Wednesday, June 24, 2020

Just Another 6-Piece Burr, Or Is It? - Welded Burr

Welded Burr by William HuJust when you think that nothing new can be done with a 6-piece burr, a new design comes out.  I have quite a few puzzles in this particular format.  I like to see how designers transform such an innocuous looking puzzle into a serious challenge that belies its appearance.  So, when Cubicdissection offered Welded Burr by William Hu, I made sure to acquire a copy.  After maturing in my puzzle pile for 6 years, I figured that it had reached its peak character and I pulled it out for a go.

In no time at all, I had separated the puzzle into 3 sets of 2 pieces.  Unfortunately, Eric Fuller apparently had some gluing snafus and the pairs were stuck together.  It was like they were welded together…

The pieces were made from Aformosa and the ends beveled for a nice finished appearance.  Each piece does look like it was made by gluing 2 standard burr pieces together as the name would suggest.

With a level of 4.2 and no rotations, you would assume that this puzzle is not difficult and you would be right.  Even as an assembly puzzle, the characteristics of the pieces hint at how they are paired together.

Welded Burr PiecesJoining the pieces together was an interesting take on the 6-piece burr, which makes me wonder if anyone has done an exhaustive search over all possible welded 6-piece burrs to see what new possibilities can be generated.  For all I know, William has already done that and Welded Burr is the result of that search.  If not, it may be worthwhile for someone to take on that challenge.

Welded Burr is a great puzzle to offer to a new puzzler.  With only 3 pieces, a low level of difficulty, and hints for assembly, it is very approachable for just about anyone.  It’s also a good stress reliever to play with if you are having issues solving more difficult puzzles, which is why I pulled this one out of the to-do pile this week.  And you thought that I only pushed the difficult puzzles into the pile.


  1. How many other variants of this are out there?

    I'm only familiar with Glued by Benedetti.

    1. Don't know, but Terry Smart mentioned on Facebook that he found a level 5.3 version.

    2. These are the three permutations: (x+y), (y+z), (z+x). I seem to recall reading or seeing, many years ago, a variant that is the three permutations of (x+[y/2]+[z/2]); but I cannot recall if the level was as high as 4.2.
      So, Ken, who will take on the challenge of investigating the possibilities -- you or me?

    3. I already have 2 large investigations underway. You can have this one. :)

    4. I have 397 tests remaining from my current project of 472 tests. When I am done all that, I will have to ask you to remind me about this. If William Hu is reading, perhaps we could get some further info... -Tyler.