ferrum Senior Member Joined: 17 Oct 2007 Posts: 17 Location: Zurich, Switzerland Expertise: I live coffee
Espresso: Dalla Corte Mini (Carbon... Grinder: Fiorenzata HZ50
Posted Sun Dec 9, 2007, 11:32am Subject: Gaggia MDF: successful doser-amputation ;)
My last post in this forums concerned with modding the GAGGIA MDF grinder to become doserless.
The grinder itself does it's job,... but I found the doser to be close to a complete joke, being unprecise, being not "centered" with it's large output orifice... also coffee leftover stuck everywhere inside making cleaning a very very frequent job...
as I've just acquierd a new coffee machine and a good ammount of beans, my coffee-budget for this year is already "gone"... so a new grinder is at the moment not an option... (will get a better one somewhen next year....).
thus I decided to bring my gaggia to my shop (machine-shop) and have some major surgery perfomed ;)
the result? some may call it a waste of good materials ;) 6Al4V Titanium sheet (it was a badly scratched (one side) leftover... so not much other use...)... V4A Stainless steel tubing... some Stianless M3 Torx Screws... some pieces of steel... a bit of modern hi-tech thermo-plastics and a bit of black spray paint... some hard rubber-sheet (I attached new "foots" to it... with a non slip, vibration damping rubber sheet... it now is quite "silent" compared to before)
basically 2 to 3 hours of work. I'm quite pleased with the results. it works really well...
Work Steps: - complete disassembly - sawing off the front piece where the doser would have been sitting - cutting the portafilter rest of - grinding parts flush - squaring up a piece of stainless tube to match the exit orifice of the grinderunit - machining of two tiny fixtures with an internal M3 thread.... - bolting the fixtures to the side of the grinders "exit"-port - milling two lashes from steel pieces and welding these to the stainless tube... the slotted lashes help with aligning the unit - cutting the overlength of the original rubber gasket to fit the new tube - polishing the tube - forming a thermoplastic to act as an outer gasket of the tube - cutting the Titanium sheet and machining an oversized hole (so it can be easily adjusted)... the grinder's exit isn't centered and points slightly to the left... not much can be done about that so one needs to compensate otherwise - suface fine-grinding of the TI-sheet - using a special strong-bonding hot glue and a hot glue gun to glue the different parts together - using polyester-kit (hardening type) tol fill some gaps - molding a plastic cover for the top-edge of the TI-sheet - sand the worked surfaces flat and smooth again - cover parts not to be spray painted with masking tape - spray the stuff - reassemble everything and test run - successfull - glue rubber-sheet to base
Another possibility is a sort of doser bypass, where you create a tube or enclosed "slide" from the burr area down to the opening in the doser's bottom. This one is pretty cool but looks like it took a good deal of work and special machinery. Nice job.
Old thread I know but I've recently acquired an MDF with a broken impeller (doser) and would like to try your mod. I have been thinking about the manifold or piece that connects from the square burr exhaust area (sorry for automotive nomenclature- old mechanic) to the round tubing output....what does this square to round manifold look like? What did you make it out of? How did you fasten it to the square opening on the grinder?
I know many questions but I want to save myself work if I can..
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