Fixture Plate

A Fixture Plate, Modular Tooling Plate or Pallett System can be a great addition to your machine. Let's discuss why you would want one, what options there are and how you can make one yourself.

WHY WOULD YOU WANT A FIXTURE PLATE ?

If you have any experience using a mill then you are familiar with the T-Slot table and the chore of tramming in a vice. This step can be time consuming especially for a one-off part. Using a fixture plate, the vice will go exactly into its "home position" no tramming and adjusting necessary. It's a big time saver.

In short, the Fixture Plate offers the advantage to secure and position your work at the same time.

Advantages of a Fixture Plate:

Reduced set up time
Precise and repeatable positioning
Lower mounting than a vice (increased Z-Height)
It can extend the machine table to hold stops and toe jacks.
It can be customized for your parts i.e. a circular hole pattern
The added mass to the table can reduce vibrations and yield a better surface finish for light duty desktop machines.

Check out the video I made, making a Fixture Plate for my CNC-Router.

I use a shoulder bolt to fasten and locating the plate to my machine table.

My Goal was to clamp aluminum parts low to the table.

Positioning and holding a low-profile vice is the main use of my fixture plate.

Materials For a Fixture Plate

Industrial plastic like Acetal (Delrin)
Cast Aluminum plate like you see in the picture Alcoa brand ATP-5
Low stress steel, possibly with hardened inserts (professional use)
Cast Iron - vibration dampening, heavy and expensive.

My Pro Tipp

Use a shoulder bolt like in the picture (ISO7379) you can position and fasten your parts and fixtures with it.

To make a precise locating pin yourself just cut the head off the shoulder bolt and cut a slit (I used a Dremel) into the end face.
3 of them will locate a part precisely on your plate

Making the Plate

Here are a couple of pointers machining the Fixture Plate:

You will need access to the entire top surface and the perimeter. Think how you can hold the plate without any obstructions and without machining into your table.
- My solution is Tape and Superglue
- The use of the fastening holes is also possible
To get to a precise thickness I first machined the back side then measured the remaining thickness using a micrometer and used that value to post the g-code for the top side facing.
Before you start make a test part to determine the fit for the thread (a tad loose is preferred here) and the critical dimensions for the shoulder bolt. Use the actual bolt if you can. Copy these dimensions into your drawing. This will give you the desired fit using your tool on your machine.
If you use a 20mm thick plate you will have to use a "Fog Buster" set up, no way around it. Making this many holes without it will result in a chip weld and a broken tool.