TLDR: If you want to really hold a door closed with magnets, this is the print for you!

I'm using 2 of these to hold one cupboard door shut, because I really really wanted it closed.

I've created (or plan to create) models for the following:

327.6mm long - 12/24 Magnet Version https://www.crealitycloud.com/model-detail/magnetic-door-latch-extra-super-duper-strong-24-magnet

248.72mm long - 9/18 Magnets Version https://www.crealitycloud.com/model-detail/magnetic-door-latch-extra-super-strong-18-magnet

169.95mm long - 6/12 Magnet https://www.crealitycloud.com/model-detail/magnetic-door-latch-extra-strong-12-magnet

91.17mm long - 3/6 Magnet https://www.crealitycloud.com/model-detail/magnetic-door-latch-strong-6-magnet

A 2/4 Magnet Version

A 1/2 Magnet Version

Background:

I admit this is a bit mad, but if you want to really hold a door closed with magnets, this is the print for you!

Why did I want this crazy thing? I wanted to seal my filament storage cupboard, so I put "D" seals all around the mating faces, and needed something to hold it closed tight against the seals. I could have done this mechanically, but I decided to do it with magnets, I bought some very strong magnetic latches from Amazon, but found them distinctly disappointing, mostly because I wanted them to attract over a range, but also because I needed more adjustment as the seals held the door open a bit.

Printing: These are very easy to print. Turn on precise outer wall for a nicer finish.

Assembly: You can choose how many magnets you need. I suggest you probably won't need all of them, but who am I to stop you?

You should orientate all your magnets the same way in one part and the opposite way in the other, unless that's not what you want. I suggest you check it works how you want it to before you screw it to anything.

They press into place, it shouldn't require much force and they can be pressed out from the other side.

Installation:

The wall strip goes inside the wall the door closes against.

The door strip is 6mm thick, you need to allow at least this gap when installing the wall strip, or your door won't close.

If you allow too much gap, I've also included a shim, see below. Don't print this if you don't need it.

I've made the wall strip 2.4mm offset, so the door strip won't catch the wall, if you get my drift. When you measure to place the door strip, remember to take this 2.4mm into account. The magnets are loose in their holes, so it will still be fully effective if you're slightly off.

I designed these parts to take 4mm wood screws.

The magnets I used were 20*10*5mm, specifically these ones: https://www.amazon.co.uk/dp/B0DQXNH9MP, though I expect any equivalents will work.

The Shim: (If you don't need a shim, don't print it and don't read this, unless you want to.)

I made this in case you need it. If you're super precise, you don't need it. To get the most our of your magnets, you want them to meet as close together as possible, without quite touching.

This part is to go between the door strip and the door to space it off a bit., only if necessary.

You can make it thicker or thinner according to your needs by scaling in z.

Angled Shim Instructions: (I really really doubt you need this)

You can also make angle it, if you need the top and bottom to be spaced separately. this is mildly mind bending but actually straightforward if you think it through, I'll offer an example:

Say you want to space one end 2mm and the other 1mm:

1. Scale the part's z to the largest spacing (2mm)

2. Rotate the part about y until it's total height is the largest spacing + the smallest spacing (1+2=3mm) this is a bit trial and error, but the answer in this case is ~0.175°. it's close enough to linear that you can scale this angle for your purposes.

3.Offset the part downward by the difference between the two (so subtract 1mm from the parts current z height, in this case 1.5-1=0.5)

4.Cut the part and only keep the top

5. Allow a repair if it needs it.

6. Print and enjoy - Maybe drop me a boost :D

Help Stop Bowel Cancer:

I'm offering this design for free, and yes I know you probably wouldn't have paid for it anyway, but I don't like bowel cancer and neither should you. So, please consider putting a money or two into my just giving. This won't benefit me financially and I'll never have access to the funds, they're sent straight to the charity. You can contribute in multiple different currencies.

https://www.justgiving.com/page/t-t-t

Help Stop Bowel Cancer

Magnetic Door Latch - Extra Super Duper Strong (24 magnet)

0.2mm layer, 2 walls, 15% infill