Hollow forms are where woodturning starts to feel like a different craft altogether. You go from being able to see everything you’re cutting to working blind inside an enclosed vessel, relying on feel, sound, and experience instead of sight. It’s challenging, occasionally terrifying, and deeply rewarding when you get it right.

If you’ve been turning bowls and platters and you’re looking for something that will push your skills, hollow forms are the logical next step. Here’s how to get started without too many expensive mistakes.

What Is a Hollow Form?

A hollow form is any turned vessel where the opening is smaller than the widest part of the interior. Think of a vase shape — narrow neck, wider belly. Unlike a bowl, you can’t see the inside wall while you’re cutting it, and you can’t easily get conventional tools in there once the opening is smaller than about 40mm.

Most hollow forms are turned end-grain — the grain runs vertically, parallel to the lathe axis. This orientation lets you create tall, vase-like shapes and means the grain pattern wraps around the piece rather than running across it.

Tools You’ll Need

You can rough out the exterior with your standard bowl gouge, but the interior requires specialised tools. At minimum, you’ll need:

A hollowing tool with a curved shaft. The curve lets the cutting tip reach past the narrow opening and into the belly of the form. Many turners start with an articulated hollowing system like the Rolly Munro or the Simon Hope tools, which have a swivelling cutter head.

A boring bar for the initial hole. A straight bar with a cutter on the end, used to drill out the centre and establish the depth. Some turners use a large drill bit in a Jacobs chuck instead.

A wall thickness gauge. You cannot see the walls, so you need to measure them. Bent wire callipers or a dedicated laser thickness gauge are essential. Without them, you’re guessing, and guessing leads to walls that are either 15mm thick or 2mm thick in one spot.

Starting Simple

For your first hollow form, keep it modest. Choose a blank about 100mm in diameter and 120mm tall. Use a stable, even-grained timber — silver ash or Queensland maple are good first choices. Avoid highly figured or spalted wood until you’ve got the process down.

Mount the blank with the grain running vertically. Turn a tenon on the bottom to fit your chuck, then shape the exterior profile. Keep the walls relatively straight for your first piece — a gentle cylinder or slight taper is fine.

Decide on your wall thickness before you start hollowing. For a piece this size, 5-6mm is a reasonable target.

The Hollowing Process

Start by drilling a depth hole straight into the centre. This establishes how deep you can go. Leave at least 8-10mm for the base.

Now begin hollowing from the opening downward, working in sections. Clear the material from the top 20mm first, check the wall thickness, then move down another 20mm. This staged approach means you’re never reaching too far into the piece, and you can correct your wall thickness before you’re committed.

The key sensation to develop is feeling the cut through the tool handle. Inside a hollow form, you can’t see the shavings or the surface. Instead, you feel the tool engage, hear the pitch of the cut change as the wall gets thinner, and sense vibration when you’re getting close to your target thickness.

Keep your tool rest close to the work and make sure the shaft of your hollowing tool is well-supported. Any flex or chatter gets amplified inside an enclosed form.

Common Problems

Uneven wall thickness is the most common issue. Check frequently with your callipers, working around the full circumference. With practice, you’ll develop a more consistent technique.

Torn end grain on the interior. This is almost inevitable with the grain running vertically. Sharp tools help, but accept that the inside won’t be glass-smooth. Nobody sees it anyway.

The piece comes loose. Hollow forms can be top-heavy as you remove material. Make sure your chuck grip is solid, and if the piece starts to vibrate, stop and re-check your mounting.

Finishing Up

Once the interior is done, refine the exterior. Sand and finish the outside while it’s still on the lathe. For the bottom, reverse-mount using a jam chuck or vacuum chuck, turn away the tenon, and finish the base.

I typically finish hollow forms with Danish oil, applied in thin coats with a small brush poked through the opening for the interior.

I won’t pretend that my first hollow form was anything special — it had walls you could measure in centimetres, and the shape was more potato than vase. But each one after that got better. The fifth one was something I was genuinely proud of.

Start simple, stay safe, and don’t be discouraged by the first few attempts. The timber is cheap and the lessons are priceless.