Hollowing out a log with a chainsaw: step-by-step guide

From offcut to planter

Inspirations / How to

19/12/2023

Estimated reading time 5 minutes

Chainsaws are multifunction tools: useful for pruning in the garden and countryside, essential for collecting firewood in woodland, and invaluable for DIY around the home. In terms of technical characteristics—and therefore range of applications—they come in compact, medium-power, professional or pruning models, and can be powered by petrol, electricity or battery.

Do you have a spare log or large branch? With a little work, you can transform it into a coffee table or stool with a minimalist style. If you prefer a more rustic appearance (think alpine huts), you could make a planter, a drinking trough, a fountain or other imaginative furnishing item. In this case, the task is a little more complicated because you will need to hollow out the log. We tell you how to do that in this article, illustrating step-by-step how to make a planter.

Tools for hollowing out a log

Before you start, the wooden trunk, planter or ornament must be cut to size with a chainsaw. It is better if the log is already debarked, but there’s no harm in hollowing out a log planter with the bark left on. The effect will be more rustic, and in any case, the bark will peel off over time, as the wood dries out. Bear in mind that debarked wood lasts longer, because bark provides protection for insects and parasites to live under. If you are foraging the log from woodland, it is better to debark it there and then, so as to leave as many nutrients as possible in the forest ecosystem.

There are several tools you can use to debark logs by hand: a draw knife (a knife with two handles), billhook, axe or bark spud (like a bladed spatula with a handle). You can work faster by mounting a debarking attachment to your chainsaw.

Now let's now look at what you need to hollow out a log using a chainsaw:

  • Chainsaw

  • Chisel

  • Carpenter's hammer

  • Metal tape measure

  • Blackboard chalk

Depending on the result you have in mind, you can also add a sander, sandpaper, wood stain and other tools to your equipment list. You’ll also need various protective clothing to work safely: protective glasses; noise filtering ear defenders or earplugs; and cut-resistant trousers, gloves and boots.

In terms of a suitable chainsaw for hollowing out the trunk, you can opt for a medium-power (i.e. H series) or professional Efco petrol-engine model. As a finishing tool, instead of a chisel and hammer you can use an adze (similar to an axe, but with the blade perpendicular to the handle, like a hoe). Also on the market you will find chainsaw carving mill attachments that can be used specifically for hollowing out wood. In particular, they are used by tree surgeons to clean tree trunks affected by diseases that damage woody tissues.

If you don't already have a chainsaw, to help you choose from the many models available you can take a look at these guides on the differences between power sources, the best pruning chainsaw and chainsaw accessories. Here you will find a video on correct use of a chainsaw.

How to hollow out a log using a chainsaw: step-by-step guide

The ideal log for making a planter with is a straight piece of wood, preferably already seasoned, with a diameter of around 30 cm (although slightly irregular shapes can deliver interesting results). It’s not always possible to choose the most ideal or suitable wood species. Among the many species you can use are birch, chestnut, larch and pine.

Let's now see how to hollow out a log using a chainsaw:

  • Secure the trunk on the ground so that it won't roll around, for example using wedges.

  • Draw the outline of the cavity on the log of your planter using a tape measure and chalk (or carpenter's pencil).

  • Using the lower edge of the guide bar on your chainsaw, cut along the short edges of the outline you previously traced, then cut the long sides using the tip (this last step increases the risk of kickback, which we discuss in this article on how to use a chainsaw).

  • Deepen the cuts you just made, still being careful to avoid kickback.

  • Separate the wood that you want to extract from the trunk by making cross cuts, which will help you in the following steps.

  • Remove the wood inside the cavity using a hammer and chisel.

  • Repeat the previous three steps until the excavated cavity is of the desired depth (the time this will take depends largely on the hardness of the wood).

  • Clean any wood scraps out of the cavity.

  • Level and smooth both the trunk and the cavity using first a sander and then sandpaper (how thoroughly you perform this optional step depends on the finish you want for your planter).

  • If the planter will be situated outdoors, apply a coat of primer to protect it from the elements.

You can give stability to the planter by creating a base from two stumps (it’s better to debark them first). Carve out a U-shaped notch halfway along the length of each stump, then secure them to the planter with long screws. Alternatively, you can cut grooves into the lower face of the planter so that it fits snugly on top of the stumps. Otherwise, you can simply purchase a base or feet.

Once the planter is ready, before bedding in any plants you can line the cavity with a sturdy plastic sheet, secured along the edges with staples. If you instead decide to dispense with a waterproof liner, before adding soil it is advisable to drill some holes through the bottom of the planter so that any excess water can drain out. As an alternative to plastic sheeting, you can apply waterproofing liquid to the walls and bottom of the cavity.

If you are an avid DIYer, here you will find our guides for making a do-it-yourself wooden bench to go with your planter, as well as tips on how to obtain wooden planks from a tree trunk. Not all tree species or parts are suitable for carpentry or woodworking, but you can use them as fuel: here's how to prepare firewood.

Below are links to a series of articles on chainsaw maintenance, which is essential both for proper cutting and for your safety:

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