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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