Modifying a Grinder for Single Dosing

galumay

I guess most of us who travel down the path of trying to make the best possible coffee we can, come across the issue that good quality grinders on the whole are designed for operation in a commercial cafe or restaurant application.

This inevitably leads to finding a solution to avoiding the stale coffee that gets left over in the grind path and there are a few solutions to the problem. Firstly you can just grind a few grams extra at the start and push out the stale coffee, dispose of it, and then grind your dose. Secondly you can minimise the waste and stale coffee with a doserless design or finally you can modify your grinder to maximise the operation as a doser style grinder.

The drawback with the first solution is waste of coffee, the second is you lose the benefits of distribution with a doser and they tend to be messier, and the final solution is time consuming in bumping the grinder and brushing out the leftover grinds in the grind path.

None the less, having tried all variations and solutions my preferred option is to modify the doser type grinder, not only do we need to modify to improve the grind path and open it up for brushing out, but generally the doser has to be modified to improve sweeping.

For those interested in tackling the mods i am going to walk you through the steps with a few images to help, the grinder I am modding is a Wega 8.6A which is a Compak K10 clone, its a commercial, conical burr grinder but the principles apply to most grinders.

DISCLAIMER - THIS INVOLVES ALTERING ELECTRICAL WIRING AND SHOULD NOT BE DONE UNLESS YOU ARE FAMILIAR WITH BASIC ELECTRICAL WIRING - GRINDERS ARE 240V AND ELECTRICITY CAN KILL YOU! ENSURE GRINDER IS DICONNECTED FROM POWER POINT

The wega on the bench.

Here you can see the first thing we need to remove - the mechanism for auto switching the grinder, we dont need it single dosing, and it completely blocks the grind path so we cant sweep it out. In this case we just remove the screws holding it in place,

Lift the top of exposing the micro switch, disconnect the wires, cut off the spade terminals and solder the wires together, wrap in electrical tape and poke back into the cavity out of the way while removing the entire assembly. ( i have already done all of this before taking the photos so I just placed the parts back in place for the images.

I then unscrewed the 2 screws holding the black plastic throat in place and pulled it out and used a jigsaw to carefully cut the 'roof' or top section of the black plastic throat off to give better access to the grind path. While I had those screws out I did the mods on the doser which I will outline in the next post.

galumay

So then the next step is to modify the doser, the 'knob' in the middle unscrews and exposes a 'C' clip which needs to be removed to allow the doser elements to be lifted off, I could see no good reason for this clip and left it off when I re assembled. this is the components,

(not my image) The plastic washer sits between the top sweeper and the metal plate, i moved it to under the plate as the top sweeper was leaving a lot of grounds on the stainless plate (red arrow). On the bottom sweeper I stuck self adhesive backed foam strips to every second arm to make it sweep the doser clean. People use various mods for this, electrical tape, velcro tape etc.

You can see how clean the doser sweeps now, it was terrible out of the box, probably a couple of grams left behind. Finally for grinding for clients where i grind 200g at a time, i modified the hopper so it fits under my cupboard, I put wide silver adhesive tape around the hopper, used a long bolt and black texta to scribe a line around the hopper at a suitable level, drilled a hole and then used a jig saw to cut it off.

For my single dosing I have a little funnel made by Orphan Espresso and I just drop an old tamper in it on top of the weighed dose of beans to stop the popcorning.

Hopefully this may help others considering similar mods to their grinders!

Koffee_Kosmo

Thank you for the thread I also have modded my BNZ Conical grinder to suit home use I have removed the flap and positioned the cut out circuit switch behind a panel (to make the mod easily reversible) See Photo #1 - This flap removal mod gives me full access to the exit chute See Photo #2 - The exit chute uncluttered See Photo #3 - Then I use a brush to clean the chute of any coffee KK

hiphipharar

on 1341275834:

This inevitably leads to finding a solution to avoiding the stale coffee that gets left over in the grind path and there are a few solutions to the problem. Firstly you can just grind a few grams extra at the start and push out the stale coffee, dispose of it, and then grind your dose. Secondly you can minimise the waste and stale coffee with a doserless design or finally you can modify your grinder to maximise the operation as a doser style grinder.

There is another way I wasn't keen on doing any mods on my grinder. My solution was to use a narrow wire bottle brush , bend it at almost 90 degrees to enable me to reach under the autoswitch to sweep the throat out. Very effective, I found. The grinder sweeps clean so no sweeper mod needed  . I've retained the large hopper until I find a suitable replacement but it offers the advantage that I can do a further purge by turning the grinder on and operating the hopper lid like a bellows to blow any grinds out. This can only be done if the hopper and throat is empty, of course, but I always only add enough for the shots I make.

Koffee_Kosmo

I have also made another small modification to the doser exit I manufactured a small funnel at he end of the exit hole Although it was probably not necessary as this grinder sweeps clean and straight down

Brett H

Great thread Gal and really interesting read guys.  I too have modded my doser chute of my F5 and the pastrybrush I use very effectively sweeps the exit chute.  Mine had no electrical mod required... PHEW.

Thomas

G'day All, I have done most of these to my Super Jolley to great effect. The use of the lid as a bellow is a great help, but I got sick of the little hairs in my coffee from the pastry brush so I now use a silicon one and no more hair. It can also go through the dishwasher when it gets too brown. I have also put 2 stainless hooks on the front to hang it from so I'm not searching for it all the time. Thomas

Brett H

G'day Thomas,  great idea.  I have fallen victim to the hairy puck syndrome... Especially when I put the brush in a bit far and gave it a haircut!

Koffee_Kosmo

on 1341354594:

G'day All, I have done most of these to my Super Jolley to great effect. The use of the lid as a bellow is a great help, but I got sick of the little hairs in my coffee from the pastry brush so I now use a silicon one and no more hair. It can also go through the dishwasher when it gets too brown. I have also put 2 stainless hooks on the front to hang it from so I'm not searching for it all the time. Thomas

And

on 1341360547:

G'day Thomas,  great idea.  I have fallen victim to the hairy puck syndrome... Especially when I put the brush in a bit far and gave it a haircut!

I normally use the colour application brushes that hair dressers use They are only a couple of bucks and come in different widths to suit the many types and sises of the grinders exit chutes KK

Thomas

G'day All, Brett these brushes also suffer if you put them in with the burs still spinning, which is why I have a spare in the draw. KK, What are these like at dropping Bristles? The main reason for the silicon brush, and it was in the draw. Thomas

Koffee_Kosmo

on 1341917070:

G'day All, Brett these brushes also suffer if you put them in with the burs still spinning, which is why I have a spare in the draw. KK, What are these like at dropping Bristles? The main reason for the silicon brush, and it was in the draw. Thomas

Zero bristles drop off However if you are rough with them the bristles will bend and curl over time KK

galumay

I am not convinced on those points, i weigh in 14g and get 14g out - as long as i brush the chute out. Sure there would be a small amount in and around the burrs but i reckon its a tiny amount and doesnt all get pushed out each grind anyway. It must be a very small amount because even with the Pharos where there is nowhere else for grinds to be caught except on the burrs, i get basically no retention at all. The problem with extra beans to 'flush' it through is that I then dont know how many grams of coffee I have ground. I guess its different routines for different grinders and coffee machines.

Brett H

I'm of a similar opinion G.  I brush the chute out because I have to but my poor-man's Mazzer (F5) leaves very little around the burrs.  To be brutally honest I was pulling it down weekly to clean when I first bought it, but the exercise yielded so little stale dirt I left it 6 months and attacked it at Easter.  Guess what, should have left it another 6 months.  I'm sure if I was doing 12kg per day and not 120g it would be a different story.  I also weighed in and out or a small time but I prefer spontaneity and living dangerously.  Plus my wife gave me too much sh!t. The rebuttable Rocky on the other hand with the click clack is a bit more of a trap for fines. What's a BSG AM?  Is it a rebadged Macap or something?

Muscles

on 1341927121:

What's a BSG AM?  Is it a rebadged Macap or something?

Breville Smart Grinder  :thumb:

beanflying

My K8 has the same stop mech as Galumay's Wega and I haven't found the time to remove it but as it has only been used in commercial work so far it hasn't presented a problem like with home use. My couple of Cimbali DRM's on the other hand only trap around 2g compared to the Compaks 7 or 8g so a quick purge to waste on them is easy. My K10 WBC on the other hand has major problems with grind retention and so far I have not dealt with it at all.  :doh: Procedure for me is do dump nearly a complete single dose to waste before making coffee/coffees to clear the old grinds from the chute. The other option is a fiddle but I have used a modified takeaway spoon to remove the bulk of the grinds and used them for shots but this is just a PITA to do each time. Wasteful I know so as it is in home use more than it is in commercial use I should get out the dremel and get modding. I am also going to get a bit heavy on the Aluminium part of the burr carrier as it is part of the issue. Not my shot but you can see the top of the plastic chute removed and the lip/drop from the aluminum to the plastic part is the bit I want to attack. I suspect it will still hang grinds but maybe a little less and certainly will be easier to clean.