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Mark's 1lb Fluid Air Bed Roaster - First Run, Not so much
KramE

Quote

HoldTheOnions wrote:

Cool. Can I ask what sized shop vac you used for 1lb?


Of course,

http://www.amazon.com/gp/aw/d/B003M2F...SX200_QL40
KramE
Hey all,

In looking through the threads, there doesn't seem to be a lot of discussion on how people are sealing the cocktail shaker top to the bake-a-round.

I see the OGH uses O-rings along with a very nice looking machined sandwich, I also saw that someone had used o-rings with a hose clamp.

The machined metal sandwich is out of the realm of possibility for me, but the hose clamp method is within reach.

So my question; How hot does the pipe drain tube to shaker top, and shaker top to bake-a-round actually get?

The highest temp silicone sealant I can find is rated to 700 degrees (and actually pretty cheap).

For those using o-rings, what size, thickness, hardness, and material? (I didn't see a specific one mentioned on OGH's build, or anyone else)

Has anyone caulked the two together?

Has anyone use Kapton tape?

I apologize if these questions have already been previously addressed but I have not found an obvious answer.

Thanks,

Mark
Lawnmowerman
Something to keep in mind: the vacuum is optimized for vacuum, But not necessarily for blowing. I used one with my build, and it will require numerous seals around switches, cord holes, and any other openings before I'm confident that a consistent output can be obtained. (higher pressures cause more air to leak out then lower pressures.) So it may be the same with other vacuums.
Bad coffee prevails when good coffee roasters stand by and do nothing.
coffeeroastersclub
I use this for real high temp applications:
http://www.homedepot.com/p/3M-10-1-oz.../100390499

It is a silica based sealant, dries hard as a rock. Good for over 1000 degrees. It is not a silicone based sealant, so note that.

Silicone usually smokes above 500 degrees. I really do not see the differences in the heat ratings of different silicone based sealants. Some say 500, some say 700. Silicone is silicone you'd think.

Len
"If this is coffee, please bring me some tea but if this is tea, please bring me some coffee." ~Abraham Lincoln
KramE
Where on the roaster did you apply? Between the shaker and glass? Have you found any issue with expansion and contraction of the roaster? Or is that concern negligible?
oldgearhead
Oh I used silicone 'O' rings and Permatex Red silicone sealer on the drain tubing joints and wire openings. For silicone 'O' rings all you need are a pair of calipers and a McMaster-Carr catalog. They are listed in both metric and English sizing. You have to fill the gaps YOU have. Aside from reading the calipers, subtraction is the only skill required. or you might try a dress-makers tape measure and divide by pi if you need the diameter.

I've never noticed any smoking, but I never run process variable temperature above 525°F.
Edited by oldgearhead on 04/26/2015 3:34 PM
Omega
I used an automotive "high temp" red/orange silicone to hold the perf plate in the roast chamber, right above the burner. Although ugly, the silicone lasted through dozens of roasts, until I removed it to have the perf plate welded permanently in place.

It seems that the upper limit for "high temp" silicone is quite high.

I use regular clear silicone to hold the roast chamber window in place. Although not as hot as the perf plate, it routinely sees temps up to 450*F.

Barry
KramE
Hello all,

I'd like to thank every one for their help along the way.

Here is my build so far:

farm9.staticflickr.com/8708/17159665739_f7518fe043.jpg20150502_140402 by M. A. E., on Flickr

I was not able to achieve first crack with the current configuration. I feel like I was not able to slow the beans down slow enough to allow enough heat to permeate the mass and I had too much dead space above the beans.

So, my suggested fixes:

1. Move the heating element closer to the shaker top. It's about 2" away currently

2. Cross drill a couple holes between the element and the hose connection to decrease pressure, hopefully allowing finer control as the beans get lighter.

3. Move the pipe halfway up the bake a round to reduce dead space

4. Find something to restrict airflow out to increase retained heat(?)


Any thoughts? Any other suggestions?

Thanks,

Mark
Edited by ginny on 05/02/2015 2:36 PM
coffeeroastersclub
Are you getting big time agitation? If so why not try a variable fan switch (not light dimmer switch) for the vacuum instead of drilling holes in tube before the element. http://www.lowes.com/pd_155194-539-FS...%20control

Len
"If this is coffee, please bring me some tea but if this is tea, please bring me some coffee." ~Abraham Lincoln
KramE

Quote

coffeeroastersclub wrote:

Are you getting big time agitation? If so why not try a variable fan switch (not light dimmer switch) for the vacuum instead of drilling holes in tube before the element. http://www.lowes.com/pd_155194-539-FS...%20control

Len


Not terribly large agitation. I'm currently using a HF router control (Forgot to mention that).
Omega
Lower air flow would help to get the beans heated up. A smaller bean load would help you to attain higher temperatures, too

In my experience, raising the burner has a limited effect on increasing bean temps. Two inches is pretty close, IMO.

Barry
HoldTheOnions
I don't think you need to move it closer either, just turn down speed. Beans only have to be rotating from top to bottom, not blowing all over the place. If that doesn't help then prolly need more power for beans you want to do, or do less beans.
KramE
The vacuum is turned down as low as it will go, and the beans aren't jumping, as it were.

Would drilling a couple holes between the blower and element solve this problem?

What are other people using as a baffle to retain heat? I know OGH has a nifty contraption that is out of my realm

What about another shaker top?

(Thanks to the Mod who condensed my threads)
HoldTheOnions
Are you using the 2000 watt element as in the roastuino build? It seems really odd to me you can't get to 1c on low fan speed with 2000 watt element. If you haven't, I would measure the voltage and current draw of the element to make sure you are getting full power. Also if you haven't, I would also measure the air temp and the bean temp the roast is stalling out at to use for comparison with the changes you make down the road, so you know if they are better or worse.
oldgearhead
Cross-drilling the manifold between the RC and the blower will result in:
1) a cooler blower motor.
2) lower air-flow and pressure.
3) four easy to plug if needed holes. I used a 0.25" bit.
During roasting the beans need to be in close contact with each other.
You must have good bean movement before bothering with heat.
Edited by oldgearhead on 05/05/2015 7:46 AM
KramE

Quote

HoldTheOnions wrote:

Are you using the 2000 watt element as in the roastuino build? It seems really odd to me you can't get to 1c on low fan speed with 2000 watt element. If you haven't, I would measure the voltage and current draw of the element to make sure you are getting full power. Also if you haven't, I would also measure the air temp and the bean temp the roast is stalling out at to use for comparison with the changes you make down the road, so you know if they are better or worse.


I've actually been using a cheap HF heat gun element. I just purchased the HAS-04K element as used in OGH's build.

I cross drilled the manifold and I had a much improved experience. I thought I could have gotten 1C, but I was using the same beans probably six times in a row so I don't know if they still could have cracked after being through all of that.

I figure with a bump in wattage and a couple more holes, I, in theory, should be close to a successful roast.

Quote

oldgearhead wrote:

Cross-drilling the manifold between the RC and the blower will result in:
1) a cooler blower motor.
2) lower air-flow and pressure.
3) four easy to plug if needed holes. I used a 0.25" bit.
During roasting the beans need to be in close contact with each other.


Thanks!
oldgearhead
Your motor controller needs to be able to turn-down the voltage to 20V,
and back up to 80-90V for cooling. Too many holes may require you to plug some holes for bean cooling, or are you going to dump them?

The temperature of your ambient air is a major factor in heat gun element roasting. If it's 50F you will probably need two of the 1550 watt elements to raise the air temperature from 50F to 500F with one pound of beans. I'm able to roast 440 grams with 1000 watts because my blower inlet temperature is always about 120F.
Edited by oldgearhead on 05/05/2015 8:11 AM
KramE
At this juncture, My plan is to dump them.

I roast indoors, so inlet temp with be around 70F

If I still would need two elements, I'll probably have to bow out of this project for a while due to moving half way across the county in a couple months.

Thanks again!
oldgearhead
1500 watts should do 350 grams with 70F inlet air if most of the beans are in contact with each other...look for roast times around 12-14 minutes.
KramE
Thanks!
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