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  • Roaster Motor?

    As the Popcorn Makers at Big W are all $30 bucks and dont look that good, Im thinking of making a Roaster..
    I May have sourced a slow speed Motor
    http://www.adelaideelectricmotors.com.au/trgd.htm
    The Rep is getting back to me tomorrow hopefully, and best of all Its "made in OZ"
    Think the unit may cost under $100 so I have to visit the Metal Recyclers and Find some SS Mesh, Mate has a Tig..
    Now any input here is appreciated..
    Id be looking to roast 200grams at a time ..
    Tepin

  • #2
    Re: Roaster Motor?

    The motor I used for my roaster is very similar if not the same as the ones in your link. I cant remember the stack size but mine was the best part of $200. It is a heavy little bugger. See blurry photo below.
    What RPM are you going with?
    It seems a bit like mine is overkill. Although Im a better to have and not need sort of guy.

    Tip # 1 for making a roaster at home; check your local home brew supply shop. When I was at mine the owner mentioned he worked with stainless all the time, especially keg/ drum shapes. Just a thought.

    Comment


    • #3
      Re: Roaster Motor?

      That certainly looks like one of the little suckers, I can probably scam it through my Brothers Work (Component Brokerage) at Resellers Price or as a Product sample..
      I have Access to a Retired Marine Engineer with an old Pommie Lathe, and he works for Chateu de Cardboard, My Mechanic has the Tig and I am fairly SS rich, A mate is an serious senior Aircon Engineer (Ex York), and his sheet metal guy has Folders etc ..
      We made our own Electric Smokers/ Another guy we know makes Electric Elements,,.
      So have you drawn plans of yours?

      Tepin
      Im having serious Router Problems so may not be online much this week, Cya

      Comment


      • #4
        Re: Roaster Motor?

        Sounds like youve got the materials and manufacturing covered

        No final schematic type plan of my roaster. I made some initial drawings for the enclosure and the drum, but the motor, shaft, bearings et al all kind of made up as I went along.

        You mentioned elements, are you going electric?

        Comment


        • #5
          Re: Roaster Motor?

          Electric is an Option as one of the Guys in the Pistol Club makes them for the Plastics Industry, Im kinda more inclined to Gas as I have a Heap of old bottles half full from the local recycling station/
          Gas is not very expensive if one uses stove burners, the BBQ ones are not very efficient ..
          Id be interested in your drwaings , if thats not a Problem as It will give me Direction..
          Cheers
          Tepin

          Comment


          • #6
            Re: Roaster Motor?

            Ill have a dig around and see if I can find the drawings, I should have a copy.

            Are you building a sample style roaster that tips forward to remove the beans? Or are you going to take on the classic drum type?



            Comment


            • #7
              Re: Roaster Motor?

              Probably the Classic Drum type..
              Tks

              Comment


              • #8
                Re: Roaster Motor?

                Ive not looked at one but would a BBQ spit motor run at a suitable speed? Ive no idea of the cost of one.

                Ron

                Comment


                • #9
                  Re: Roaster Motor?

                  From what Ive read BBQ spit motors run at about 6 rpm. Ive also read that while this will work, it is not ideal.  The slower the drum is rotating, the longer the beans will be touching the drum surface. I suppose that could lead to scorching?

                  Tuning a roasting drums speed is something people do, but Im not quite sure what the difference between 35rpm and 45rpm would be. I chose 55 rpm for my drum. It seems that higher speeds (45-60) mean the beans spend more time in the air, which in turn means a change in heat transfer mechanisms that come into play. If the drum speed was really high then the beans would just cling to the surface. Remember that ride (centrifuge?) at the show where you stand up and it spins fast enough to induce vomitting

                  There might be an argument that if you want faster, therefore hotter roasts, then perhaps you should increase the drum speed. Im guessing the opposite is true.

                  Comment


                  • #10
                    Re: Roaster Motor?

                    You could go a Windscreen wiper motor from a car. Im using one to power a stirring arm.

                    I got mine for free, and Ive heard others buying them for $10. So its a very cheap option, and they take a lot of heat punishment (I can attest to this).

                    They have very high torque also, so ample to drive the drum, and they have 2 settings - high and low as per windscreen wiper. I use the low setting which works very well for a stirring arm, therefore I believe it would work equally well for a drum motor.

                    Cheers,
                    Andy

                    Comment


                    • #11
                      Re: Roaster Motor?

                      From what I have seen on sample roasters the solid drum units rotate at about 50rpm and the perforated drum units significantly slower. This is probably because the solid drum units have air flow control while the cheaper perforated drum units do not.

                      If your roaster has air flow control (drawing air from the combustion/heating chamber into and through the drum) youll want a faster rpm for the drum. If it doesnt have any air flow control then youll most likely want a slower turning drum.

                      Java "Marching to the beat of a coffee drum" phile
                      Toys! I must have new toys!!!

                      Comment


                      • #12
                        Re: Roaster Motor?

                        Originally posted by AndyCJ link=1149589545/0#9 date=1149653706
                        You could go a Windscreen wiper motor from a car. Im using one to power a stirring arm.

                        I got mine for free, and Ive heard others buying them for $10. So its a very cheap option, and they take a lot of heat punishment (I can attest to this).

                        They have very high torque also, so ample to drive the drum, and they have 2 settings - high and low as per windscreen wiper. I use the low setting which works very well for a stirring arm, therefore I believe it would work equally well for a drum motor.

                        Cheers,
                        Andy
                        Also much easier to update to variable speed should you wish to "tune" your drum in to your particular setup ,

                        Mal.

                        Comment


                        • #13
                          Re: Roaster Motor?

                          Framey

                          Where did you but that motor in the picture

                          Ian *****************

                          I am making a roaster need about 50 rpm or perhaps 60 rpm.

                          thanks

                          ian

                          Gday Ian,
                          Welcome to CoffeeSnobs mate [smiley=thumbsup.gif]. Have removed your personal details above as this could potentially lead to serious security implications for you and/or your family. Best to keep personal information away from a public forum and when you need to exchange this sort of info with someone, its much better to use the Personal Message system.... Keeps such things away from prying eyes.

                          Cheers,
                          Mal.

                          Comment


                          • #14
                            Re: Roaster Motor?

                            Hi Framey

                            Im guessing but I suggest the ideal RPM is related to critical speed. The critical speed is the speed at which the beans will just stick to the top of the drum as it goes around.

                            In order to get the beans "air time", that is time in the air, as apposed to against the drum you should look at 70 to 80% of critical speed.

                            Critical speed is given by square root of ( g / 4 * pi^2 * r)
                            where critical speed is in revs per second
                            g is acceleration due to gravity = 9.81 m/sec^2
                            r is the radius of the drum in meters

                            In RPM this is approximately equal to =30/r^0.5

                            So if your drum was 300mm in diameter the critical speed is 30/0.15^0.5 = 77 RPMs

                            75% = 58 RPMS

                            Looks like your in the ball park with your choice

                            Good luck

                            Comment


                            • #15
                              Re: Roaster Motor?

                              Originally posted by wrstikoff link=1149589545/0#13 date=1180010407
                              Hi Framey

                              Im guessing but I suggest the ideal RPM is related to critical speed. The critical speed is the speed at which the beans will just stick to the top of the drum as it goes around.

                              In order to get the beans "air time", that is time in the air, as apposed to against the drum you should look at 70 to 80% of critical speed.

                              Critical speed is given by square root of ( g / 4 * pi^2 * r)
                              where critical speed is in revs per second
                              g is acceleration due to gravity = 9.81 m/sec^2
                              r is the radius of the drum in meters

                              In RPM this is approximately equal to =30/r^0.5

                              So if your drum was 300mm in diameter the critical speed is 30/0.15^0.5 = 77 RPMs

                              75% = 58 RPMS

                              Looks like your in the ball park with your choice

                              Good luck
                              I knew I should have paid more attention in Science...or was it Math? So pardon my ignorance here...

                              Shouldnt the weight of the beans play some part in this equation?

                              Comment

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