Collection: SPOILBOARD SYSTEM

The Broinwood CNC Spoilboard System turns a standard MDF spoilboard into a configurable fixture plate.

A grid of pockets is machined into the spoilboard once. Split Expansion Bushings, Guide Pins, and Low-Profile Clamps can then be installed anywhere in that grid and moved whenever your setup changes.

You do not need hardware in every pocket. Use only the components you need for the current job, then remove or reposition them for the next one.

This gives you a reusable workholding system for different workpiece sizes and shapes without repeatedly driving screws into the MDF.

All components use the same pocket grid.

Guide Pins are inserted directly into the pockets and can be used as stops or fences for positioning the workpiece.

Split Expansion Bushings are installed wherever a threaded mounting point is needed. Tightening the Threaded Insert expands the bushing inside the MDF pocket and locks it in place.

Low-Profile Clamps attach to the bushings and hold the workpiece down while remaining close to the spoilboard surface.

The Long Guide Pin can also accept a Threaded Insert and bolt, allowing it to be used as an adjustable pushing or holding point.

For larger workpieces, simple wedges can also be used against the Guide Pins.

When the setup changes, the components can be removed and installed somewhere else in the grid.

Driving screws directly into MDF works, but repeated use gradually damages the spoilboard.

Even with pre-drilled holes, screws can raise MDF fibers and create small high spots around the mounting locations. For thin or precision-machined workpieces, those small surface changes can affect how the material sits on the spoilboard.

Permanent threaded inserts solve some problems but create another limitation: the hardware remains in fixed locations whether you need it there or not.

This system keeps the grid permanent but the hardware removable.

If a bushing or Guide Pin is in the way of a toolpath, remove it. If you need a mounting point somewhere else, move it.

The spoilboard stays configurable instead of being permanently committed to one workholding layout.

The system is designed for CNC machines using an MDF spoilboard.

I recommend a spoilboard at least 3/4" thick, with 1" preferred.

The nominal main pocket diameter is 25.3 mm, but the actual machined diameter can vary slightly from one CNC to another. For this reason, always machine a test pocket first and verify the fit using a Guide Pin.

Start at 25.0 mm and increase the diameter in 0.1 mm increments until the Guide Pin fits snugly but can still be inserted and removed by hand.

The recommended main pocket depth is 17 mm.

Because the grid is created on your CNC, its overall size can be adapted to your machine's working area.

You only need to machine the spoilboard once.

After determining the correct pocket diameter for your CNC, create the pocket grid across the area you want to use as your fixture plate.

I recommend 25 mm edge-to-edge spacing between the main pockets.

If your table configuration allows it, I also recommend an 8 mm bolt relief hole below each main pocket. This gives longer mounting bolts additional clearance.

A light chamfer around the upper edge of each main pocket is also recommended. It removes the sharp MDF edge and helps reduce lifting or chipping of the fibers when components are repeatedly inserted and removed.

A Vectric setup file is available as an example and includes the test pockets, grid, relief holes, chamfer, layers, and corresponding toolpaths.