So many of the projects and home improvements we make include the use of plywood. We work with it a lot, including a recent project involving repairing and replacing the flooring in a 125+-year-old house.
We’ve also used a higher grade of plywood to make a workbench in the shop and another for a shed behind that very old house. Yes, there is a variety of plywood, the use of which is determined by your project. We want to talk about that today and give you some ideas for finishing off the better plywood grades using tools – both hand and power tools – you likely already have in your shop.
What is Plywood?
We’ve written about plywood in the past, and you will find what we consider to be a very good piece on plywood grades here. If you want to just stay here, though, we’ll highlight that piece for you.
The term plywood gives a hint to what it is. It’s an engineered and manufactured wood product that is made from thin layers, also called veneers or “plies.” These plies-in sheets are glued together and compressed with great pressure to form the sheets of plywood we find at the lumber yard and the big DIY stores.
As each ply is added to the sheet during manufacturing, the grain is rotated 90 degrees to the grain to which it is being glued. This accomplishes a few things:
- It will help reduce expansion and contraction from changing environments;
- It will help prevent splitting when nailed or screwed; and,
- It will enhance the sheet’s strength in all directions across the sheet.
Plywood sheets will be labeled by a number, whether 3-ply, 5-ply, or multiple-ply, for instance, to refer to how many plies the sheet is composed of, with 3-ply being the more common. A 3-ply sheet will measure about 2-3 mm in thickness. This will be the ply used in many indoor projects as it has a more “finished” appearance than the thicker, higher ply sheets and can be made to appear more decorative for those indoor projects.
Sheets will usually come in a 4’ x 8’ size at the lumber yard and the big DIY stores. There are specialty sizes, though, that are available if your project, for instance, is the building of cabinets (kitchen, workshop, garage).
If you have ever frosted a wedding cake, you know that the early layers of icing will be crudely applied, while the top layer, the layer that will be on display for the bride, groom, and guests, will be perfect. It’s the same with plywood sheets.
The top layer of the sheets, the face veneers, will be of a higher quality ply material than the core plies. This is especially so in the plywoods that will be used for indoor projects where it will be visible. The plywood sheets used for subflooring are not going to be visible, and so the quality or grade will be lower.
In that previous piece, we noted that plywood’s benefits include stability, strength-to-weight ratio, and resistance to chemicals. This makes it a good choice for concrete forms work, for instance, as it will not corrode.
What Are The Different Plywood Grades?
There are 4 main grades of plywood, and we’ll not go too deeply into them except to say that they include:
- A grade – highest quality, most expensive, sanded smooth, and finished without blemishes or knots. The face layer of A grade plywood will often be Baltic birch, an excellent wood that looks great and finishes well, even taking to stains.
- B grade – solid surface but with some defects in appearance, although repairs will also have been made to the most serious ones. You’ve likely seen the football-shaped repair pieces in sheets you’ve used in the past. The cost is less than A grade, as you’d expect;
- C grade – not sanded, not repaired, defects clearly visible and often discolored. This grade will be used for sub-flooring since it will not be seen over a hardwood or carpeted floor; and,
- D grade – not sanded, with even more defects, some of which you will want to repair, including splits, missing pieces of core plies, and knots. Also, to be used where it will not be seen.
What Tools Can You Use to Round Plywood Sheets?
Now that you have an idea of what plywood is and a bit about the different grades and their uses, we’ll address the rounding of it. Since you are not likely to want to put a fine finish with rounded corners on a sheet of plywood that will not be seen (floorboard, for instance, or concrete forms), we’ll be considering the A grade plywood sheets.
First, let’s be clear. Yes, you can round off the corners of plywood, and there are a variety of tools, both power, and hand, that you can use for this task. It can withstand well that kind of finish work.
- Sandpaper. You certainly have sandpaper in your shop, and this can easily help create rounded edges and rounded corners. Whether using it entirely by hand or by using a sanding block, you can achieve smooth surfaces on plywood. It’s a cheap solution requiring only a strong hand and a lot of elbow grease, but it is doable. The feel that goes along with hand sanding or sanding block work keeps you in touch with the piece you are sanding, and the result can be better than machine sanding. This leads us to…
- A belt sander. This is the power tool option for sanding plywood. It’s a good choice if you have a lot of material to remove, both along the plywood edges as well as the corners. Smaller pieces of plywood make more sense, as you must hold the plywood sheets against the sander, and you also want to be careful about just how much material you are removing, as the belt sander will remove a lot of material quickly.
- Hand plane, rasp, or chisel. These hand tools can also be used to round edges and corners. Like the belt sander, a hand plane will remove a lot of material quickly; the rasp, on the other hand (no pun intended), is a more finesse hand tool. If you have a small piece that requires a more precise material removal done with care, the rasp or wood file is the better choice. The chisel is just a cruder material removal tool than a hand plane, and will take edges down and round with a steady hand.
Using A Router to Round Edge Plywood
If your shop inventory includes a router, and you are experienced in its use, this is an easy choice to make. If your project involves a lot of plywood edges and corners to round off, this is also a smart choice for the task.
In the latter case, a router table is the best option for you. An edge round over bit will do the trick, and attaching it to your router table and running your plywood sheets over it will round the edges and corners very nicely.
Plywood glue can be a little bit sticky (pun intended) when using a router, though, so you should be aware of that. Plywood glue can gum up the router drill bit and cause it to go dull on you faster than it does when used on solid wood. The best approach is to make sure you are starting with a newly sharp bit for the best approach, although that is good advice no matter what you are using your router on.
Here is a very short but helpful video that shows one woodworker’s solution to using a router on a small piece of plywood to round the edges. Notice how he slows as he approaches the end of the edge in order to avoid tear-out. Please take note of that and remember to do the same if you use your router in this way.
You can round over plywood, yes. You have several options for the right tool for that job, too. Two final points to make:
- We have considered only the A grade plywoods, as these are the most likely to be used in projects where they will be seen, and thus the desire to finish them well with rounded edges and corners.
- Always wear your safety goggles when you are using tools that will be removing materials and spitting up dust and debris from your workpiece.
When done right, an A grade piece of plywood can be made to look quite nice with rounded edges and corners. Be safe and have fun.