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  • Eds KKTO

    A while back a certain forum member introduced me to Coffee Snobs and the KKTO design, so I thought Id have a go at making one myself. Heres a run-down of the parts and construction:

    Motor-drive Base
    • Sheet of MDF, 1200x600x16 - $16
    • Floor tile, 300x300 - $1
    • ¼" socket drive extension, 6" - $10
    • Round-headed hex-drive bolt - $2.75 for 2
    • Pedestal fan motor and oscillator gearbox - $0 (at the side of the road)
    • Chopstick, screws, nails, glue, angle brackets, wood scraps, 8cm PC cooling fan - close to $0 (lying around)

    The drive is provided by the pedestal fans oscillator gearbox. This contains two gears driven by a worm on the motors shaft. The gear driven directly by the worm turns at about 30 RPM, with more than enough torque to spin 600g of green beans in the pot as a single mass. This is the gear that houses the disengaging mechanism that pokes through the top of the motor housing on the original pedestal fan. The round-headed hex-drive bolt is a perfect replacement for the disengaging mechanism, once it is cut to length and the plastic "bearings" are removed from the plastic housing. This is glued into place to provide a hex-drive to an appropriately shaped stub of melamine chopstick. The chopstick must also be glued, otherwise it has a tendency to pop out under load, but can be removed easily for replacement. An 8cm computer fan was butchered and stuck onto the other end of the motors shaft to provide some of the airflow that the motor would have enjoyed in its original deployment.

    The motor assembly is mounted onto a 300x300 sheet of MDF, which forms the removable base of an MDF box. A small hole is cut in one side of the box to accommodate the computer fan, and a larger hole in the opposite side permits operator access for the purposes of lifting up the drive shaft to attach the agitator, and electrocution. By which I mean to say: this is a home-made, mains-voltage appliance, lacking some of the polish and safety features of commercial offerings - the motor body is earthed and everything else on the inside is at-least single-insulated, but I dont recommend anyone stick their hand inside it while its plugged in.

    The MDF sheet with the motor attached fits inside the bottom of the base, and rests against a couple of strips of pine running along opposite sides of the box. It is screwed to these strips rather than nailed/glued in place, so that it may be removed easily for maintenance. The top of the box is slightly recessed to accommodate the floor tile, with the sides of the box protecting the fragile edges of the tile. The tile isnt strictly necessary (the bottom of the pot never gets all that hot), but provides a durable, non-staining surface for the pot to rest on.

    The drive extension bar runs through a hole in the top of the MDF box and the tile, and is driven at the bottom by the square end of the chopstick stub. The chopstick probably isnt needed for heat-resistance, but given that everything else in the power-train is glued or otherwise rigidly locked in place, Im hoping it will break before worse things happen (like the worm drive stripping the main gear).

    Roaster
    • Pasta pot - $50
    • Turbo oven - $79
    • Fibreglass blanket - $10
    • Spark-plug lead - $5
    • ¼" drive socket and mild steel, 180x25x3 - $0 (lying around)

    The fibreglass blanket is wrapped around for insulation (mostly to stop me from idiotically grabbing bits of steel at 250°C). The spark plug lead was slit lengthwise and the outer sheath removed. The outer sheath slips onto the top of the pasta pot to provide an interface to the glass of the turbo oven, and the core sits in the gap between the two parts of the pot to help seal and keep everything steady.

    The top (hex-drive) half of the socket has a slit cut in it to accommodate the mild steel agitator, and the agitator has a notch cut in the bottom to accommodate the bottom (square-drive) half of the socket, such that the mild steel sits about 1mm off the base of the pot when the socket is sitting in place. The two are assembled and welded, and the mild steel twisted along its length such that the ends of the agitator have a leading edge at the bottom, angled at almost 45° from vertical.

    6 vertical chaff slots are cut in the inner pot and levered open, narrow at the bottom where the beans are, and wider at the top where a lot of large bits of chaff spin around. The turbo-oven spins the chaff counter-clockwise, so the slots are bent open in such a way that they guide the chaff out, while keeping the clockwise-moving beans (mostly) in.

    Thats about it except for all the trials and tribulations along the way, like the version of the agitator made from 10mm rod - which made for some very uneven roasts.

    All in all, given the price, Im pretty damn happy with the results Ill post a shot of the next roast here as soon as its done.

    Attached images:[list][*]The finished base.[*]The roaster, complete.[*]The inside, showing the chaff slots and the original version of the agitator.[*]The inside, showing the chaff slots and the original version of the agitator, covered in beans, not working very well.








  • #2
    Re: Eds KKTO

    Originally posted by 72534056455374370 link=1270451012/0#0 date=1270451012
    like the version of the agitator made from 10mm rod - which made for some very uneven roasts.
    Once you understand the way the beans move and the even mix required... It is verry clear as to why that single rod will not produce great results.

    You need to ensure that all the beans get good movement. With that some will bove better than others and if a small bean; many on the bottom may never get full a full mix and exposed to all the heat available.

    Comment


    • #3
      Re: Eds KKTO

      looks like a good setup

      could we get a pic of the drive motor set up please.

      does the 3 speed fan setting effect the "oscillation" speed?

      I am off to look at at the fan , nearly winter it wont be missed

      Comment


      • #4
        Re: Eds KKTO

        Encouragement is my middle name thats why I put so much detail in my original build post/thread

        Now some advice & I apologise If I have posted this in other threads

        In my tests I have found that 65 to 75 RPM is the ideal speed standard for this roaster design

        Volume should be a maximum of 9 litres including the TO cavity to a low of 6/6.5 litres

        Good mixing goes hand in hand with the agitation speed. Most agitators will push the beans around but dont mix the beans very well

        Its important to have a mixing action that takes beans from the outside in and from the inside out & from the bottom to the top and back down again

        It goes without say that good mixing will yield better roasting results

        Its a great build job Edward with a few tweaks to be implemented for best results

        Keep us in the loop [smiley=thumbsup.gif]

        KK

        Comment


        • #5
          Re: Eds KKTO

          Originally posted by 012E2725320D212E2127252D252E34400 link=1270451012/1#1 date=1270454326
          You need to ensure that all the beans get good movement.  With that some will bove better than others and if a small bean; many on the bottom may never get full a full mix and exposed to all the heat available.
          Yep, that was the main issue with the rod - it looked like it was doing an alright job from the top, but underneath it was skimming over the tops of a lot of beans.

          Originally posted by 2D212825252C400 link=1270451012/2#2 date=1270460925
          could we get a pic of the drive motor set up please.

          does the 3 speed fan setting effect the "oscillation" speed?
          Ive got a photo through the access hole that Ill be uploading shortly. Once I get a little more free time Ill open it up and take a couple of pictures that should show how it all fits together a little more clearly.

          The unloaded fan motor spins at the same speed regardless of the setting, the lower settings just provide less torque, so in the original fan the load of the air on the fan-blades slows it down. Im not sure if 600g of beans is going to provide enough load to really slow it down much, even at the lower settings, but Ill be experimenting with it when I get some more time (around the same time I get around to taking those photos )

          Originally posted by 07232A2A29291307233F21234C0 link=1270451012/3#3 date=1270462530
          In my tests I have found that 65 to 75 RPM is the ideal speed standard for this roaster design

          Volume should be a maximum of 9 litres including the TO cavity to a low of 6/6.5 litres

          Good mixing goes hand in hand with the agitation speed. Most agitators will push the beans around but dont mix the beans very well

          Its important to have a mixing action that takes beans from the outside in and from the inside out & from the bottom to the top and back down again
          I figured I might get away with the lower speed since I have a double-ended agitator...then you had to go and make a double-ended agitator at your higher speed, so Im back to half the effectiveness again ;D. Nonetheless, Im happy with the current results...at-least until the right motor falls into my hands

          I think my volume may be a little high - Ill measure it soon. Im also looking at the option of replacing the glass lid with a flat disc of stainless that fits inside the top lip of the pasta-pot.

          As for mixing action, Im sure mine could be improved, but the roasts Im getting now are pretty good, so I might take a break from agitator design for a while.

          Now I need to get the pics off the camera - hopefully this shouldnt take too long...

          Comment


          • #6
            Re: Eds KKTO

            Some images from tonights roasts:
            • The mark-2 agitator
            • Some mark-2 agitation - the whole bean mass turns, but the blades spin faster, picking beans up from the bottom
            • The drive mechanism - you can see the back end of the motor where the oscillator gearbox is, and the chopstick and ¼" drive
            • Some PNG Wahgi AA - around CS8/9
            • Some PNG Wahgi AA chaff and escaped beans - the PNG doesnt seem to produce a lot of chaff (there are mountains of it from the Brazillian)










            Comment


            • #7
              Re: Eds KKTO

              Two more pics:
              • The hot bean extractor - a $46 addition to the setup - it doesnt do much cooling, but makes the beans easier to handle and shakes off any remaining chaff
              • Some Brazil Pulped Natural - also around CS8/9




              Comment


              • #8
                Re: Eds KKTO

                Ive played with the different speed settings on the fan motor, and it seems to make very little difference which is selected, so Ive wired it to use the lowest setting, hopefully generating less heat.

                Okay, as promised, here are the drive mechanism pics:
                • Most of the inside of the base. Normally those bare wires would be terminated and a cover screwed over that area, but I was in the middle of testing the different speed settings.
                • A close-up of the entire motor drive. The motor is held in place by those two angle-brackets, and a sturdy shaft at the bottom which is firmly embedded in the MDF base.
                • Looking inside the gearbox. The gear you can see under the worm-drive drove the oscillator in the original fan, but is now disabled.
                • Top - a bolt like the one used in the main gear. Middle - the main gear with the head of the bolt glued into it, and a piece of chopstick glued into that. Bottom - the original disengaging gear that used to sit where the bolt is glued.








                Comment


                • #9
                  Re: Eds KKTO

                  Tell me thats NOT 240V !!!

                  Please tell me that the grommet just fell out..

                  Please tell me the ends hanging loose are there for the sake of demonstrating what not to do.. I mean if the bare wires touched a live terminal... Where does teh other end go..


                  Please tell me that the whole system and the pots etc etc all have earth tags and separate earths


                  NO... Second on thoughts...


                  I DO NOT WANT TO KNOW.



                  The KKTO has one thing over most other do it ya self systems..

                  SAFETY.  

                  No mods to 240V equipment and every thing else is ELV.

                  Comment


                  • #10
                    Re: Eds KKTO

                    Great pics, and the cooling fan is a great idea.
                    Mounting brackets look simple and effective.
                    i reckon a new fleet of "raosters" will be being built or considered using the fan motor

                    keep us updated on how it performs.



                    Comment


                    • #11
                      Re: Eds KKTO

                      Originally posted by 527D7476615E727D7274767E767D67130 link=1270451012/8#8 date=1270547682
                      Please tell me the ends hanging loose are there for the sake of demonstrating what not to do..  I mean if the bare wires touched a live terminal... Where does the other end go..
                      I know youve said you dont want to know, but here goes:

                      The ends hanging loose are there to demonstrate exactly what exists under the covers. They attach to the medium and high speed windings of the motor and if one of them touched a live terminal I suspect very little would happen, though it is possible the motor might burn out. This is not an issue since, as mentioned in my previous post, the bare wires shown in the picture are normally terminated, and a cover is placed over the entire junction. The whole lot is screwed inside a stout MDF box. Once assembled the only metal inside the box that the ¼" drive might be able to touch is the body of the motor, but only if you were trying hard to make it happen. Also, the body of the motor is earthed as it was in the original fan design. Toasters scare me more than this thing.

                      That being said, the following disclaimer applies: The people involved in the design and construction of this motor drive have extensive experience with mains wiring, mains-voltage motor setup and mains-voltage appliance repair. I do not allow anyone but myself to operate my roaster, and (though it is far from a guarantee of safety) only operate it on circuits protected by an RCD. The design is presented solely for entertainment purposes, and I do not recommend anyone implement it.

                      Comment


                      • #12
                        Re: Eds KKTO

                        Originally posted by 373B323F3F365A0 link=1270451012/9#9 date=1270547888
                        Great pics, and the cooling fan is a great idea.
                        Mounting brackets look simple and effective.
                        i reckon a new fleet of "raosters" will be being built or considered using the fan motor
                        See disclaimer above

                        Comment


                        • #13
                          Re: Eds KKTO

                          Looks good Ed. Nice & compact. Leaves me wondering where I can scavenge a metal 90 degree gear to make my unit more compact, although I do find its a good height to stand over. Of course, you do have a height advantage over me, so its probably fine on your bench.

                          BTW, on the sealing of the pot lid, I popped down to clark rubber & picked up a meter of oven door seal (heat resistant silicone). It was about $15, but obviously designed for this sort of job. Its "glued" to the rim of the pot with a thin bead of high temp copper RTV silicone. Seems to have done the trick. Worth keeping in mind if your spark plug lead insulation starts giving off odours.

                          Comment


                          • #14
                            Re: Eds KKTO

                            Originally posted by 415642434D250 link=1270451012/12#12 date=1270605774
                            BTW, on the sealing of the pot lid, I popped down to clark rubber & picked up a meter of ovendoor seal (heat resistant silicone).It was about $15, but obviously designed for this sort of job.Its "glued" to the rim of the pot with a thin bead of high temp copper RTV silicone.Seems to have done the trick.
                            Or use the blue high temp silicon tubing. See this post:
                            http://coffeesnobs.com.au/YaBB.pl?num=1261484678/132#132
                            and posts on the next page(s) following the post will show the blue tubing as fitted. Doesnt require gluing.

                            Comment


                            • #15
                              Re: Eds KKTO

                              I just lacked the patience to mail order & wait, and I had the sealant anyway Just let me get roasting sooner.

                              Comment

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