Introduction: Classic Horseshoe Puzzle
This horseshoe puzzle is a classic that's been around for many years:
Two horseshoes are permanently joined with short sections of chain, and a metal ring encircles the chains and appears to be irremovable from the apparatus. But if you know the technique, you can remove it!
I thought it would be fun to make this to add to my collection of homemade puzzles. This Instructable covers how I made two versions of this same puzzle - one requires welding and the other does not.
And at the end I'll show you how the puzzle is solved!
Step 1: Supplies
To make either a welded or non-welded version of this puzzle, you need the same basic supplies.
You need two horseshoes. Where I live I was able to pick some up at a local ranch supply store. If needed you can order them online, although you might have to get them in bulk. If you plan to weld them you'll want real forged steel horseshoes rather than cast iron "craft" horseshoes.
You need a metal ring. For my welded version I used a ring that is 1/4" thick with an inside diameter of 2". For my non-welded version, I used a ring that is 1/4" thick with an inside diameter of 2.5". I bought these at a hardware store.
You need some chain. I had some old car tire snow chains, and this is what I used. The links are about 1/8" thick, and 1.5" long. A note about welding these chains: the chains I used were coated in zinc, which if welded will release toxic gas. I soaked my chains overnight in household white vinegar which removed the zinc coating. This is a great method if you plan to weld any zinc coated hardware - you can grind it off, but this is easier and much more thorough.
You need tools. I'll cover the various tools I used in each step.
Steps 2 - 5: Welded horseshoe puzzle
Steps 7 - 8: Non-welded horseshoe puzzle
Step 2: Welded Puzzle
I used my metal band saw (in this homemade stand) to cut off the rounded tips.
I did this just to quickly get to clean weld-able steel, but then I ended up grinding away the surrounding mill scale anyway, shown in the next step.
If you're not familiar with welding, you should go read through the Welding Class here on Instructables. Also worth your time is this Tested video, in which Jamie Hyneman gives the most perfectly concise introduction to mig welding.
Step 3: Weld Prep
I used a flap disc on an angle grinder to clean up the scale around the tips to reveal clean, bare metal for welding. The horseshoes were held to a sawhorse with a clamp to do this.
The shoes were positioned on my metal welding table next to the chain, which was propped into position with some laminate sample chips (which I find endlessly useful around the shop - grab some next time you're at the home store in the countertop area).
Step 4: Tack and Bead
I tacked the chains in place to the horseshoe tips.
I then welded full beads to connect the chain links permanently to the horseshoes.
If you're using similarly sized chains and ring to what I've used, I'd recommend aiming for an open gap of 5/8" inch between the tips of the welded chain links.
This results in a puzzle that borders on literally impossible, due to very tight tolerances . . which is great!
However it is perfectly solvable without any force, but it does require very precise positioning to get it apart and back together.
Step 5: Clean Up
The welds on the left side in this photo had been steel-brushed to clean them up. The ones on the right had not been.
After steel-brushing both sides I went back with a flap disc on an angle grinder and cleaned up the welds a little more. This is not necessary but since this is an object that will get a lot of handling, it's nice to have it be pretty smooth without weld spatter or any rough snaggy areas.
Step 6: One Down, One to Go
Top photo is the welded version just completed.
Bottom photo is the non-welded version which follows.
Step 7: Non-welded Puzzle
For this version you need two solid chain links along with four cut links.
I used an angle grinder with a cut-off wheel to cut out the link ends as shown in the 2nd photo. Be sure to fasten the chain link securely in a vise before attempting to cut it.
A grinding disc was then used to clean out the cut link ends a little as needed, as well as to remove some material from the tips of the horseshoes.
The links just need to slip snugly onto the horseshoe tips.
Step 8: Epoxy Putty
I love epoxy putty and use it all the time.
I used SteelStik for this. I positioned the links so the tips were about 1 3/8" apart, and mixed up and applied small mounds of epoxy around the chain links to affix them to the horseshoes.
Be sure to not mix up more than you can apply within a couple minutes though - this stuff cures very quickly. I was doing this in a hot garage on a 90° F (32° C) day, and I think that sped up the cure time even more.
Once the epoxy putty was fully cured I used a drum sander on my rotary tool to sand the mounds into smoother, less blobby shapes. Wear a dust mask if you do likewise, along with safety glasses.
Step 9: How to Solve It
Half the fun of a puzzle like this is figuring out how to solve it. But here's some guidance if you need it.
The 2nd photo in the series shows the trickiest part of this puzzle. You basically need to twist the horseshoes in a way that creates a gap in the chain section where the ring can fall down and be wriggled down the horseshoes, and slid off as shown.
These photos don't reveal how incredibly challenging this actually is, especially on this version. It's a very precise, narrow fit to make this happen and more elusive than it appears.
My non-welded version has wide open tolerances and you can pretty much get it apart by just randomly shaking and moving the horseshoes around. If you want to make a non-welded version, but just more challenging - simply reduce the gap between the links that are attached to the horseshoes, and use a smaller metal ring.
If you make one, I'd love to see it. Please leave a comment and a photo!
Thanks for reading!