EM04xx Grinder Hints & Kinks

[Xanthine]

Thanks to the 'Pay it Forward' section of this Forum I have been able to acquire both an EM6910 and an EM0480. Whilst neither of these were in anything near working condition they have proven to be valuable candidates for a 'teardown' and , in the process have given valuable insight into the workings of these machines and also the confidence to tackle repairs on other similar machines. So "thanks" to the people who have taken the effort to make them available rather than dump them.

In an earlier post I described a repair to the grinder which got it working, but I will probably lend it out for reliability testing as I have a Compak K3 which is too nice to not be using,even for a while!

In the process of working on the 0480 I have come across a few ideas which may be a help to anyone else who has one of these or the similar Sunbeam grinders.

First, a couple of photos showing the common places for grinds retention in the 0480 -




From reading a long list of previous posts it seems that many people get around this problem by one of the following means -

1)Banging, tapping or thumping the machine to dislodge them - probably not such a good idea because of the mainly plastic construction and also the possibility of getting grinds into the works and altering the settings.

2)Regularly dis-assembling the machine to clean it out - the dis-advantages of this are that it seems to drastically alter the grind setting and also increases the chances of not getting it back together exactly the same, requiring tedious re-adjustment, and also the increased possibility of damaging something.

3) Brushing and vacuuming can effectively dislodge the buildup at the top of the spout but is inconvenient.

4) A pre-purge before the grind proper is probably the quickest and easiest treatment but wastes coffee and certainly will not dislodge the buildup.

And so the list goes on!

The thought has occurred to me that it may be possible to fill the build-up areas to provide a smooth path out of the grind chamber.
The problem with this is what to use as a filler. Fibreglass filler or knead-able epoxy putty would work but may not be too food-safe. Possibly one option could be neutral cure silicone sealer as it is used for roofs which catch water - any ideas as I would be keen to give it a try.


With regard to dis-assembly, one of the biggest frustrations is getting the safety cutout pin and spring back in place while fitting the cover.
A simple aid is to press a small square of sticky tape on top to temporarily hold it in place-




Once the lid is screwed on remove the tape and press the pin to listen for the switch click to make sure everything is in place and working before going further.

Another idea I have found useful is to use a multi-meter to make sure the burrs are not touching on the finest setting after adding shims. Most meters have a continuity buzzer option on the Ohms setting. By touching a probe to each of the top and bottom burrs it's easy to tell if (when) they touch. It also pays to push the bottom burr sideways to tell if they are getting close. If you don't have enough hands one of the probes can be connected using a short clip lead.
Note - this only works with grinders like the EM0480 which have a plastic mounted top burr and would also not work with ceramic burrs.

[mulquemi]

Thanks Trev,
As usual you are a exceptionally reliable source of really interesting stuff (coffee related).
Cheers,
Mick.

[Xanthine]

Thanks for the kind words Mick - hopefully the info will help some one keep their equipment going a little longer and save some frustration along the way.

Along those lines, another hint I have found is for a quick repair to stripped threaded holes in plastic. The grinder I have been playing with had one of the 4 screw holes in the top plate stripped out and the screw would not pull up tight. Initially I tried pushing a short length of thin walled plastic tubing into the hole and doing the screw up but the heatshrink tubing that I used proved too soft and fell to pieces. I then thought of lining the hole with a thin layer of epoxy adhesive (Araldite) but decided I could not wait for it to set.
Instead I coated the inside of the hole with a layer of super glue (cyanoacrylate) applied with the end of a ball point pen 'refill' which was just the right diameter. To make the superglue set instantly and give it some bulk I sprinkled in a light dusting of baking soda (sodium bicarbonate). This acts as an accelerant and filler for the glue causing it to set immediately. I was then able to do the screw up and have it cut a new thread in the hole but was careful not to over-tighten it. Note that I did not glue the refill tubing into the hole. I just used it as a glue spreader.

It is worth keeping in mind this trick of using baking soda (not baking powder!) as a gap filler/accelerant for super glue but a little care needs to be taken as the reaction is exothermic and also tends to release irritating fumes. Gaps in items to be joined can be filled with the powder and the glue dripped into it.

[Xanthine]

When I got my first EM6910 several years ago I did not have a suitable grinder, but was later given one by a friend who no longer used it saying that he could never get the grind setting right for his coffee machine.
Of course the first thing I did was pull it apart to see how it worked and what could be done to improve it.
What I did notice when I had it apart was the way the bottom washer of the thrust bearing seemed to bear on both the white plastic support ring and a shoulder on the drive shaft. This seemed to defeat the purpose of having ball bearings to take the rotating load and replace it with higher friction sliding surfaces at the shaft shoulder and/or the outer plastic support ring. It could also result in the plastic support wearing down over time and making grid adjustment vary. I figured that the easiest way around this was to enlarge the centre hole in the bottom thrust washer so that it would fit over the shaft and enable the ball bearings to take all of the load and transfer it directly to the support ring.
I have drawn a rough sketch to illustrate what I am talking about by showing the cross section of the bottom burr arrangement-




I proceeded to enlarge the centre hole in the bottom thrust washer using a conical grindstone in my Dremel as it was made of hardened steel which could not be drilled out.(Warning - gets very hot to touch!)
From memory, extra shim washers were needed under the burr to get the grind fine enough, but, when re-assembled, the grinder worked a treat and showed no signs of 'settings creep' the whole time it was in use.

When I eventually replaced it with a K3 I gave it back to the original owner who has since loaned it to another friend (who is currently using it with one of my 'spare' EM6910s which I have loaned him and says I'm not getting back ) So it's certainly done some work and still seems to be fine.

The second grinder modded in this way was an EM0450, bought at an op shop by my wife for $10, and labelled as "won't grind fine enough". This seemed to work OK after the treatment but has been relegated to the entertaining area outdoors and has not seen a lot of work. From memory I did not have spare shims, so used a thin card disk between the black plastic cup assembly and the top steel thrust washer.

Then came the 'Pay it Forward' special. I'm not sure what had happened to this but the bottom thrust washer was badly cupped with 6 dents in it from the ball bearings of the thrust bearing.



Figuring that this would not do wonders for the grind quality I went hunting in the washer tin in the shed and found an odd shaped hardened steel washer about the right diameter, but thicker than the original, and with a square hole in the centre. Once again, using the Dremel, I managed to enlarge and round the hole to fit the shaft. When re-assembling it I found I had no spare shims so found a suitable washer which I ground down almost to the right thickness on an oilstone - with it the burrs just touch at about the "8" setting so I will either reduce it further on the oilstone or get some more shims when I get time.

One other point before I finish and that is concerning 'end play' in the shaft. On one of the machines I found that I could almost completely remove this by juggling shims and packing but am not sure how much difference it would make to the grind quality - open to experimentation.

Well, as you can see, my experiments have not been very controlled but seemed to yield some promising results for improving the performance of these grinders. If anyone tries something similar with an old grinder I would like to hear your results.