Introduction: Hardwood CNC Scrabble Board
This Instructable shows how to make a 20"x20" Scrabble Board out of hardwood. The main board is cut from walnut on a CNC router. Laser cut inlays are pressure-fit into deeper pockets for the special tiles. An optional lazy susan base allows it to spin between players, and laser cut letter tiles fit the pockets precisely to prevent slipping.
I designed this as a holiday gift for my family (and as a way for me to learn to use a CNC router).
The project will take several days, since glue needs to dry and finishes must set at several stages. The CNC cuts take <6 hrs total (excluding test cuts).
Step 1: Materials and Tools
- Wood for the Scrabble board.
- I went with two walnut pieces, and glued them together. You will want some combination of wood that will create a 23"x23" square. (Or something close to that; the final game board itself is 20"x20", and you will need at least an inch of extra material on every side for fixturing.) My wood was ~0.8" in depth.
- 3mm laser cuttable sheet wood for letter tiles and insets for special squares.
- I used pine plywood sheets, with two different surface colors (one for insets, one for tiles).
- Lazy susan.
- I used this one from McMaster Carr
- Wood for the base.
- The base is 14"x14"x0.5" square, so you need at least a 16"x16" piece for fixturing. I used pine plywood, though I recommend some nicer hardwood that matches your board choice.
- 4 screws and washers
- To attach lazy susan to base plate.
- Cork sheet.
- Extra wood for running test cuts.
- Ideally some of this is of the same type as your final wood, but starting on plywood or something cheap is a good idea.
Optional Drawstring Bag
- 14"x9" piece of fabric.
- 16" of ribbon.
- Wood glue.
- Mineral oil.
- Or other finishing solution.
- Table saw
- CNC router
- 1/4" straight flute router bit with 2 flutes
- I used this one from McMaster Carr
- 1/4" inch ball end mill
- 1.5" face mill
- 1/4" straight flute router bit with 2 flutes
- e.g. sandpaper, saw, clamps, utility knife
Step 2: Modeling
First step in making this board is to model it in CAD. I've provided my files here. They can be used as is, or modified as you wish.
There are two CAD files for parts that must be CNC'd: the base plate, and the board itself. I've included the native Fusion 360 format, and an IGES file for each.
The Illustrator files for laser cut parts (tiles and inserts) are in the same place.
(The gcode generated from these files is also there, but mostly for reference. You will need to modify the files and re-generate gcode based on your stock, tools, and machine speeds.)
Step 3: Prepare Wood
Once you have your wood for the board, it needs to be prepped for the CNC. It's highly unlikely that you managed to find a single piece of 23"x23" hardwood, so you will need to glue your pieces together. First, cut the edges on a table saw to get straight, clean edges. If the boards are different lengths, trim them to size.
If your wood is particularly un-flat, you may wish to plane the boards; I did this with my pieces. However, you will also be able to face the board in the CNC, so planing may be unnecessary if they're already mostly flat.
Once your boards are ready, align the grains, apply wood glue, and clamp firmly until the glue has dried.
(Unfortunately, I did this step a year ago, and failed to take any pictures...)
Step 4: Test Cuts
CNC routers are all slightly different. With your particular router, bit, and material choice, you may find you need a different set of feeds and speeds than I used. Test cuts are essential to getting a good finish on your final piece.
One issue I ran across was wobble in the machine itself. That results in misshapen pocket cuts. So test your machine on scrap before running it on your good wood.
Settings I used:
ShopBot CNC Router
- spindle speed: 12000 RPM
- feed: 200 in/min
pockets and edge:
- spindle speed: 18000 RPM
- feed: 100 in/min
Step 5: CNC the Board
Now's the time to do it for real. Double check your fixturing, so that it matches the CAD stock. The full cut takes about 4.5 hours, so budget enough time. If you have to split up the job, make sure to do the rough and finish cuts for the pockets at the same time. It may be possible to re-align the board if you have to take it off and do the edge cuts later, but it won't be precise enough if you interrupt the pocketing.
- Facing (face mill)
- < 15 min
- Rough pockets (straight flute)
- 1 hr 30 min
- Finish pockets (straight flute)
- 1 hr 45 min
- Rough edge (straight flute)
- 30 min
- Finish edge (ball nose)
- 20 min
Once it finishes, take it off the CNC and cut the excess wood off. A thin layer will be left around the base of the edging; this is easy to cut through with a saw or utility knife. Be gentle to avoid tearing, especially if you are using any sort of plywood.
Step 6: CNC the Base
The base plate is a simple piece to hold the lazy susan. A 15cm x 15 cm x 3mm pocket is cut in the center of a piece of half inch plywood (you can also use hardwood, which would probably look much better). This fits the bottom of the lazy susan, though you will need to chisel out the corners to square after the router finishes.
I used the same straight flute bit here. There are only two toolpaths: the central pocket for the lazy susan and the outer contour.
Step 7: Finish the Wood
The first step to finishing the wood is to sand it.
...And then keep sanding it.
Try not to soften the edges of the pockets, but do get into each and every pocket to remove any chips that didn't cut cleanly, or else the tiles will not fit properly.
The edges will be stepped after the CNC finishes; round these out into a smooth curve. It should go relatively quickly. Try also to remove any lines left by the facing bit on the top surface.
After sanding, I finished the surface with a single coat of mineral oil. You may prefer to stain or lacquer your wood. (If you intend to use any thick kind of finish, make sure you resize your pockets before the cutting stage to leave room.)
Step 8: Laser Cut the Tiles and Insets
The letter tiles and insets need to be sized for the pockets on your board. Use calipers to measure the actual size of your pockets, then cut some test pieces at various sizes around the nominal value to find what fits the best. I suggest trying 0.1mm less and 0.1mm greater than your measured values.
The proper sizing will depend both on the precision of your CNC cuts, and the power of your laser cutter settings.
My board (and the files) use 19.1mm edges for the insets, and 19.0mm edges for the letter tiles. This makes a tight press fit for the insets (they should be hard to get in), and a firm but easy to remove fit for the letters.
Once you have the proper sizing for your tiles and insets, you can alter the font or style of the tiles to your preference. I liked the effect of using symbols rather than words for the insets, and the Illustrator files reflect that. It keeps the visuals of the board itself less cluttered.
- double letter score = broken single outline
- triple letter score = broken double outline
- double word score = solid single outline
- triple letter score = solid double outline
- center tile (which is a double word score) = filled in single outline
Use your extra test pieces to try out oils, stains, or dyes for your insets and letters. I ended up going with mineral oil for the insets and no finish for the letters, but you may like the effect of colored wood dyes or stains.
Scrabble Letter Distributions
- 2 blank tiles (scoring 0 points)
- 1 point: E ×12, A ×9, I ×9, O ×8, N ×6, R ×6, T ×6, L ×4, S ×4, U ×4
- 2 points: D ×4, G ×33 points: B ×2, C ×2, M ×2, P ×2
- 4 points: F ×2, H ×2, V ×2, W ×2, Y ×2
- 5 points: K ×1
- 8 points: J ×1, X ×1
- 10 points: Q ×1, Z ×1
(Wikipedia has a nice list of other languages' tile distributions as well)
Special Tile Distribution:
- 1 center tile (double word)
- 8 triple word
- 16 double word
- 12 triple letter
- 24 double letter
Step 9: Insert the Special Square Insets
The tiles that you cut should fit tightly in the pockets. Lay out the tiles and double-check the positioning -- they won't come out once you get them in. Align the grains of the insets with the grain of the board.
You may be able to press the insets in with your fingers, but I found the plastic end of a screwdriver helpful in pounding the more stubborn ones in. Be careful not to dent the pocket edges.
Step 10: Assemble the Base
Once the base is cut, sand and stain the base. (I used a medium walnut stain.) Once it is dry, cut the cork sheet to shape for each corner. This will keep the board from scratching or sliding on a tabletop. Glue it together with wood glue, and clamp for 24 hours to dry.
I added cork to the top of the lazy susan as well. This lets the board sit on the turntable without scratching, using friction to keep it in place. (You can also screw the lazy susan directly to the bottom of the board, however I preferred a removable base.)
Finally, screw the base to the bottom of the lazy susan. (Make sure your screws aren't going to poke out the bottom of the base.)
Step 11: Optional: Sew Tile Bag
Having been storing the tiles in a leftover plastic bag, I decided I wanted a nicer bag. So I sewed a simple drawstring bag from black velveteen, with a gold ribbon.
First, hem the two side edges. Because the top inch or so of the bag will not be seamed, you don't want the raw edges showing.
Then, fold the top edge of your fabric over by 1.5"-2". Lay a piece of ribbon or string under the fold, at the top edge. Sew a straight line along the middle of the folded edge, being careful not to catch the ribbon.
Fold the fabric in half vertically, with the outside facing in, and sew along the bottom and side edges. Only sew the side edge only up to the seam of the drawstring sleeve, so it remains open.
Turn your bag right side out, and tie the ends of the ribbon together so it won't slip out.
Step 12: Play Scrabble!
You're done! Play games!
(And borrow some tile racks from another scrabble game...perhaps I'll make those next.)