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Thanks to ideas I got from postings on HRO I finished my new air roaster using familiar components from similar projects here.

Air source is a 600W minivac motor from Goodwill, heat source is a heat gun element from Grainger which I think is about 14A.

This first pic shows the original RC I was going to use. It was a vase I saw in Goodwill but my brain saw a RC. However, the moment I saw it it was doomed from the start. I managed to cut the bottom out of it with no chips or cracks so naturally it was doomed. I attached it to a drink shaker top using RTV silicone and it was standing on the work table when I moved my arm and bumped it. It hit the vise and broke. I was not a happy roaster.

So I had to go to plan B and use a globe from a old lantern I found in the shop. The globe works well but I really liked the looks of the vise.



I mounted the blower in a PVC reducer and the heat element inside the plumbing pipe. The pipe is mated to the PVC using a floor flange. Pics show the heater wires protruding through one of the mounting holes in the flange but have been rerouted through a hole in the PVC along with the blower wires.







I built a cheesy wood box to house it in. It won't win any points for being pretty but it keeps the noise level down. Really it's pretty quiet compared to the loud mini shopvac I was using with the Jethro. There is a hole cut in the box on the left end where the blower input is. The RC just fits into the drain pipe with a little snugness. It could fall out if I bumped it hard so I may rig up a removable wire frame to prevent that.

Finished product:





A little video of it roasting. Sound may be loud in the video but standing there next to the roaster it isn't. Not many beans in this roast, maybe 150g.



I really need to learn to make a trial video so I don't move meters and timers around to get them in view in the posted video. I've only done a few small roasts in it so far and have been pleased with the results.

Beaner:

WOW, fabulous job there, beautiful, clean workmanship.

Sweet...




-g

Sa-Weeeet!!!

Very nice! Now try 300 grams. I'll bet the fluid-bed action is very good..
btw - I like your avatar.

Very nice work.

I tried 280g and I couldn't get the RC temperature past about 410. I'm using the Grainger HG element 2A443. Wattage isn't listed but it's meant for the HG-751B HG which they list at 14.5A so I assume that's almost 1600W. I would've thought that would be enough for 280g but I never even heard a first crack.

It might be the shape of the RC, or maybe the air flow holes. I'm in no hurry to try and solve the problem though since I never need roast that much anyway. I usually roast from 100g to 150g.

Speaking of RC shape, see my next post.

So I saw a little vase in Goodwill and decided to experiment with it. After cutting (grinding) the bottom off and expoxy'd it to another drink shaker top I had laying around. Unfortunately this shaker top was not of same design as the other one currently in use with the other RC I posted.

This one fits down into the plumbing pipe but it was kinda lose and didn't seal very well. The fix was to attach a clamping ring with epoxy and now I can just screw it onto the plumbing pipe. I wish the thread count was much less so it didn't have to be turned so many times to tighten it. that's a very minor annoyance though so no biggie.

A couple of pics and short vid:

I wanted more air flow from the shaker cap holes but drilling more of them was not a pratical option. Instead I enlarged the center hole and put a piece of SS screen on the inside. This works well as the larger center hole pushes the center bean mass more than the outer holes. This prevents all of the beans from sort of lifting up and down in unison, like I've seen with some other bottles I used with the Hillbilly/Jethro roaster.







I like this RC better than the lantern globe since I can see more of the beans.

Btw, this video is one of the small roasts that Ginny gets by drawing my name in the Christmas swap. Ginny is the lucky person chosen to be the test subject for the first roasts from this new RC. I'm sending her a variety of small roasts since I can't roast larger batches. Silver lining for me is that I have a better chance of one of them being good.

This RC is a bit trickier than the lantern globe, I guess due to it's shape. When the RC temp reaches about 380 it can take off fast from there so I learned from the first two roasts. Hopefully one of the batches is drinkable. <wink>

So say a prayer for Ginny, she might be calling in sick shortly after Christmas.

Spouting is very full, even and no unnecessary launching upward. It takes a lot of R&D for many of us to ever arrive at such a nice bean circulation. I'm betting you're getting as good as one can get in heat transfer.

No reason why this roaster can't produce remarkable tasting coffee! Great job.

Allen

Because I use the same heating element and I achieve 520?F in my RC,
I think your minimum air-flow is too high. I suspect too much heat is going out the top of the RC.

I would suggest a few holes or a waste-gate between the heater and the RC. This should allow the motor to run cooler and the flow to be turned down more.

You should be able to turn down the air until the green beans stop flowing. I usually turn down twice during a roast, at 3 and 6 minutes.

I understand you are not reusing any RC air, but 1450 watts should easily do 300 grams. A lowly Nesco can do 180 grams with 500 watts.
;
;

OGH, if you notice there is a drink shaker top sitting on top of the lantern globe RC which restricts air outflow and I can turn the blower low enough for no bean movement. I read through the build of your roaster and is the reason I mentioned the temp problem I had. I saw I was using the same heat element as you and read your roast capacity of 1lb. I did read about the return air you are using and figured that helped but as you say, without that I should be able to roast 300g.

I think if I played around with a few variables like RC intake flow, air outflow, and maybe a little better insulation around the air feed pipe I could the temp up higher. Maybe cutting out the bottom of the shaker top the the globe is epoxied to and replacing the original holes with a screen might help.

Really though, as I mentioned, I'm not concerned with it since I don't ever roast that much at once. If that changes I might scrap that wide globe and replace it with a cylinder.

In reference to Allen's comment and yours regarding bean flow I made another video with the new vase RC. I threw in some more beans for better representation of bean movement. No heat applied, just blower:

Thought I'd go take a pic of the lantern globe bottom air intake. I would think those holes would let enough air and heat through for 300g but maybe not. Like I said, maybe if I cut out all of the holes and replaced with a screen it might help.

I'm not even using this RC now since I made the newer RC with the glass vase.

Very nice bean flow!
How do you dump the beans?

Your shaker looks a lot like mine,
19 holes about 0.150" ea.

OGH, the glass vase RC just screws onto the end of the chrome elbow plumbing pipe. I used epoxy to mount a connecting nut onto the shaker cap. I don't recall what the nut is actually called but it's what is used to connect a two pieces of plumbing pipe together. Like a straight sink drain pipe piece to a p-trap.

If you go back and look at the first two pictures in this post you will see the chrome elbo piece with threads on the end. The RC simply screws on to that. More turns than I'd like to get it snug but that's no biggie.

I have holes 1 & 7 plugged.
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