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Maple wood crutch - grain across or vertical?

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Dennis Toth:
Going to start a project that will require a full length maple crutch. I have some long motor mount wood that will fit the pattern but the way it was cut would have the grain running vertical through the piece. This is a FOX 35 ship and the maple on its side is 1/2" thick. I don't think it will crack but wanted to see what others think before hacking up really nice maple.

Best,    DennisT

Tim Wescott:
I can not envision what you're trying to do here -- take a pic of that part of the plan, or post a link?

If it's an old design they may have used maple in a way that required cross-grain strength because they didn't have anything else -- I could be utterly wrong (because I can't envision what you're doing) but could you use aircraft plywood?  Or build a box that looks like the plans piece, but has a lot of hollow inside for lightness sake?

Brett Buck:

--- Quote from: Dennis Toth on August 15, 2021, 04:02:01 PM ---Going to start a project that will require a full length maple crutch. I have some long motor mount wood that will fit the pattern but the way it was cut would have the grain running vertical through the piece. This is a FOX 35 ship and the maple on its side is 1/2" thick. I don't think it will crack but wanted to see what others think before hacking up really nice maple

--- End quote ---

    As a general rule, the grain has to run the long way. But the way you describe it I am not sure we are talking about the same thing. Typically a crutch is made by 1/2x3/8 cross-section, length long enough to go from the nose through the second former (and maybe further), with the grain running the long way. That is typically separated by 1/2" thick medium balsa with the grain running from one mount to the other from right behind the engine to the second former. Epoxy it all together on the bench to make sure it is absolutely planar, then sand it flat.

     Brett

Dennis Toth:
OK, what I am building is a simple rat racer type ship. The fuse is from two pieces of full length motor mount stock, this forms the crutch, then a top and bottom block is added for some shape. The crutch pieces I have the grain running down the length but if you look at it from the end the grain is vertical for the width (1/2" x 3/4") I need in order to get the shape (similar to a speed pan shape). My question is really about the wood splitting, particularly when installing blind nuts?

Best,    DennisT

Tim Wescott:
Are you talking about the growth rings?  If you're looking at the end of the wood you can see light and dark stripes, often a bit curved.  These are not grain, but rather the tree's growth rings.

See the picture.

For some kinds of woodworking you do care about the direction of the growth rings with respect to the wood (i.e., the difference between A grain and C grain balsa is how the wood is cut with respect to the growth rings).  But I don't think you care here.

As long as you're not jamming anything into the holes that's just too big to fit, you're not going to split the wood.  While maple may be a bit stronger in one cross-grain direction than the other, I have never heard of or experienced any splitting (of maple) along a growth ring boundary.  If you have to pound in the T nuts -- the holes are too small.  Otherwise -- don't worry.

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