Horizontal Laminate

[fryovanni]

"so is it a stronger construction, the horizontal laminate? or weaker... hmm I am a bit confused.. But I am sure going to try to build one that way sometime in the future .. "

So to dig in and get a good answer as far as construction. Plus and Minus....Given it is a cool idea and you are going to give it a shot.

As far as strength(as it refers to stiffness). We are talking about grain orientation (given you remove the glue joint factor). Given you are using straight grained wood. Flat sawn and quarter sawn wood should have very similar stiffness. The slight exception would be certain woods that have non-interlocked grain and there may be a slight advantage to quartersawn.

As far as stability(as it relates to shrinkage and expansion due to moisture content). We know wood shrinks very little along its length with the grain. We know it does not shrink at the same rate in it's radial or tangential directions. Thus it is best to oriient the grain as square to the neck as possible. This does not stop the shrinkage or expantion, but will keep it as even as possible.

As far as strength added by lainations. We know that wood is not as strong cross grain as it is with the grain. If we wanted to even out the strength in both directions we could alternate the grain. In our application we don't care so we want to keep it optimal in one direction (as the main force acting on the neck is in one direction). We want all the grain the same direction. A wood that is not particularly strong can have strength added by laminating stronger(stiffer) wood(and we do love to do that). One way or the other laminating stronger wood to a weaker wood is where we would see an increase as compaired to the entire neck being made of the weaker wood.

Now the biggest issue.. Glue joints. Doug mentioned proper glue joints are stronger than the surrounding wood. This is true as long as the proper joint is possible and the glue achives sufficient penetration to generate that much holding strength(this is next to impossible with end grain to end grain joints). Not all woods have the same ability to let the glue grab(so to speak). Dense woods do not allow glue to be pushed in as easily as less dense woods. To get the glue in deep enough to make that glue grab well it may take more pressure. The trick is that if you push(clamp) too hard you can starve the joint. Viscosity of the glue also effects how hard you can push the glue into the wood before you push it out of the joint. So this becomes a balancing act (and can be tricky when you mix low and high density woods). Other factors that make it harder for glue to penetrate are oils and resins that make it tuff for the wood to accept the glue. Proper surface prep of course huge since we are trying to generate as much even pressure in the joint as possible (uneven surfaces allow an easy path for the glue to squeeze out thus lower potential for pressure and higher risk of starvation). Freshly planed wood or wood sanded smooth with milder grit paper is best. Compressed ,clogged or burnished surfaces are obviously going to not work well. Wood needs to be effectively dry so that it redily accepts the glue. The humidity and moisture in the work space needs to be controlled(50% +/- 5% is great).

Keep in mind the forces acting on these joints will be different than the forces acting on a vertical joint. You have to keep in mind what some ofthese guys are telling you. The forces may not lead to failure, but peeling force can be a very nasty thing if it is able to start seperation (That is how acoutic bridges like to let go, you don't generally see them just release they lift at one edge and the rest is history).

Depending on how square the grain is when you orient it in the laminates. You can introduce internal stresses that can absolutely lead to joint seperation and failure. Look closely at what you are putting together and think about how much imbalance you will create when the wood shrinks or expands with seasonal changes in moisture(remember nothing stops this transfer- film finishes only slow the rate.). Also remember the worst impablance is created by having a 45 degree relation(rift) as opposed to 0 or 90 degrees(quarter or flat).

I don't know if that is really covering everything, but as you can tell a lot of the success or failure will be based on how well you place the joints, glue the joints, and select the wood. Most the information I pick up is from the woodworkers handbook. This is a link to the whole book chapter by chapter in PDF form(download it and keep it handy)-Click

I sure hope that has some of the answers you were after.

Peace,

Rich

[tirapop]

so is it a stronger construction, the horizontal laminate? or weaker... hmm I am a bit confused.. But I am sure going to try to build one that way sometime in the future ..

The answer is... it depends.

It depends on where you put the bondline in the thickness of the neck compared to where you put the bondline for the vertical laminate.

A horizontal laminate can work. People keep mentioning an example that does work: the fretboard. It bends with the neck, picks up load, and gets that load through a horizontal bondline. For a beam in bending, which is what the neck is, the peak horizontal shear is near the center of the thickness. It stays pretty close to that as you move out from the center and then tapers off rapidly near the edges.

You asked whether one construction was stronger or weaker. A better question is, "is it strong enough?" Probably. Think about glue-lam beams used in construction. They're subject to bending loads in the same direction as a guitar neck... horizontal laminations. If you want cheap insurance, you can dowel through the laminate stack (part thru, so it doesn't show through the back and gets covered by the fingerboard) to take some of the shear out of the bondline and into the dowel.

[hendrikjan]

Thanks guys,

It sure is a whole lot more complicated than i ever imagined .. haha I aprreciate the answers and will let you all knwo how hings go Cheerio

[doug]

I love the science behind even what seems like simple things! "Is it strong enough" nails it. Careful preparation and execution of good woodworking practice should yield a strong enough neck.

Many of us have seen necks that make us wonder how it ever kept from just breaking but still holds. Even fractured ones. So I think he has a pretty good chance of this horiz. lam neck actually working.

-Doug