# Help with disassembling and cleaning a Gaggia MDF



## ShaunChris (May 4, 2015)

Hey guys,

A friend gave me a Gaggia MDF for free, about 1.5 years ago.

I was very thankful for it. It seemed to be in decent condition, so I found the Gaggia MDF stepless mod here -->


http://imgur.com/hZG39


And I followed it. Cleaned the machine thoroughly too.

The grinder has been working perfectly for me for the past 1.5 years, pulling an average of 1-2 espressos a day for about 18 months straight now.

I have not cleaned it since 18 months ago.

A few days ago, I realised that although it was still grinding, it was giving out a weird sound.

1.) Usually during grinding, it's a smooth, high pitched whine. However this time, there was an extra sound, it sounded like a bit of a rough whirring sound, as though there was a cardboard flap affixed inside somewhere, and the grinder was regularly hitting the cardboard flap. *It did not sound like a harsh, jarring, metallic screech or anything "hard", *it just sounded like a semi-soft object was stuck

somewhere.

2.) This sound was more obvious when I switch off the grinder. As the "engine whine" fades, the "whirring" sound becomes more obvious.

I was a bit concerned, so I opened up the grinder to give it a thorough cleaning, thinking it's just a buildup of gunk.

I've got all the top bits off, and both burrs removed.

Now I'm left with this picture below.

Essentially, I've removed the hopper, the measurement gauge, the top burr, and the bottom burr.

When I run a test by switching on the grinder *as it is pictured below*, I still get that weird sound, meaning the burrs are not responsible for the sound. Judging by the sound and feel of it, I think the issue is just that there's a lot of grime and dirt caked UNDERNEATH this brass/copper plate.

Problem is, I don't know how to remove this.

I feel quite sure that if I can remove this, I can clean the underside of it, and it would be much better, but I'm not sure how to.

I've tried using a wrench to unscrew the hex nut in the middle, but I can't get any grip, because if I try to turn the nut, the whole brass/copper plate turns along with it.

Any advice?










Here are some extra pictures in case it helps!



http://imgur.com/5Rdtx


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## dsc (Jun 7, 2013)

Get a socket on the hex and do keep in mind its a left handed thread so you want to unscrew it the other way (so lefty tighty, righty loosy). To stop the plate / shaft from spinning you can wedge a 10mm wooden stick through the burr chamber output hole and in towards the center of the shaft, under the brass burr carrier, one of the "wipers" will eventually make contact with the wedge and you'll have something to lever against when undoing the bolt.

It is possible that the grime / dust got into the bearing, but you'll know soon enough when the burr support comes off.

Any more issues, let me know, I've disassembled this grinder a million times years ago, so can probably help a bit.

T.


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## ShaunChris (May 4, 2015)

Thanks very much!

I don't have any suitable wooden stick, but do you think a screwdriver, if I hold it firmly and try not to "gouge" it around, will be safe to use?



dsc said:


> Get a socket on the hex and do keep in mind its a left handed thread so you want to unscrew it the other way (so lefty tighty, righty loosy). To stop the plate / shaft from spinning you can wedge a 10mm wooden stick through the burr chamber output hole and in towards the center of the shaft, under the brass burr carrier, one of the "wipers" will eventually make contact with the wedge and you'll have something to lever against when undoing the bolt.
> 
> It is possible that the grime / dust got into the bearing, but you'll know soon enough when the burr support comes off.
> 
> ...


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## grumpydaddy (Oct 20, 2014)

Better to find a local tree or bush then prune the right size of stick. You don't really want to use anything metal


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## ShaunChris (May 4, 2015)

grumpydaddy said:


> Better to find a local tree or bush then prune the right size of stick. You don't really want to use anything metal


Roger that!


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## marcuswar (Aug 19, 2013)

Never use anything metal.. it WILL damage the burr carrier. In the past I've used one half of a wooden cloths peg, a plastic chopstick and a wooden spoon handle.


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## dsc (Jun 7, 2013)

You could use aluminium if you have a suitable round rod / piece, but it is indeed better to use wood. Anything will work as long as it fits into the exit chute and under the burr carrier. Try a pencil / pen / thin marker, end of a wooden spoon, end of a plastic spoon (needs to be thicker, not the dispensable ones as it will break), end of a small paint brush, heck you could even try a piece of paper rolled up into a roll and chucked into place. All you are looking for is to stop one of the "wipers" from going past the exit chute hole. When you have the "stopper" in place, rotate the burr carrier until the "wiper" rests against the "stopper" and try to unscrew the hex nut (remember to go clockwise).










T.


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## Me(no)Coffee (Apr 14, 2018)

Sorry to hijack, but was seeking an answer to a similar query and found this.

My doser broke (the "fan" in the doser snapped from the bit underneath) so I repaired and decided to give it a good clean (which I hadn't done in 18 months of 2 shot daily). I bought some nice new burrs too. I took it all apart, replaced the burrs, cleaned everything and put it back. Then (admittedly this is probably because I took too long trying to find the zero point) I manage to loosen that hex bolt photographed, entirely accidentally.

Now, when I re-set to zero, and start the grind, the bottom burr spins normally for a few seconds, then looses momentum. The bolt and nut spin happily away, but not the burr.

I've used a chopstick to stop the burr spinning, and tried gripping the top of the protruding bolt (using needlenose pliers where I've coated the nippers in duct tape to avoid damaging the thread) but nothing seems to work.

I am almost at last resort - epoxy on the base of the bolt. Is there something else I should try first?
​
thank you!


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## dsc (Jun 7, 2013)

Silly question perhaps, but you say that you've loosened the bolt photographed, I'm guessing here that you mean the nut and not the bolt? The bolt is in effect the end of the shaft on which the burr carrier sits and all is tightened with the nut seen on the photo. Main thing to keep in mind is that it is a left hand nut, so you go clockwise to loosen and anticlockwise to tighten.

If it is indeed the nut that was loosened, have you tightened everything back up nicely? You don't really need the chopstick in place and it doesn't need to be uber tight as it should do itself up when it's grinding (assuming it's tight enough to start grinding in the first place).

T.


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## Me(no)Coffee (Apr 14, 2018)

Sorry - yes, it's the nut I've loosened. I've been turning it counterclockwise to tighten. When I get it as tight as I can, it reaches a point when I turn the nut further the bolt/shaft rotates with the nut, so its not getting tighter.

When I turn it on to test, the burr spins. But if I touch the spinning burr with a pencil, it slowly stops but the nut carries on spinning. Similarly, if I re-assemble it, the burr will spin, but then when I add beans I get about a teaspoon worth of ground coffee, then the burr loosens (and the bolt/nut combo continues spinning).

It so odd, as I didn't touch the nut at all; the only thing I can think of that caused the issue was when I was cack-handed setting the thing to zero as I had it too tight and the was a split second when the motor was trying to turn but couldn't.


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## dsc (Jun 7, 2013)

It almost sounds like the nut isn't compressing the burr holder but instead gets stuck on the thread and doesn't want to go lower.

Can you remove the burr carrier and check that the nut can go all the way down / up the thread?

T.


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## Me(no)Coffee (Apr 14, 2018)

Well it seems I cannot get the nut off... I got it to the top of the bolt, and that was far from easy. I had to apply a lot of pressure (the bolt, obviously spinning as I tried, so had to twist and apply some upward pressure). It took about 10 minutes to get it to the top, but now the nut is sitting about 1mm above the top of the bolt, and there it's stuck.

Given the amount of pressure I've had to apply, I would say that the threads are damaged - which is possible, but I was careful to grip the bolt with pliers with 3 layers of duct tape. Or the bolt was incorrectly threaded. It was a second-hand machine, and (while I've cleaned it out before) this was the first time I changed the burrs.


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## dsc (Jun 7, 2013)

This would explain why you couldn't get the burr carrier to sit tight, the nut was most likely getting stuck on the thread, rather than bottoming out on the carrier. Perhaps someone used the wrong nut, or the bolt was cross threaded at some point, or it got damaged from the pliers, hard to say without seeing it.

One way to try and get it off is take the base off and get access to the other end of the motor shaft. Perhaps there you can get a better hold of it, then remove the nut and assess damage. No idea what the thread size is, but you could run a tap along the bolt to "repair" the thread and try a new nut.

T.


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## davewuff (Oct 26, 2012)

Me(no)Coffee said:


> Sorry - yes, it's the nut I've loosened. I've been turning it counterclockwise to tighten. When I get it as tight as I can, it reaches a point when I turn the nut further the bolt/shaft rotates with the nut, so its not getting tighter.
> 
> When I turn it on to test, the burr spins. But if I touch the spinning burr with a pencil, it slowly stops but the nut carries on spinning. Similarly, if I re-assemble it, the burr will spin, but then when I add beans I get about a teaspoon worth of ground coffee, then the burr loosens (and the bolt/nut combo continues spinning).
> 
> It so odd, as I didn't touch the nut at all; the only thing I can think of that caused the issue was when I was cack-handed setting the thing to zero as I had it too tight and the was a split second when the motor was trying to turn but couldn't.


Ive just done a complete strip down of one of these...

The only think I can think of is that the nut is tight on the threads but not clamping the burr carrier, so either the burr carrier has been loose for a long time and has worn enough to prevent clamping, or the threads are tight (or short ) enough to stop the nut clamping down far enough. Assuming your 'stick' isnt under the carrier and being squashed as you tighten (but preventing the nut going all the way home), try cleaning out the threads with a small wire brush, and/or putting a small washer under the nut to take up any wear in the carrier?


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## Me(no)Coffee (Apr 14, 2018)

Yes, due to the central bolt being free, once the nut gets near the burr carrier, it stops and the nut simply turns the bolt without tightening fully. I've tried several times today. Cannot get the nut off either - it will come close to the top but it seems now I've damaged the threads at the top so it causes the same issue when the nut reaches the top of the bolt (the bolt just spins).

I've now taken rather drastic action. I've raised the nut as far as I can, then cleaned it thoroughly to remove any residual oils, then applied some epoxy to the underside of the nut (with a broken/rightangle match), then brought the nut down as far as I could, then left the wrench on the nut and turned the machine on (really dangerous - don't try that at home). I think it managed a further 1/4 turn now I'm going to leave it over night.

Given it's second-hand and likely 15 years old, I'm probably better off just buying something new rather throwing more money/effort - the cost of takeaway coffees whilst I've sorted this and faffed around with my Silvia PID install means I could have probably bought a new machine and grinder.

If I do have to go new - will either look at La Pavoni Jolly (seems to be discounted from £423 to £223) or a Rocky Doser (£219)....

Thanks so much for your time and helpful suggestions.


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## dsc (Jun 7, 2013)

Agreed, damaged threads are typically not something fixed easily, you'd need a tap and tap wrench to re-cut the top section at least, which will set you back £10-£50 depending on make / condition. Borrowing one would most likely be way cheaper, but it seems like you got it working to some extent, fingers crossed it works.

T.


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## Me(no)Coffee (Apr 14, 2018)

Sunday morning, after an over-night cure for the epoxy. With trepidation, I re-assembled the MDF, plugged it in and filled the hopper. Then I pushed the button and heard the familiar sound of burrs burring and held my breath (I normally got between 2 and 20 seconds of grinding before the burr carrier stopped rotating) - result! It continued the grind and now I'm drinking my first self-made coffee in a week!

The espresso is a little thin - I think my setting 5 may now shift to 4, and also it really won't have helped that the beans have been sitting uncovered in a cereal bowl on my worktop for a week (this was the last of that bag - Caravan house roast).

I've got some new beans for tomorrow - Allpress Redchurch blend.

Thank you so much for your help with this - it's been a frustrating week, but thankfully it ended well.

By the way - this is something I discovered which readers may be interested in - when steaming milk I find if I continually tap the bottom of my jug firmly with two fingers as I steam, the quality of the foam always comes out much more velvety (better than bashing the jug on the tamping matt at the end).

Cheers!


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## tamamma (Jan 28, 2020)

Me(no)Coffee said:


> Sorry - yes, it's the nut I've loosened. I've been turning it counterclockwise to tighten. When I get it as tight as I can, it reaches a point when I turn the nut further the bolt/shaft rotates with the nut, so its not getting tighter.
> 
> When I turn it on to test, the burr spins. But if I touch the spinning burr with a pencil, it slowly stops but the nut carries on spinning. Similarly, if I re-assemble it, the burr will spin, but then when I add beans I get about a teaspoon worth of ground coffee, then the burr loosens (and the bolt/nut combo continues spinning).
> 
> It so odd, as I didn't touch the nut at all; the only thing I can think of that caused the issue was when I was cack-handed setting the thing to zero as I had it too tight and the was a split second when the motor was trying to turn but couldn't.


 Can I ask you something? How does the burr holder take off after removing the nut? Is it just fitted in and kept locked from the nut?

I've read this tread too late(to know that that nut was clockwise to loose ) and I've broken the bolt as you can see in the photo.

Now I would try to disassembly all to see what I can do but the burr holder won't take off, I've even tried to leverage from bottom but nothing so I would understand how take of this to comlpete the disassembly.


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## El carajillo (Mar 16, 2013)

I do not know this particular M/ch but I would think the lower carrier is a 'press fit' possibly with a keyway either in the side of the shaft OR possibly underneath.

To remove it you could use 3 bolts threaded into the lower carrier , then turn them alternately to 'jack up' / remove the carrier. The only disadvantage is that it gouges marks into the base of the grinder. A kinder / correct method is yo use a simple puller made from a piece of flat steel with 3 holes corresponding with the burr holes with bolts/ screws through into the L/carrier. A hole in the centre of the plate with a bolt through and a nut underneath will pull the carrier off.

See information in Mazzer carrier removal in earlier post / sticky.

You will need a stud extractor to remove the broken bolt sections.


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