Building Gas Grill Roaster - What Motor?

Home roaster modifications, homemade roasters
DougGuy
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Building Gas Grill Roaster - What Motor?

Postby DougGuy » Mon Apr 03, 2017 8:43 pm

I have started on a BBQ grill roaster, I picked this Sunbeam model 340 because it was cheap, I gave $45 for it off craigslist with a full bottle of propane. I chose this particular model because it had a nice high arched top, plenty of room for a drum, and also because the single burner put out a nice size flame which by looking at the picture off craigslist SHOULD have enough btu output to roast coffee. In the photo, the burner is let to a low setting. I can't find anything online that gives the btu rating of a single 15" x 4" oval burner.

McNichols has some nice perforated sheet metal made of 304 stainless, 3/16" holes staggered 1/4" apart should be plenty for air circulation in the drum and also big enough that much of the chaff will fall through the holes. I plan on making a drum 12" in length, 8" in diameter, and I think this will do a 3lb roast in 17 to 18 minutes once the roaster gets up to temp.

I have seen drums made with a spring loaded door on one end, but I am very tempted to make this drum like a sample roaster, with a tapered cone and a straight neck that is open like an old style metal milk jug, it would allow chaff and smoke to exit, it would also allow me to reach in with a spoon to fetch the beans for visual inspection as they roast and it would be quick and easy to dump and then reload using a funnel with a large opening like a typical canning funnel would have.

My question, is what motor to use? I would like to turn the drum faster than the standard rotisserie spit turns, 15 to 20 RPM should be plenty to keep the beans agitated. Suggestions as to an inexpensive motor that will work?

Here's some pics, will post more as work progresses...

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DougGuy
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Re: Building Gas Grill Roaster - What Motor?

Postby DougGuy » Wed Apr 05, 2017 1:21 pm

Found a motor right under my own NOSE! :roll:

The Ronco rotisserie I was going to convert into a roaster has a motor that turns about 20rpm which will work just great for a drum roaster!

DougGuy
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Re: Building Gas Grill Roaster - What Motor?

Postby DougGuy » Wed Apr 12, 2017 5:44 pm

Got a few measurements, ordered the perforated stainless 16ga. from McNichols, the other stainless was scrap left over from a food trailer upgrade, the ring was leftover from a previous coffee roaster project that I abandoned, but I can see it will be the perfect size for this BBQ roaster so I went with it. The drum will be 9 1/2" x 16" with a cone and a nozzle on one end to faciltate dumping roasted beans and loading green beans. I wanted it to work like the Probat sample roasters..

Here is the material laid out:

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Here is the material after splicing together the stainless sheet metal with the TiG welder, and rolling the cone:

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DougGuy
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Re: Building Gas Grill Roaster - What Motor?

Postby DougGuy » Sat Apr 15, 2017 7:30 am

Cone rolled fitted and welded:

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Neck welded to cone to make "Tin Man's Hat"

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Drum all tacked up and laying in the grill to check fitment and location of drum before committing to welding it all together:

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DougGuy
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Re: Building Gas Grill Roaster - What Motor?

Postby DougGuy » Sun Apr 16, 2017 6:10 am

Looking inside the finished drum, I used two vanes about 1 3/4" in width, should be sufficient to keep beans moving and falling through the hot air gathering heat from convection.

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Drum is finished, this is the bottom which employs a Craftsman 1/2" socket cut off short and welded to the base. I will use a 3/8" drive extension as a drive shaft and this should allow quickly disconnecting the drum for emptying roasted beans and refilling with green beans.

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CucamongaDan
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Re: Building Gas Grill Roaster - What Motor?

Postby CucamongaDan » Sun Apr 16, 2017 7:29 pm

This is looking really nice, Doug! I'm glad you have the construction supplies and skills and know-how to fabricate that bad boy. I have enjoyed seeing your pictures of it coming together and look forward to hearing about your roasting success!

Not being at all versed on the design of drum roasters, I was wondering what roast capacity and range of usable batch sizes you were shooting for, and if you're thinking ahead much yet how your roast control and monitoring is going to work out.

Go Doug!

DougGuy
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Re: Building Gas Grill Roaster - What Motor?

Postby DougGuy » Tue Apr 18, 2017 5:51 pm

Thank you for the compliments.. Brackets to mount the motor and shaft and bearings the drum will turn on were made today, will weld it all to the grill pretty soon, and be ready to start testing batches of beans.

As far as capacity, I was only going for 3lb batches, but I think it will do 5lb without issue. I am sure there will be a "magic" weight that works the best for the size and diameter of this drum.

For controls I am hoping that putting an open neck on the drum will allow me to use a tryer of sorts to snatch out beans while it is turning, and possibly allow a thermocouple to be mounted on a rod that will stick into the beans and measure bean temps while running. Hadn't planned on using a PID or a laptop, plan on running it manually but you never know, there is a lot of technology available now for the home roaster that I might think about later on.

DougGuy
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Re: Building Gas Grill Roaster - What Motor?

Postby DougGuy » Fri Apr 21, 2017 8:54 pm

More progress made, I got a motor from a buddy that said 43rpm on it, but after testing it was way slower so I can't use it. Bit the bullet and ordered a new one from fleabay, 45rpm, with a coupler that will fit both the motor shaft and the drive shaft that I have machined to 10mm diameter. A guy on ebay had some 10mm shaft but he wanted to be greedy so I machined my own from some 1/2" cold rolled stock I had on hand. I cut a 3/8" drive extension and welded that onto the 10mm rod to make my driveshaft. Brackets were made to mount pillar block bearings on the drive side, and ball bearings on the neck side, I used a piece of 1/4" cold rolled stock as a layout tool to establish centerline and align the brackets and bearings all on the same center.

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DougGuy
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Re: Building Gas Grill Roaster - What Motor?

Postby DougGuy » Sun May 28, 2017 7:02 pm

Well I did finally get the roaster done, and it works great!



[video=youtube;3IIBpPLXstU]http://www.youtu.be/watch?v=3IIBpPLXstU[/video]

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CucamongaDan
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Re: Building Gas Grill Roaster - What Motor?

Postby CucamongaDan » Tue May 30, 2017 12:29 pm

Wow, looks great! That thing means business!

Let's see if I can get a clickable link for the YouTube video you posted . . .

https://www.youtube.com/watch?v=3IIBpPLXstU


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