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Thread: Coffee machine experiments
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9th Aug 2019, 08:34 PM #1Member: Blue and white apron brigade
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Coffee machine experiments
I have what used to be a fancy Italian espresso machine that still makes a decent espresso even though I've had it for just over 15 years. One thing that annoys me is the noise made by the vibe (electromagnetic) pump which can almost drown out any nearby conversation. I've replaced the pump but it did not make much difference.
Around at my mates place (his coffee machine is newer and fancier and makes anything I do coffee wise pale into insignificance) a few months ago and noticed his machines (yes he has more than one!) are really quiet. Turns out they use a outboard pump with a centrifugal type water pump so I thought I'd have a crack at putting one on my machine. At the same time I thought, why not make it a 3 phase motor and add small VFD to get a bit more control over the flow rate through the ground coffee. As it so happens, - as you do, I already had a suitable 1/5HP motor and a 1/2HP VFD on hand.
Turns out said mate also has discount access to an Italian coffee machine spare parts mob in Milano and my mate was about to place an order so I jumped on board. As well as a bunch of other parts I ordered a beaut SS pump and the standard pump/motor coupler/connections.
IMG_3893.JPG
So the first task at hand was to mate Motor (M) to Pump (P)
C are the component parts of the coupler.
F and F2 are two nice bits of 6 and 10 mm SS that I decided would hake good flanges.
Here is what the back and fronts of the couplers look like. The 3 pins on each plug into the holes in the rubber ring to smooth out the power transfer.
I bought two sets of each as they were less than 2 euros for each set!
Coupler0.JPG
You can see the pump side of the coupler has a slot - no problem so does the pump - the problem is the other side of the coupler which is designed to suit a shaft with a flat spot or D shaped shaft while the motor has an 11mm shaft and a 4mm keyway. It turns out the D shaped hole is also 11mm - no worries I thought, I will place the coupler in the lathe, bore away the flat and cut a keyway in the hole and all will be honky-dory.
Well I have no idea what those couplers are made of but the TC tipped boring bar was having a very hard time so I stopped as I was worried about the 4mm Keyway broach I had not being able to cut the keyway. When I tried to scratch the coupler with the keyway broach it barely scratched the surface.
So plan B - make up a new 3 pin coupler with built in keyway hole/slot and the same 3 pin arrangement on the other side.
First problem with that was my keyway broach bush set only goes down to suit 12 mm holes/shafts = so let's make an 11mm one.
Vey soon I found out why the set stops at 12 mm - the spine of the broach is ~6.5mm wide (presumably to give it some strength) but this means the size of the accommodating slot in the smaller bush leaves very little metal left to hold the whole bush together.
Here on the left you can see the 11mm bush whereas the 12 mm bush is on the right.
You can see how little metal is left area the corners where the broach spine slides.
KeywayBroachBush.JPG
This also made it difficult to cut the 6.5mm slot because any vice hold would just crush the bush.
In the end I made the bush out of some 16 mm stock with ~30mm of excess length to hold, both while turning and then cutting the slot, where I held the 30 mm of extra length in a collet held in a collet block in a vice, with the bush/slot section just hanging out in the breeze and just took fine cuts.
It's not absolutely symmetrical but the proof is in the fact that the bush works and together with the broach has cut two 4mm slots (first one was a cockup!) that neatly fit the motor shaft and keyway.
K below shows the finished piece with the 3, 6mm pins in place.
The other 3 holes were my first attempt at holes for the pins but due to poor marking out the holes were not symmetrically located and BOY - did this create some vibe.
Some of this was due to the pins not being of equal length/weight so I subsequently ground them to equal length/weight
I am much happier with the current pin locations but I think the old hole locations maybe still are throwing the thing out of kilter.
I will try filling the holes with short stubs of equal weight threaded rod to see if that makes a difference.
Keywaypiece.JPG
And here it is assembled and on the motor.
Pumpcoupler.JPG
So now I have to make up a flange arrangement that couples the whole lot together. IT Hs to be pretty sturdy because the pump just hangs off the end of the motor.
Basically I'm going to use the two round plates of SS shown in the first picture bound together by some lengths of 8mm SS all-thread.
Getting everything aligned could be tricky.
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9th Aug 2019, 08:50 PM #2Most Valued Member
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Keep it coming this is really interesting.
Being a keen coffee drinker I appreciate the effort you are going to. Also given that (if your like me) you have several coffees a day, you will really appreciate this little mod!
Simon
Sent from my SM-G970F using TapatalkGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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9th Aug 2019, 09:44 PM #3Member: Blue and white apron brigade
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Thanks Simon, yes I do like my coffee and have 4 - 6 double shot coffees most days.
I have cut back from a true double shot (14g basket) to a reduced double shot (12 g basket)
Usually start the day with a double short espresso and the either long blacks or milk based coffees. In summer I extract the shots over ice and then add full cream milk, in winter I usually go with steamed milk. Some 3 months ago I weaned myself off milk completely and over to a shot of thickened cream topped up with hot water as this combo has less sugar in it and being diabetic means I am trying minimise surge. It doesn't work over ice unfortunately so I don't know what I'll do this summer.
The excuse of the quieter pump is just to placate SWMBO - I have something much nerdier in mind but won't spill the beans on it util I get the new motor and pump working.
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9th Aug 2019, 09:54 PM #4Most Valued Member
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Hi Bob. Have you tried other "milks"?
I used to drink nearly 1 L of cows milk a day, have all my life but I recently gave up cows milk and reduced my dairy. I feel much better for it too.
I now use almond milk in my coffee. Took me a bit of getting used to but I like it now.
I also used to have 2 sugars in coffee, eliminated sugar in coffee too. Never thought I could do that but it's just a matter of training your taste buds.
Still love ice cream though. I'll never give that up!
Simon
Sent from my SM-G970F using TapatalkGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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9th Aug 2019, 10:09 PM #5Member: Blue and white apron brigade
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Yes have tried them all but don't like any of them - I can tolerate the taste of almond milk but I find the texture, I dunno - sort of rubbery? I love coconut and make my own coconut yoghurt using coconut milk but I don't like the taste in coffee.
I haven't had sugar in coffee since my early 20's but what I do like is a double espresso with a shot of grappa followed by the rinse, the dregs of the previous plus another shot of grappa. Unfortunately my diabetes limits these to special occasions only.
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9th Aug 2019, 10:26 PM #6Member
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What model espresso machine are you running Bob
Good coffee is worth being obsessive about
Tony
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9th Aug 2019, 10:49 PM #7Member: Blue and white apron brigade
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It's a La Cimbali Junior.
The only thing I have modified is the water handling system.
It came standard with water tanks for input and output water but I removed these and plumbed it in on both the inlet and the outlet.
The inlet water is sediment (1) and charcoal (2) filtered followed by a reverse osmosis filter (3).
The water is forced through the reverse osmosis filter by a pump (4) and the impurities (basically salty water) pass away from the reverse osmosis filter through the red tube to a drain point D.
Water comes out of the reverse osmosis filter very slowly so it is stored in a pressurised 8L tank (T)
From there the water goes up to a pressure reception valve and control solenoid to CM where it heads off to the coffee machine.
M is a meter that monitors total dissolved solids after the reverse osmosis filter.
Filter 5 is not part of the coffee water system but a lab grade deioniser that I use to produce clean water for fume bluing. Its slow - about 2L/hour but it produces VERY clean water which I run into 20 carboys.
IMG_3068ptr.jpg
The water filtration system alone cost more than a budget end espresso machine.
Here's a photo of my "shrine" taken some 12 years ago.
The left hand grinder is for SWMBO's decaf.
shrinex.jpg
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10th Aug 2019, 08:09 AM #8Philomath in training
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You know, most people use that drain outlet on the sink S bend for a dishwasher. I guess that means the coffee machine is the more important appliance.
Michael
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10th Aug 2019, 09:09 AM #9Member
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Having drunk WA's salty water I can understand you going to a bit of trouble to get pure water, but definitely obsessive. Tas has some of the best drinking water in Oz so no such treatment required here.
Will watch with curiosity to see if this gives you any improvement in control over the coffee shot compared to the regulator valve and standard pump.
Tony
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10th Aug 2019, 09:49 AM #10Member: Blue and white apron brigade
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The grey corrugated hose is the dishwasher waste drain (DWW).
The Reverse Osmosis drain (D) is the red line.
The brack 1/2' PE pipe (CMW) is the coffee machine waste drain pipe.
ALL three connect to the same spigot on the sink waste drain.
CMwater.jpg
Which brings me to something that happened about a decade ago.
Just before bed one night I stacked and set the dishwasher going.
At around midnight I got up to get a drink and went into the kitchen in the dark and felt my feet getting wet.
Turn on kitchen light to see brown dirty water coming out of the base of the coffee machine dribbling down the cupboards and covering most of the floor. For a moment I thought the machine had somehow turned itself on but there was no filter handle on the machine and then it dawned on me the water was soapy so it must have been coming from the dishwasher and back up to the coffee machine.
What had happened was the end of the dishwasher drain where it entered the sink waste line had become blocked and when the dishwasher had gone to discharge its waste the waster had nowhere else to go except back up through the coffee machine drain line. What had blocked the spigot into the sink waste line was a single olive pit. The plumber who had installed the dishwasher had used a 1/4" drill bit to break open the connection of the drain spigot to the waste line. So I drilled it out using a 1/2" bit and all was good.
After a few months another problem arose because the coffee machine drain line slope was too shallow, coffee grounds were over time blocking the coffee machine drain line. To counteract this I subsequently moved the coffee machine drain line straight down from the coffee machine through the cupboards and kitchen floor, to under the house where I connected it to the PVC sink waste PIPE.
SWMBO is constantly amused and my "playing around with the coffee machine" but does not comment too critically as she really likes her coffee.
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10th Aug 2019, 11:37 AM #11Golden Member
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10th Aug 2019, 12:19 PM #12Most Valued Member
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Holy Bob!
That's quite a rig you got worked out there!
I feel so inadequate (more inadequate) now.
I've got myself a Jura but I do like it. Not in the same league as yours!
Simon
Sent from my SM-G970F using TapatalkGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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10th Aug 2019, 01:21 PM #13Diamond Member
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Back in the early 90's when I got my first machine (a Saeco "Magic" from memory) I had to replace the pump - it was a little Ulka vibrating positive displacement pump, and I suspect the same pump is used in pretty much all small domestic machines.
I'm relieved to see Bob has found another thing to stick a VFD on, but a little disappointed his machine doesn't appear to have a PID temperature controller on it???
Hopefully he'll at least add a pressure transducer and run the VFD in a closed-loop constant pressure mode.
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10th Aug 2019, 01:49 PM #14Member: Blue and white apron brigade
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Simon, nothing wrong with Juras. We had one at work and with good beans it made many dozens of good coffees each day. When I think about it, It got flogged mercilessly and when the dude who normally serviced and clean it went on LSL it died from misuse.
When I visit my coffee nerd mate I'm the one feeling completely inadequate.He used to work in the coffee machine maintenance and the coffee roasting business during which time he acquired and disposed of various machines. He also owned a water purification business for about 5 years which is what enabled me to get my water setup otherwise it would have been out of my price range. Currently I think he has 3 machines, two of which are "multiple group head", 3 phase machines and he's in the process of converting one of these to single phase. His regular single group head home machine is fairly tricked out with dual boilers with PIDs, various gauges, coffee cam, and coloured LEDs that display a raft of machine conditions. It has an outboard pump but it's only single phase so no VFD. He has a number of pro grinders including a monstrous 3 Phase Mazzer with a VFD on it, and another one that cost more than my coffee machine.
About 12 years ago we both qualified as barista competition judges but only judged a couple of comps because keeping up the qualification required judging at a certain minimum of competitions each year but that was out of my financial bracket - you had to pay for your own travel and accomodation to attend events. Anyway it was a bit of fun and I learned heaps about coffee.
Yep these Ulka pumps are the standard pump - as I said, over time mine seemed to get a bit noisy so I replaced it but it didn't make much difference.
I'm relieved to see Bob has found another thing to stick a VFD on, but a little disappointed his machine doesn't appear to have a PID temperature controller on it???
Hopefully he'll at least add a pressure transducer and run the VFD in a closed-loop constant pressure mode.
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10th Aug 2019, 02:37 PM #15Most Valued Member
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