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Compak K6 Grinder Conversion to Doserless By Flavio Spedalieri

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  • Nightlase
    commented on 's reply
    Hi Ted, thank you.

    I will PM you some further details.

  • Nightlase
    commented on 's reply
    Thank you Mal much appreciated

  • Ted2013
    replied
    Very impressive and, and for me, inspirational.

    I have just about finished a doserless mod on a Rossi RR45. Just need to make a brass anti-static flap and a base for a portafilter rest.


    Anyway I also own a Compak K8 which looks much like your K6 and was wondering how to tackle it.

    I want to do another 'octopus' batter funnel mod (looks like a Mazzer Mini doser cone) rather than use a spout .


    Could you post some detail pics of the Wood Infill and Neodymium magnet construction and the aluminum front face?

    My K8 came without a bean bin so I found a top of an old cocktail shaker that fitted perfectly and turned a lid out of a piece of she oak

    Leave a comment:


  • Dimal
    replied
    Nice work....

    Mal.

    Leave a comment:


  • Compak K6 Grinder Conversion to Doserless By Flavio Spedalieri

    Introduction
    Click image for larger versionName:	20191311_K6_1.JPGViews:	0Size:	91.8 KBID:	832670






    Firstly, a huge thank you goes out to Dean and Rose Kiner, Owners of Siboni’s Coffee in Pymble NSW for their kind and generous donation of the Compak K6 Grinder, for Dean’s invaluable input throughout the build and inspiration to have made this project possible.
    The following words details my recent project journey of converting a Compak K6 Dose Grinder to doserless / grind on demand with a custom designed, programmed and built timer module.

    The Compak K6 Grinder was donated in 2019 with the prospect of a project to restore the former Siboni’s Coffee shop grinder to a functional doserless grinder.
    This grinder will find its new home in Newcastle where its being donated to my sister and Brother-in-law together with my old ECM Giotto to replace their Nescafe capsule machine.

    Project Details And Timeline

    Work commenced on the project on 2 January 2020 beginning with the complete dismantling of the grinder and cleaning of all components.
    The conversion to doserless would require the removal of the old dose chamber and considerable thoughts and re-engineering the grinder outlet port and mounting a spout or cone.

    In keeping with simplicity, a Rancilio Rocky Grinder Doserless spout (which Dean also provided) was the first choice, however other thoughts considered included retrofitting a dose cone from a Mazzer Mini, however, these are rather expensive (over AU$250) and later in the project timeline would prove to have been too tall, pushing the placement of the portafilter holder much lower where the screen is positioned.

    The next task, reducing the size of the hopper. This accomplished by marking and hand-cutting the hopper and finished off through hand sanding. A felt strip was used on the inside edge of the hopper lid to make for a very nice and snug fit.

    As covered, one of a number of engineering challenges was how to engineer and modify the existing casing (which had a curved section where the outlet port is) to mount the Spout (which is a flat mating flange) and mate the spout with the grinder port – this would require modification to both the case and the original plastic coffee outlet adapter.

    With the onset of COVID-19 lockdowns, the next three months would put the main grinder project on engineering bench (to decide on how many holes would need to be cut and further, what display to use). The lockdowns would prove useful as allowed for a second project which focused on the development and programming of the timer module that would eventually be installed in the grinder.

    Timer Module


    The design brief for the timer; Functional, simplicity and ease of use with a nice clear display.

    The timer features two programable Presets (selected with the white button), adjustable “on-the-fly” timer offset (allows timer adjustment independent of the stored preset and can also be stored by pressing the knob) and Manual Grind (Red Button). The grinder is operated using the silver button (with green ring light).
    Additional features include screen saver mode (screen is turned off after 5 min), and visual LED fades.

    The timer module is designed and programmed around the Arduino platform (ATmega328) and finally ported to the “ProMini” board.
    The additional challenge during development, with considerations to the limited physical space to be able to mount the electronics, was what display to use, its physical location and the size of the display.

    In the early stages of the project, a standard 16x2 character LCD was the original display, however as the project evolved, with consideration that space was limited, the goal was set to develop the programming for a tiny 128x64 pixel graphical OLED (24mm diagonal) screen, with white pixels. The bonus of being a graphical display, allowed for some nice graphic additions as well as a much nicer looking Display.

    Another advantage of OLED Displays, is their excellent contrast and clear text.

    To pay homage to Siboni’s Coffee and one of my favourite blends, “Romeo” I programmed the “Romeo” graphic that appears on power-up (can also be user enabled / disabled).
    With the timer program and hardware decided, work on the grinder case recommenced in late May 2020 with cutting and drilling holes for the switches, screen and the mounting point for the portafilter fork. For this project, a Mazzer Mini Portafilter holder has been used.

    Click image for larger version  Name:	20200624_K6_Display.JPG Views:	0 Size:	216.2 ** ID:	832673







    The timer module firmware development was completed on 3 June 2020 together with the completion of the hardware module that would be installed into the grinder.

    With the month of May at an end, a great deal of work through June, would see the project come to completion.

    Timer Integration

    The timer module operates the grinder via a Solid-State Relay (SSR), a 480V DC-AC 25A zero-crossing high-end module is used. The original 16A mechanical relay was replaced with the SSR controlling the motor directly. The SSR was also mounted onto the main power module.

    A small 5V power supply module is used and also mounted to the main power module for providing 5V supply rail for the timer module.

    Final integration of the components, switches and control encoder neatly fitted into the existing case.

    Click image for larger version  Name:	20200622_K6_Electrical.JPG Views:	0 Size:	113.6 ** ID:	832672







    Aesthetic and Cosmetic Details

    Among several engineering challenges (or rather more on final aesthetics), was ongoing brainstorming on how to fill in the original gap at the top of the grinder and how to tidy up the front face.

    For the top of the Grinder, the choice of wood in-fill was first on the list. Wood would add a “warm tone” feature to the project.

    The front face was first mocked up in card, then 3mm ply and eventually translated to 1.2mm aluminum. The aluminum stock was fully hand-cut (using a hand nibbling tool) and finished by hand final fitment test was completed prior to paining.

    Above the portafilter holder, a space was built into the front face to allow for positioning of the filter under the spout, as a bonus can also aid in holding the filter.

    With the grinder housing completed, all holes cut, drilled & tapped, fitment test and completion of the timber in-fill, it was time to sandblast the case and prepare for final painting.

    The Case was given 5 coats of black satin paint with a final sandy texture finish and sealed with clear topcoat.

    Final assembly of the grinder completed on 22 June 2020 prior to full test, adjustment and calibration.

    Initial Tests

    As part of the original reengineering, a Mazzer Anti-static screen was Initially installed on the spout, however during the initial test, it was found the flow of grinds was poor, and eventually the outlet chocked up.

    Following further discussion and brainstorming with Dean, some modifications was made to the screen by removing a segment and opening the screen a little further, this proved very successful with nice consistency in the dose.



    Naturally, there is come coffee retention within the outlet, however this is expected considering the original design of the grinder outlet was to a dose chamber.

    Following successful testing, the screen was position on the outlet port and foam tape used to form the final gasket.

    Wood Infill

    Throughout the project, a constant design thought was placed on how to fill-in and blend and the existing inset at the top of the grinder (which was where the lid of the dose chamber was mounted) in an aesthetically pleasing way.

    Eventually, Tasmanian Oak was used as the material of choice. Three sections of wood were cut and glued prior to sanding and contouring the piece.

    Two Neodymium magnets are used to secure the piece to the body and allow for its removal if require disassembling the front to remove the spout for servicing purposes.

    The wood feature was given several coats of walnut stain before two coats of Scandinavian Oil, and final coats of beeswax.

    Grind Size and Direction Indication

    Following the completion of the project, a final added detail to the wood infill was grind finesse and direction Indicator.

    A simple series of brass rod sections with different diameters where inserted into the top edge of the wood to provide a visual aid.

    Click image for larger version  Name:	20200625_K6_InFill.JPG Views:	0 Size:	126.7 ** ID:	832671







    The final testing and official completion of the project on 25 June 2020.


    Click image for larger version  Name:	20200624_K6_Complete.JPG Views:	0 Size:	92.9 ** ID:	832674

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