Over the past few years selling flat table CNC machines, I’ve collected a list of frequently asked questions related to spoilboards, so I’ve put together this FAQ to answer the most common questions.
What material do you recommend?
For most applications, the correct material to use is low density fibreboard (LDF), however some applications work better with a medium density fibreboard (MDF). A spoilboard needs to be solid enough that it doesn’t compress when the vacuum pump is turned on, and needs to be porous enough to allow good vacuum airflow. Ultra low density fibreboard is too soft and will not hold the accuracy, and less porous materials will not allow enough vacuum flow through the table. A client of ours did some head-to-head material testing, and found that a fibreboard density of 34 to 40 pounds per cubic foot worked the best for them. Contact us for more information.
Okay, where can I buy LDF?
Start with the company that supplies your plywood, particle board or MDF core products. If they don’t carry the right LDF, they should be able to point you in the right direction. Ensure you ask for a fibreboard with the density listed above.
***Update: We currently stock 5×12 spoilboards in two different densities, and will ship them within Western Canada. Contact us to place an order.
Should I flatten both sides of the spoilboard before I use it?
Yes, you should flatten both sides for a few reasons. The first is that the thickness of an LDF or MDF sheet will vary across the sheet, and this will mess with your finished product thicknesses. The second is that while the core of an LDF or MDF board is quite porous, the faces of the panel are not porous at all. If you do not remove both faces of the panel, air will not flow through properly, and your parts will not be held down properly.
How do I flatten my new spoilboard?
Every CNC machine we deliver includes a “surfacing” program for flattening the spoilboard, and we always add in a face milling cutter with the tooling package. After adjusting a work offset in the controller to set the new thickness of the board, you load and run the surfacing program – using the face milling cutter – and you will have a nice fresh surface.
Do I need to do anything to the edges?
Yes, the core of the panel is very porous, and this means that the cut edges of the panel will flow air very freely. If you use a spoilboard without sealing all four edges, you will bleed most of the airflow out the edges, and you will have very little vacuum at the top of the spoilboard where you really need it. There are a variety of ways to seal the edges of a spoilboard, ranging from simply applying edgebanding to all four edges, painting the edges (two solid coats please), coating the edges with wood glue, or even taping the edges.
Do I need to bolt the spoilboard down?
This is somewhat personal preference, and depends on how you want to work. We typically recommend bolting the spoilboard down, but some people prefer to slide the spoilboards on-and-off the machine after each cut cycle. Some of the reasons to bolt spoilboards down include: Less chance of getting dust and debris under the spoilboard and into the vacuum pump; Eliminates bowing and warping of the spoilboard due to moisture and/or stresses in the panel; Allows you to slide your product on and off the spoilboard without the spoilboard moving. In short, unless you have a good reason not to, you should bolt it down.
How often will I need a new spoilboard?
This is impossible to answer, because it depends on the amount of cutting you do, the depth you cut through your finished material into the spoilboard, how small the parts are that you’re cutting, how picky you are about having a smooth spoilboard, and other factors. We recommend buying some spare spoilboards so you’re not stuck if the one you’re using gets damaged.
Can I cut a 2′ x 3′ part on a 5′ x 12′ spoilboard.
If you place that small piece on a full spoilboard and leave the rest of the spoilboard uncovered, you will lose a large amount of vacuum pressure, and that will reduce the holding power. With a wide range of sizes to cut, or if you’re only going to cut small pieces occasionally, it’s easy to cover the open areas with scrap material. When you need to cut smaller – and fixed – sizes regularly, you could paint or apply glue to the open areas, or we can custom vacuum zone your machine at the factory (contact us for more information). In a pinch, a layer of duct tape on the open areas will also work well.
I have more questions.
If you have any spoilboard related questions, or would like more information about the CNC machining centers we offer, please contact us.