Hand Tools

Edge jointing accuracy

Bill Tindall, E.Tn.
When hand tool enthusiasts discuss minutia I withdraw because I don't have the hand tool expertise to join the fray. But now we are discussing a topic, panel gluing, where I expect I have vastly more experience than most, and as much as any. I did some quick calculations and several thousand bdft of lumber have gone through my shop and a lot of it has been turned into panels of one sort or another. I have a clamp rack with 4 dozen panel clamps hanging on it. At times all have been in use assembling panels. I have never had a edge joint fail that I know about.

If you have been fretting over a few thousandths of an inch of gap in a panel before the clamps are tightened you have been needlessly fretting. But likely you have because you could, not because you needed to. You probably even enjoy striving for perfection in making edge joints. I get that part. You need to understand that if you have always strived for perfect joints you don't have any experience in knowing how imperfect is good enough. You likely work on a time scale that enables each joint to be prepared perfectly.

I have never assembled a panel with hand planed joints. I didn't have the skill, and probably still don't, to prepare a board edge for gluing. But that does not disqualify me from a panel assembly discussion. If you imagine that running a board across a power jointer results in a perfectly straight edge you haven't had much experience using a power jointer. If the edge is not perfect then what? Well, you learn what is good enough or you don't get to make much stuff.

There is a technique for fixing a convex edge with a power jointer but it is one I rarely resort to unless the edge is severely bowed, and it doesn't always work(for reasons I have never understood). You learn the degree to which imperfect is good enough. You learn when it comes to clamping. If intermediate clamp pressure mates the joint it is good enough. Thousands of edge joints have proven this fact to me, and anyone using a power jointer.

The stress in a joint pulled together does not last for infinity. Wood cold flows and relieves stress. Bridge a board across two saw horses and set a cement block in the middle for a week. Remove block and note the board does not return to straight. If the pulled together joint stays together when the clamps come off there is nothing that will cause the stress to pull the joint apart next week.

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