Impossible Screw in a Block of Wood




About: -----------------------------------------------------------------16 year old, sick with a deadly disease called DIY-itis!-----------------------------------------------------------------Hi FTC! My I'bles con...

A few months ago, I came across Seamster's Instructable Impossible Nail in Wooden Block. I thought it was really cool, and knew I had to make one!

You show it to people. They look at it, look at it more, flip it around... Wha...HOW?

And then you show them!


Many times I see, or think of projects, and don't make them immediately since I'm busy working on other stuff. They can stay in my list of projects for months. Every couple weeks something might remind of the project, and while thinking about it, a random idea for improving it might pop into my head.

After a few months, I can end up with a long list of modifications for the original idea. It's what I call good procrastination. I'm probably not the only one, but this is where many if not most of the project ideas that I'm proud of the most have come from.

For example, in this project, I didn't want to use a nail. I also thought of using a bolt, screw, or an old drill bit.

Out of nowhere, I also had the idea that since wood will always break or split only from one side of end-grain to the other (think of how an axe is used). I thought that breaking the piece of wood vertically makes much more sense than horizontally. It's simpler to break (especially for a smaller sized puzzle like mine. Think locket-sized for a necklace!), easier to glue both parts together, and easier to drill and screw in the screw.

To do that, all I needed to do was flip the orientation of the board! If you look closely, you'll see that Sam's puzzle has side grain on the top, so the break line will be horizontal. To make mine break vertically, I would need to make it have end-grain on the top.

I think my way just makes more sense. If you have a better way of explaining this, please comment below!

Let's get started!


(Watch the quick Youtube build video and see it in action!)

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Step 1: ​What You'll Need:

Want to make this project? Here's what you'll need, or at least what I used!

For those who aren't able to salvage parts for free, I've added some links below. Keep in mind that these parts can be acquired at a hardware store, or anywhere else online. If you don't see something that you think should be here, or would like to know more about a specific tool/part that I used, feel free to ask in the comments.

I made it for FREE since I already had everything that was needed on hand.


Hardware, Materials & Consumables:



Approximate Time: A few hours. If I made another one it would probably take me about 2 hours...

Difficulty: Fairly Easy


Step 2: Choose the Wood, Screw, & Holes Size

Technically, everything here relies on everything, but these were my basic considerations. I had to do with what I had, which made for quite a bit of experimenting.

The considerations for choosing the screw - I wanted it to be...

  • A wood screw
  • Have a wide thread (perfect terminology doesn't belong in my I'bles :)
  • Not too long or too short
  • Head diameter not bigger than wood board thickness

The considerations for choosing the piece of wood - I wanted it to be...

  • Wide (so I would be able to cut it to square)
  • Thin
  • Square
  • Easy to break

The considerations for choosing the size of the holes - I wanted them to be...

  • Not too big, not too small
  • Make it look impossible for me to screw the screw in from the side
  • Not to big, so there would be enough wood so it wouldn't break
  • Not too small, so the screw could be seen well enough (on camera, to be honest)
  • 20mm spade bit was what I had, and I thought it would work well

Pictures above :)

Step 3: Drill the Holes (don't Forget to Rectangle-ify It)

I marked a line in the middle (height-wise) of the piece of wood, about a centimeter away from both SIDEGRAIN edges. I then put one side of the spade bit on the line, and marked a dot right in the hole of the spade bit. This was where I was going to drill the hole, as you can see in the pictures.

I chucked up a inserted 20m spade bit into my cordless drill since I needed the lightest drill that I had/no annoying cord in the way. My small one is really light.

The timelapse of the Youtube video doesn't really show it, but drilling was really hard. Soft wood, a spade bit, and a lot of tearout*. A hole saw would have been ideal, but I didn't have one that was small enough. I cleaned up the mess with my homemade-ish drum sander

I think rectangular objects look better than square shaped objects, so... That's what I did with my handsaw and magnetic saw guide (I have another I'ble on that)!

*ᴼᶰᶫʸ ᵒᶰᵉ ᵒᶰᵉ ˢᶦᵈᵉ, ᶜᵒᶦᶰᶜᶦᵈᵉᶰᵗᵃᶫᶫʸ ᵗʰᵉ ᵒᶰᵉ ᵗʰᵃᵗ ᴵ ʰᶦᵈᵉ ᶠʳᵒᵐ ᵗʰᵉ ᶜᵃᵐᵉʳᵃ :)

Step 4: BREAK IT!

I clamped the piece of wood in my homemade wooden vise, and...



I BROKE IT! Perfect - exactly where I wanted it to!

Ok, it wasn't actually that hard ;) Especially not with the huge hammer that I used!

Step 5: Screw in the Screw!

I first practiced on a piece of scrap wood, and then drilled a pilot hole for the screw. I drilled the pilot hole only a teeny tiny bit smaller than the threads of the screw so the threads would BARELY engage. I didn't want the screw to be loose, and I didn't want to make the wood expand, which could ruin the perfect glue joint.

The drill that I used to screw the screw in has a really sensitive clutch that allowed me to screw the screw in really gently, without damaging or cracking the wood. Screw. Screw. Screw...driver. It's an alternative and another reason to add screw again into this paragraph!

Step 6: ​Glue the Pieces Back Together

I was planning all along to use CA glue, but decided to use wood glue (a weaker type than what you probably use) instead, since it doesn't cure immediately (good when nothing goes wrong!), and because I thought it would fill the gap better. IT ALSO DOESN'T LEAVE HORRIBLE STAINS! Ask me how I know...

I applied a small pea-sized amount to each side, andI clamped it tightly in my vise, and of course it was the perfect time for the vise to break!

After the issue was fixed, I tried to push teeny tiny bits of glue and fine sawdust into the crack, and into other random places, which I thought would help conceal it. I don't think that this helped, though. It mainly made small stains that were slightly darker than the wood because of the dust that was on my fingers when I applied it.

Step 7: Sand (and More and More and More)

About an hour after I glued both pieces together, I removed the puzzle from the vise, and started sanding.

While typing up this I'ble now, I can't see any visible signs of a glue joint on the face or end-gain! However, I can, unfortunately, see a small stain from CA glue that I used to glue a small piece of wood that chipped out while I was working. But it still isn't very visible, and I think can be removed with more sanding (I didn't want to breath more fine Pine dust).

I think I spent close to two hours sanding it (and rounding over the edge), but I think I could have saved a lot of time if I progressed through the grits instead of starting from fine.

I have to admit that this looks way better than I thought it would. Pine can actually look quite nice!

DO NOT USE CA GLUE FOR GLUING IT! It will make sanding way harder!

Step 8: ​DONE! | More Thoughts | Video!

See the end result, and a quick video of the process of making it, on Youtube!

Some more thoughts:

  • This is a project that can be made only out of wood! As far as I know. How about graphite?
  • I normally don't work with Pine since I'm really sensitive to it, but the piece that I used was salvaged from a 15+ year old wine crate, so it smells only when I produce a lot of sawdust. Luckily I was working outside, on a fairly windy day, so it was fine.
  • Couldn't this be an awesome gift? It can be made fairly quickly with only a few tools.
  • If you haven't had a lot of luck disguising the joint, how about charring the wood slightly with fire? Just an idea that might help.
  • Do you think seasonal expansion and contraction might be an issue? If yes, how do you think I should seal it without bringing out the grain, which could make the crack more visible?

I will be giving away free Instructables memberships to members that make their own screw (or anything else) in a block of wood. Will you be the first one?


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I read ALL comments, and reply to as many as I can, so make sure to leave your questions, suggestions, tips, tricks, and any other ideas in the comments below! - Thanks!

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45 Discussions


1 year ago

Nicely done! You mentioned this is a project that could only be done with wood. I think it's quite possible to do something like this with metal. You would need a few more tools, but I think quite possible for sure!

12 replies

Reply 1 year ago

Thank you!

How could this be done with metal? I mean, metal won't snap in half if you hit it with a hammer... It will stretch, bend, and then maybe break.

Plastic is kind of the same, I guess.


Reply 1 year ago

You can use carbon steel. Take your block or piece, drill your holes, insert your item, TIG it closed, grind it clean, then tarnish to a fine petina.


Reply 1 year ago

But wait!

I was thinking of a softer metal like aluminum. But what if you freeze steel, and then smash it with a hammer?

That would be interesting. I've heard that bike thieves freeze bike locks with gas, and then break them. I wonder if something like that could work here too. Then it could be welded (or maybe glued with silver colored epoxy) and then polished.

If anyone has done something like this before, please do post a comment!


Reply 1 year ago

My thought was to do it exactly the same way you have done with the wood, but instead of gluing it on the seams, you would MIG weld it back together. Then you could clean up the seams by sanding it to a nice finish. It would be a lot more work, but I definitely think its possible. Check out this video, its not the best video but it does show you the general idea.


Reply 1 year ago

I think I will try that if I ever get a welder. It really will make it impossible for people to guess!


Reply 1 year ago

You could cut the metal puzzle apart, then fasten it back together with small bolts. Then by polishing the seams and filing/polishing the head of the fasteners, you wouldn't ever know they were there.


Reply 1 year ago

Do you mean cut it in half, for example with an angle grinder? And then drill and tap the holes of one half, fasten them together with screws, and grind/polish the heads of the screws so they aren't seen?

But then I think you still would need to fill the gap between the two pieces (from the kerf of the blade/twisting of the blade) by welding, and then grinding and polishing it out.

Sounds very interesting! :)


Reply 1 year ago

You could do it with silver. Expensive, yes, but a silver solder line is very hard to distinguish from surrounding silver.


Reply 1 year ago

I like that idea, you just gave me a thought, I wonder if this would be possible to do by making a mold and pouring it all in one piece so the screw was embedded into it. If so, you could do this and end up with the screw inside something like a clear resin block, which I think would be amazing! Thoughts?


Reply 1 year ago

On a second thought, I don't think I have a way to contact him without him thinking I'm the average spammer...


Reply 1 year ago

Goes back to my idea of a locket for a necklace :)


Reply 1 year ago

This version is literally impossible by bending the wood with hot water. I would love to see someone prove me wrong.

Technically, all illusions are created by "cheating" in some way. Bend it, break it, boil it, modify it, rebuild it... etc.