Official Luthiers Forum!

how would one go about testing some prospective top plates for run out ? thanks Jody

Well, you can look at them and tell a lot.
Opened up, the light will refract differently (different colors) one side to the other. You can study the edges...noticable runout will be obvious as lines not running parallel to the length of the edge.
You can take a small test cut out of one corner (far outside the pattern) and see if the wood wants to slough off in a steep angle, or just keep plowing through. (i.e., what's the wood grain doing to a sharp chisel blade)
You can also lightly run your hand over the top. You can feel short grain catching your fingers in one direction on one side, and the other direction on the opposite piece.

Hope this makes sense.

Steve

_________________
From Nacogdoches...the oldest town in Texas.

http://www.stephenkinnaird.com

Often, I find the only way is one of Steve's suggestions, to cut a little piece off the corner and split it with a chisel. Unfortunately, you can't do that as you're looking through a stack of tops deciding which to buy. If they're not sanded, they're often too rough to see the runout on the surface by looking at the way light reflects. Steve says you can get some information by studying the edges. I'll have to get Steve to show me how to do that, if he's able to on spruce. If there's a growth ring line visible on the edge, that may wander in any direction, since the edge is a flatsawn surface; that doesn't tell you anything. With the naked eye, I'm not able to see the fibers themselves. Maybe there's something I'm missing. When buying tops that aren't sanded, for me it's often a leap of faith and trust in the sawing ability and integrity of the vendor. It helps to know them! Sometimes you get lucky and see a top with a split edge, rather than a sawn edge. Then, it's obvious.

_________________
Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

Same here, I split as little as I can afford off the center (whch is not much with euro or adi).
Here is a really nasty one. These same lines should also be followed when cutting braces, if You don't split them.

_________________
Build log

as luck would have it , I have one rough edge and one split outer edge, from looking at the split edge I can see I have a near perfect addi top . I took a chisel and shaved a bit off the other outer edge at about a 45 % angle, then I could see the grain lines, wearing a pair of magnifying lenses . so Todd maybe your supplier will let you shave a bit off the outer edge of the tops! thanks for the help guys . Jody

Aww heck, I hate it when someone calls my bluff.

Actually, Todd, the pic that Alexandru posted is just what I'm talking about. You can see that on a cleanly sawn or jointed edge and you'll have an idea of the runout or lack thereof.

Steve

_________________
From Nacogdoches...the oldest town in Texas.

http://www.stephenkinnaird.com

Okay, Steve, you're talking about a cleanly sawn or jointed edge. That's a horse of a different color. I was thinking of looking at tops in their rough form while in the process of buying them. Honestly, I'm not sure if I've ever looked for the grain direction on the jointed edge of a top. By that point, I've already done some sanding, so I can see if there's runout by looking at the surface in raking light, and I'm just getting ready to glue it up.

_________________
Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/