Introduction: HDD Magnetic Doorstop

Simple doorstop made from powerful magnets, recycled from a broken hard disk. Works best with wooden floors and lightweight doors.

Step 1: You Will Need

Tools:
Screwdriver or battery drill
Pencil
Old chisel or door wedge.

Materials:
Old hard disk (To cannibalise for parts)

Step 2: Disassemble Hard Disk

First you need to open your hard drive up. You'll probably need to use some torx bits and a screwdriver to prise the case open. I've included a few examples in the images below.

(Warning: The hard drive is going to be useless after this step. If you don't have an old one to hand, there are places you can find them. I've seen very cheap, old rubbish hard drives for a few pounds each at PC fairs, and also the electronics department of an army surplus depot).

Once you're inside, there should be a few screws securing the magnets and the read write head. Hard disks obviously vary a lot from one manufacturer to the next, but they all have a similar layout and design. It's a fairly straightforward disassembly job to get the magnets and read wirte head loose, then separate them all.

Hard drive magnets are ideal for this project. They're strong, and they're glued very solidly to backplates that already have handy mounting holes. Be careful with them though, because they can hurt your fingers if you're not. Here's a quick demo of the speed and range at which they can snap together:


Step 3: Remove Door, Add Magnet, Rehang Door

Carefully remove your door, propping it up at the bottom with an old chisel, door wedge, offcut of wood, etc. To minimise strain on the hinges, keep it supported and leave a screw in each hinge until you're ready to get it down quickly.

Once you've taken the door off, screw one of your magnets into the bottom near the hinge side, as shown below.

Rehanging the door should be fairly easy. Support it with the wedge/chisel while manuvering it into a position where the hinges are more or less aligned properly, then start putting screws back into the holes thy came from. Screw them all in halfway, then you can gradually take turns tightening them and adjusting the position of the door. Just take your time and keep tweaking the position; its unlikely to align perfectly at first. When it's aligned closely enough, the screws will pull the hinges back into the right place.

Step 4: Mark Floor, Fix Second Magnet

The nub shown in the photos on the last step was put on closest to the side of the door that faces in, because that makes this step easier by giving an obvious reference point for marking the floor and aligning the magnets. Magnet backing plates don't always have nubs, but in this case both plates did and they aligned when the magnets were facing each other.

So:

Put your pencil against the door, with the point touching the floor. Close the door, and it will mark a curve out, allowing you to align the bottom magnet with path of the one fixed to the door.

Now, decide where you want the door to stay when it's open. I went for less than the maximum travel of the door because I have some shelves in the way.

That's it, you're done! Once you have it fixed down, as long as the magnets are close enough (and you'd need a pretty big gap or heavy door for them to be ineffective), they will catch the door and gently hold it in place.

I've put some videos below to demonstrate the pleasing wobble this creates, and I've also detailed a couple of optional extras in the next step.




Step 5: Extras

I did two things to make this better: Raise the floor magnet, and pad the door.

There was quite a big gap between the door and the floor. Not enough to make the magnets ineffective, but enough that I decided to increase the power by raising the floor magnet, fixing it through two washers at each end.

Also, since I wanted the door to open as far as possible but not bang against the corner of my shelves, I stuck a semicircle of felt padding to the bottom of the door where it was hitting. I can now throw the door open, and it will hit the shelves then come to a halt over the magnet almost silently.

Comments

author
TomC57 made it! (author)2015-10-20

I've used hdd magnets on the fridge but this is a great idea for a door especially to hold it open!

author
randersen6 made it! (author)2013-12-11

will that door be able to shut with the magnet underneath it ? (say you wanted to shut the door at some point)

author
pokermind made it! (author)2012-08-31

wouldn't it be easier to remove the pin from each hinge instead of removing the hinge from the wall? Just saying.

author
AdamVigneaux made it! (author)2011-01-09

Good idea! I honestly never would have thought of using magnets as a doorstop. Great for lazy people like me who don't want to knock over and prop back up a doorstop every time they want to close or hold open a door.
Unfortunately I can't do this project because I'm not allowed to create unsightly holes in the floor, but I'll keep it in mind for the future.

author
lemonie made it! (author)2009-02-23

Do you think it would have been possible to glue the magnet to the underside of the door? (And if so with what) L

author
Nachimir made it! (author)Nachimir2009-02-24

Epoxy would probably do it as long as the magnets weren't too close or powerful. It can be very strong, but isn't so good when it comes to pulling or shearing forces. If it was strong enough, that would mean not having to take the door off and rehang, but rehanging is nowhere near as difficult as hanging a new door, and I prefer screws to nasty smelling glues :)

author
lemonie made it! (author)lemonie2009-02-24

Thanks, this is sort of what I expected. Where I live it's not uncommon to find very old and heavy doors with rusty-screws covered by 10 layers of paint. Just getting these off can be a tough job. L

author
Oroka made it! (author)2009-02-23

I did something similar to this at work for a screen door. The frame was metal, so I put 2 of these on the door itself. There is no mechanical latch, just the magnets, and it works great. I also use a few of these magnets for other things like on my fridge, that is where I put my keys. I can throw my keys at it from several feet away, and as long as I hit it, it will stay every time. I also have a few in my locker at work, I clip my pens to them (the ones with metal clips).

author
CameronSS made it! (author)2009-02-22

Good idea! My door tends to swing shut, but it needs to be left open for airflow. It has a little latching thing, but it requires way too much force to latch and unlatch. However, I think that I'll attach the magnet to the back of the door, as it needs more holding power than the bottom mounting seems to provide.

author
TheScientist made it! (author)TheScientist2009-02-22

worth paying attention to his picture tips in step 4... (3rd pic) apparently that was one of his prototype ideas, so if you do it you might need to separate the magnets by a small distance so they can't latch together, or you'll end up damaging the door. really neat idea though. maybe if you put one inside the door (if it has space/you can make space) and one flush with the skirting board it could work and be invisible!

author
CameronSS made it! (author)CameronSS2009-02-22

The door opens out over a stairwell, so it's not very easy to mount a magnet underneath. ;-)

author
Nachimir made it! (author)Nachimir2009-02-23

(Thanks all) If it's a solid door, or even if it's a plywood skinned door with plenty of wood reinforcing the bottom, it should be fine to surface mount. The wood you see in the bottom of mine is only about 1/2 an inch thick, so when I tried surface mount the fixings for the magnet went straight over it. Might be a good idea to pad your magnets a little if they're going to touch, I was going to stick a layer of felt on one of mine if the first version had been workable.

author
TheScientist made it! (author)TheScientist2009-02-22

i'm not saying it's a bad idea, just to be wary of them sticking together so hard that you wreck your door (as he shows in step 4) :) you could stick it on a pole/support on the stairs as an artistic piece though :)

author
Transquesta made it! (author)2009-02-22

See, this is the kind of stuff I really like: 'good old fashioned' innovation! In lieu of an HDD magnet, one could use a neodymium plug of the likes which can be had at any hardware store these days, but the idea itself is killer sound!

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Bio: I live in the UK. Half my working time is spent running indie games events, the rest is spent prototyping… things ¬¬ I used to take ... More »
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