1" thickness: laminate or not?

Bob_Brunswick | Posted in Joinery on October 27, 2001 07:18am

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For a jig project I need a hardwood board with finished dimensions of 1″ x 6-1/2″ x 17″, and that is essentially flat on both sides with all corners/faces square. My local wood sources give me 2 choices of starting point: buy s2s 3/4″ oak and glue them face to face, or buy s2s 5/4 oak. Will one or the other generally yield the most stable piece? Is red oak bad, average or good with respect to the amount of movement that takes place when you start to cut/plane it?

Replies

Major_H._Patterson | Oct 20, 2001 06:44pm | #1
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Bob: Not knowing the end use of the jig detail,it`s a little hard to reply.However,I usually make my important jig details of laminated Baltic birch plywood. This is a very stable material and has so many plies that the number of plies remaining after thickness sanding to exact final thickness doesn`t seem to matter.
as for the OAK, I would glue up the two pieces of 3/4" stock face to face as for book matching.After flattening one side and planing to final thickness,this may be stable enough for your purpose.Try to keep the glue line centered on the 1" diminsion as close as possible.PAT

Bob_Brunswick | Oct 22, 2001 02:20am | #2
*Thanks for the advice. For this jig, I'll be tapping the side for several 5/16-18 screws, so I'll glue up the 2 pcs of 3/4" stock and go that route.

Major_H._Patterson | Oct 22, 2001 03:05am | #3
*Bob: For the threaded holes, you may want to consider the use of brass threaded inserts. FWIW_ PAT

Jim_Hassberger | Oct 22, 2001 07:46pm | #4
*Laminating 2 4/4 planks would work, but there is a real possibility of warping, especially with flat-sawn planks. Best bet for laminating such pieces is to glue (either) the inner (or outer) surfaces to each other. That way stresses induced by the glue moisture are more balanced.My choice would be to start with 5/4 material for four reasons. 1) less expensive, 2) less waste, 3) less work, and 4) less potential for warping. The 5/4 is only 1/16 to 1/8 or so over 1". Choose a flat plank to begin with, and plane equally from both faces to get your final 1".

Danford_C._Jennings | Oct 27, 2001 07:15am | #5
*Bob,I agree with Pat on the use of Baltic Birch ply as a material for most jigs. However, I would recommend against the use of Red or White Oak. It sounds as if precision and stability is a major concern.Because of the open grain that Oak has, movement could would be a concern, even quarter sawn. My suggestion would be to use quarter sawn 5/4 Beech or Maple for the reasons Jim mentioned and if your wood source only offers two choices, ask him to order some for you. Or, find another source. FWIW.Dano