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I am building a small door. I have a frame that is glued and nailed together that is 1 inch thick shown here:

Enter image description here

1/4" birch plywood will be glued to both sides of this. The plan was to glue oversized pieces and then trim them to the frame. The difficulty is that the longer edges of the frame are cut at a 3 degree angle so that the door will not snag on the jamb. I can trim the plywood with a router on the short ends, but what is the best way to trim it to the angled edges?

In retrospect, I should have cut all the pieces square, done dowel joints or something similar so there are no nails in the way, put on the plywood skin, then trimmed the edges at the proper angle with a circular saw.


What I ended up doing

I up-voded all the answers because they all seem like sound advice to me. Thank you, everyone. The accepted answer most closely matches what I actually ended up doing.

I initially trimmed the plywood with my circular saw within a 16th of the desired edge with the intention of sanding it down flush. I have a clamping cutting guide so I used that. But then sanding was taking a very long time and I was afraid I would round off the door edge in the process so I trimmed it closer and noticed that the edge of the door was bowed in. At that point I decided that fortune favors the bold and trimmed the full edge of the door, plywood faces, framing, and all, with my circular saw at 3 degrees. Did it by creeping up on the right guide position with multiple cuts. I have a nice fine-toothed blade on the saw so I saw no tear-out. Nails didn't get in the way because they were already driven deep. Worked pretty well but running over the door face 100 times with the saw left stains. Not ideal but I plan on painting the doors anyway.

And yes, I do have a preference for methods that involve 10 minutes of prep work and 10 seconds of actual cutting. Thanks again!

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    Can't you still do the circular saw thing? Angle at 3 degrees and take multiple passes until the blade touches but doesn't cut the frame. Or am i missing something here?
    – Max
    Feb 9 at 14:58
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    Creating a bevel angle like this with a circular saw seems sketchy to me, far too easy to make a minor error that could lead to damaging or even writing off what is essentially a finished door at that point. The standard way of creating such a relief angle in a cupboard door (normal for this to be on one long side by the way) used to be by hand planing it, and that could still easily be the method of choice in a power-tool centred workshop — no setup time, just grab the plane, clamp the door and start work. The surface quality will regularly be better too, which could be a further plus.
    – Graphus
    Feb 9 at 16:06
  • I presume you're intending to trim the ply on the short edges using a pattern bit or flush-trim bit yes? In either case, just to mention something in case it isn't obvious: you'd need to fix one plywood skin at a time for this to work.
    – Graphus
    Feb 9 at 16:09
  • @Max I could still do it with a circular saw and a cutting guide but it would be tricky. There are nails in the long edges and I don't want to make it any narrower so I would just leave a little plywood and sand it down. Feb 9 at 17:20
  • @Graphus Yes, plan to trim the plywood on short edges with a flush trim router bit. It's not readily obvious to me, why do I need to do it with only one plywood skin attached? There is room for the bit's bearing to ride on the wooden frame between the sheets. Feb 9 at 17:23

6 Answers 6

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Using a circular saw is a good option and it's not as scary or difficult as you might think.

First, if not already done, punch any nail-heads below the surface. You can fill those later. Then, with your saw unplugged (or battery removed) and the guard raised, position the saw as if it were making the cut and set the blade angle by flushing it up with the edge of your frame. This will give you an exact match, far better than trying to measure it and/or relying (guessing) that the scale on your saw is 100% accurate.

All you have to do then is clamp a straightedge down on the work and use that as a guide to run your saw along. A 2m (6") spirit level works well for this. Get the distance you need to set the straight-edge back from your cut-line by measuring from edge of your saw base to the edge of a tooth on your saw blade using a combination square. (Just make sure your saw is unplugged when you do this.)

To avoid splintering the edge of your plywood, cut one side at a time and either make a very shallow first pass cut with the blade depth set to just score the surface or use a clamped straight-edge and a Stanley knife to score the cut-line prior to making your cut proper.

Take your time and you'll be fine. It's a tried and tested method so just measure accurately and clamp your straight-edge down firmly, and you'll get a really professional look with crisp, flush, beveled edges - and no tearout.

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  • +1 except for "is best option". This is good method + clear instruction but I would have finished before circular saw is adjusted!
    – Volfram K
    Feb 10 at 7:46
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    Isn't this what I said about the circular saw, except with more explicit instructions?
    – FreeMan
    Feb 10 at 13:26
  • Hey FreeMan, for sure. I only did the step-by-step as a confidence booster as I noticed the OP had commented on your answer expressing some doubt as to his ability to pull it off without making a mess. Feb 11 at 10:27
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    Hey Volfam K, you're right, the best method is actually a tracksaw. That's what I use but I'm hardly going to advise someone to go out and spend $$$ just for one project. The "poor man's tracksaw" method I outlined does just as good a job though, it just takes a bit longer. I used it for years before I bought myself a dedicated system and it works just fine. Far better than a router which always carries the risk of a snipe at either end where it's unsupported, even more so for someone who's still developing their skills as well as tearing or burning the edge - especially when it's plywood. Feb 11 at 10:37
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    Tracksaw is not best method either! -1
    – Volfram K
    Feb 12 at 8:59
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If you have a hand plane plywood edges are easy to plane. Size of plane does not matter, this can be done with block plane if this is only type available.

Without hand planes I would trim close with router, then remove the rest with hand sanding. Start with P60 grit.

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  • +1 Unfortunately most of my tools are "framing grade" stuff. The plane I have is a dinky cheapo buck brothers thing from a box store that I mostly use to take high spots off wall studs. I don't trust it to plane down a plywood edge without tearing off a big chunk without warning. Feb 9 at 17:29
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    I'm no expert on planes or sharpening, @aquaticapetheory (paging Dr. Graphus, Dr. Graphus to the white courtesy phone), but I'm fairly convinced that even a cheapo plane can be sharpened and adjusted to do a reasonably decent job. Of course, if you're like me, the time to sharpen & adjust could be used to sand the plywood, hang the doors, paint 'em and move on through 3 more projects. (I really should practice my sharpening...)
    – FreeMan
    Feb 11 at 17:27
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If you cut the bevel on a table saw, just tip the blade 3° the other way, flip the frame over, raise the blade just high enough to cut through the plywood and be done with it.

If you used your circular saw, tip it to 3° again, clamp a straight edge down to the top of the door skin, and again, set the blade just deep enough to cut through the plywood.

If you have both the TS and circular saw, but the blade on one won't tip the opposite direction, use the other tool to cut from the other (long) edge of the door so the tip angle matches up.

In both cases, I'd suggest cutting just proud of the frame by 1/16" or less (assuming the frame fit is exactly what you want now), and do a finish sand or plane to the final dimension. Not only will this give you a nice clean edge, but it will finalize the edge if there was any tearout on the plywood and will prevent you from cutting into the door if you don't get the blade alignment exactly in line with what it was when you cut the initial bevel.

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  • +1 but 1/16" is "just proud"?? If I were doing it this way (I so wouldn't but never mind that LOL) I'd want to have to take off a 64th or less of extra material
    – Graphus
    Feb 9 at 16:17
  • I changed it 1/16" or less, @Graphus. Some of us are still working on our workshop skills... Also, do you own any power tools?? ;)
    – FreeMan
    Feb 9 at 17:02
  • +1 This is probably what I will end up doing just from tool availability. Feb 9 at 17:31
  • "Some of us are still working on our workshop skills..." OK yeah but but a 16th is like, a lot to sand down. "Also, do you own any power tools??" Well I have five power drills and a plunge router, does that count? :-P In terms of stationary power tools, zip. I have the equivalent of the old-school British hobbyist workshop in a shed (wayyy smaller than most US "small" workshops). I'm interested in turning but I'm making a lathe using one of the 'spare' drills as the basis (that'll do for now at least). I might possibly get a benchtop bandsaw at some point because bandsaws are so versatile.
    – Graphus
    Feb 9 at 19:59
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Looks like the top will be less that 1/64” too proud if you just flush trim at 90 degrees instead of worrying about matching an angle etc... 0.25 inches rise with a 3 degree pitch gives about 0.0125 (1/80) of an inch for the run. So less than a third of a millimeter. I don’t think it’ll be visible or even physically interfering with the function based on those numbers.

If it is somehow tight, sanding for maybe 2 minutes matching the structures frame angle of 3 degrees will get you there.

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  • +1 because true and sound advice but I just subjectively don't want to do this. Feb 24 at 19:24
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You could screw an angled baseplate under you router and run this against an edge instead of using a flush trim bit.

Take a piece of plywood (slighly larger than your router base). Cut a hole in the middle for the bit. Cut one straight edge on the plywood base to run against a fence clamped to your door to prevent altering the angle. Screw the plywood base under the router. Use some wedges or distance rings on one side to get the angle. Might be a bit fiddly to get the proper angle.

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I can trim the plywood with a router on the short ends but what is the best way to trim it to the angled edges?

Do you want the plywood edge to be square to the face, or cut at the same 3° bevel that the sides have?

If you want the edge trimmed square to the face, an easy way to do that is to temporarily attach another piece to the bottom of the rail, so that the edge is even with the line you want to trim to. You can use thin double-sided tape, a few dabs of hot glue, or a few brads. Or just clamp the frame to your workbench and use the edge of your bench if it's nice and straight. In any case, the idea is to just supply a straight edge to guide the bearing.

If you want the edge of the plywood to match the edge of the frame, you'll need to tilt your router. First, extend the line from the edge along the edge of the plywood face, so that you can see where the corner should be. Use your table saw to trim the panel to that width, so that the face of the plywood is the final size, and only the thickness of the plywood needs to be trimmed. Next, cut a strip 1/8" thick and at least as long as your frame from a piece of scrap. Set your router on the edge of the frame and put the strip under the base, about 2 3/8" from the edge, adjusting the position until the bit matches the angle of the edge, and secure the strip in place. Now the router will sit on the edge of the plywood and the edge of the strip, tilted the correct angle, and the bearing will ride on the edge of the frame and guide the cut.

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