Centering the Bowl Upside Down for Trimming
Okay. Your bowls are leather-hard now, which means they're firm enough to handle but not bone dry. This is the window. If you waited too long, some of this is going to be harder than it needs to be, and that's fine, you'll know for next time.
Trimming is where a lot of people quit, honestly. It's not the fun part. There's no pulling a wall up, no watching a shape appear under your hands. It's cleanup work. But it's the difference between a bowl that sits flat on a table and a bowl that rocks like a boat every time you set it down. I think finishing the piece is the actual line between "I took a pottery class once" and "I made a bowl I use." So bear with me on this one.
Getting it centered upside down
First thing: your bowl is not attached to anything right now. It's just sitting there. So before you touch the pedal, you need to get it roughly centered on the wheel head by eye, upside down, rim down.
Here's how I do it:
- Find the middle of the wheel head. Most wheels have concentric rings scored into the metal. Use those. Set the bowl down rim-first, centered as close as you can eyeball it.
- Bump it gently while spinning slowly. Turn the wheel by hand, not with the pedal yet, just a slow spin with your palm. Watch the bowl's edge. Wherever it wobbles out furthest from center, that's the side sticking out too much.
- Tap it toward center, not away. Use your fingers or the heel of your hand to nudge the bowl in the direction it's wobbling away from. Small taps. You're not shoving it, you're coaxing it.
- Use clay coils or a chuck if you've got one. Three or four small balls of clay pressed onto the wheel head in a triangle around the bowl will hold it steady once it's centered, sort of like bumpers. A chuck (basically a clay cup that cradles the bowl) does the same job better if your studio has them. Either works. Neither costs you anything extra, they're just leftover clay.
- Bring the wheel up to a slow speed and check again. Once it looks steady by eye at a stop, spin it slow and watch the rim edge again. If it's still doing a visible wobble, stop and adjust more. Don't try to trim through a wobble. It won't get better once the tool touches it, it gets worse.
This is fiddly. It is genuinely one of the more annoying parts of the whole process, more annoying than centering the clay in the first place, because now the piece is already made and you don't want to mess it up. Take the time here. I'd rather you spend fifteen minutes getting a bowl centered upside down than rush it and trim a divot into one side.
An opinion, stated as an opinion
Some instructors will tell you to get it perfect, dead-on, no wobble at all, before you touch a trimming tool. I don't go that far. I think "close enough that the wobble is barely visible at slow speed" is fine for a beginner bowl. You're not making museum pieces yet. You're learning what trimming even feels like. Perfect centering here is a skill you'll build over your next twenty bowls, not something you need to nail on bowl number six.
A word on going slow with the tool
Once it's centered and held with your coils or chuck, resist the urge to crank the wheel speed up right away. Trim at a slower speed than you think you need. A trimming tool catches an edge at high speed a lot faster than you can react, and that's how you either gouge a hole clean through the bottom or send the whole bowl flying off the wheel head. Neither is dangerous exactly, but it wastes a bowl you already put real time into.
I bring this one up because of my first attempt at any of this, back when I was teaching myself off a video. I felt ready after maybe forty minutes total on a wheel, decided I understood centering well enough, and turned out what I still call a wet gray ashtray that nobody asked for. It wasn't even trimmed, it was just misshapen from the start. But the lesson that stuck was the same one that applies here: feeling ready and being ready aren't the same thing, and the wheel will tell you the truth whether you want to hear it or not. That ashtray still sits on a desk holding paperclips. I kept it on purpose.
Before next time
Get one bowl centered upside down using coils or a chuck, and just sit with it spinning at a slow speed for a minute before you trim anything. Get comfortable with what "centered enough" looks like from the outside, that's really the whole skill for today.