How to: Make your own trim

Trim–it really does tie a room, woodworking project or built-in project together. And, in spite of all the varieties available commercially, I recommend you make your own. There are three reasons using a router table as a trim-milling machine makes sense, the last of which is the substantial money the process saves. Trim quality and variety are more powerful motivations for me, and they’ll probably become yours too. Give the mill-it-yourself option a try and you’ll never go back to store-bought. Crisp edges, smooth profiles, top-quality wood and unique designs all have a way of raising the bar on the projects you produce. Once you’ve reached a certain level, those qualities are not things you’ll want to give up. The key to good trim, of course, is getting the details just right–starting with wood preparation.

Making your own trim is the closest you’ll get to an industrial process in your workshop. And like all industrial processes, this one needs consistent inputs. In this case, wood strips need to be created with a specific width and thickness, with perfectly square edges. At first, your trim might look OK even with slightly inconsistent strip sizes, but eventually this error will catch up with you because profiles won’t meet properly during installation.

Most of the trim I make is relatively small (ranging from 1„4" x 3„4" to 1" x 21„2") and used as part of a layered approach that couples one moulding profile with another. Even if you choose to mill larger trim, the need for accurate stock preparation remains the same.

Stock Preparation

Although you can use a tablesaw to prepare stock for milling into trim, a jointer and thickness planer make it faster, easier and more likely that you’ll succeed because of the consistency these machines impart to your wood.

I always start by jointing one face of my trim stock flat. Then I create a 90° edge along an adjacent side with another set of passes over the jointer. Next, rip your stock to width on the tablesaw. Be sure to make extra strips to be used for machine set-up and to replace any installation blunders you may commit.

The thickness planer really is the ideal tool for the final sizing of trim blanks. It’s more accurate than sawing strips, and it creates a smoother surface. Just be careful. If you’ve jointed your trim blanks, it’s key that you complete the initial planing passes with one of the jointed faces of the wood resting against the planer bed, not one of the sawn surfaces. Look closely as you feed your wood into the planer, since planing with one of the sawn edges down against the bed could ruin the all-important square edges you have created on the jointer. Once you have all sawn edges planed smooth, however, it doesn’t matter how the trim blanks are fed into the machine. Continue planing until the strips are sized correctly for the trim profile you’ll be milling. Are your trim strips narrower than 1„2"? Check out “On the Edge” (below) for more planing tips.

At the Router Table

Although you can use just about any style of router table for milling trim, the shape of the top and the design of the fence are critical. The top must be flat or slightly convex, never dished. A dished shape causes the trim strip to rise and fall relative to the router bit as the wood is being milled, and that’s a huge problem.

As the leading end of the strip first encounters the cutters, the wood is in full contact with the “valley” at the centre of the router tabletop. But as the end of the strip slides farther along, it travels up the side of the valley, causing the middle part of the strip to move up along with it before sinking back down again as the trailing end moves down the dished side to the centre of the table. Dished tops create inconsistently routed profiles that rarely meet properly at mitred corners.

Use a carpenters square or jointed piece of wood to determine how flat your router tabletop really is, then adjust if necessary. Wooden shims placed in the middle of the top before its ends are fastened to the support base with screws can sometimes pull a dished top flat.

Tabletop Set-Up

Featherboards are another essential part of milling trim because they support each strip firmly as it slides along, ensuring consistent routing action from one strip to the next. You’ll know a good fence and tabletop by their ability to accommodate a lot of featherboards. At a minimum, you’ll need one on both the infeed and the outfeed sides of the fence–pushing trim strips down tightly to the tabletop–and another pair on the infeed and outfeed sides of the top–pushing strips against the fence as they slide. That’s at least four featherboards in all for small and medium-size strips. Add another pair of strips on the fence if you’re working with large stock.

The adjustment of a featherboard’s position is key. But before that happens, you need to install the bit you’ll be using, then position and lock the fence in its final location. I find it helpful to mill the first few inches of one trim strip at this stage, to help me get the height of the bit and the fence location just right. Routing just the end of a strip like this allows me to keep my fingers well away from the spinning cutters.

Tabletop Set-Up cont'd

With fence position finalized, adjust the featherboards’ locations with a trim strip sitting against the fence. Too far away from this wood and the featherboard fingers won’t hold trim strips with sufficient firmness. Too tight and the wood becomes difficult or impossible to push past the router bit smoothly.

Aim for a slight compression of the springy fingers of each featherboard as the wood passes by. Gauge each featherboard’s adjustment by sliding a trim strip or two across the table with the bit lowered temporarily, then tweak each featherboard’s position as necessary.

With the strips of wood in hand and the featherboards in place and adjusted, it’s time to readjust the router bit height. Set it into position by eye, and then push one of your extra trim strips through and see how the results look.

Pace Yourself

You can have all the details of your trim routing machinery set up correctly, and still get substandard trim. The final key involves feeding the wood across the router table the right way, and consistency is the name of the game. It’s essential that wood move at the correct speed and without pause. Stopping invariably leaves a little ridge in the wood, and perhaps a small burn mark. I find a feed rate that mills about 36" of trim in 10 seconds works best. While speed is easy to maintain at the beginning and middle of a cut, it takes some planning to keep the speed consistent all the way to the end of a trim strip.

Get a helper to support and pull the leading end of the trim strip for the final part of the cut, after you can’t push it anymore because the end is too close to the bit. You’ll get even better and faster results if you keep your pile of unmilled strips close at hand, pointed in the right direction to feed into the system. Once there’s about 12" of trim left to rout on a given strip, let your helper continue pulling it through at the correct rate while you grab the next strip and use it to push against the end of the first one. This way, the routing of one strip meshes seamlessly with the strip following it, ensuring the smoothest possible results and boosting productivity. There’s no down time because the bit is constantly cutting.

Even considering the cost of router bits, milling your own trim definitely saves money–although that’s just icing on the cake. Once you see what crisp profiles and unique shapes have to offer, you’ll be turning lots of scraps into key parts of beautiful projects.

Mopping Up Your Trim

Even with a sharp router bit and an ideal router table and fence, your trim still needs a bit of sanding. This process removes the slight mill marks that are inevitably left behind and any stray wisps of wood that sometimes remain on sharp, crisp corners. Although you can do this final sanding by hand, a sanding mop gives better results more quickly. A Canadian invention, the sanding mop is made with circular pieces of cloth-backed sandpaper mounted on a mandrel. Each disc of sandpaper is snipped around the edges to form small strips. Mount the mandrel in a drillpress or handheld drill, turn on the machine, and then press your newly milled trim against the frilly edges as they spin. Somehow, against all expectations, the surfaces of trim profiles are sanded smooth, without rounding over the all-important, crisp trim edges. For more information, go to stockroomsupply.ca.