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How to cut a 90-degree angle with a hand saw

2024年9月3日

Right-Angle Guide for Hand Saw

In woodworking DIY, you often need to cut a 90-degree angle with a hand saw, but it’s really hard to get it perfect.

In such cases, a jig can be quite useful. A jig is any tool used to help with completing tasks, and a saw guide is one of them.

This article will help you build a highly effective hand saw guide, and make sure you can cut at a precise 90 degrees.

There are three kinds of saw guides, depending on how difficult they are to make and their accuracy. You can choose and read about them as you like.

《For beginners》Magnetic guide blocks for hand saw

一番シンプルな治具『ノコギリ用ガイドブロック』
Magnetic hand saw guide blocks

The simplest jig is a magnetic saw guide block as shown in the photo above. The black part is a magnetic sheet.

はろ子(Haloko)

What's this... squared timbers?

These are the jigs. It allows you to cut straight with a hand saw.

さくや(Sakuya)

How to make a magnetic hand saw guide block

簡単に作れるマグネット式ノコギリガイド
Square pieces of wood with adhesive magnetic sheets

It is very easy to make a magnetic hand saw guide block. Simply attach an adhesive magnetic sheet to a square piece of wood. The saw blade sticks to the magnetic sheet, which makes it work as a saw guide.

If you don’t have any magnetic sheets, you can also drill holes in the wood and embed magnets instead.

How to use a magnetic saw guide block

You can either attach it to the workpiece with double-sided tape or secure it with clamps.

For example, clamp the workpiece and magnetic hand saw guide block together as shown below.

ノコギリ用ガイドブロックのクランプの仕方
Secure the saw guide block with clamps

Leave the saw blade attached to the magnetic sheet and move it back and forth.

ノコギリ用ガイドブロックに沿わせてノコギリを動かす
Leave the saw blade attachet to the magnetic sheet

This will help you cut straight and perpendicular!

ノコギリ用ガイドブロックをつかえば、かなりの精度で垂直切りができる
You can cut straight and perpendicularly
さくや(Sakuya)

If you don't have a workbench to clamp on to, try building a small workbench like I did.

What you can do with the guide blocks

Using magnetic hand saw guide blocks allows for precise grooving as well.

現物合わせで正確な幅の溝を掘ることも可能
Saw guide blocks allows for precise grooving as well

The photo above shows thin square timbers attached with double-sided tape and grooved all together.

If you take the attached pieces apart and reassemble them, you can make a trivet with halved joints.

正確な溝で相欠き継ぎが可能
A trivet with halved cross joints

This is explained in detail in another article, so if you are interested, please read it later.

はろ子(Haloko)

But with this method, you need a square each time to get a right angle, right?

A little troublesome...

If you feel so, I recommend the "magnetic cross-cut guide for hand saw" explained next.

さくや(Sakuya)

《For intermediates》Magnetic cross-cut guide for hand saw

The magnetic hand saw guide block is very useful, but cannot be used to cut a right angle.

An alternative is a Magnetic cross-cut guide for hand saw. In Japan, this technique is known as the 'Sugita woodworking method'.

ノコギリ用直角ガイド
This jig allows you to cut at right angle every time

You will be able to cut almost any type of wood accurately at right angles with this jig.

If you want to do accurate woodworking, this jig is the first thing you need, so be sure to try making one.

How to make a magnetic cross-cut guide for hand saw

ノコギリ用直角ガイド
A magnetic cross-cut guide for hand saw

This is the magnetic cross-cut guide for hand sawing. To make it, you have to attach a right-angle fence onto a base board.

Materials of the right-angle saw guide

ノコギリ用直角ガイドに必要な材料
Materials of the right-angle saw guide

The magnetic cross-cut guide for hand saw is made of three materials. The base-board (the larger one in the photo above), the fence-board (the brown one), and the magnetic sheet(not shown).

Although it looks simple, there are important points to improve accuracy.

The base-board requirements

The best material for base-board is one that will not warp or twist, so I used 250 x 150 x 24mm laminated pine wood. The greater the material thickness, the better the accuracy.

Make sure that the edge of the base-board (to which the magnetic sheet is attached) is straight and perpendicular, or 'square'.

ベース板の木端面は垂直にカットされていること
The edge of the base-board must be straight and perpendicular

The fence-board requirements

You can use any type of wood for the fence-board, but it must not have any warping, bending or twisting, and must have the straight edge.

I used 160 x 30 x 5mm sized wood. The length should preferably be slightly longer than the base-board.

フェンス板は木端面が直線のものを用意する
The fence-board must have the straight edge
take a break
take a break

How to assemble the magnetic cross-cut guide for hand saw

step
1
Attach a magnetic sheet to the edge of the base-board.

ベース板とマグネットシート
The base-board and the magnetic sheet

Prepare a larger magnetic sheet and stick it on first; then, trim the edges with a cutter for a clean finish.

マグネットシートは大きめのものを貼り付けるのが良い
It is best to use a larger magnet sheet
余分なマグネットシートを切り落とせばOK
Trimming off the excess magnet sheet

step
2
Attach the fence-board to the base-board.

さくや(Sakuya)

This is the most important part!!

When attaching the fence-board, position a square approximately 30~50 mm away from the edge (short side) of the base-board, and ensure that the fence-board is perpendicular to the magnet sheet as you glue it on.

フェンス板をマグネットシート面に対して直角に接着
Mount the fence plate perpendicular to the magnet sheet surface

Attach the fence-board with a slight overhang over the magnet sheet. This will help you trim the excess later to make it flush.

さくや(Sakuya)

The fence-board might move while the glue is drying, so keep an eye on it now and then until it’s fully set.

Don’t we use screws or nails here?

はろ子(Haloko)
さくや(Sakuya)

I wouldn't do that. The wood grain might make them shift a bit.

step
3
Trim off the excess fence-board.

After the glue is completely dry, turn everything over, clamp it down to the workbench, and use a saw to trim off the excess fence-board.

余分なフェンス板を切り落とす
Trim off the excess fence-board
さくや(Sakuya)

It’s better to use a saw without the set-teeth here, because the set-teeth might damage the magnetic sheet.

How to use a magnetic cross-cut guide for hand saw

ノコギリ用直角ガイドと材料を一緒にクランプ
Clamp the magnetic cross-cut guide together with the material

Clamp the magnetic cross-cut guide together with the material for use. When placing the guide on the material, ensure the back fence is flush against the material.

裏面のフェンス板を材料の端にぴったり当てる
The back fence is flush against the material

If the fence is flush with the material, the magnet sheet surface will be at a perfect right angle, vertically aligned, and straight.

At this point, put the saw blade on the magnet sheet and cut slowly.

直角ガイドにノコギリを貼り付けて切り下ろす
Put the saw blade on the magnet sheet and cut

Be sure to keep the saw blade touching the magnet sheet at all times.

さくや(Sakuya)

Watch out for the front part of the saw blade wobbling left and right. We moved the fence back by 50 mm to avoid that.

The results from using this magnetic cross-cut guide are shown in the picture below.

直角ガイドで切ったときの直角精度
The horizontal right-angle accuracy is very high

The horizontal right-angle accuracy is very high, and it’s at the highest level of precision for hand saw cuts.

While the vertical precision is quite good, there may be some minor errors as shown below.

直角ガイドで切ったときの垂直精度
There may be some minor errors
はろ子(Haloko)

Wait, are there errors in that picture?

There’s a little gap at the left edge if you look closely, so it’s not perfectly vertical. But if that doesn’t bother you, it’s fine.

さくや(Sakuya)

Vertical errors occur because the magnet sheet is narrower than the saw blade.

To improve vertical precision, you can thicken the base-board and widen the magnet sheet to over 40 mm. (Just be aware that this will make the saw harder to pull.)

《For experts》Adjustable magnetic cross-cut guide for hand saw

The magnetic cross-cut guide we made earlier can't fix the errors that happen when you’re cutting. Actually, you still get errors sometimes due to your manual work or bending of the fence-board.

Therefore, I implemented the following three improvements:

  • Making the base plate 36mm thick for better vertical precision;
  • Changing the fence-board to an aluminum one to reduce deformation errors;
  • The fence-board was secured using bolts and nuts embedded in the base-board, allowing for fine adjustments of the angle.
直角ガイド(角度調整式)
Adjustable magnetic cross-cut guide for hand saw
さくや(Sakuya)

Making these improvements means I’ve run into these problems myself.

If there are any errors when using the guide for cutting, you can adjust them by loosening the aluminum fence and fine-tuning the angle.

I’ll skip the detailed instructions, but you can look at the miter-cut article, which covers a similar jig.

Overview

正確な直角カットが高精度な木工の第一歩
Being able to make a right-angle cut is a fundamental aspect of woodworking

For those who are just starting with DIY, as well as for those with some experience, cutting wood at a right angle can be a challenging task.

However, any woodworking project begins with cutting the wood at a right angle. Being able to make precise right-angle cuts is the first step.

It is said that you can master this skill with years of practice, but for us DIYers, spending years practicing with a saw isn't realistic. This is where the 'jig' that I introduced comes in as a practical solution.

Jigs are incredibly useful, but they do have their limitations when it comes to precision. This isn't necessarily a bad thing, as it means that the accuracy can be adjusted depending on how the jig is made.

From my experience, I can say that:

  • The precision of a jig directly reflects the accuracy of the materials used to make it.
  • If the jig is large, it will be more precise but harder to handle.
  • If the jig is small, it will be easier to handle but less precise.
  • In the case of jigs, bigger does not necessarily mean better.

The level of precision you achieve with a jig is entirely up to you, and if you are determined, you can pursue accuracy to any extent.

The jig introduced this time is easy to make and use, even for beginners, but I hope this will serve as an opportunity for you to discover the joy and depth of making your own jigs.

Once you get comfortable with making right-angles, I think you’ll find it interesting to challenge yourself with miter-cuts next. Although the complexity of the jig will increase, once the jig is made, miter cuts become easy to execute. If you're interested, please check out this related article as well.

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さくや

DIYと木工と刃物研ぎとキャンプが趣味のシステムエンジニア。賃貸住宅のリビングでもできる『静かなDIY』をテーマにブログを運営しています。