Replies

1. 
   Elcoholic | Oct 20, 2003 10:56pm | #1

   Flat or bent laminations?

   For flat yellow glue is fine and most would place the boards so the rings ran out.  This places the natural tendency to cup on the inside which keeps the glue line from opening along the edge.

   The width of bent laminations are limited by the width of the form and or the ability to evenly distribute the clamping pressure.  In general wider, tighter, and compound bends do better with 2 piece forms or vacuum bags.  The thickness of the plys is determined by the bending radius, they have to be thin enough to be cold bent or pre-steam bent before laminating.  The first time I did bent laminations I used poly urethane glue (PL brand) and it worked well although I did some foaming in the small gaps between plys.  The next time I used Plastic Resin Glue and like it even better because it cleans up with water instead of acetone.  I will stick with PRG unless it's an outdoor piece where I'll use epoxy.

   John O'Connell - JKO Handcrafted Woodworking

   Life is tough.  It's tougher if you're stupid - John Wayne

2. 
   YesMaam27577 | Oct 21, 2003 01:11am | #2

   Just a week and a half ago, I was in Atlanta, attending a two day seminar with Sam Maloof as the teacher/speaker. As you may know, he uses laminated rockers on all of his rocking chairs.

   When asked the same question about glue, he said that he had tried a lot of different types, and that he has been using Titebond 2 for quite a while. He uses it for everything (laminations, dowelled joints, chair leg joints), unless the wood is one of the oily exotics.

   Vast projects should not be founded on half vast ideas.
1. 
   blindau | Oct 24, 2003 02:17pm | #3

   Did Sam say anything about his logic for using Titebond II ? I'm wondering if Titebond II has some superiority over regular Titebond other than being weatherproof? Would it have better creep resistance. I remember years ago watching Sam in his video using white glue to do his bent laminated rockers. I know PVA glues have a bad reputation for creeping, but is this mainly under extreme bends, where there is enormous pressure on the joint? I'm sure he has access to the best information and wouldn't be using an inferior ingredient in his high dollar chairs.

   Bill

1. 
   YesMaam27577 | Oct 24, 2003 02:35pm | #4

   Did Sam say anything about his logic for using Titebond II ?

   Only that he had tried others, and that he had settled on "the type 2 yellow carpenter's glue". Later, when asked during a break if that meant Titebond 2, he said yes.

   As to 'his logic', certainly none of us in the class would have questioned him any further. It was obvious that he was satisfied.

   If I understand "glue creep" properly, it is a tendency for some glues to swell out of a joint, well after the piece has been finished. If that is the correct definition, then I've never seen it, although I believe the many who have. The wide aceptance of Sam's work as 'masterful' is probably a testament to his ability to avoid it altogether.

   Vast projects should not be founded on half vast ideas.

1. 
   Elcoholic | Oct 25, 2003 04:16am | #5

   Creep refers to movement along the glue line whereas what was previously described are raised glue lines.  PVA may creep a bit but at the same time it's plasticity may be a benefit as a shock absorber in his laminated rockers.   Brittle hide glue in this application would not last over the long hall.  That's probably why there wasn't a whole lot of bent lamination work done prior to the advent of modern adhesives.  Besides creep in this example is irrelevant since the runners only have to be close to a matched set, the joinery doesn't require an exact bend and each chair is hand fit anyway.  Compared to a production product where consistancy of the curve and the joinery required a uniform curve and you can bet creep would be a factor and they wouldn't be using PVA. John O'Connell - JKO Handcrafted Woodworking

   Life is tough.  It's tougher if you're stupid - John Wayne

1. 
   blindau | Oct 27, 2003 02:21pm | #6

   John, I'm glad I asked. Thanks

   Bill Lindau