Painters tape hold down works with thin aluminum. Here’s how.

Aluminum is a softer metal. This makes it easier to cut with a low-end CNC machine. But because it is a softer – and in my case thinner – material, it flexes. This results in a cutting surface that is not flat. The situation is made worse by my up-cutting end mills, which pull material up slightly as they cut.

I did lots of reading about how people try to solve this “lifting” problem when cutting thin aluminum. Obviously, the number one solution is to use a vacuum table. But I don’t have one. So, two other solutions were frequently mentioned:

• Make a fixture to bolt on top of the material to hold it down. Then cut around the fixture. This requires careful control of the tool path to make sure the tool does not hit the hold down.
• Use adhesive to glue the material to the sacrifice board. The most frequently mentioned adhesive was double sided tape.

I decided to try the adhesive approach.

From my research, the biggest problem is using adhesive is removing the parts after they have been cut. Adhesive really sticks and requires solvents to remove.

Painters tape hold down – DIY double sided tape

I have used a lot of blue painters tape while printing with PLA plastic. It has good adhesive properties. I heard about the idea of combining painters tape with Superglue. Here is how.

Spread strips of painters tape across both the aluminum material and sacrifice board. Press it down firmly and remove any air pockets. Leave a bit extra sticking out from the edges. Make sure the strips are aligned with each other.

Spread some Superglue along each strip of painters tape on the sacrifice board.

Turn the aluminum plate over and press it onto the sacrifice board. This will Superglue the two strips of painters tape together.

Put the sandwich of material into the hold down fixture. Apply pressure.

It works. Removing the parts is easy because you just need to strip back the painters tape.