September 20, 2022 4 min read

The correct CNC spoilboard can mean the difference between an excellent project and a mediocre one. But what is a spoilboard, and how does it help? Below, we’ll answer these questions and more like them.

What is a Spoilboard?

A CNC spoilboard (often referred to as a sacrificial or bleeder board) is a disposable work area that attaches to the top of your router table. It protects the factory surface table from sustaining damage during processing while the tool works through the active material.

A spoilboard protects your router table from potential damage.

Spoilboards also help to ensure that the router cuts smoothly by creating extra traction and providing more space to clamp the workpiece.

What Can I Use for a CNC Spoilboard?

You can use various substances to create a spoilboard. The two most commonly used are MDF boards and LDF boards. Let’s discuss the differences between them.


MDF, or medium-density foam, is one of the most common choices for a CNC spoilboard. It’s hardy, easy to work with and relatively inexpensive.

MDF makes excellent spoilboard, thanks to its porosity and solidity.

It’s not as smooth as finished plywood or HDPE boards, but it’s readily available and can take a lot of abuse.


LDF board, or low-density foam, has most of the advantages of MDF. It’s not as solid, though. LDF is also lighter in weight and more porous. It’s ideal for dusty projects that require an effective vacuum pump.


Plywood is a fantastic spoilboard choice if you're looking for something with a smoother face

The main application for plywood as a spoilboard is when you’re doing intricate work. It has a much smoother face than either MDF or LDF and is more affordable than HDPE.

High-Density Polyethylene (HDPE)

HDPE is one of the newer CNC spoilboard options and has the advantage of a smooth face. While these boards can give you better results on intricate workpieces, they also generate less traction.

HDPE board can be expensive when compared to the other options. However, it’s also easy to work with. What it comes down to is, would you rather spend more time or more money on your wasteboard?

How Thick Should Spoilboard be?

Your preferred CNC spoilboard thickness is ultimately a matter of preference. However, many CNC experts prefer a board that’s at least ¾ inch. Some recommend MDF or LDF board as thick as 1¾ inch thick.

Bear in mind that, though you can use thinner boards, you’ll be more likely to cut through them accidentally. If that happens, you may damage your router table.

Some experienced machinists make their spoilboard much thinner, but we recommend starting with at least a ¾-inch thickness.

What to Look for in a Spoilboard

When you’re choosing a material for constructing your CNC spoilboard, there are a few things you should consider. The following segments will explore some of the most essential.


If you’re working with a vacuum pump (which you probably will be), you need a spoilboard that’s porous enough to allow airflow. At the same time, it needs to be solid enough that the vacuum doesn’t compress it further.

Your spoilboard should be porous enough to let the vacuum pump operate through it.


If you make your CNC spoilboard, you want something that’s easy to work with. Spending hours on a spoilboard is undesirable if you damage it in a matter of minutes.


Since your spoilboard is essentially PPE for your router table, it’s a disposable element. You don’t want to pay hundreds of dollars for spoilboard if you’re going to replace it regularly.


Once again, you’ll damage your spoilboard and will need to replace it. It’s best to choose a readily available material. That way, you can easily buy more materials when your board reaches its end.

How Do You Make a CNC Spoilboard?

Whether you use LDF board or MDF board, making a CNC spoilboard is straightforward. Let’s take a look at the process, step-by-step:

  1. Determine the size of your router’s worktable. Typically, the machine’s size refers to the size of its worktable. I.E., a 4x4 CNC has a worktable that’s four feet long and four feet wide.
  2. Buy MDF or LDF board that’s large enough to cover the worktable twice.
  3. Use a table saw or circular saw to cut the board to length. You want two equal portions that you can fit one on top of the other.
  4. Use high-strength wood glue or epoxy to glue the two sheets of board together.
  5. Clamp them together, and allow the glue time to harden.
  6. When the glue is dry, use a table saw or jigsaw to finetune the board. Its dimensions should ideally cover the CNC’s entire worktable without jutting out.
  7. Determine the locations of the bolts on your CNC router’s surface.
  8. Measure your MDF or LDF board, and mark the areas that directly correspond to the bolts on the CNC.
  9. Countersink holes on the upper surface of the markings you’ve made to accommodate the washers and nuts.
  10. Use a smaller drill bit (large enough to accommodate the CNC’s screws) to drill holes through the bottom half of the board.
  11. Attach your new CNC spoilboard to the worktable (bolt it into place with the existing bolts).
  12. Program a design into your CNC software that will remove around one-eighteenth of an inch from the top. Most MDF and LDF boards aren’t perfectly planed, and this step will ensure that you’re working on a perfectly level workspace.
  13. Run the CNC design you’ve created to level the workspace.
  14. Use a brush to remove any remaining debris from the board.
  15. Congratulations, You’ve made a spoilboard!

Final Thoughts

Choosing an appropriate CNC spoilboard can change your project from a good one to a fantastic one. MDF and LDF board are the most common, and they serve well in most cases.

We’d love to help you learn more about the right board for your project. Please feel free to contact us, and we’ll help you choose a suitable CNC machine and the right spoilboard to go with it.

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