The video “This stuff changed my mind about MDF projects” is by Stumpy Nubs (James Hamilton). In this discussion, James dives deep into the world of medium density fiberboard (MDF), shedding light on its strengths, weaknesses, and practical applications for woodworkers.
Understanding MDF
In a perfect world, every woodworking project would be crafted from luxurious mahogany and rosewood, allowing woodworkers to boast about using only the finest materials. However, as James points out, we don’t live in that world, and that’s why manufactured products like MDF exist.
First and foremost, it’s crucial to understand that MDF is not just junk wood. James encourages woodworkers not to let the elitist attitudes of some in the community deter them from using MDF. The key is knowing when to use it and when to opt for other materials.
MDF excels at creating large panels that need to remain flat without warping. It’s also beneficial when a stable material is required, especially in situations where the natural grain of wood could be problematic. However, it’s essential to remember that MDF lacks the long bundles of fibers found in natural wood that provide strength, making it somewhat brittle.
When it comes to joining two pieces of MDF, the material’s structure presents challenges. MDF consists of sawdust mixed with resin and compressed into sheets, which means that when gluing, you’re only bonding the outer bits of sawdust from one piece to another. This results in minimal structural integrity.
Joining MDF Pieces
To fortify that joint, many woodworkers might turn to screws. However, James warns that using screws without proper preparation can lead to disastrous results. The density of MDF means that screws can act like wedges, forcing fibers apart and splitting the material.
To avoid this, it’s crucial to drill a properly sized pilot hole. This means the drill bit should match the solid shaft of the screw, not the threads. This technique allows the threads to grip the MDF fibers securely. Choosing the right screw is also vital; coarse threads will hold better than fine threads.
Furthermore, don’t over-tighten the screws. Once the screw head is seated on the surface, stop driving. Over-tightening can tear the fibers inside, leading to a weak joint. For joining MDF, James recommends mechanical joints like dados or rabbits, which provide a more robust structure.
Cutting MDF
When it comes to cutting MDF, James emphasizes that it’s highly abrasive. This abrasive nature can dull cutting tools quickly. While it might be acceptable to use a cheap circular saw blade, it’s not wise to cut a lot of MDF with your best table saw blade. If you need to run profiles in MDF panels, consider using a cheap router bit that you can discard afterward due to dullness.
Another critical point to consider is the dust created when cutting MDF. The dust can be harmful to your lungs, so James stresses the importance of using a proper dust mask, ideally an N95, and wearing safety goggles to protect your eyes.
Even when the tools are off, MDF dust lingers in the air. If it settles on the floor or your tools, it can be agitated back into the air as you move around your workspace. After finishing your work, keep your mask on and vacuum up the dust before removing it.
Sanding and Finishing MDF
While the surface of MDF is smooth, the edges are often rough due to the manufacturing process. If you plan to paint or finish the edges, they require special attention. James advises a multi-step process for achieving a smooth finish:
- First, sand the edges to 220 grit.
- Next, apply drywall joint compound, pressing it into the fibers.
- If you have many identical parts, stack them together to work on the edges simultaneously.
- Once the filler is dry, lightly sand again with fine grit.
- Apply primer, sand smooth once more, and you’ll have a glassy surface ready for paint.
When to Use MDF
MDF can be a great choice for many projects, but James cautions against overusing it. For items that will remain stationary, like built-in cabinets, MDF is suitable. However, for furniture that may be moved around, especially if longevity is a concern, solid wood is the better option.