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The stub that won’t go away
Here’s a situation a lot of growers know too well.
You remove a branch. You use a decent concave cutter, you get in close, and it looks fine. Then a year later there’s a little swelling right there. Maybe it’s a stub you didn’t quite get. Maybe it’s an old knob from years of pruning in the same spot. Either way, it’s sitting on the trunk line you’ve been working on for a long time, and it’s not going anywhere on its own.
That’s the job a knob cutter is for.
It isn’t a fancier concave cutter. The jaws are rounder, almost like a ball, and they bite deeper into the wood. You can take out a knob, clean up an old stub, or hollow a spot slightly below the bark so it heals flat instead of bulging.
Knob cutter vs concave cutter, quickly
People mix these two up all the time, so here’s the plain version.
A concave cutter has straight or slightly curved jaws that meet at an angle. It’s built to take a branch off flush with the trunk and leave a shallow hollow. It’s the tool you’ll use most.
A knob cutter has rounded jaws that close in a cupped shape. It takes a smaller, deeper bite. Because of that shape, you can nibble away at something bit by bit: a knob, a stub, a swollen old wound. You can also use it on roots, which a lot of people don’t realise at first.
So they’re partners, not replacements. Most growers who do any structural work end up with both. The concave cutter does the first cut. The knob cutter cleans up what’s left.
The trouble is picking one. Kaneshin alone sells around ten knob cutters in different sizes and blade widths. Masakuni has straight, spherical, long-handle and tilted versions. Prices go from about $60 to well over $120 before shipping.
In my experience, the mistake people make most often here isn’t choosing the “wrong brand.” It’s choosing the wrong size for their trees. So size gets a lot of attention in this guide.
Who this article is NOT for
A quick filter before you read the whole thing.
It’s not for you if you don’t own a concave cutter yet. For most people, a concave cutter is the first serious cutting tool, and the knob cutter comes after. If you’re still deciding on that one, start with our guide to the best bonsai concave cutters and come back here later.
It’s not for you if you want a budget tool. Everything below is made in Japan. There are cheaper knob cutters out there, and some of them work. They’re just not what this article covers.
It’s not for you if you only keep small indoor trees and never do structural work. A knob cutter earns its keep on trunks, thick branches and roots. If your pruning is mostly twigs and leaves, you probably won’t reach for it much.
Still with us? Let’s go.
How we picked these (3 things that actually matter)
1. Size, matched to your trees
This matters more with knob cutters than with almost any other bonsai tool.
A small cutter (around 145–150mm) gets into tight spaces on shohin and mame trees. A medium one (around 175–180mm) is the most flexible. A large one (210mm and up) gives you the leverage for thick branches and big trunks, but it’s awkward on small work.
If most of your trees are under about 30cm (12 in), go small or medium. If you work on larger trees or collected material, you’ll want something in the 210mm range, and plenty of growers end up owning two sizes.
2. Steel: carbon, stainless, or coated
Same story as with other cutters.
Carbon steel is sharper, cuts cleaner, and costs less. It also rusts if you don’t wipe and oil it. Stainless steel handles humidity and the occasional lazy day much better, but it usually costs about twice as much. A few makers also sell carbon steel with a black coating that helps a bit with rust, without changing the edge.
Knob cutters often get used near soil, on roots, or on wet wood during repotting. That’s worth thinking about if you tend to put tools away dirty.
3. Jaw shape: standard or spherical
A standard knob cutter has rounded jaws that leave a hollow wound. It’s the general-purpose version.
A spherical knob cutter has jaws that are more fully rounded, closer to a half-ball. It takes a deeper, rounder bite. That’s useful for large knobs and for work near deadwood, but it’s more than most people need on small trees.
Some makers also sell long-handle and angled (“tilt”) versions. These are specialist tools for reaching into the middle of a dense tree or cutting at an awkward angle. Nice to have. Rarely your first knob cutter.
Prices below are approximate and were checked in September 2026. Yen prices are from Japanese stores before international shipping. Always check the final total at checkout.
Comparison table
| Knob cutter | Steel | Jaw type | Length | Approx. price | Best for |
|---|---|---|---|---|---|
| Wazakura Hand Forged Knob Cutter | S55C carbon (black coated) | Standard | 210mm | ~$60 | First Japanese knob cutter |
| Kaneshin Knob Cutter No.9 / No.10 / No.11 | Carbon | Standard | 150 / 175 / 210mm | ~¥10,600 each (about $70) | Matching size to your trees |
| Kaneshin Stainless Knob Cutter No.810 | Stainless | Standard | 210mm | ~¥21,200 (about $135) | Low maintenance, larger trees |
| Yagimitsu Stainless Knob Cutter | Stainless | Standard | 180mm | ~£125 (UK retail) | Shohin and small trees in stainless |
| Masakuni Knob Cutter No.0035 | Carbon | Standard | 180mm | ~¥12,800 (about $85) | A lightweight premium everyday tool |
| Masakuni Spherical Knob Cutter No.0335 | Carbon | Spherical | 210mm | ~¥17,800 (about $115) | Advanced work on big knobs and trunks |
Individual reviews
1. Wazakura Hand Forged Knob Bonsai Branch Cutter (210mm)
Wazakura’s knob cutter comes from the same town as its concave cutter: Sanjo in Niigata, which has a long metalworking history.
The specs are simple. S55C carbon steel with a black coating, 210mm long, 15mm blade, 230g. It’s $59.99 on Wazakura’s own store, with free shipping to the US, Canada, the UK, the EU and some other regions. Import tax may still apply depending on where you live.
There’s also a version with an asymmetrical handle at the same price. Wazakura says it gives a more balanced grip and less hand fatigue on detailed work.
Pros
- Lowest price on this list for a Japanese-made knob cutter
- Free shipping to a lot of countries from their own store
- 210mm length gives good leverage on thicker wood
- Asymmetrical handle option if grip comfort matters to you
Cons
- Only one size, and 210mm is on the large side for shohin
- Less long-term feedback in forums than Kaneshin or Masakuni
- Carbon steel, so it still needs oiling
Who it’s for: Someone who already has a concave cutter, mostly works on medium to large trees, and wants a real Japanese knob cutter without spending $100+.
2. Kaneshin Knob Cutter (carbon steel) — No.9, No.10, No.11
If you want to match the tool to your trees, Kaneshin makes it easy.
The carbon knob cutters come in a spread of sizes. On a Japanese store, No.9 is 150mm, No.10 is 175mm and No.11 is 210mm, all at about ¥10,600. There are also “B” versions (like No.9B and No.10B) with a thinner blade for tighter spots, at around ¥12,500. At the very top, the No.12 is a 300mm, 750g tool for really heavy work.
Eastern Leaf in the US sells a Kaneshin carbon knob cutter for $79 and lists it as an advanced-level tool.
In my experience, the Kaneshin line is where the size question gets answered most cleanly. You’re not stuck picking one length and hoping it fits.
Pros
- Wide range of sizes, so you can buy exactly what your trees need
- Thin-blade “B” versions for dense or refined trees
- Solid reputation built over a long time
- Good value for a well-known Japanese brand
Cons
- The model numbering can be confusing across different shops
- Carbon steel, so drying and oiling are part of the deal
- Prices and available sizes vary a lot between retailers
Who it’s for: Pretty much anyone who knows their typical tree size. Small trees: No.9 or 9B. Mixed collection: No.10. Larger trees: No.11.
3. Kaneshin Stainless Knob Cutter No.810 (210mm)
This is the stainless version of Kaneshin’s large knob cutter.
It’s 210mm and around 345g, which is noticeably heavier than the carbon No.11 at around 250g. On a Japanese store it’s about ¥21,200, so roughly double the carbon price. There’s also a smaller stainless model, No.808, at 180mm for the same price.
Why pay double? Mostly rust. Knob cutters tend to see dirty, wet work: roots during repotting, damp wood, soil. Stainless deals with that a lot better.
Pros
- Much more forgiving if you don’t clean tools right away
- Good for root work during repotting
- Extra weight helps on thick material
- A 180mm version (No.808) exists if you want stainless in a medium size
Cons
- Roughly twice the price of the carbon model
- Heavier, which you’ll feel on long sessions
- Stainless is harder to resharpen well at home
Who it’s for: Growers in humid climates, people who do a lot of root work, or anyone who’s honest that their tool care is hit and miss.
4. Yagimitsu Stainless Steel Knob Cutter (180mm)
Yagimitsu shows up more often at UK and European retailers than in the US.
The 180mm stainless knob cutter sells for around £125 at UK bonsai shops. One retailer describes it as aimed at smaller shohin and mame trees, with clean cuts that help healing.
So this is the stainless option for people with smaller trees. Kaneshin’s stainless range starts at 180mm too, so the two are close. Where you live and which shops you trust may decide it.
Pros
- Stainless steel in a size that suits smaller trees
- Easy to find in UK and European shops
- Premium build from a respected Japanese maker
Cons
- Less information available online in English than the big two brands
- Similar price to Kaneshin stainless, without the wide size range
- Harder to find in the US
Who it’s for: Shohin growers, especially in the UK or Europe, who want stainless and a smaller cutter.
5. Masakuni Knob Cutter No.0035 (180mm)
Masakuni’s standard knob cutter is lighter than you might expect.
No.0035 is 180mm and 150g. There’s a small version, No.0036, at 145mm and just 80g. Both list at about ¥12,800 on a Japanese export store. That’s not far above Kaneshin, which surprises people who assume every Masakuni tool is expensive.
In my experience, low weight is one of the more underrated things in a knob cutter. You often hold it at odd angles, inside the tree, for a while. A lighter tool makes that easier.
Pros
- Very light for its size, comfortable for long or fiddly work
- Price is closer to Kaneshin than most people expect
- Masakuni’s reputation among professionals and collectors
- Small version (No.0036) for mame and shohin
Cons
- Carbon steel, so it needs the usual care
- Harder to buy locally outside Japan, and prices overseas vary
- Lighter build may feel less planted on very thick wood
Who it’s for: Intermediate and advanced growers who want a premium, lightweight everyday knob cutter.
6. Masakuni Spherical Knob Cutter No.0335 (210mm)
This is the specialist pick on the list.
No.0335 is a spherical knob cutter, 210mm and 210g, at about ¥17,800 on a Japanese store. There’s a smaller No.0336 at 170mm for the same price. The fully rounded jaws take a deeper, rounder bite than a standard knob cutter.
Masakuni also sells a long-handle version (No.0135, 230mm) and a tilted one (No.0235, 230mm) for reaching into the middle of a tree or cutting at an angle. If you already know you need one of those, you probably don’t need this guide.
Pros
- Deep, round cuts for large knobs and old wounds
- Useful for trunk work and cleaning up near deadwood
- Fairly light for a 210mm spherical cutter
- Small version available
Cons
- The most expensive knob cutter here
- The deep bite is too much for a lot of everyday cuts
- Probably not the right only knob cutter for most people
Who it’s for: Advanced growers who already own a standard knob cutter and regularly work on thick trunks, collected trees or big old knobs.
Recommendation by use case
“I’ve got a concave cutter. Now I want my first knob cutter, without overspending.” Wazakura Hand Forged Knob Cutter if your trees are medium to large. At 210mm it’s a bit big for shohin, though.
“I want the right size for my trees, and I don’t mind looking after carbon steel.” Kaneshin carbon. No.9 for small trees, No.10 for a mixed collection, No.11 for larger ones.
“I live somewhere humid, or I do a lot of root work.” Kaneshin No.810 stainless for larger trees. Kaneshin No.808 or Yagimitsu 180mm for smaller ones.
“I mostly grow shohin and mame.” Kaneshin No.9B (thin blade) or Masakuni No.0036 if you’re happy with carbon steel. Yagimitsu 180mm if you want stainless.
“I want a premium tool I’ll reach for every week.” Masakuni No.0035. Light, well made, and not as expensive as you’d guess.
“I work on big collected trees and old knobs.” Masakuni Spherical No.0335, ideally alongside a standard knob cutter.
Conclusion: pick the size first, then the brand
Here’s the short version.
Get the size right before anything else. A great 210mm knob cutter is still the wrong tool for a mame juniper, and a small one will struggle on a thick trunk.
Then think about how you’ll actually use it. If it’s mostly cleaning up after the concave cutter, a standard knob cutter is plenty. If you’re working on old, lumpy trunks, that’s when a spherical one starts to make sense.
After that, it’s the same choice as with any bonsai cutter. Carbon if you’ll look after it. Stainless if you won’t, or if your tools see a lot of wet soil and roots.
And if you haven’t picked a concave cutter yet, do that first. Our concave cutter comparison covers the options.
Ready to choose?
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