Laminating wood

[jondecker76]

I'm going to be laminating some wood for a set of 16' wooden blades. What should I use to laminate them together? Regular epoxy? Wood glue?

Amy advice would be appreciated!

thanks,

Jon

[DanG]

A slow cure epoxy is best for fine grain woods like old growth Western Cedar 'heart' wood that can stil be found here in the midwest, gourgeuos heavy straight grain and clear of knots and naturally rot resistant. A polyurathane wood glue that foams as it cures is best for coarser grained woods with knots and wide ring spacing.

Also remember any commericial piece of lumber can get lightly oiled or have a silicone lubricant applied to it as a machinery handling aide to reduce friction and wear on the  sawmills equipment - don't trust a factory edge or surface to have a 100% bond w/o sanding or planeing that top mill finish layer off. For cabinet making and general lay-up it is okay to use just as provided but for wind turbine lamination don't risk having a bond fail early.

~

[RogerAS]

Jon,

I would ONLY use the powder and water mixed type. Weldwood is one brand name. I made decoys using this stuff and once cured the wood will splinter before the bond gives up. Totally water proof. Buy more than you need and experiment. Test a couple times to understand the nature of the process. Start by mixing small batches. I has a pot life that depends on temperatre and humidity. On a mission critical wood bond I would trust nothing else.

[Phssthpok]

Are there any drawbacks to carving larger (4'+ length) blades from a single piece of wood?

Also, where could one find a list of desireable,and undesirable woods to use for blades?

[RogerAS]

Hey,

I would say there might be several drawbacks to use of single wood sections in long blades.

More importantly are the advantages of using laminates. If one turns the grain like this ASCII example, when viewed from the end.

()()()()

These represent the curvature of the tree growth rings. When alinged this way the strength of the lamination increasess, the tendancy to distort decreases and stiffness increases. Plywood uses similar methods to become stronger than a single board of the same thickness.

[wdyasq]

If one can get good Vertical grain wood of a proper species it is as good as it gets and better than laminating. As John Staudacher once said in a conversation about airplane spars "I never could better the original manufacturor.".

It is doubtful one will afford such material and will attempt to laminate. All truely waterproof glues I have used in the last 25 years have developed wood bonds greater strength than the wood fiber itself. I have used resorcinol, casins, plastic resins, epoxies, urethanes, modified alaphilic resins and I am sure two or ten others. If you are really trying to build correct, find a good local woodworker. Folks who have built boats and/or aircraft sometimes will know WTF they are talking about. Some are ignorant and like to stay that way. OK, most are ignorant and care to stay that way.

The desirabiity of wood is dependent on what one is wanting as a finished product. It depends on how much money one cares to spend, the durability of the secies and section where the board was cut, moisture content and method of drying. These factors will depend on other factors. The question is pretty openended as we don't know your skills, where you are located or half a dozen other factors.

The folks who make the glues are a good source of information on adhesives. Please remember they also have an interest in selling their product and another company may, or may not, have a comprable or superior product at a better price.

"Wood as an engineering material" and the old Aircraft Manuals are good resources. Believe them before you believe folks posting here where the ability to put words on a screen often outstrips the knowledge and experience one has or just claims.

Ron

[RogerAS]

Ron.

You have some valid points but surely you must agree that a well made piece of plywood is stronger (pound for pound) and less prone to distortion than any single piece of wood. Take the same verticle grain and make a laminate and you have a far superior product. Just because John Staudacher made a statement long ago doesn't make it so today. I wouldn't sit my backside in any airplane with wood as a major component, other than for a ground check, even if he built it. Get off the ground? No way no how! I've been an airport manager and helped rebuild aircraft from wheels up. Aluminum and steel make a better airframe period. The days of using wood as a major part of an airframe passed several years ago and for good reason. I say any aircraft with an wooden airframe should never pass another annual, but I don't make those rules. Go ahead and fly around in a kite, I'm not going to or stand by while anyone I care about does.

Are not props for aircraft, similar to the application here, that are made of wood built with laminates? Maybe one should contact one of the several companies still building these to see what glue and wood they use.

The "Spruce Goose" would have flown very well if not for the extensive use of heavy wood.

Wooden archery bows made from a laminate are far superior to single piece bows in every way.

I have 15+ years experience as a master carpenter. I've built everything from houses to musical instruments. I DO know what I'm talking about when it comes to woodworking and properties thereof. Take any single board of any species you like and match that with the same species of wood in a laminate, that is done right, and the laminate will perform better in every way. Unles you want warping, twisting and  breakage under load. In a laminate the defects can be milled out. A solid cannot make this claim. A properly made laminate can be designed to enhance the strengths of any species. However garbage in garbage out holds true with a laminate too. It is possible that Mr. Staudacher didn't have the tooling and adhesives to produce a laminate that we can produce toady.

[willib]

how does anyone think laminated balsa would work as blade material

just asking , its very light and ranges from 6 to 19 lbs per cubic foot

[Titantornado]

> Are not props for aircraft, similar to the application

> here, that are made of wood built with laminates? Maybe

> one should contact one of the several companies still

> building these to see what glue and wood they use.

Try here:  http://www.sensenichprop.com/  I got one on my plane.

[wdyasq]

"It is possible that Mr. Staudacher didn't have the tooling and adhesives to produce a laminate that we can produce toady."

http://www.iac78.org/panzl/Staudacher.htm

We were talking about a jet powered radio controlled hydroplane he and his father had built of wood in the 50's. I put Jon (sorry about the spelling of your name first time Jon, I know better too) on par of above 99.8% of woodworkers and defiantly a knowledgeable designer, builder and pilot.

"you must agree that a well made piece of plywood is stronger (pound for pound) and less prone to distortion than any single piece of wood."

No, plywood is cross-grained. What one gains one way they loose the other. Your choice on taking a wood aircraft up.

"Are not props for aircraft, similar to the application here, that are made of wood built with laminates? Maybe one should contact one of the several companies still building these to see what glue and wood they use."

Lonnie Prince builds his "P Tip" props with a laminated rock maple core, The true structure is in the carbon fiber skin. I know and converse with Lonnie on a personal and professional basis.

"The "Spruce Goose" would have flown very well if not for the extensive use of heavy wood."

The Hughes H-4 Hercules was of 'Duromold' - IIRC- birch laminates. Properly designed, wood can be as strong in the pounds/weight of any material up to the advent of carbon and aramid fibers. Perhaps the Mosquito fighter is a decent example of wood construction.

"Wooden archery bows made from a laminate are far superior to single piece bows in every way."

Here I have to agree. But, the Turks and Mongols built laminated bows also - using horn. It is one way to vary spring rates. There lies the real reason for using laminates.

"Take any single board of any species you like and match that with the same species of wood in a laminate, that is done right, and the laminate will perform better in every way. Unles you want warping, twisting and  breakage under load. In a laminate the defects can be milled out. A solid cannot make this claim. A properly made laminate can be designed to enhance the strengths of any species. However garbage in garbage out holds true with a laminate too."

Here you have a few miss-statements and a few true facts. laminates will not preform "Better in every way". If one has true clear vertical grain wood of a long grained species and severs the grain to make laminates the only way to gain strength is in the glue line. Then, the glue is adding strength to the structure. Good vertical grain material seldom warps, breaks or twists under load. The guitar and mandolin tops I have built, as well as the backs and necks of said instruments are all vertical grain material. Guitar, mandolin, and violin sides are vertical grain material. The soundboards of fine pianos are vertical grain material. They are all known for their stability.  

In the late 60's and early 70's I was building houses and concrete forms of wood. In the early 80's I was building timber frame homes and boats. By the late 80's I had built 22 wooden boats, 1 complete aeroplane, rebuilt 2 antique wooden airplanes and built several hundred pieces of furniture. I have worked on numerous larger and more complex projects. Oh, there were some luthier projects, some coach work, wooden wheels (I got to call myself a real carpenter after I had constructed a wheeled wooden conveyace) in there too and a few sets of wind turbine blades.

Ron

[wdyasq]

willib,

IIRC, balsa is a tropical hardwood that runs from 2 to 22 pounds per cubic foot at 12% moisture content. The lighter stuff grows at lower elevations and is seldom found in lengths greater than 6 foot. It has low fiber strength but is great as a vertical grain core in laminates. It soaks a bunch of glue up and gains some weight in that manor.

It is also expensive.

Ron

[TomW]

Titan;

Thanks for ruining my ability to read this post without sideways scrolling back and forth by posting that oversized photo.

Really.

T

[AbyssUnderground]

Its hardly oversized... I can see the whole topic perfectly. Its hardly our fault your monitor isnt at the "average" used resolution. Quit complaining or get a new monitor.

[shroodoo]

hes right, just because you have a crap monitor it doesnt mean you should make everyone suffer by putting smaller pictures on. get a new monitor or quit moaning