Thursday, May 3, 2012

[Help!] Better Mitres By Hand?

I've been having a difficult time getting mitred mouldings to line up exactly. The way it's explained in the Joiner and Cabinet Maker is to draw the line, cut slightly on the waste side, and then plane it down. Planing odd and thin strips of mostly end-grain at a strange angle is not trivial, even with a freshly sharpened low-angle block plane, but this is what I have been trying to do. I invariably end up taking off a little too much, which leaves a piece critically short. Even a hair's width shows as a faint dark gap. I have gotten good at filling and hiding these cracks, but those are not the skills I really want to build right now. I realize that practice is the only answer, but if you have exercises which have helped you, or things to think about while cutting mitres, I would love to hear about it. I have a Stanley metal miter box, but I think it does more harm that good, since it has a bit of slop. I'm tempted to make one of wood, but that depends on the ability to cut a perfect mitre to begin with, which sortof defeats the purpose!

While my dovetailing has coming along quite nicely, and I am able to saw to the line at most angles, there is sometime about the narrow moulding which has me tilting the saw in an odd way. It usually looks great from the front and top, where the line is, but towards the back it goes awry somehow.

Any tips or considerations left as a comment here will be most welcome.  Thanks!

8 comments:

  1. Two ideas: Miter shooting board, and "burnish" the joint closed by running a burnishing rod or screwdriver shaft along both flats.

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  2. I do have a mitre shooting board, but it is a convertible... it takes a long time to switch between it and its 90-degree configuration that I am not wanting to bother anymore. Also, it doesn't really do well with tall mouldings, where the proper angle to be shot would mean the board standing on edge about 1.5" tall. I feel that shooting loses efficacy when the material is much over 1" thick. Maybe I just need a new plane (using my #7 for shooting currently).

    I feel the burnishing is a bit of a cheat, but I am open to all ideas!

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  3. Miters are tough. Tougher than dovetails by far. The real answer as you know is practice, but there are a few things you can do to help. First, check the angle of the case corner. No matter how careful we are, sometimes the outside corner of the case doesn't come out perfectly 90 degrees. In a miter, even a tenth of a degree off will show a gap. So check each corner for square at the top and bottom of the molding.

    Next, start at a corner and work your way around the case. If you start at the front left corner, cut the miter on the side piece first. Leave it long at the back; i.e. don't cut the miter on both ends of the side molding yet. Check the angle of the side miter with a miter square and adjust it with a plane if necessary. When that first cut is as good as you can get it, cut the mating miter on the front piece of molding. Hold both pieces in place and make adjustments to the front piece until the miter closes tightly. Once the first corner closes well, move to the front right. Scribe the length of the molding (the short side of the miter) on the back face and layout the miter on that piece. Cut it and carefully make any adjustments without overshooting the scribed length. Then work on the right side. Continue this way around the case.

    As for burnishing the corner, it's not cheating. But it's only useful for VERY small gaps. And the harder the wood the smaller the gap needs to be for burnishing to close it. I prefer to take a shaving or three off the back side of the molding instead. This can "lengthen" a molding slightly but again it won't work for gross gaps.

    Mostly, it's just a matter of practice and making sure the case is as square as possible before adding the moldings.

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  4. Thanks Bob! I realize they need to match the actual casework in question, but I would be pleased just to get 90 degree corners with no casework involved at all. I have some techniques to do this with my (ahem) miter saw, but really want to lock down this hand-tool skill. I am really wondering if most people mess with mitre boxes or just go by marks.

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  5. Have you considered using a "donkey's ear" shooting board? That little appliance works wonders for my mitres. I find that the donkey's ear provides a much more stable platform for taller slender mouldings than a flat mitre shooting board (like the one featured in The ATC). Because the plane is always moving in a horizontal plane against the widest dimension of the stock, it remains more stable against the fence. Also, if you're shooting smaller pieces, I find it easier to wield a jack plane or smaller (I use my LN 4 1/2, it has plenty of mass to keep it in the cut and it's small enough to handle easily). Happy shooting Rob!

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  6. I suppose this would be considered cheating: https://plus.google.com/u/0/118008739813896870087/posts/H52YwWYWSdw

    It is an old design, so I can live with my Normite tendencies to make up for my lack of skill.

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  7. thanks everyone! I have gotten a ton of private replies, too. I'll post a follow-up when I discovere a system that works well. I should probably have said that my mitres are currently just about acceptable, but I want them perfect!

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