How to Make a Padlock Shim

Co-authored by Trevor Maclise

Last Updated: December 26, 2022 Approved

Have you lost the key to a padlock? You could call a locksmith or cut the shackle, but you may be able to quickly and easily open it with a shim, a thin piece of metal that you slide into the locking mechanism. You can buy shims for anywhere from $2-20, or you can make them with metal you have laying around the house. Here’s how to create and use a shim made from an aluminum can.

Steps

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You can use just about any aluminum soda or beer can. They are all thin enough to cut a shim.The only requirement is that the sides of the can be smooth (without ridges), since you will be using the metal from the sides to make the shim.^{[1]
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Use scissors, tin snips, or a knife to cut off the top and bottom of the can. Cut right at the border at the point where the sides taper at the top and bottom. You may want to use a knife or razor blade to make a small starter cut in the taper so that you can easily get your tin snips or scissors in. Try to make the cutting line as straight as possible, but don’t worry about it too much, as you will trim them later.^{[2]
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- To maximize the metal you have to work with, try to avoid cutting too much into the flat part of the can’s side. Instead, err on the side of the taper.
- Take your time when cutting the shims. The straighter and smoother your cuts, the better your shims will work. You’ll also be able to make more shims per can if you’re careful with your cuts.
Try to make the cut as straight as possible––many cans have a “seam” that you can use as a guide. You want to be able to flatten out the piece of metal into a rectangle.^{[3]
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Now that the can is easier to work with, trim the top and bottom to get rid of the rough edges. If the metal still has some sticky residue on it, scrub and rinse it off with warm, soapy water, and rinse off the cutting tool, as well.
Divide the metal into two long strips.^{[4]
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You should be able to make four or five squares, each about 1.5-2 inches (3.8-5cm) on each side. Make sure the edges are smooth and straight.^{[5]
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You should have two equal rectangles.
Aim to create the point of the shim by cutting out two humps a little bit in from each side of metal (see picture). Try to make the cuts as smooth as possible, and try to get rounded humps, as opposed to pointed triangles.
The fold should bring it down just above the humps of the “M”. This will be the handle.
Bend the flaps back and away from you, over the handle piece.
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Aim to round the shim so that its shape fits the lock shackle. You can do this by bending the shim around the shackle itself, or you can shape it around a pen or pencil (as long as the pen or pencil doesn’t have ridges). Your shim is now finished.^{[7]
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Use the shim on a padlock. Some more advanced locks will require you to use two-one shim on each side of the shackle.
- Using a shim takes a bit of practice. It’s easy to bend them or tear them in the small space between the shackle and the locking mechanism, and it can be hard to get them into position. Fortunately, you can make many shims out of a can, and once you get the hang of it, the process will become much easier. Just don’t try to force anything, because if you get a piece of the shim stuck in the lock, it will make your job even harder.
- Once you have driven the shim into the shackle housing, take the tabs you created and pull on them from side to side. Even if the shim itself doesn't move, this motion is vital to opening the lock.
- Some locks require that you insert a shim into both sides of the shackle (both holes where the shackle enters the lock). If you can't seem to get the lock open with one shim, try two.
- Once you hear a click similar to that of when you pull an unlocked shackle out of its housing, the lock will be able to be opened.

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What do I do if the padlock is a small one used for a suitcase?

Adrian

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Make a smaller shim.

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What if the shim doesn't go in?

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Make a new shim and use that.

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Tips

These shims also work well on combo locks if the tip of the shim is rounded rather than being pointier.

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Not all padlocks can be opened with shims, particularly those with a double-ball locking mechanism. Most older locks, and many of the cheaper newer locks can be opened, however, so give it a try before you resort to cutting a lock or calling a locksmith.

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Commercial shims come in several different sizes, each specialized for locks of different sizes. You can simply adjust your cuts if you find that you need a larger or smaller shim than the one produced with these instructions.

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Warnings

Be extremely careful when cutting the shims and when handling them to open a lock as the edges of the aluminum can be razor-sharp, so you can easily cut yourself. Also, be sure to exercise caution when using your cutting tools.

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In some jurisdictions, possession of shims is illegal, even if there is no illegal intent. Be sure to know the laws in your area before constructing or carrying shims.

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Carrying shims in public may be illegal because in some areas they are considered weapons.

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Don't use these shims to open locks that do not belong to you unless you have explicit permission from the owner to do so.

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Things You'll Need

A lock to open
A smooth-sided aluminum can
Tin snips or scissors; tin snips are the easiest tools to cut the aluminum with, but you can also use scissors or a knife. If you use either of the latter tools however, use some that you can afford to destroy, because cutting the metal may dull them significantly.
Needle-nose pliers