How to Cut Irregular Shapes in Wood

Irregular wooden shapes can enliven any woodworking project. When the same ol’ 90 or 45-degree cuts become too rote for you, look to cut irregular wooden shapes. Irregular wooden shapes can even be a good reason to expand your toolbox.

There are several tools that can be used to cut irregular shapes from wood. I will focus on how to use a few tools, some less common than others, that can be used to cut irregular shapes from wood. I will look first at power tools, then to hand tools.

Using Power Tools to Cut Irregular Shapes in Wood

There are several power tools that can be employed to cut irregular shapes in wood. Some of my favorites for this type of project include table saws, scroll saws, and chainsaws. The combination of freedom of movement and precise cutting of the jigsaw makes it ideal for this project.

Using a Jigsaw to Cut Irregular Shapes Out of Wood

Within the power saw family, the jigsaw comes in with an entry-level price tag. Jigsaws are often one of the first components of a DIYers’ workshop. The arrival of barrel-grip and battery-powered jigsaws have raised the bar of this saw’s already-impressive mobility. 

A jigsaw comes in at an approachable price point, but even against a more expensive specialty saw such as a scroll saw, it has marked advantages when cutting out irregular shapes in wood.

Without guides, it is difficult to make precise, straight cuts with a jigsaw. However, it can be used to cut out interior voids without damaging the integrity of the outside walls of the shape being cut. Let’s walk through a brief tutorial on how to cut irregular shapes in wood with your jigsaw.

Tools:

• Jigsaw equipped with a fine-toothed, wood cutting blade
• Personal protection equipment: safety glasses and earplugs
• Stable work surface
• Clamps to hold the board in place
• Template for irregular shape
• Optional: if your shape has an interior void, a power drill and a drill bit or spade bit wider than your jigsaw blade 

Method:

1. Secure your wood to be cut to your stable, level work surface. Be sure that areas to be cut overhang your work surface, so that the jigsaw can cut through the wood without gouging into your work surface. Depending on the size of the wooden shapes you are going to cut, it can be helpful to support the edges of your piece with sawhorses.
2. Copy your irregular shape to your securely clamped wood. If your irregular shape has beveled or angled exterior edges, the shape you trace onto the wood must be as wide as the widest parts of your irregular shape.
   
   For example: if you were cutting a tapered cylinder that is wider on the top than the bottom, the shape you copy onto the board should be the shape of the widest part of the cylinder.
   
3. Put on your personal protective equipment, including safety glasses and ear plugs.
4. With the jigsaw guide plate resting on the edge of your wood AND your jigsaw blade not touching the wood, power up your jigsaw to its maximum speed.
5. Smoothly push the jigsaw into your wood following the outline of the irregular shape you drew earlier.

Optional, if your irregular shape has internal voids or openings:

1. Measure the width of your jigsaw blade.
2. Find a spade bit or drill bit that is slightly wider than your jigsaw blade.
3. After attaching your drill bit or spade bit, drill a hole through the void or voids of your irregular shape.
4. Place the jigsaw through the hole you have just drilled without squeezing the trigger or activating the blade.
5. With the jigsaw blade not touching any wood and the guide plate flush against your wood, power on the jigsaw to its maximum speed.
6. Guide the jigsaw from the hole in the wood to the interior lines of your void. For tight areas, work from the center and create many lines that radiate outwards. Thin slivers of wood between the cuts can easily be chiseled or broken by hand. For large voids, cut out the interior void similar to the method used to cut the exterior of your irregular shape.

Tip: If your irregular shape has sharp angles, it can pose a unique challenge to smoothly use a jigsaw. Consider working the jigsaw gently back and forth to create a broad curve. After the curve is created, you can create a series of tight cuts to carve out the tight, sharp angles. Clean up any jagged wood with a chisel or sandpaper.

Option, if your irregular shape is beveled or has sloping angles:

Cutting copes or beveled edges is one of the biggest challenges in irregularly shaped wood. It requires precision, control, and mastery of your tool. Please only attempt this if you are a practiced woodworker with the appropriate tools. Completing these cuts is easier with a barrel-grip jigsaw.

If your irregular shape is small, do not use a jigsaw. Find an appropriate hand carving tool such as would be found in a carving kit.

1. Secure your irregular shape into a sturdy vice. Consider placing a piece of rubber between the vice and the wood you will be cutting. This can prevent marks from the vice and create greater holding power between the vice and the wood.
2. Determine which side will be your widest and which side will be narrowed, or beveled.
3. Use a marker to draw a line on the side to beveled that indicates the wood to be cut away. 
4. Put on your personal protection equipment, especially safety glasses and ear plugs.
5. Think of peeling an onion. Start on the outside edge of your wood and take off thin layers of wood at an angle matching the angle of your bevel.
6. Continue cutting away bevel layers until you have a smooth line from the widest point of your irregular shape to the bevel line drawn earlier.
7. Use sandpaper to smooth edges as necessary.

Using a Scroll Saw to Cut Irregular Shapes Out of Wood

A scroll saw offers much better control than a jigsaw for cutting irregular shapes. With a scroll saw, the user manipulates the wood into the saw blade, rather than jamming the saw blade into the wood.

When it comes to irregular shapes in wood, scroll saws may offer a slight advantage for fluted edges or thin delicate exterior cuts, but scrolls have a marked weakness when compared to the jigsaw: an irregular shape with an interior void or opening cannot be cut without slicing through the shape itself. 

Here is the process for cutting odd shapes with a scroll saw:

1. Place the wood on the scroll saw table a few inches away from the actual blade.
2. Turn the scroll saw on and adjust the blade speed. Harder woods = softer speeds. However, with irregular shapes, you always want to go slower.
3. Aim the blade of your scroll saw so it is in line with the first line you are cutting and guide the wood slowly into the blade.
4. Turn the wood so that the saw blade is positioned above your next line. Guide the blade onto the line to meet with the first cut.
5. Slowly work along with the curved cut until you have completely finished, all the way around.
6. For internal cuts, drill a hole in the wood to make room for the saw blade to go through. After making the hole, pull the scroll saw blade out and place the piece of wood over the clip. Then, put the blade back in through the hole.
7. Make your interior cuts the same way you made your exterior cuts.

A scroll saw will be slower, but more precise than a jigsaw.

Finishing Your Irregular Shapes in Wood

Now that you have used your jigsaw or scroll saw to cut irregular shapes in wood, it is time to polish up the project. You likely do not want splinters or jagged edges sticking out. Use a chisel to trim away at rough areas.

If you have tight corners where chisels will not work, folded sandpaper can usually access those areas. If necessary, wrap sandpaper around the shaft of a screwdriver and use the screwdriver to access areas deep within the wood.

Anytime you sand rough wood, begin with a coarse grit to remove large, unsightly areas, then step into a finer grit. Between each grit of sandpaper, use a pneumatic blow nozzle or compressed air to blow away dust.

When you have sanded the irregular-shaped wood to your satisfaction, use a tack cloth to get rid of all the remaining pesky dust. Wood sealer or polyurethane can then be applied to make your irregular shape pop.

Conclusion

With a little planning, cutting irregular shapes in wood can mostly be done with a jigsaw, although tougher projects can be completed with a scroll saw. Having a good grasp of spatial reasoning helps. Work from the widest area of your irregular shape and narrow it from there. Be patient with yourself and your project and you will have fun cutting irregular shapes in wood!