Announcement

Collapse
No announcement yet.

Another KKTO on the cheap

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Another KKTO on the cheap

    I thought there may be some interest in another variant on KoffeeKosmos design, using some recycled equipment to keep costs down. Of course being retired, so that  the time involved in developing the unit is not "costing" helps. I suspect there is something over a full weeks work involved, but should anyone be sufficiently masochistic to take it on, this may save you some time.

    I should make the point that I had almost a a metre of 1/4" stainless steel rod, and a sheet of SS about 1.2mm thick and a small block of aluminium about 6mm thick in my "stock."  I also had access to a moderately good bench drill press, and a MIG welder - on which i am almost as much a novice as I am a coffee roaster.


    Major recycled components were a 12v drill  whose batteries had died and a computer power supply capable of delivering about 10 amps at 12v.

    Heres the completed unit: Fig 1

    The base is simply MDF supported on wooden legs to clear the motor, right angle drive box and power supply. Fig 2

    The right angle drive consists of bevel gears for a model  car, with a 2.3:1 reduction. Bearings are the thick aluminium sheet, doubled, and with about 8 roasts done thus far, seem to be holding up. The box itself is sheet galvanised iron, folded and welded, with the lid held by screws into T-nuts in the MDF.

    After an initial foray into a bottom turning stirrer, I was attracted to the design shown in http://coffeesnobs.com.au/YaBB.pl?num=1228631426/176  with the arms on the top. Therefore I extended the vertical drive shaft and added  the stirrer made of sheet SS put together with SS rivets. You can see the thermocouple end sticking up through the bottom of the pasta pot.  Drive is simply a slot cut in the end of the shaft, and bracing on the stirrer to reduce "spreading" of the slot.  Fig s 3 and 4

    Variable speed control is achieved by turning the screw: Fig 5

    The basics of converting a standard computer ATX power supply are at http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply.  One thing  I discovered to be necessary with my unit was to put a 3A diode in the positive line supplying the motor, otherwise the PSU would shut down.


    Otherwise, a Tiffany oven, a pasta set I was given (on request) for my birthday and a disused fire blanket for use during roasting sessions.

    You can see the edge of my cooler - aluminium flyscreen on a wooden frame with a 30cm fan blowing over it.

    I havent done an exact costing, but probably about $200 before buying the datalogger would cover most of it. Of course if you had to buy the SS rod and sheet specifically, that would increase costs.

    I hope it is of interest and perhaps helpful to someone.

    Thanks to KoffeKosmo for the initial idea and encouragement along the way

    Russell










  • #2
    Re: Another KKTO on the cheap

    Excellent work Russell

    I particularly like the agitator blade as I was working on a similar design (based on the commercial roasters cooler agitator)

    Got a video of the agitator working so I can have a look :

    KK

    Comment


    • #3
      Re: Another KKTO on the cheap

      Thanks KK

      Ill see what I can do in the next day or two.

      One thing of interest is that the drill is set at the lowest torque setting, to protect the gears and I have heard no slippage.

      Russell

      Comment


      • #4
        Re: Another KKTO on the cheap

        Wow russell!

        That Agitator is amazing!, to be honest im quite scared just looking at it! ;D, you wouldnt wanna stick your hand in there with it spinning

        Jokes aside, i love the idea of the Agitator, ive been playing with a few designs of late with limited success and this would do the trick i reacon, looking forward to the video!

        Great job mate!

        warren/\/



        Comment


        • #5
          Re: Another KKTO on the cheap

          My Congrats also Russell, I also am impressed with the agitator as it has been and currently remains my main problem . Well done again and enjoy the coffee that comes from it

          Steve

          Comment


          • #6
            Re: Another KKTO on the cheap

            OK, heres a couple of pictures of the agitator, so you can see how its fabricated, also one of my latest roast (Honduras Los Bancos 500->430grams) and a brief video showing the thermocouple highlighted with a black ring, then the roast circulating. I turned the speed up to about 100 rpm as I thought I was getting more variation in roast than I should, but the roast still looks rather variable. Id be grateful for more experienced comments on the appearance of the roast. Its been resting for a few days, will go in the cup tomorrow.

            Russell

            Some problem with the video, but heres the stills:





            Comment


            • #7
              Re: Another KKTO on the cheap

              Try the video, its .swf !MB so should fit:

              No failed again. I think the 5000KB limit may be wrong - perhaps 500KB. 5000KB would be 5MB by my reckoning:
              From Attachment info: Maximum Attachment size: 5000 KB

              Ill find somewhere else to put the video and post a link.

              Russell

              Comment


              • #8
                Re: Another KKTO on the cheap

                you tube!

                Does your agitator hit the bottom of the collander? or is it siting higher, i really like what youve done, it may be a little dificult for me to impliment on mine as i have a much thicker agitator rod coming through the bottom.......im keen to try something though

                Comment


                • #9
                  Re: Another KKTO on the cheap

                  Here it is - my first Youtube effort:

                  [media]http://www.youtube.com/watch?v=1wCwxmcAtCo[/media]

                  Comment


                  • #10
                    Re: Another KKTO on the cheap

                    Originally posted by 50575151474E4E40220 link=1265700152/5#5 date=1265776373
                    I thought I was getting more variation in roast than I should, but the roast still looks rather variable. Id be grateful for more experienced comments on the appearance of the roast.
                    Russell
                    You need to test your agitation as a cold test

                    Put in your normal batch of green beans
                    Add to the green beans a few colour marked indicator beans and observe on how well the are mixing

                    Insulation is also important

                    KK

                    Comment


                    • #11
                      Re: Another KKTO on the cheap

                      Thanks KK

                      Do you imply that you think the variation is a bit much? Looking at the CS reference card, the pictures there show moderate variation, and I suspect that varies from bean to bean.

                      I was aware of the need for testing bean movement, and putting in coloured beans they seem to travel throughout the bean mass reasonably readily. I had only 5 colours of food colouring, so a somewhat limited test. For insulation, I have been wrapping the whole unit in a fire blanket, doubled.

                      One interesting feature has been that the temperature of the beans seem to be lower than most sites suggest for the various stages of roasting - up to 400 lower. I thought it must be because of the insulating effect of the beans, and other systems exposing the sensor to hot air. Readings on the thermocouple seem OK at room temperature, and "cracking" is mostly readily audible at about the times I would expect. Second crack can be a bit difficult to hear. I think most of the noise comes from the drill motor/gearbox.

                      Regards

                      Russell

                      Comment


                      • #12
                        Re: Another KKTO on the cheap

                        Originally posted by 7671777761686866040 link=1265700152/10#10 date=1265782795
                        I was aware of the need for testing bean movement, and putting in coloured beans they seem to travel throughout the bean mass reasonably readily. I had only 5 colours of food colouring, so a somewhat limited test.  
                        Make sure that the beans a mixing as opposed to being pushed

                        The ideal is that the agitator moves the beans - towards the centre, away from the centre and lifts from bottom to top.

                        Originally posted by 7671777761686866040 link=1265700152/10#10 date=1265782795
                        For insulation, I have been wrapping the whole unit in a fire blanket, doubled.
                        Good

                        Also look at any heat loss between the pots and the TO
                        Silicone tubing will seal the joins and prevent heat escaping (if any on your system)

                        Originally posted by 7671777761686866040 link=1265700152/10#10 date=1265782795
                        One interesting feature has been that the temperature of the beans seem to be lower than most sites suggest for the various stages of roasting - up to 40  lower.
                        Got me on that one
                        If the probe is placed in the bean mass it should read true

                        Experiment on probe placement
                        Also test DMM accuracy

                        KK

                        Comment


                        • #13
                          Re: Another KKTO on the cheap

                          Some beans will turn out a little uneven, others more experienced roasters will be able to tell you why that is, ethiopians can be bad for it,but it hasnt made them any less amazing!, having said that! i have found beans i have roasted from honduras have turned out very evenly roasted.

                          As for your temps, what temps are you hitting first crack and second crack at? have you placed the probe in icy water to test 0C and just off boiling water for 100C? its a good guage as to the DMMs accuracy, for the record i hit first crack around 195C and second crack at around 215C

                          cheers
                          warren

                          Comment


                          • #14
                            Re: Another KKTO on the cheap

                            Thanks

                            I do have silicon tubing at the top. Perhaps I was too generous in specifying it, as I see it is breaking up somewhat, though I doubt it is leaking a lot of air. "Air-off" temperature from the element must be significantly above the 2500C set on the dial which was what I considered in ordering the tubing.

                            I have already checked on ice water/steam and the thermocouple is within a degree or two of 0/1000C

                            Actually, warren, your temperatures are about what I am seeing.

                            I was guided by http://www.sweetmarias.com/roasting-VisualGuideV2.php -this seems to suggest rather higher temperatures when converted to 0C


                            None of my roasts have been undrinkable, but definitely improving with practice.

                            Sorry Warren, just saw your question on the agitator hitting the bottom of the pot. The answer is "occasionally." On the whole not a problem, and the SS sheet is sufficiently malleable to be able to bend it up with pliers if necessary. In the fourth picture of my original post you can see a little marking of the pot where it has scraped. The drive slot I have made was just a hacksaw cut, opened out a little with a disc on a Dremel. The side pieces bear on the shaft and help keep the top level.

                            Regards

                            Russell


                            Comment


                            • #15
                              Re: Another KKTO on the cheap

                              Can you please check your roaster volume including the outer pot

                              Add 1 lt for the TO to equal =

                              http://www.aqua-calc.com/calc_vol_cone_trunc.php

                              KK

                              Comment

                              Working...
                              X