Introduction: Hardwood Serving Trays/Cooling Racks/Objects D'Arte
I love graphic design, particularly emblems, and transforming these 2D ideas into useful 3D objects. This Instructable is an overview of my idea-to-realization process. With the required skills you can replicate these designs and hopefully it will spark your creative process.
Also, I plan to produce these designs in quantity, so this is the first exploration of specific production processes.
- Basic CAD
- Basic woodworking (or access to woodworking equipment and competent operator)
- Basic CNC router operation (or access to a CNC router and competent operator)
Tools: CNC router, table saw and/or band saw, planer, belt sander, clamps, chop saw or fine hand saw, sand paper.
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Step 1: Use Basic 2D CAD to Develop Your Idea
In these examples, my process was to explore designs that would surround a tray-sized area. CAD makes it easy to rotate (array) and mirror elements to yield unique designs.
The choice of 1/4" thick slats with a 1/2" space between is my constant. After developing your own frame designs, lay out an array of 1/4" x appropriate length "slats" that will cover your frame design and group that array.
Step 2: Fooling Around With Slat Positioning
The challenge is positioning the slats to align with the frame parts and add structural integrity.
After defining slot locations with the 1/4" outlines, replace each outline with its center line. The slots will be cut on the CNC router with a 1/4" router bit following the center line.
Create an 1/8" outside offset of each part and then trim the center line to this offset. Extending the center line beyond each part's outline ensures that the router bit will travel beyond each outline and the slats will glue in cleanly. See above pictures.
Step 3: Group Each Part With Center Lines and Nest for Cutting
Each part is grouped and then nested on three boards. The main reason for combining these two trays is because the parts of one nest efficiently in the "wasted space" of the other. Very little waste!
Step 4: Glue Boards to Plywood
Frames: My CNC router has an 18" x 24" envelope, so I am nesting the parts on 24" boards.
A method for machining parts, when not using vacuum hold-down, is to add a plywood substrate to the board being machined. Screwing this to the table allows for each part to be completely milled without any additional hold-downs.
After machining, the parts are "shaved off" on the band saw and cleaned up for assembly.
Step 5: Machine Parts on CNC Router
The slots are cut first with a 1/4" diameter downcut spiral bit, around 1/4" deep. Then the perimeters are cut with the same bit.
Parts are cut out with band saw and sanded with random orbit sander.
Step 6: Machine the Slats
Collect wood scraps/strips: The bundle of hardwood strips (above left), outside a local hardwood retailer's milling shop, is 3' x 12'! Show up with a pickup and they load it with a forklift. Virtually every wood shop has off-cuts that are destined for the wood stove or dump. Just ask.
- Slats: A 1/4" router bit is used to make the slots in the frames. Make a test slot with the actual bit to test fit the slats. With a table saw or band saw, cut strips just larger than 1/2" x 1/4" and then use a planer to trim to slide firmly into the slot. It is too tight if needing to hammer the slat into place.
- The smaller tray has approximately 27' of slats and the "spinning" tray has 36'. Yes, you will need to spend some time at the table saw or band saw and then with the planer to mill these slats. It is satisfying, though, to make waste into an heirloom.
Step 7: Assemble the Trays
Positioning the frame parts and slats is crucial. Carefully place the slats in position without glue for a test fit. Clamp a few random slats to hold the parts in position.
Gluing: Use a water resistant glue like Titebond II, which is easy to clean up. These trays are not intended to be immersed in water, so a totally water-proof glue is not necessary.
Install slats in groups of at least two using any type of clamp with pads to not mar the surface. Gluing multiple slats simultaneously aids in the slats seating accurately.
This is one of the steps requiring finesse. Unless you like spending lots of time cleaning up glue, or on the other end of the spectrum, having the slats fall out, take your time and experiment with application. Hint: Try to keep the glue from squeezing out from the inside, where the slats enter the frame part. The outside edges of the tray are going to be sanded, whereas the inside is more difficult to access.
A damp rag with a kitchen knife-like implement is an effective way to clean up the glue.
Glue parts together on a flat surface to ensure flatness in the final product.
Step 8: Trimming and Sanding
After glue dries, trim the slat ends extending past the frame with a band saw or fine tooth saw, such as a Japanese hand saw.
Sand outside edge of frame/slat ends: use belt sander or random orbit sander. Carefully round over exposed slat edges.
Slats surface: the ultimate is a wide belt sander for the exposed side, but a sandpaper/wood block with elbow grease will suffice.
Slat edges: Contact cement sandpaper around a 1" square (or so) wood block. This makes fairly quick work of the slat edges on both top and bottom of the trays by running the block along the length.
Step 9: Ready for Finishing
The go-to finish for food-related wood items is mineral oil. Virtually every grocery and hardware store carries mineral oil. The generic and inexpensive brand is exactly the same as the expensive cutting board version. If needing quantities, stores that carry horse supplies carry gallon jugs that are quite inexpensive.
Brush on the oil generously and let it soak in overnight. No need to wipe it off. I have totally immersed quantities of trays and cutting boards in mineral oil using a large plastic bin, then let them drain in another bin. Usually they only need a light wiping the next day. Warning: the oil never dries completely. Resting it against fine linen is not advised!