Introduction: Impossible Lock in Wood

About: My name is Troy. I'm a Mechatronics and Aerospace Engineer. I make things out of wood and electronics and spend time outdoors (especially SCUBA diving).

Puzzles and impossible objects have always fascinated me. Anything you can hold, think about, and envision how it was made, piques my interest. That is why this and many of my projects have been created.

The inspiration of this impossible object came from seamster's Impossible Nail in Wooden Block instructable.

Where many of my previous impossible objects utilize the elastic properties of wood through boiling, this instructable uses a much different technique.

Step 1: Tools and Materials



  • Hole saw or Forstner bit larger than your lock
  • Chisel
  • Rotary Tool
  • Glue
  • Clamps
  • Table saw
  • Band Saw
  • Disc Sander

Step 2: Drill a Hole

Select a pice of wood that is quite a bit larger than your lock. Since we will be splitting the wood down the grain we want to be flexible and conform to the location of the split. If the wood is too thin, the split might not happen in the middle causing un-alignment issues in later steps.

Drill a hole larger than the combination lock to be used.

My combination lock is 1 7/8 in. in diameter so I drilled a hole 2 1/8 in. in diameter giving 1/8 in. clearance around the lock. You can drill a larger hole if you'd like more clearance.

If the hole is burnt or not smooth, you can use a spindle sander to smooth out the inside surfaces of the hole.

Step 3: Split Block

Using a large chisel, split the block down the middle.

Step 4: Mark the Wood

Holding the lock in the hole, mark the location of the shackle with a pencil.

Repeat with the other side.

Step 5: Cut Out Channel

Using a rotary tool, cut half a channel in each side of the block.

Because no one will see the inside of the block, the channel doesn't need to look smooth, it only needs to allow clearance for the shackle to be placed inside. Test fit the lock as you go to ensure that the wood can be glued back together without interference from the lock.

Step 6: Glue

Apply glue to one side, insert the lock, and apply equal pressure with many clamps.

If you can, wipe away as much glue as possible around the lock face. No real need to worry about glue seeping in around the shackle as it will not be visible in the finished product.

Step 7: Cut Away Waste Wood

Using a combination of table saw, band saw, and disc sander, remove the excess wood to have the desired result of a lock shaped piece of wood surrounding the combination lock.

Once you have your desired shape, sand everything. Remove all traces of glue within the hole around the lock.

Remember to sand a flat face on the bottom of the wood to allow it to stand up.

Step 8: Apply Finish

Since I didn't want a lacquer applied to my lock, I went with a beeswax based finish applied with a cloth rag.

Step 9: Admire Your Work

Now proudly display your impossible lock in wood to your friends. Watch them look on in amazement and wonder as they try to figure out how you did it.

If you made it this far, you may like my other impossible objects and puzzles

Epilog Challenge 9

Participated in the
Epilog Challenge 9