Thanks for all the warning about using Galvanized metal. I just tested with it using cold air. I bought this funnel to test with because of it shape and its low cost. Here is a link so you will know what I mean. http://doityourself.com/store/6241533.htmIt is not a typical cone funnel. The sides are vertical about 5 inches in height and the funnel portion is not very steep. It allows for 2 lbs of beans to spread out so that in the center the beans are only 1 1/2 to 2 inches deep. With a small 2 gallon 3.5 amp Sears Wet/Dry vac that I used with a standard 600 watt dimmer. I was able to get a continuous foutain of beans flowing up the center and back down to the sides. I had to use the dimmer because full power would shoot them over the top. I found that I got better flow without the removable brass strainer screen,but with the screen removed I had to get the air flowing a little bit before adding the 2 lbs of beans. The beans would settle in the 3 inch spout and stall the air flow. But a simple solution was about 1/2 power, add the beans and then increase to get the foutain flowing. I did experiment with the center column design for about and hour and found that I got better movement with it with the stainer screen in at the bottom. The flow is much better without the screen or column. I will leave out a screen and column from the next step. The next step is to make wide based funnel out Stainless steel. My plan is drill a 3 inch hole in the bottom of an 8 quart mixing bowl and add a sink drain. Total Cost about $30 because of $15-20 metal hole drill bit. Can any one else think of a cheaper,better way or where I can by one that is complete. I spent way too much time playing in the garage on Sunday afternoon and I ran out of Roasted beans last night. The grill has finished preheating so it is time to start roasting. Mike Walls, Columbia, SC. Do you Yahoo!? Free Pop-Up Blocker - Get it nowhttp://companion.yahoo.com/
Hi Michael, Sounds like you are well on your way to making something that works. As far as the hole goes, I have made holes like this by first drilling a pilot hole and then using my saber say with a metal cutting blade. Run the saw at the slowest speed and use lubricant. Should work fine. I have been thinking of doing this same kind of an experiment, and here are some of my thoughts. You blow hot air into the tube, and up the funnel, the beans get heated by the incoming air, but then they fall out of the stream into a cooler area. How do you insure that the whole mass stays at the temperature you want? Do you have to insulate around the outside of the funnel? Respectfully, PeterZ Michael Walls wrote: <Snip>
I'm going to build a small air roaster using a stainless canning jar funnel, a piece of stainless screen and a heat gun. The canning jar funnel has a hole in it that is about 2 " in diameter and is a match made in heaven for a heat gun to make an air roaster.http://www.happycookers.com/wc.dll/products/divulge/1-4837.htmlBed, Bath and Beyond also has them. Sivetz has a setup similar to what I'm talking about as shown here,http://www.sivetzcoffee.com/online%20catalog.htm#30gmbut I think this would be even simpler and the shape of the canning funnel might be even better. Definitely easier to buy one than make it as he did, and the stainless canning funnel is attractive in design too. A chamber mounted on the canning funnel would allow for a larger batch size and keep the beans from going all over the place, as I'm guessing they might with Sivetz design. The idea of using a heat gun to roast coffee is definitely not my idea, but using the canning jar funnel puts a new slant on it and might allow an easy build for homeroasters who want to build their own. *********************************************** Ed Needham To Absurdity and Beyond! homeroaster ... d.o.t ... com ***********************************************
Ed, thanks for the link to the ss canning jar funnel. I've been scouring the restaurant supply stores etc., here in San Diego for parts for experimental hot-air roasters for a couple of months now. I've currently got a 10 ounce air-roaster working "proof-of-concept" with a 35,000 btu BBQ Its a kluge but I will share the heat exchanger picturehttp://members.cox.net/kentaj/heatexchanger.jpg.Have you had any experience using hair driers as the hot air source? I'm concerned about the air flow needed. Harbor-freight has 3 types of heat guns for sale but they look like they might not have enough air flow to float even 1oz of beans. I saw a 1600 watt hair-drier in a thrift store the other day and wondered if it would have enough air flow to fluidize 3 oz of beans for a sample roaster. Of course not being designed for the high temp some mods might have to be made...but for $5? Jonny (posting after reading Ed's message in homeroast digest. #1617. Not exactly real time) Original message: on Tue, 2 Dec 2003 22:58:20 -0500 Ed Needham wrote: | I'm going to build a small air roaster using a stainless canning jar funnel, | a piece of stainless screen and a heat gun. The canning jar funnel has a | hole in it that is about 2 " in diameter and is a match made in heaven for a | heat gun to make an air roaster.
Wow GBL, I am impressed! I picked up a Hair Salon Chair in a thrift shop very cheaply a few weeks ago, and found that it will 'float' a half pound of beans very nicely. The problem was keeping them from blowing all over the garage! The heat was another problem, and I was stymied with trying to heat such a large airflow to the right temperature, using electricity. May need to jump to 220 volts. In consideration of my electric bill, I have started thinking about supplying a gas heater for the unit. What you have will work just fine I bet. Now if I can just find a heat exchanger in a thrift shop... Thanks, for the JPG PeterZ GBL wrote: <Snip>