MDF vs. LDF: Which spoilboard is better for CNC?
Spoilboards represent one of the least talked about but most important aspects of CNC work, playing an essential role in preserving the condition of your CNC machine while also adding stability and accuracy to the cutting process.
When it comes to choosing the right spoilboard for your operation, medium-density fibreboard (MDF) and low-density fibreboard (LDF) are two primary options, both offering different advantages depending on the specifics of your project.
Here is a closer look at what to look for in a spoilboard, the unique differences between MDF and LDF, and some additional tips for making appropriate use of spoilboards within your day-to-day shopwork.
What to look for in a spoilboard
The main reason spoilboards are such a minimal topic of discussion is because their role is ultimately sacrificial – but that doesn’t make them any less important.
Spoilboards are used as a base surface for cutting to prevent your CNC table from being damaged by the cutting tool. Because of this, a spoilboard needs to be solid enough that it doesn’t compress when the vacuum pump is turned on while also being porous enough to allow for appropriate airflow.
If the spoilboard material is too soft, it will not hold properly and your accuracy will take a hit. If the material is not porous enough, it will not allow enough vacuum flow through the table itself.
Medium-density fibreboard (MDF)
MDF is a composite wood material that typically comes in the form of large, thin sheets with a density of between .5g/cm3 and .8g/cm3. It is a type of hardboard with two smooth surfaces made from wood fibres and particles glued together under heat and pressure. MDF is not considered true lumber and has no grain patterns.
MDF is widely used across applications due to its high density, which also results in enhanced strength and durability. Because it’s so durable, some think of it as the superior spoilboard – but this is not always necessarily the case.
Both sides of MDF are heat-sealed to a smooth finish, making the surfaces less porous. You may need to skim both sides prior to use in order to achieve better suction. You may also need to ensure all edges are sealed after skimming to prevent a loss of suction from the sides. This may not be required in some cases, such as when working with ShopSabre’s HiFlow vacuum technology.
Low-density fibreboard (LDF)
LDF – as it is aptly named – is a composite wood material with a lower density ranging from .35g/ cm3 to .5g/cm3.
For most CNC applications, it is considered the better spoilboard option because its lighter weight and density allow for better suction between the board and the vacuum beneath the table. This increased suction translates to better stability and accuracy when cutting the material as the board is less likely to move during the process.
Additional spoilboard tips
When utilizing a spoilboard, it is also recommended to flatten both sides of the material before use. Thickness often varies across the LDF or MDF sheet, which can alter the thickness of the finished product being cut. While the core of the spoilboard is porous, the faces of the panel are not. If you do not remove both faces of the panel, air will not flow through properly and parts will not be securely held down.
As mentioned in regard to MDF, it is also a good idea to seal all four edges of the spoilboard. Due to the porous nature of the core of the panel, the edges must be cut in order for air to flow more freely. If you don’t seal all four edges, you will bleed most of the airflow out of the edges and will have very little suction at the top of the spoilboard – where it is most needed.
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