Wooden Burr Puzzles | Popular Woodworking Magazine

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Notch a few sticks and drive your friends crazy.

Something must give way when pieces of wood intersect at 90˚ angles. This is the reality behind the curious assemblies shown here. Known as burr puzzles (because they resemble seed burrs), these puzzles are made up of three or more jagged pieces that go together at right angles. Give one of these cheaters to an unsuspecting friend and watch the fun. Taking apart each puzzle is the easy part. Putting the pieces back together is the real challenge!

Accuracy is the key to making puzzles work effectively. Each part must be carefully marked, milled and cut. One option is to make the parts purely with hand tools, as students did nearly 100 years ago, when puzzles like these were used to teach woodworking skills in manual arts lessons. To follow this option it is sufficient to take the dimensions from Figs. B, C and D and go to town.

The power tool option

Making parts using power tools is faster and easier – useful considerations if you plan to make more puzzles. The first step in any puzzle is to mill long blanks to their final size – be precise and make sure the blanks are square. Then cut the individual puzzle pieces to the exact length from the blanks.

Fig. A) Dadoing Jig

A shop-made jig makes it easy to carve the pieces for all three of these puzzles on the table saw, using a die set (Fig. A). This mask consists of a sled with guides, a clamp and a fence. The guides fit into the oblique slots of the saw, so the sled makes perpendicular cuts. For clean, tear-free results, a portion of the mask should be dedicated to each size of the notch. If the blade is offset between the guides as shown, both sides of the slide can be used. The wide enclosure houses the nut set from both directions, for safety. The stop blocks and spacers precisely position the pieces, so that the notches (actually the slots) are cut precisely. Like the puzzle pieces themselves, the spacers must be precisely cut. To set the mask, lock a stop block to the right of the slot (the exact distance, called the “mask setup size”, depends on the puzzle you are creating). Use a puzzle piece and spacers to locate and block the other stop. After installing each piece, secure it with the toggle clamp before cutting the nut.

The dice need to fit snugly, so always make extra puzzle pieces and start making rough cuts. Testing nut widths and depths is easy enough, because most of the pieces go together with the girth joints. When the dados fit perfectly, their widths are correct; when the joint surfaces are flush, the rebate depths are correct. The pieces will go together easier if you lightly sand the edges. That’s all; are you ready to leave.

The drool in three pieces

On the surface, this simple puzzle is my favorite, because it can’t be real! It is the only one of the three puzzles that requires cutting hooves in two dimensions.

Create the pieces

  1. Cut 2-1 / 4 “long blocks from the 3/4” square butt, including the extras for trial cuts (Fig. B).

    Fig. B)

  2. Set the saw and jig to cut 3/8 “by 3/8” nut.
  3. Lock the right mask stop block 1-1 / 8 “from the edge of the 3/8” slot.
  4. Place a test piece and both 3/8 “spacers against the right stop. Fit the left stop block against the spacers and secure.
  5. Make a test cut and check the width and depth of the nut.
  6. Install piece # 1 and cut the first nut (Photo 1).

    Photo 1. Cut a 3/8 “by 3/8” nut after locking the stop blocks in place and installing piece # 1 with both spacers to the left.

  7. Rotate piece no. 1, reposition the spacers and cut the second nut (Photo 2).

    Photo 2. Cut a second nut in Part # 1 after turning it 90˚ towards the nut set and reinstalling with a spacer on each end.

  8. Rotate the end of the jig to end and set it to cut 3/8 “by 3/4” nut.
  9. Lock the right stop block 1-1 / 8 “from the edge of the 3/4” slot.
  10. Repeat steps 4 and 5.
  11. Install piece # 2 and cut the first nut (Photo 3).

    Photo 3. Use the opposite side of the jig to cut 3/4 ″ wide nut in pieces # 2 and # 3. Cut the first nut, rotate each piece 90 ° towards the nut set, then cut a second nut. Make all cuts with a spacer installed on each end.

  12. Install piece 3 and repeat step 11.
  13. Turn piece # 3 and cut the second nut.
  14. Re-install part no. 2 and repeat step 13.
  15. Smooth out the corners of the bridge on piece # 3 to create an octagon.

Assemble the puzzle

  1. Connect pieces # 1 and # 3 (Photo 4).

    Photo 4.

  2. Install part no. 2 from above (Photo 5).

    Photo 5.

  3. Rotate piece no. 3 90 ° clockwise (Photo 6).

    Photo 6.

The burr in six pieces

By all accounts, this burr is the best known, because the six pieces can be carved in many different ways and still assembled to create the same shape.

Create the pieces

  1. Cut 2-1 / 2 “long blocks from the 3/4” square butt, including the extras for trial cuts (Fig. C).

    Fig. C)

  2. Set the saw and jig to cut 3/8 “by 3/4” nut.
  3. Lock the right mask stop block 1-1 / 4 “from the edge of the 3/4” slot.
  4. Place a 3/8 “spacer against the right stop, followed by a test piece and the remaining 3/8” spacer. Fit and lock the left stop block against the spacer.
  5. Cut the nuts into a couple of test pieces and fit them together to check the width and depth of the nuts. Make the necessary changes.
  6. Install piece # 2 with a spacer at each end and cut a nut. This completes piece # 2. Piece # 1 has no die: it’s already done.
  7. Cut the same nut into pieces # 3 to # 6.
  8. Rotate piece no. 3 90 ° towards the nut set and install it with both spacers on the left. Cut a second nut. This completes piece # 3.
  9. Cut the same second nut on pieces # 4 through # 6. Complete these pieces by moving the spacers to the right and cutting a third nut.

Assemble the puzzle

  1. Connect pieces 3 and 4 (Photo 7).

    Photo 7.

  2. Insert piece # 5 from the top. Then, slide piece No. 6 from the front (Photo 8).

    Photo 8.

  3. Slide piece # 2 from the side (Photo 9).

    Photo 9.

  4. Fill the remaining cavity with piece # 1 (Photo 10).

    Photo 10.

  5. There are at least 4 other ways to assemble these pieces to complete the puzzle.

The twelve-piece drool

A good nickname for this puzzle is “The Intimidator”, because all twelve pieces are identical and taking the puzzle apart is as complicated as putting it together.

Create the pieces

  1. Cut 4-1 / 2 “long blocks from 3/4” square stock, including extras for trial cuts (Fig D)

    Fig. D)

  2. Make a pair of 3/4 “x 3/4” x 7/8 “spacers.
  3. Set the saw and jig to cut 3/8 “by 3/4” nut.
  4. Lock the right mask stop block 1-7 / 8 “from the edge of the 3/4” slot.
  5. Place a 3/4 “spacer against the right stop, followed by a test piece and the other 3/4” spacer. Fit and lock the left stop block against the spacer.
  6. Cut the nuts into a couple of test pieces and fit them together to check the width and depth of the nuts. Make the necessary changes.
  7. Cut this nut into all twelve pieces.
  8. Flip the end of the end piece over and reinstall it between the two spacers. Cut a second die into all twelve pieces. Both dice should be on the same face.
  9. Rotate the piece 90 ° towards the nut set and reinstall it with both 3/4 “spacers to the left. Cut this nut into all twelve pieces. This last cut creates a tab, which can be used to help mount the puzzle.

Assemble the puzzle

  1. Assemble four pieces to form a tic-tac-toe grid. “Slip match” the vertical pieces, with their tabs to the left and facing forward. Then slide the pieces horizontally as if they were paired with a book, with the tabs facing inward and at the back (Photo 11). A rectangular space should appear in the center.

    Photo 11.

  2. Match the next two pieces together and install them with the tabs at the top and left (Photo 12). Slide a piece from the left side and pin it around the vertical piece. Slide the second piece through the rectangular gap from the front, then move it to the right and lock it around the other vertical piece.

    Photo 12.

  3. Book matches the next two pieces, with the tabs facing inward and downward. Slide them down from the top and lock them in place (Photo 13). You now have two grids that intersect.

    Photo 13.

  4. Slide back the vertical grid of the tic-tac-toe (Photo 14).

    Photo 14.

  5. Install the last four pieces (Photo 15). Slide two vertical pieces, one from the front and one from the back, and lock them in place. Bookmatch these pieces, with their tabs facing out and to the right. Then install the two horizontal pieces, one from the top and one from the bottom. Bookmatch these pieces too, with the tabs facing outward and to the left. Lock these pieces in place. You may need to hold the bottom piece until the next step is complete.

    Photo 15.

  6. Complete the puzzle by sliding the horizontal and vertical groups together (Photo 16).

    Photo 16.


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