"In the first days of 2025, I received a new shipment of metal folders from Tim, and with it was the first iteration of what would a year later become the Corner Mate."
 
Read this to find out all about the design and the thinking process behind the Corner Mate, a game-changing tool for bookbinders.

Who's Tim?

Tim (Timothy Bindery) is a bookbinder and toolmaker from Saigon, Vietnam, born in 1992. His career is in software development, and bookbinding is his passion. His enthusiasm for the craft transpires through everything he does, from his bookbinding creations to his knowledge of the craft, his research, his connections, and last but not least the incredibly complex and highly polished tools that he creates, because, as he says - "in Vietnam we don't have a bookbinding tradition, so I need to make everything myself".

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I met Tim, like many other colleagues in recent years, through Instagram. Beside the production of our deluxe metal folders, him and I are always discussing bookbinding-related things, and especially tool making, and one day in 2024 he dropped the following line:

We were both thinking about the same tool at the same time. Great minds think alike?
OK so let's back up for a second. Corner cutters (or more accurately: corner covering material cutting jigs): What are the options?

Option #1: Scissors

This is the traditional way. Doing it by eye, with scissors. There is nothing wrong with it. Except that without practice, it's intimidating. And I must admit that even as a trained professional, I cannot guarantee 100% accuracy or consistency. Now, those things might not be issues, we might welcome small inaccuracies as part of an aesthetic (This is for a large part what we find lovely in old books).
But, there are definitely cases when consistent accuracy is desired. I started using jigs when I started making full leather boxes. It's very comforting to be able to test the correct distance to cut on one corner, set your jig and then go ahead and cut all four with no more guess work, especially (but not only) when the material is expensive and you don't want to take any risks... 

Option #2: Home-made jigs

There are many ways to create home-made jigs. One of the most common ones is to use a piece of cardboard of appropriate thickness, and put it up against the corner with a 45° square, and cut along the board. This works.
In the wire edge binding tutorial, Dan Kelm describes a neat method using a 45° square and a piece of masking tape (photo above)

Option #3:  Machine-cut, or bought jigs

Corner jigs from ibookbinding, with kind permission from Stepan Chizhov

It is quite possible to have corner jigs machine-cut. It's a pretty basic design and if you have access to a Fab Lab you can even do it yourself. I've seen some in acrylic, metal, wood. You can also buy those ready-made, like the well known 3D printed ones from ibookbinding. Hewitt also supplies their own model, and surely many others that I'm not familiar with.

Option #4: Jeff Peachey's corner cutting jig

American book conservator and tool maker Jeff Peachey supplies a tool which is probably the first truly adjustable corner cutting tool. A great invention but with a number of issues, which are all resolved with the Timbentool Corner Mate. 

Starting point

In the first days of 2025, I received a new shipment of metal folders from Tim, and with it was the first iteration of what would become a year later the Corner Mate.

It is clear that Tim based this off of the design of a "trace-coins", a tool to mark the position of the corners in a half leather binding (of which he produces beautiful ones). We can see that the moving arm mechanism is similar, but they go in the opposite direction. Also, he made them both movable.

Trace-coins, W.Leo Nachfolger, Stuttgart, date unknown

We can also see that he came up with a very nice feature, that is now a defining feature of the finished Corner Mate, the half circle cut-out in the arms, which provide grip for the fingers to pull the tool towards the board.

At this point, Tim's idea was to combine two functionalities into one single tool: trace-coins, and corner jig.
This is nice, but it leads to a critical issue. What is a feature of the first functionality (trace-coins) becomes a bug in the second function (corner jig): there is a gap in the cutting edge!

We decide to leave out the trace-coins function and focus on one thing: to make the best possible corner jig in the known universe.

Designing

This is what I send to Tim early February 2025 (almost exactly a year before the launch of the final product: 12 February 2026). The main points are: a smaller size, only one moving part, an uninterrupted cutting edge, and a graduation scale, to be able to have control over the tool settings.
A few months later (May 2025), Tim came back with this:

These CAD drawings show a huge leap forward towards the final result. Tim has found a way to create a system of graduation by raising the male part of the movable leg to be flush with the main body of the tool, adding a single mark on it and a scale with half millimeters on the main body. Just brilliant!

Branding

While Tim was busy with 3D designing, we started thinking about branding. Since this is a collaboration between the two of us, the first idea was to put both our logos on it. 

But it soon became obvious that that this lacked personality and that there was a need for a stronger identity.

And one day this came up:

Adjustable, Tim, Adjustim...Bin Met = anagram of Ben + Tim. There were more ideas. 
But Timbentool stood out. A tool made by Tim and Ben = Timbentool
As this was initially going to be the name of this particular tool, I thought about adding 'the original' to establish its originality.
Design wise, I found a font with a retro and kind of 'tooly' look, and embedded it in a cartouche with the same shape as the slide and lock mechanism opposite. We're onto something!

But then a question arose, looking into the future, what if we create new tools together, how should we call them then?
Will there be a common denominator among all our future tools, and what should that be?
It took a while, but suddenly it was clear: Timbentool shouldn't be the name of this particular tool, but instead, the name of our collaboration!
All tools created by Ben and Tim are Timbentools. That's it, awesome, we have a brand name!
But as far as the name of the tool itself, we were actually back to square one.
So, again, how do we call it?

Descriptive, but rather boring don't you think?
And then this came up:

We all voted for corner mate, agreeing that this sounded friendly and catchy, but also because it offered a template to call future tools: shoulder mate, bevel mate, etc (stay tuned!).

The glue issue

As I started working with one of the early prototypes I realised there was an issue we hadn't considered. When using the corner mate on dry turn-ins (when we glue the board and not the covering material), there is no problem. But when gluing the covering material, the backside of the tool would quickly become saturated with adhesive, which would build an ever-growing layer.

We discussed different possibilities to tackle this problem including lining the back side with Teflon film, but in the end we decided to create a recess into the back side, leaving only 2mm along the edges. That way, the contact with the adhesive is reduced and it is easier to clean off. 
It also creates a very attractive pattern caused by the journey of the milling cutter.

Final words

I hope we were able to paint a good picture of the development process of this new tool, which it simple to use, but rather complex to design and engineer. There is of course much more to it, but those were the most telling details.
In total there have been three prototypes (not counting the very first iteration). All sent from Vietnam to France, it isn't nothing.
I'll leave you with a few videos that were sent to me by Tim along the way:

The first prototype, without scale and unbranded. Notice how the male part of the slide and lock mechanism isn't yet flush with the main body of the tool.

The engraving machine at work:

The second prototype, before painting the engravings:

The second prototype, after painting the engravings:

 

Thank you for reading.

We hope that our tool will be a good companion to you, and it will help you create many beautiful things in the future.

With gratitude,

Ben and Tim

All photos and videos, unless stated otherwise, are by Ben or Tim