In the "Building the KRMx02 CNC" book, I take you through the process of building a wooden clamp.

While this chapter in the book is more devoted to showing you the basic operation of the KRMx02, the value of these clamps should not be understated.

They work perfectly for most operations and are forgiving if you crash your tool into them.

The clamps I will be showing you in this project are not meant to replace the wooden clamps, but work much better at holding things like vices, when working with aluminum.

In previous posts I showed you these Incra Clamps that I used to hold my vise in place.

These work fine, but can be a bit a little clunky to use.  They are a little finicky with spacing, and can move the item you are trying to clamp when tightening.  They are also expensive.

Lets take a look at the basic design of the clamp.  The clamp is 4.5" long and 1" wide.

It has a small lip at one end that will allow you to slip over the edge of the stock or item you are holding.  This holds the stock down and keeps it from moving towards the clamp.

There is a slot running the length of the clamp that is to secure the clamp to the table.  

I have also added four holes that can be used with an optional support bracket.

The drawing file for this clamp can be found here: 4.5" Basic Clamp Drawing

In order to mill the end of the clamp with a 1/8" end mill, I had to add some more architecture in order to create the tool paths in the CAM software.

I export an eps file for use with my Vcarve CAM software.

4.5" Full Clamp Drawing

I drop my exported clamp drawing into my CAM software (Vcarve Pro).

Step 1

I change the stock size to 4.65" x 1" and the thickness to .25".

Step 2

I deselect the "Use origin offset" and click the Center data in job option.

Step 3

I re-select "Use origin offset" and enter -.15 into the X field.

This is the first time I have ever used this option. It allows me to reset the reference point on the drawing to the actual edge of the aluminum I will be cutting. This needed since I added a little path geometry to left side to allow me to machine the tip.

Normally Vcarve (and many other CAM packages) set the reference to the edges of the drawing.  By using the offset settings you can bring the reference back into its proper position.

I start by creating the paths for the four holes used for the optional support bracket.

I do a cut path with:

• RPM: 24000
• DOC: .03"
• Feed: 20IPM
• Plunge: 20IPM
• Ramp: .5"

I cut a finish path with"

• RPM: 24000
• DOC: .27"
• Feed: 10IPM
• Plunge: 10IPM
• Ramp: .5"

Next, I create the mounting slot paths.

I do a cut path with:

• RPM: 24000
• DOC: .03"
• Feed: 40IPM
• Plunge: 40IPM
• Ramp: .5"

I cut a finish path with"

• RPM: 24000
• DOC: .27"
• Feed: 10IPM
• Plunge: 10IPM
• Ramp: .5"

Next, I create the slot paths for the tip.

I do a cut path with:

• RPM: 24000
• DOC: .03"
• Feed: 40IPM
• Plunge: 40IPM
• Ramp: .5"

I cut a finish path with"

• RPM: 24000
• DOC: .27"
• Feed: 10IPM
• Plunge: 10IPM
• Ramp: .5"

Next, I create the path for the lip:

I do a cut path with:

• RPM: 24000
• DOC: .03"
• Feed: 40IPM
• Plunge: 40IPM
• Ramp: .5"

I cut a finish path with"

• RPM: 24000
• DOC: .27"
• Feed: 10IPM
• Plunge: 10IPM
• Ramp: .5"

The Gcode is loaded into Mach3. Before I can start the job I need to setup my stock.

I will be using a piece of aluminum 4.5" x 1" x .25" for the clamp.

The optional support will need a piece of aluminum .75" x 1" x .25".

The clamp stock is mounted in the vise, roughly centered.

X Axis

We will be referencing the stock to the front left corner.  I start by touching the bit against the left edge of the stock.

I then set the X DRO to -.0625.

Y Axis

I touch the tool to the front edge and set the Y DRO to -.0625.

Z Axis

My KRMx02 has a depth probe, so I use it to set my bit to the top of my stock.

The machine is now setup and ready to run the job.

If you plan on making more than one clamp, I recomend adding a stop, like the one shown here.

This will allow you to quickly insert a new piece of stock and run the job again without any setup.

The support allows you to raise the rear of the clamp.  This makes it easier to clamp thicker stock.

By inserting screws through the holes and adding nuts as shown here, you can easily slip the rear of the clamp over the support as shown here:

The support is designed to have the same hole pattern as the clamp. The support is selected and saved as an eps file for import into Vcarve Pro.

Support Bracket EPS File

I drop my exported support drawing into my CAM software (Vcarve Pro).

Step 1

I make sure the stock size is set to .75" x 1" and the thickness to .25".

Step 2

I deselect the "Use origin offset" and click the Center data in job option.

I start by creating the paths for the four holes used for the optional support bracket.

I do a cut path with:

• RPM: 24000
• DOC: .03"
• Feed: 20IPM
• Plunge: 20IPM
• Ramp: .5"

I cut a finish path with"

• RPM: 24000
• DOC: .27"
• Feed: 10IPM
• Plunge: 10IPM
• Ramp: .5"

I then add a couple tool paths for the pockets. These are used to keep the heads of the screws off the table.

I do a cut path with:

• RPM: 24000
• DOC: .03"
• Feed: 40IPM
• Plunge: 40IPM
• Ramp: .5"

I cut a finish path with"

• RPM: 24000
• DOC: .27"
• Feed: 10IPM
• Plunge: 10IPM
• Ramp: .5"

Support Bracket Gcode

The Gcode is loaded into Mach3 and the stock setup much like I did with the clamp. You wont have to set the front edge if you have not moved your vise.

The basic clamp consists of the clamp, 1/4" Tnut, washer, and knob as shown here. As long as you are clamping thinner items this is all that is needed.

You can raise the rear with four #6 machine screws and nuts as I have done here.

If your raise the clamp this way, make sure you add some acorn nuts to keep the screws from digging into your table.

Here I have added some longer screws to raise the clamp even more.

To use the support brackets to raise the clamps, insert some machine screws into the bracket as shown here.

The bracket is placed under the clamp as shown here. Since the clamp is only set on the four screws, it is very easy to remove the support bracket.

Since the clamp is only set on the four screws, it is very easy to remove the support bracket.

Here I have used longer screws to the support and added some nuts to the screws for easy adjustments.

Here I have added some nuts to affix the support bracket to the clamp.

Here four clamps are used to hold a machine vise.