End stop for drawer self closing damper

Que?

We have a couple of these pull out spice drawers in the kitchen. They are 150mm / 6" width and are basically filling in a 30cm gap in the cabinets next to the cooker.

They have those nice self-closing / soft closing mechanisms. Or rather they did when they were new about 15 years ago. Now neither work, although in different ways. The one to the left simply slams against the back of the cabinet when closed, whereas the one on the right stops short of closing by an inch or two. Both are thus annoying and need seeing to.

The mechanism is a kind of cartridge that drops into the steel framework of the door. It's plastic, although there's no identification on it anywhere, neither admitting to a manufacturer's name, nor model serial number nor even the type of plastic (for recycling purposes). The only letters identify left, right and forward in German, which suggests it's almost certainly German in origin. Probably also explains why they have both failed - the old myth of "solid German engineering" etc.

The one that slams has suffered a broken spring. The other one has suffered wear where this (right hand) tang is supposed to engage with the drawer running. The runner has a sharp tab sticking out that is supposed to engage with the tang - but as you can see, it's worn away. Doesn't look like a very robust design - as evidenced by the lack of functionality of course.

The operating principle is pretty simple. That piston is a one-way damper (easy to withdraw the piston, hard to push it back) and there is a slider that acts against a spring. When you pull the drawer open, the spring is stretched and the piston pulled out (there's a magnet on the white bit and a magnetic screw on the slider) before the slider latches into the siding at the top (ie extended) end in this photo. When you close the drawer, the slider is released from the end of travel and the spring then pulls the drawer shut against the piston.

An extensive search of the internet suggests it may have been made by Blum - but there's nothing shown as a current product and the only UK stockists haven't heard of anything like this.

Checking ebay, AliExpress etc doesn't bring any joy. Instead, it looks as if a replacement will require some work to fit. So let's do that, while trying to keep things fairly quick and simple.

Here's a suitable looking part from a UK supplier:

They are almost free, at £1.62 per pair of closers so naturally, The Stupid Fat Bloke ended up buy 4 pieces instead of 2. The postage at £3.95 cost more than the actual products.....

Design something suitable?

So now, I need to figure out how to mount these and make them work. They come with a white nylon peg thing that catches the white slider on the damper mechanism. That doesn't look like something I can fit simply, so time to flash up Fusion and the Elegoo printer.

Here's the installation. The outer shell is attached to the moving drawer, so some sort of peg mounted on its top could be made to interfere with the damper assembly mounted on the cabinet wall just above the rail.

Here's the new (bottom) and old (top). For one thing, it's clearly not going to be possible to simply drop the new one into the old position.

Something sort of like this might work, although it could actually be fitted on the lower runner where it would be less visible (there are 2 runners per drawer):

I need something like this:

This is based on a sketch that is extruded lengthways, then a transverse cut made to generate the reduced width for the peg. There's also a 20mm long slot for an M5 screw so that I can finesse the closing position. I can fit this with the front panel off, so that the damper is pretty close to where it needs to be, then make a fine adjustment with the slotted screw.

Print that out in PETG+ with 100% fill (for strength) and it looks good:

With the supports  etc removed:

It would fit together like this, although obvs it would be sited further inside the cabinet:

The bracket fits nicely. There's room for an M5 tapped hole in the runner, right where there's a random hole in the backing plate for clearance. The first attempt used an M3 screw but I increased this to M5 for the final version.

Good. So  now it's time to fit the thing - and print a second one for the other drawer.

But - does it fit. And does it work?

'Fraid so. The return spring isn't fantastically strong, so the runners could probably do with some lubrication. But it works - the drawers close themselves (just) and don't slam into a hard stop. As you can see, I left the installation to The Stupid fat Bloke, who couldn't be arsed to install it at the bottom of the cupboard. But it doesn't look too bad TBH. 

There.