By Jim Heavey
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Perfect Molding-Opener

Sometimes it's easy to take the simplest-looking things for granted. While working on a scrollsawn picture for one of my kids, I spent more time thinking about the process of making the picture than the frame I would put around it. After all, how hard can it be to miter a simple frame? I'm pretty happy with the frames I've made, but the skill came from a lot of practice and some solid techniques. Here are some of the things I've learned, occasionally the hard way. Note:I focus on making a frame using a mitersaw. See this article for a quick tutorial on tuning your mitersaw for best performance.

First, select a molding

You can choose from a huge variety of stock moldings at framing stores, below. (I found three shops close to my home with a quick online search.) You can also make your own frame from some of the special wood you've been saving, second photo below.

Perfect Frames-Moldings
Buy stock molding. Prices depend on intricacy of the profile and finish, but if you do some shopping, you can find attractive molding for under a dollar a foot.
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Make your own moldings. Create unique frame moldings by experimenting with a variety of router bit profiles, cutting depths, and types of wood.

To calculate the minimum required length of frame material, you need to know the outside dimensions of the picture or mat, the width of the rabbets on the frame, and the width of the frame.

As an example, let's consider an 8×10" picture and 2 38 "-wide stock with a 38 " rabbet. Because the width of the frame (for calculation purposes) is the stock width minus the width of the rabbet, you would have a frame width of 2" (2 38 " less 38 "). Calculate the length using this formula:

  • Multiply the width of the frame by 8 (2"×8=16").
  • Double each dimension of the item you are framing (8"×2=16") (10"×2=20").
  • Add those dimensions, plus another 14 " (18 " in each dimension) to allow clearance between the framed item and the shoulder of the rabbet.

We end up with 16"+16"+20"+14 "=5214 " total length. This is the exact measurement, but you'll need more to account for kerfs and for correcting any errors you might make. I like to allow enough extra that I can recut the longest frame piece if needed. So in our example, add 21" more for a length of 7314 ". If you make your own molding, this continuous length, plus a bit extra, allows for a wraparound grain pattern that adds some visual interest. Now that you have sufficient stock, it's time to head to the mitersaw.

Cut a perfect miter

The keys to flawless miters, besides having a well-tuned saw, are clean cuts and assuring that opposite sides of the frame are exactly the same length.

Trying to cut to a pencil line doesn't guarantee accuracy, so I begin by rough-cutting each of the four moldings 14 " longer than needed. To eliminate chip-out, work with the good side of the molding facing up and cut from the inside edge of the miter to the outside [below].

Perfect Frames-A
Adding a backer board assures tear-out free cuts. Use double-faced tape to adhere hardboard or MDF to the saw's fence to support the molding during the cut.

Then, I set up a stopblock and miter one end of each piece [below]. (This works for square frames. For rectangular frames, cut two pieces, then reset the stopblock to cut the two remaining pieces.)

Perfect Frames-B
Start with a stopblock. Clamp the stopblock in position to provide just a bit of extra length on the workpiece. I allow about 1⁄4".

To cut each opposite-side pair to equal length, place the stopblock on the opposite side of the blade and pivot the blade to the opposite 45° setting [below].

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Fine-tune your length. This is where that extra 1⁄4" length comes in handy. You can now dial in the exact cut on one length of molding and use the stopblock so the second piece matches it.

Now it's time to see how you've done. Test for perfect alignment by dry-clamping the frame without glue [below].

Perfect Frames-D
Join the band. A band clamp is ideal for assembling a frame. Turning the handle cinches up the band and spreads pressure equally to each corner clamp.

The inside and outside of each corner should fit without any gaps. When you're satisfied with the fit, apply glue to each mitered edge, making sure each edge aligns perfectly, and reclamp. Pieces can slide a bit as the clamp is tightened, so readjust as necessary. I apply moderate pressure with the clamp to assure good glue and edge bonding. When mitered edges fit well, there is no need for excessive clamping pressure. Allow the glued-up frame to cure overnight and you're ready to add glass and a picture.

Troubleshoot the gaps

Did your miters go awry? Here are fixes for some of the more common problems you may encounter.

During the dry-clamp test you notice that three of the miters meet nicely but the fourth shows a gap. If the gap is all but imperceptible, quit while you're ahead. Many woodworkers strive for that elusive perfection only to find that the joint was fine before they decided to "fix it." Sometimes, just a hint of glue rubbed into the joint and then sanded allows a bit of fine dust to mix with the still-wet glue and fill that spot that no one would have seen anyway.

If the gap is pronounced, or if gaps show at each miter, attempts to fix them will result in changes to the length of all the sides and will mean that your initial alignment of the saw needs to be rechecked and all the pieces recut.

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With the saw off and the blade down, slide the end of the mitered molding against the blade body (not the teeth). Hold the molding in place, raise the blade, and shave the end. The amount removed equals the offset of the blade's teeth from the blade body.

If the gap is small, you can remove a minute amount [above] from the heel or toe to correct the misalignment, as shown in the four photos below. A couple of attempts will usually fix small gaps.

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Fix the heel. To trim more from the toe of the miter than the heel, place a sticky note or business card shim between the fence and the end of the workpiece nearest the blade.
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Perfect Frames-H
Fix the toe. Cutting more of the heel than the toe is done the same way, with the sticky note or business card placed between the fence and the far end of the mitered stock.
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I prefer using the shim over trying to fine-tune the miter angle of the saw because I can more easily control how much material is being removed, and where.

Armed with your newfound skill and confidence in making a simple frame, it's time to think about new profiles and adding accents and inlay to your frames. Think of the possibilities!

Try a better joint

Perfect Frames-MiterHalfLap

Gluing miters means joining end grain—not the best glue joint. I've found that with a well-fitted joint, PVA glue (Titebond, Elmer's etc.) applied and clamped correctly, results in a strong frame. Large or very heavy frames may benefit from corners reinforced with splines or pin nails, or you might even opt for a half-lap or bridle joint. Like the look of miters, but want the strength of half laps? Try a mitered half-lap.

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