Knob cutter

The spherical branch cutter (kobukiri)

knob cutter tian bonsai
Tian bonsai tools
The spherical cutter
knob cutter spherical branch cutter bonsai

Concave Cutter is also known as Bonsai Knob Cutter.

Used for removing the stub of a branch left after cutting, and producing a concave cut on the trunk to speed callousing.

Tian bonsai Knob Cutter

This bonsai tool is an average size basic bonsai knob cutter. Great for clean, deep cuts close to the trunk with great scar control.

What do we use the concave cutter for?

The Traditional Spherical Knob Cutter is used in bonsai to cut flush to the trunk without having any further pieces of the branch left.

Makes somewhat of a hole, so when scarring does occur, it is minimal as the healing takes place it will then fill in the hole leaving a flush effect.

bonsai knob cutter

Comes sharp and in steel for heavy duty branch or wood removal. Designed to tackle small to medium tree parts with a sharp cut.

Use your knob cutter when entire branch removal is needed. Can be used on small branches and branches up to about one-half inch think.

Used for removing the stub of a branch left after cutting, and producing a concave cut on the trunk to speed callousing.

Creates a deep rounded cut into wood for healthy scar healing on bonsai trees.

Great for cutting imperfections, knobs, trunk parts, roots, and branches. Use this tool for clean cuts, rather than sawing or multiple cutting with shears. One quick pressure applied cut is achieved.

Identify problem areas and remove them by one-stoke cutting with the tool. After you target the area to be removed, place blades opened on each side and press down hard.

knob cutter spherical branch cutter bonsai

Spherical Cutters are also known as Bonsai Knob Cutters.

Used for removing the stub of a branch left after cutting, and producing a concave cut on the trunk to speed callousing.

How to choose a bonsai knob cutters

In this section, we are going to be talking to you about knob cutters and how to choose them.

Some important questions

About your bonsai treesThe size of our trees. What kind of bonsai do you have? Big or small?
Do You like yamadori with trees from the field?
You have trees with dead wood like juniperus or pines.
About your experience Do you need the highest quality tools?
Are you a beginner or you have been in the hobby for a long time?
Budget What budget do you have?

You know some people call them knuckle cutters as well but essentially they are tools with a rounded head in both angles.

The main use of knuckle cutters is to give you a concave cut after you’ve removed the branch from the tree.

The concave cut will assist with callus formation, so the resulting scar tissue will be smoother, instead of proud of the surrounding surface on the branch on the trunk of the tree

When you’reconsidering which knuckle cutter or knob cutter to buy if you look at the tian bonsai brand which is the brand that we primarily sell there’s a couple of features of the tool.

The characteristics of the tool that you can look at to see whether it’s of a good quality or not. Main thing to look for is how the the teeth or the cutting edges meet

On cheaper tools you’ll often find that the cutting edge meets sort of a sharp edge to sharp edge

Whereas on the better quality tools you will see that the two the cutting edges slightly overlap when the cutting edges meet directly on or against one another it will of course tend to wear a lot faster and in effect actually break off small pieces of that edge .

The function of the little stop

Some people have asked me about this little tool stop that you see near the joint on the tool.

Actually in the past, many years ago when the craftsmen were first making these tools this was a way that they used so that when the the handle the two parts of the the tool were closed, the tool stop would prevent the one half one handle from going any further

tian bonsai forged brand

Over time the techniques have improved and in fact at the moment this tool stop is actually more for decoration than anything else it serves no functional purpose

If you do see that that metal edge is not resting against the tool stop it doesn’t mean that there’s something wrong with the alignment of the tool

It’s as i say it’s really these days it’s more for decoration than for any functional purpose

Concave cutter sizes


175 mm.


205 mm.


260 mm.

Tian bonsai tools offers you three different product sizes

We stock three sizes of knob cutters.  The small one (7″) and a slightly larger one (8″) and the biggest (112)

how to choose between these if you were to choose if you had budget only for one then i would suggest that you go for the larger one.

The reason for that is that you will be able to make a wider variety or work on a wider variety of trees in terms of size.

About the quality of the material, choose the best steel you can afford

The smaller one is ideal of course for shohin bonsai trees and other mame or very small trees being that it is it’s a much more slender tool

 you’re able to get into smaller gaps between the canopy and also

because the cutting edges are much smaller and very suited to smaller branches or the removal of smaller branches

With the larger tool of course you can still make a curved cut

the same as the small one, but the resulting cut depending on how deep push the tool into the wood that you’re cutting away that will determine the size of the cut

Something else to consider when using the tool ¿is these are good quality tools made with very good quality materials?

The edges are finished off by highly skilled craftsmen and these tools if looked after will last you for many years

Care of, cleaning and maintenance

However if you abuse the tool ( i’m not saying that you purposefully abuse the tool or you might purposefully abuse the tool but just if you use it incorrectly) you can damage the tool by creating a misalignment between the cutting edges.

It is very important that you understand the limitations of the size material that you can cut with each of these tools

Typically, as a guide, you can consider that if the blade is if you look at the length of the blade or the width of the blade that you would be cons you wouldn’t cut anything thicker than half the size of the blade Between roughly a third to a half but maximum of of a third

 you definitely cannot expect to make a cut that’s the same width of

 the tool itself that would be abuse of the tool and you can expect after doing that a couple of times the tool will buckle or there would be some other issue developing with the tools

Death wood works

Another of the ways that you can abuse your tools is to cut dead wood. Ideally the tools are designed to be used on live or fresh

There are specialized tools for working dead wood such as trunk splitter.

wood and if you do cut dead wood you need to be very very carefully and ideally you need to be cutting into the live tissue behind the dead wood but knob cutters are not dead wood tools.

You need to adjust the size of the branches or the material that you’re cutting with them if the wood is dead or ideally you’re going to avoid cutting it all together.

I mentioned earlier on about the maximum width of branch that you can cut with a specific or particular size knob cutter

There is just one sort of provision that i want to add to that and that is a very generalized sort of a rule of thumb kind of indication of what you can cut with the the tool, but if you have species which wood is extremely hard and you should make provision or allowance for that as well.

If you feel a lot of resistance in the tool when you’re trying to cut the branch or the material that you’re trying to remove then rather on the side of caution then force the tool to cut because you might damage it.

We recommend, like all our bonsai tools, that it stay sharp, clean, and oiled. Keep out of humid areas for any prolonged amount of time.

bonsai Knob cutters Review

The spherical mower of Tian bonsai tools has obtained certification for the materials used, specifically under the Standard Rockwell HRC of steel hardnesses, when using Chrome, vanadium and Manganese.

Thus, its products for bonsai, are offered in several versions that are related to the price and that allow each tool to adapt to the budget deriving from Bosnai fans.

With tian bonsai you pay the best quality at the best prices.
We are clear in saying so.

the staff

And it’s not just our opinion, 9 out of 10 buyers have given a 5-star rating and the remaining four stars out of a maximum of 5.

You can have a look for some comments and reviews from amazon and draw your own conclusions.
We leave you some customer reviews about Tian bonsai tools

The knob cutter does not disappoint bonsai lovers who give their maximum score. But please, wait a bit, there is still more.

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