast 8, Gene Cafe, JYTT 1k, Quest M3, Mazzer Mini, Technivorm, various size presses and many more brewers.
 
JETROASTER
Hi John, too much juice for this set-up. 30 second roast is too quick...even for me.
Dan, thank you. That element is designed to handle about 40cfm @ 750 degrees. I'll be ordering asap.
I never completed a roast, but the experiment proved it's worth pursuing.
The blower will move 1lb. A better element will provide enough heat.
Moving on without the heat gun. Bigger cord, heftier switch
and hopefully a machine that doesn't look Frankenstein.
Thanks All -Scott

 
SteveN

Quote

Dan wrote:
I would look at the Master Appliance Heat Guns and Heat Blowers. You can buy replacement heating elements from Grainger. For instance, here is a Heat Blower Element I used on an industrial parts washer. It is 750? (with lots of air blowing over it), 120V, 16A, $38.

http://www.graing...Pid=search

images.grainger.com/B313_51/images/products/450x450/Heat-Blower-Element-1A505_AS01.JPG



Omega also has replacement elements for $24: http://www.omega...._GUNS.html
Edited by seedlings on 08/25/2010 4:16 PM
 
seedlings
Scott, shortening the element didn't work? I'm interested in how exactly it failed..!

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
JETROASTER
No failure at all!! You're advise was right on. Either shortening the element or buying a better choice would work.
The experiment was a success. I'm confident I can roast 1lb with this blower and a stronger element.
So now I move onto the actual project... which will be...
Electric, one blower, one element , and hopefully include the datalogging/controller that the others have labored on.
I've already got 85% of the components.
I was on the fence about whether to go electric or propane.
Scott

 
seedlings
Sweetness! Make sure your new element is bigger than the one in your milwaukee. You don't want to do a like-for-like.


Oh, and the last 15% of the equipment always cost more than 15% of the total.

CHAD
Edited by seedlings on 08/25/2010 5:02 PM
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
JETROASTER
New element has arrived, it is larger. How snug can i fit it inside a steel pipe? (1 1/2" ) Is there a risk of arcing?
-Scott
Edited by JETROASTER on 09/01/2010 11:20 AM
 
seedlings

Quote

freshbeans wrote:
New element has arrived, it is larger. How snug can i fit it inside a steel pipe? (1 1/2" ) Is there a risk of arcing?
-Scott


My elements came with mica paper for protection. Do you need some? I can send leftover pieces to you. OR, check inside your milwaukee for some.

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

Quote

Dan wrote:
I would look at the Master Appliance Heat Guns and Heat Blowers. You can buy replacement heating elements from Grainger. For instance, here is a Heat Blower Element I used on an industrial parts washer. It is 750? (with lots of air blowing over it), 120V, 16A, $38.

http://www.graing...Pid=search

images.grainger.com/B313_51/images/products/450x450/Heat-Blower-Element-1A505_AS01.JPG



Would someone check my math, because if this is true, it's the cheapest heat I've seen.

120V @ 16A = 7.5ohms
7.5ohms @ 240V = 7680watts

That's about right for a 5lb load!
-Marshall Hance
Asheville, NC
 
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