You may not think about it, but when you do woodworking, measuring is probably one of the most repeated actions during a project.

When measuring your workpiece, accuracy is extremely important if you want a perfect end result.

So it’s good to have the right techniques and materials to pursue that accuracy.

Digital caliper for perfect measurements

Measurements that have a major impact on the correctness of your connections are, for example, the depth setting of the saw blade or router bit.

Most of the time, I use my multi mark from Kreg for this, but if the setting has to be done very precisely, I use my caliper.

The problem

The problem with a caliper is that the surface on which you measure is very small.

An additional problem is that there is an opening just next to a saw blade or router bit.
Because of that gap, you have no fixed point to measure. 

When you move the caliper until you have a fixed point on the surface of your table saw or router table, the caliper can no longer reach the saw blade or router bit.

The solution

By clamping the caliper in this jig you always have a fixed measuring point and the problem can be solved.

In this video and blog, I will show you how you can build this jig and get the most out of your digital caliper.

After building this jig you will be able to perfectly adjust the height of your saw blade or router bit without struggling.

In addition, this jig is versatile and you can also use it to determine the distance between the saw blade and the fence or the depth of a slot.

Before we dive into the blog you can watch the video first. In that video, I will show you how I build this caliper hack.

In the blog post underneath the video, I will describe step by step the actions you need to take to make this caliper jig.
Also, I will list up the materials and tools you need for building this project.

Watch the video here

Building the caliper jig step by step

Now that we have gone through the list of what we all need for this project, I will explain step by step how to make this measurement jig.

Let’s go!

Step 1 | Preparation

The first thing I did for this project was to cut all the parts based on the measurements on the plans.

I used my table saw and the crosscut sled for this.

To work safely when cutting the smaller pieces I mounted my hold down clamps in the T track rails of the crosscut sled.

Be sure to visit my blog if you want to build this crosscut sled for your workshop. There are also free plans available for this.

Step 2 | Adjustable clamp

The most important part of this jig and the great advantage of this jig is the adjustable clamp.
This ensures that the jig can be used in many ways and that you can measure both heights and depths.

The clamp can be slid up and down because it is mounted on a sliding part that is placed in a slot in the jig.

To make this slot I marked 1 side, so I could see where to cut.

The sliding part must fit perfectly in the slot.
It should not be too wide, otherwise, the jig will not work correctly, nor too small, otherwise you will no longer be able to move the clamp up and down.

To determine the other side of the slot in a perfect way I used my kerfmaker.

Check out my blog with free plans if you want to learn how to make a kerfmaker yourself.

The saw blade may be set slightly deeper than the thickness of the sliding part you are using. 

For example, I used 6 mm MDF for the sliding part and made the slot 7 mm deep.

The dimensions on the plans allowed me to determine the two endpoints of the slot through which the bolt must pass.

In these places, I drilled a hole with the same diameter as the bolt.

With this simple router jig, I was now able to mill a slot between the two drill holes.

Now that the base was ready, I continued to work on the clamp that holds the caliper in place.

With Ca glue I attached the first part of the clamp to the MDF board that is placed in the slot.

Once the glue dried, I made the connection stronger with brad nails.

Right in the middle, a hole was drilled with the same diameter as the bolt I used. This bolt connects this part to the base of the jig.

Because the head of the bolt should not protrude, a hole was made with a hammer and chisel.

The outline of the bolt head was marked with a pencil and hollowed out to a depth equal to the thickness of the bolt head.
I used a hammer and chisel to make that hole.

Pushing the bolt into this hole keeps it firmly in place and the bolt is countersunk.

In the second part of the clamp, a slot is made in which the caliper fits exactly.
In this way, the caliper can be clamped between these two parts.

To make the slot, I set the depth of my saw blade equal to the thickness of the caliper, and with the crosscut sled, a slot was made by repeatedly sliding the block over the saw blade until to the correct width was reached.

I attached the second part of the clamp to the first part with screws.

Make sure to pre-drill and finish your drill hole with a countersink bit for a nice finish.

Step 3 | Placing the center bolt

To fix the sliding part I used a homemade button.

I’ll show you how to easily make that button yourself.

I started by drawing a circle.
For this, I used my hole drill and transferred the contours to the wood with a pencil.

I determined 8 points on that circle.
If you want, you can use more or fewer points, which will determine the appearance of your button.

A hole was drilled at each point. 
To drill these holes, I used my drill press so that I was sure of holes drilled at right angles.

After drilling the holes on the outer edge of the button, it was time to drill out the button itself. 

For this, I used a 20 mm hole saw.

To screw the knob onto the bolt I had to insert a nut into the knob. 

After drawing the contours of the nut, I was able to hollow out the knob with a hammer and chisel and insert the nut.

If you do this very accurately, you do not need to glue to fix the nut in the knob.

The end result is a nice knob with a countersunk nut.

Step 4 | Assembling

All parts are now made and ready for assembly.

To connect the parts together I used wood glue and brad nails.

I’ll show you how I did this below.

Assembling the base of the caliper jig

The base of the mold is mounted perpendicular to the base. 

Check the perpendicularity, this is extremely important for the proper functioning of the mold.

A reinforcement was applied to fix that perpendicularity.

When using nails, determine the right place to shoot them.
Later I will show you how to cut a slot in the bottom of the jig and of course, you don’t want to hit nails with your saw blade.

For the jig to work perfectly you need a flat bottom.

I used the sander with P80 grit sandpaper followed by manual sanding on a sanding board.

The sanding board was one of the 5 must-have easy to build woodworking jigs in my blog and video a couple of weeks ago.
Check out that blog and discover the other 4 must-have jigs.

Making the slot in the bottom

As I said before, this jig is versatile.

One of the applications is to measure the distance between the saw blade and the fence.

However, because you only can measure on the left side of the saw blade, the thickness of the saw blade must be removed or you will always have mis-cuts.

To saw the width of the saw blade I used a very simple trick.
I’ll show you how.

Start by clamping a piece of scrap wood on the cut sled, with the side of the block exactly where you cut. Clamp it firmly and let the block sit during this entire process.

Now cut the edge of this block.

The new edge of this block is exactly the position of the right side of the saw blade.

By sliding the jig against the block and making a cut, you have now transferred the exact thickness of your saw blade into a slot on the bottom of the jig.

Installing the adjustable clamp

Now that the base of the jig is completely ready, you can place the clamp.

Finally, you can place the caliper in the clamp. 

You can later adjust the height to the conditions in which you need to take a measurement.

How to use this jig

This jig is versatile and very easy to use. 

I’ll show you the options

Measuring the height of the saw blade or router bit

Place the caliper just a little higher than the height you want to reach with the saw blade. 

Now clamp the caliper firmly in place.

Lower the measuring point of the caliper to the surface that determines the zero point.

Press the zero button to calibrate the caliper.

Now move the jig until the caliper measuring point touches the top of the bar.

Gently rotate the saw blade upwards.

The caliper is pressed and the distance can be read on the digital screen.

Measuring the height of the saw blade or router bit

Place the caliper all the way down and reset the digital meter there. 

This is now your zero point.

Lower the caliper into the slot and read the distance from the digital screen.

Measuring the distance between the sawblade and the fence

Place the jig on a flat surface and lower the bottom of the caliper completely.
Set this as your zero point.

Tilt the jig 90 degrees and place it on its side with the bottom against the saw blade.

Lower the saw blade until it fits into the slot. The right side of the saw blade should now be flush with the bottom of the jig.

Now by extending the caliper and letting the measuring point come to the fence, you can determine the exact distance between the saw blade and the fence.