CNC technology has made its way into a large number of woodworking operations, even increasingly finding its way into hobbyist shops. When using a CNC machine, one of the fundamental requirements is to ensure that the workpiece is solidly and safely secured to the bed of the CNC. If there is any ability for the workpiece to move, the quality of the project will suffer, as the router bit will wander from its intended course and render an image that is not crisp and clean. The answer is to use hold down clamps.
Hold down clamps are an important accessory on a CNC machine because they are an inexpensive item that can quickly and easily secure the work piece to the CNC bed. Typical hold down clamps rely on a T-track system in the table , and they slide in the track and lock down at the desired location using a threaded knob mechanism. The challenge is that not all CNC beds have T-tracks, so some other means of securing the work must be utilized.
The solution that George has come up with is to use shop-made hold down clamps that do not require a T-track. Making shop-made hold down clamps is simple:
Start with scrap hardwood. Since you will be putting strain on the hold down clamp as you secure the workpiece, it only makes sense to use a hardwood that can withstand this stress. Maple, oak, birch, cherry, walnut or poplar would all be good options for these.
Ensure that they will fit most of your projects. Size the hold down clamps for the typical height range of most of your projects.
Secure using screws. Attach the hold down clamps to the CNC bed using wood screws, and position clamps for maximum holding power. Kreg coarse thread screws work very well for this. Double check the length you need.