Can You Plane MDF and Plywood?

Using a hand planer is a common means of reducing the thickness of the wood. It is an old-fashioned, but quite effective method for most woods as it removes the material one layer at a time. However, most people associate planning wood with standard hardwoods or softwood such as pine, oak, and the like. But can you plane wood that has been glued together such as MDF or plywood? The answer may surprise you.

Can You Plane Plywood?

The answer is yes. You can plane plywood and get roughly the same results as using the planer on standard hardwoods or softwoods. However, the blade on the planer will become duller far more quickly because of the glue used to hold the wood together.

Plywood is made from thin layers of wood plies that are glued together under intense pressure and heat. The glue, usually phenol-formaldehyde or urea-formaldehyde, creates a bond that is stronger than the thin wood veneer itself.

Why Planing Plywood is Not Recommended?

The presence of glue is why many people believe that plywood should not be the subject of a planer. But the truth is that you can reduce the thickness if you are willing to purchase more replacement blades or sharpen the blade in the planer more often.

There is another reason why you should not plane plywood. The outer layers are usually made of high-quality hardwood whereas the inner layers are made of cheaper woods like pine. By planing, you are removing this strong outer layer and exposing the softwood inside. In addition to that, the adjacent layers have grain direction rotated in 90-degrees. Planing across the wood grain can damage the surface especially if the blade is not very sharp.

Now, let’s take a look at how the hand planer and electric thicknesses planer work on plywood and MDF.

Hand Planer

Although the hand planer is a standard tool used to reduce the thickness of wood, it is not a good choice for plywood. There are two reasons why you should avoid using a hand planer on plywood.

Glue: The glue that holds the plies of the plywood together is hard enough to dull the blade of the hand planer. This means that you get less work done and have to sharpen or replace the blade more often. How time-consuming it is to try to hand plane plywood may not be worth the effort.

Across the Grain: If you plane across the grain of the plywood, the result will be the creation of long, stringy fibers instead of the small chip that is normally what happens. This means that the dust port of the planer will be clogged more quickly and thus have to be cleaned frequently. The result is that you get less work accomplished while putting in a much greater effort.

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However, if the hand planer is the only tool you have, then it is possible to plane the surface and eventually get the results that you want. This means doing the following.

• Plane small sections of the plywood
• Avoid going across the grain
• Regularly pause to clean and re-sharpen the blade

You may want to keep a few spare blades around and sharpen them before starting on this project. That way, you can simply switch the blades and take a break when all of them are dull. Use the downtime to resharpen all the blades and start again.

Electric Thickness Planer

can you put plywood through a thickness planer or jointer? This electrical planer takes away the stress of working by hand, but it also creates other issues when using it on plywood or MDF.

You still have the same issue with the glue and other debris that may be part of the wood. The result is that you may have to frequently resharpen the blade. This means stopping every so often, lengthening the time it takes for you to complete the project.

The device may be too clumsy to use on the plywood or MDF. The result being chunks of material being removed that are larger than desired. And if you accidentally go against the grain the result may even be worse. It is recommended that you get a good feel of using the electric thickness planer first with smaller pieces of scrap plywood or MDF and judge the results before committing yourself to the larger pieces.

How Do You Reduce the Thickness of Plywood?

There are ways to reduce the thickness of plywood without resorting to a hand planer. What follows are some of the most common ways to reduce the thickness of the wood.

Sanding

This is perhaps the safest way to reduce the thickness of plywood. Use 150-grit sandpaper on a sanding machine will let you reduce the thickness while still providing a smooth surface. Plus, you are not ripping through the veneer layers to get the job done.

Depending on how much you want to reduce the thickness of the plywood, using sandpaper can take a long time. Plus, you will have to be careful if you want the thickness to be reduced evenly across the entire sheet of plywood.

Block Plane

A block plane is a smaller-sized hand plane with a blade set at a low angle and bevel up. This tool will allow you to remove small chips off the plywood instead of the larger chips or fibrous strings that often occur when you plane against the grain. Because the block plane provides a different result, you can plane the plywood with more confidence. However, it will take a considerable amount of time using a block planer.

Planing Plywood Edges

You can hand plane plywood edges using a low-angle planer such as a block plane. Make sure that your blade is sharp and the mouth is adjusted fairly close to the blade to minimize the tear-out. The relatively smaller size of the block plane helps to control the planer movement with one hand.

Can You Plane MDF?

MDF (Medium Density Fiberboard) can be planed as well, although it is not the best type of wood for planing operations. This is because using a planer on MDF will also dull the blade rather quickly. Because of the glue that is used, the harder material will quickly dull most blades causing frequent resharpening or replacement.

One difference between using a wood planer on MDF is that the thinning process will create fine dust instead of chips. It is this fine dust that may clog the planer and cause frequent stops for cleaning. If you have an air compressor, you can blow out the dust, but you will have to wear a respirator mask to protect yourself.

As with plywood, you are better off purchasing MDF at the thickness desired rather than having to do the thinning yourself. But if you cannot find the proper thickness, then it is recommended that you use a sander, preferably a drum sander that uses 150-grit sandpaper. This will thin the MDF, albeit slowly, and provide a smooth surface if you can thin the wood evenly.

With plywood and MDF, you are far better off purchasing the wood at the thickness you desire. If that is not possible, then you should purchase the wood as close as possible to the thickness desired to reduce the amount of thinning you need to accomplish.