How to Protect a Padlock




About: Doily Grunge now doing small engine restorations, engine art and a bit of everything. Husband & Wife team.

I’d recently added a dead bolt to my workshop for added protection against any would be thieves. But I realised this left the padlock out in the open ripe for being cut with bolt cutters. So I devised a simple and cheap solution to prevent the use of bolt cutters or shims on my padlock.

While I realise this setup is no match for a grinder. It’s designed to act as a deterrent and at very least hopefully slow down anyone trying to break in.

The steps may differ depending on the current setup you have but the basic shape and principles will remain the same.

Step 1: What You Will Need

Materials Needed:
1x Piece of Scrap 1” Square Tube

Tools Needed:
1x Hammer
1x Centre Punch
1x Marker
1x 8mm Drill Bit
1x Grinder
1x Drill
1x Welder

Personal Protective Equipment:
1x Gloves
1x Welding Gloves
1x Welding Mask
1x Ear Muffs
1x Safety Glasses

Step 2: Mark Out Shackle Hole

This part will differ depending on the set up you have. Mark out and centre punch this hole to match your existing lock setup.

Step 3: Measure Shackle Distance

Once the first hole has been marked, measure the distance between the shackle (in this case 25mm) and mark the second hole.

When drilling the first hole (left) using an 8mm drill bit (shackle size), drill through both the top and bottom sides of the square tube. With the second hole (right) using an 8mm drill bit drill through the topside only.

Step 4: Elongate and Cut Hole

Mark out the second hole drilled so it runs all the way to the edge of the steel. Then grind out the area, it should look similar to the picture above.

Step 5: Cut Out Lock Groove

Flip the piece over in the vise and cut in the distance needed to be able to click the lock into place. In this case it was 20mm in. Be sure to cut to the edge of the square tube at the sides.

Step 6: Weld on Shim

Weld a shim (spacer) on what will be the underside hole. The thickness needed will vary depending on the lock used but the idea is to eliminate any up or down movement when the locked it clicked shut. It will also prevent the crucial side of the padlock from being cut with bolt cutters.

Step 7: Final Steps

Now it’s pretty much complete. Give it a paint to prevent rust, check everything fits as it should and that tolerances are tight as this will make it harder for anyone trying to cut through the shackle.

Step 8: Final Words

While this will never stop someone who is determined to break in, it won’t make it easy for them to cut through.

Also make sure tolerances are as tight as you can go the reason has to do with above picture. While there may seem to be “weak spots” as shown above with tight clearance even with these spots cut by bolt cutters the shackle will not be able to pull through due to the top curve. I have tested with an old lock to be sure.

Your hole diameter should be the same as the shackle diameter to avoid any possible slop.

Hope this helps.



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    10 Discussions


    5 months ago

    i'd say it still looks vulnerable to being cut with bolt crops. A full shroud wouldn't be any more work


    6 months ago on Step 8

    Excellent work! I'm going to share this on my locksmith blog. Just so everybody knows, off the shelf products are available that replicate this setup. They are called shrouded shackle padlocks. Not well known to the public but I sell enough of them once people see the design. The abus line is my favorite and also much harder to pick open than master lock.

    1 reply

    6 months ago

    Thanks for sharing this interesting hack. I wish I had a welder to make a few.

    1 reply

    6 months ago on Step 8

    Ere what exactly is that supposed to do ? .I hope things like that for living all you have done there is give a nice stable platform for attack I give that about 10 seconds from locked to on the floor.

    2 replies

    Reply 6 months ago

    G’day mate thank you for your well crafted comment. As previously stated in the instructable this is designed as a shackle guard, protecting from bolt cutters and shims. It’s not impenetrable if someone wanted to really break in they can grind it open, or simply unscrew a panel on the side of the shed and walk in. Thanks.


    Reply 6 months ago

    Perhaps you would be kind enough to re-state what you are trying to say. Thank you in advance.


    6 months ago on Step 8

    I'd also use something better than a Master lock. They only have 4 pins, none of them are security pins, and you can open them with a hammer blow to the side you have facing out. Check Bosnia Bill's LockLab on YouTube for recommendations. (He's picked these things with everything from bent paperclips, to a zip tie he cut some valleys into, generally in about the same amount of time it takes to find the right key on a keyring.

    Awesome shackle guard tho, I'll probably make one for my shed.

    1 reply