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Jigsaw Puzzle Tutorial: Double Cutting

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  • Jigsaw Puzzle Tutorial: Double Cutting

    The combination of reading Shawn's recent tutorial and my desire to make a trick puzzle have resulted in this small tutorial on how to double cut a trick puzzle. In this case, it's a really evil trick puzzle.

    First - take a look at this short video that shows the puzzle I made.

    YouTube - six piece trick puzzle

    I'll be following on shortly with the step by step on how I made this puzzle.


  • #2
    I'm calling this puzzle "Six Piece Trick Puzzle". I'm not all that original.

    I primarily cut freehand puzzles, but this trick puzzle begins with a pattern that I created in Powerpoint.

    The base pattern is just a circular ring, divided into 6 pieces. It also includes a duplicate subsection, which is how the double cut is made.

    I made the 6 divisions uneven (i.e. they are not 60 deg sections). I did that so it wouldn't be immediately obvious which section was double cut. If one section was larger than the rest, it would be obvious that was the "trick" piece.
    Attached Files
    Member - Level 2
    Last edited by iohonnes; 12-23-2009, 03:14 PM. Reason: typo


    • #3
      Step 1: Mount the pattern and cut out the sections. It's as easy as it sounds.

      The section marked "A" is where the double cutting will take place. Essentially, we are going to replace section "A" with a slightly larger section (let's call it "A prime") from the duplicate subsection. "A prime" will interlock with the base puzzle on both sizes, but will be too big to fit into the puzzle correctly.
      Attached Files


      • #4
        Step 2: The First Double Cut

        We are going to cut two layers of the puzzle at one time. That's a double cut. Theoretically, the top will be able to interlock with the bottom and vice versa.

        To start, I placed the duplicate subsection on top of the base puzzle and secured with masking tape. I made pencil marks were I wanted the entry and exit cuts to go. The marks are aligned with the right hand edge of section "A" on the base piece.

        I then cut the piece using a FD-SP blade. The blade is very thin and not intended to cut through 1/2" material, so you need to take it slow. If you go to fast or apply too much side to side pressure, the blade will deflect and cause an angle cut (or even break). If you end up with an angle cut, the top piece will not be able to interlock with the bottom piece and the entire puzzle will need to be either re-cut or "fixed" by performing some re-work (essentially some delicate touch up of the offending interlocks with the saw or sandpaper - not a fun time!).

        Here is the finished cut.

        Remove the tape and discard the small waste section from the top piece.


        • #5
          Step 3 - The Second Double Cut

          This is where the trick part of the puzzle comes in. I've already made one cut where the top and bottom sections share a common interlock shape. Now, I'll make a second cut, but this time the top piece will be shifted slightly.

          In the picture below, you can see the blade exit point on the bottom piece. I shifted the top piece so that the corresponding cut is now about 3/4" inch to the right of the bottom cut. I also marked where the left hand side of the "A" section is on the bottom piece. That's where I'm going to make the second double cut.

          After aligning the pieces, I again secured with masking tape and started cutting.


          • #6
            The Results of Double Cutting

            After discarding section "A" from the bottom ring and keeping the double cut top section "A prime", we have a ring with a piece that is obviously too large to be inserted. But the interlocks LOOK like they should work on each side, and they do!

            I cut the rest of the arc into the remaining five pieces; I didn't use any special tricks or cuts. They were just normal freehand cuts using the template lines as entry and exit guides.

            The following pictures show how the all of the pieces interlock in some way.


            And if "A prime" is inserted into the puzzle "correctly", the overlap just shifts somewhere else!

            That's the trick. The puzzle can never be correctly assembled.
            Member - Level 2
            Last edited by iohonnes; 12-23-2009, 04:29 PM. Reason: forgot a step!


            • #7
              Step 4 - Finishing

              I've been itching to make this puzzle for a long time, but I've always been hung up on the image that should appear on the puzzle. The image would have to be exactly the same at the interlocks of both double cuts, but the image on piece "A prime" would have to have a longer arc length than the image on piece "A".

              Given my limited Photoshop and Inkscape skills, I couldn't think of an easy way to achieve that, without drawing something myself and than carefully aligning the pieces for the double cut.

              I was in a meeting on Monday morning (love those meeting!) when it struck me that I could avoid the art problem (and the alignment problem) by painting the pieces AFTER the double cut. I'm not an artist, so I finished the piece with a really simple design.

              The first step was to give a quick coat of paint to all the pieces.

              I cut the interlocks so that it was obvious to the assembler which piece went where; I wanted the paint job to continue that trend so I started to dab white paint on the pieces ensure that some white paint when right on the interlocks - giving a look of continuity across the pieces. I painted five of the pieces first.

              I wanted that last piece to have the same continuity, so I disassembled the two end pieces in the arc and rebuilt the bottom section with the extra piece. I finished painting them in the same way.


              • #8
                And the trick puzzle is complete! We have a six piece puzzle where all of the pieces interlock and the art work is continuous across the entire puzzle, but the puzzle can not be assembled.


                As I said in the video, Stave Puzzles released a commercial version of this in the 1980s. They obviously did a much more professional job with the art work and the cutting. I have no insight into how they actually cut their version; there can't be too many ways to cut a puzzle like this, so I assume they did it in a similar way.

                If I were to do it again, I would change two things.

                1) I *might* use a slightly large blade to make the double cuts. The FD-SPs are not made for cutting two layers.

                2) I would make the overlap region a little smaller (maybe 1/2"?) On my first attempt at making this puzzle, I used an overlap of 1/4" but I was able to "stretch" the puzzle to fit in (more like wedge in) the last piece. In this copy, the overlap was large enough that it's obvious that the piece will never fit in.

                And, for the record, double cutting can be used in normal puzzles too. Puzzles that can actually be assembled. I just wanted to annoy my wife for Christmas.


                • #9
                  Thank you.
                  Wonderful idea and execution.
                  Zohar - probably the only one.

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                  • #10
                    Originally posted by iohonnes View Post
                    .... I just wanted to annoy my wife for Christmas.
                    HaHaHa !! You're an evil man, John! But I likes ya!

                    Thanks for sharing that very devious puzzle concept!
                    Shawn Ferguson

                    Come visit at The Ferguson Puzzle Company !


                    • #11
                      Thanks a bunch. I'll be doing several of these for sure!

                      This one deserved to be a sticky as well! So I made it one.
                      Grandpa making Sawdust
                      Last edited by wood-n-things; 12-23-2009, 05:56 PM.
                      "Still Montana Mike"

                      "Don't worry about old age--it doesn't last that long."
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                      • #12
                        Very cool and very evil.

                        Originally posted by iohonnes View Post
                        double cutting can be used in normal puzzles too.
                        I may try to make a piece that fits into two places in a smallish puzzle and see if I survive the experience. It'd definitely be too nasty for my crowd on a big puzzle. They generally expect that once a piece fits in, it's in the right place to stay!

                        I just wanted to annoy my wife for Christmas.
                        You have an apology gift ready?



                        • #13
                          Originally posted by Arcy View Post
                          I may try to make a piece that fits into two places in a smallish puzzle and see if I survive the experience.
                          I'm waiting for the right normal puzzle to put a couple of double cut pieces into. Because I want the victim to have maximum "enjoyment", I want to ensure that the pieces are the same exact color. That pretty much limits me to certain types of graphic art, where areas of "flat" color exist. Most paintings and photos have a color gradient to them - you know, where the sky slowly changes shades of blue across the length of the puzzle. Most puzzlers would notice the subtle change in color between pieces.

                          I'll post if I ever find the right puzzle.



                          • #14
                            That's exactly what I was thinking, John. This would work well in something Kandinsky-ish.

                            I've been digitally painting my own puzzle images, so I can either put in a flat color or (muahahahaha) duplicate a colour blend.



                            • #15
                              Kathy (my wife) has started working on it; she knows it is a trick puzzle but she can't quite figure out the trick. She's not pleased at the moment. She'll be less pleased when she figures out the trick (or is that a lack of a trick?).


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