How important is it to get the top halves planed at 90 degrees?

[fscotte]

I havent had this issue before, but somehow I planed the two top halves of my top wedge to less than a right angle. So instead of a perfect 90 degrees to the top surface, it's something more like 85 degrees.

I can't cut the halves again because the halves aren't wide enough for another cut.

Just for reference, I clamp the two halves and plane them together at the same time. When the halves are glued, the grain will be 90 degrees, but the joint will not.

[tonydxn]

Not sure I understand this . . . if you planed the two halves together, the angles should add up to 180 degrees (unless one of the halves was the wrong way round). Do you have enough wood left to skim a bit more off with the two halves oriented as they should be?

[fscotte]

No, after planing, if you put the sides together and look at them from the end, the glue joint isn’t a perfect right angle, more like 85 degrees. The grain direction is 90 degrees as desired.

[sunburst]

Do you mean that the halves will lie flat to a flat surface with the joint closed, but the joint is not at 90 degrees to the flat surface? Joint slightly "tilted"?
If so, and if it is to be a carved arched top, the joint will not show as a perfectly straight line in the finished top. That is the only "problem" I can think of, and it is only a problem if that slight aesthetic 'thing' is a problem for you. It would be purely aesthetic and not a structural concern.
If, OTOH, you mean that the two halves will not lie flat on a flat surface with the joint closed, but instead the center is high or the edges are high, that is no problem as long as there is plenty of wood to mill the under-surface of the top flat after gluing the halves. (I've had that happen before.)

[Drew Streip]

So your blank is more like a diamond than a triangle (when looking down the end grain)? Or it’s a triangle with an off kilter joint? Either way, I don’t see a real problem... I’ve done the former and just did extra flattening of the back

[fscotte]

Whew, I didn’t imagine this would be so difficult to convey, was assuming others had done this before and would just know it right away.

If looking down the end grains of a glued top, you want everything to be vertical, like: ||||l|||| Where the l is the glue joint.

Mine will look like this: ||||\|||| The backslash is an exaggerated glue joint.

[sunburst]

So that would be: "the halves will lie flat to a flat surface with the joint closed, but the joint is not at 90 degrees to the flat surface[,] Joint slightly "tilted" ".
...and that would mean: "...if it is to be a carved arched top, the joint will not show as a perfectly straight line in the finished top. That is the only "problem" I can think of, and it is only a problem if that slight aesthetic 'thing' is a problem for you. It would be purely aesthetic and not a structural concern."

[fscotte]

You know what they say, a picture is worth.. in this case a rough drawing.

The red line is the glue joint, not right angle to the grain, maybe 85 degrees as just a guess. The black lines is the grain.



Anyway, my thought is this shouldn't be much concern. I'd resaw the joint again but the wedges aren't wide enough for any more cuts.

[rowka]

If it’s unbound, the tilted glue joint “may” show when the tail piece is removed. Otherwise, non-issue.

[HoGo]

As John twice said. The joint on the outside seen after carving will not be straight line along centerline.
Wouldn't be much visible on top as both ends are hidden under tailpiece/fingerboard extension.
I would probably rejoin and add tiny wings to the outside edges, I more than once had to add tiny pieces for lower corner tip. (perhaps if you count with wood removal for binding there still is enough wood - at 85degrees we are talking about 1/16" of wood)

[fscotte]

Is there a structural reason why this joint would be less strong than perfect 90 degree joint? Aesthetics wouldn’t be an issue since it is bound.

[HoGo]

No structural reasons at all. I'm just (not completely cured) perfectionist. :-)

[Steve Sorensen]

The curving center line, means you will also be popping in and out of grain lines as you go across the arched top. As John said, the seam line will be curved like --



Steve

[fscotte]

Ah...

See this is why I ask. Completely missed the nature and impact of a carved top.

Sorry John. I could not rack my brain hard enough to understand how aesthetics would be affected.

Some food for thought now..