Glues used for laminating blades

[oregon wind]

What are folks using for the glue when laminating wood to make blades?

Anybody have any experience with propeller glues?

[windy]

 I used System Three epoxy on my 10 foot diameter blades and havn't had any problems with the blades separating. Still holding up after 2 years running.

windy

[KEG]

I used Gorilla Glue on a set of doug fur blades and they have flown for almost 2 years, and a little over two months on a set red wood blades, bouth still in one piece.

[wdyasq]

"Anybody have any experience with propeller glues?"

Are you talking resorcinol or plastic resin? Either has to be mixed to specification and not extended to legally used in aircraft. Those are the only two 'Aircraft Glues' I am familiar with.

There are so many good glues the choice is yours. When polyurethanes came out I used a lot. I am not such a big fan now as I am seeing some failures. I don't know if they are due to improper preparation, improper technique or bad product (they were not my work).

With proper preparation and clamping many glues can be used. Some have temperature requirements, some have moisture requirements, some have clamping requirements some have multiple requirements difficult to meet in the average home shop.

Ron

[oregon wind]

Penacolite Adhesive G-1131, which is a resorcinal glue.

Dura pox epoxy.

Any experience with any of these?

[wdyasq]

I've used a good bit of resorcinal. I have not used that particular blend. All resorcinals I have used requires proper temperature, tight joints and proper clamping.

I am not familiar with that blend of epoxy.

Properly used, I have not seen a modern woodworking glue that will not produce the joint stronger than the wood itself. If proper clamping procedures and temperatures are maintained I would not hesitate using any good, waterproof glue building any woodworking project, including spars, propellers or any other wood product I can imagine with the exception of certified aircraft.

Although I believe some of the modern glues are superior to the older, legal glues in joint preparation, clamping requirements or curing requirements, they are not legal for certified aircraft. Plastic resin and resorcinal are approved for aircraft work.

Ron

[GlutealCleft]

What he said about woodworking glues producing joints stronger than the wood is certainly true.  In high school shop, a teacher decided to prove it to the skeptics in the class, and did so quite convincingly.

The biggest question for props is if the glue is waterproof or not.  Epoxy and polyurethane are both waterproof, and you have no need to worry with either of them.

Other than cost differences, the application properties are about the only differences - things like the fact that polyurethane has a foaming, expansive action, or the fact that a big pot of epoxy will self-heat sufficiently to cure it quite quickly.   Whichever one you like to work with is fantastic.

[dlenox]

I used Tightbond III - simple/strong wood glue.

Laminate your blades through the thickness, not the width for flex resistance.

Then I took it another step and put a layer of fiberglass cloth over the surface of the blades, and Dynell material along the leading edge for abrasion resistance.

If you do this don't glass the tip - it needs to be porous in case moisture gets into wood.  As blades turn centrifugal force lets the water exit out the tips.

I also used Tightbond III for my 3-wheeled project: http://www.briery.com/vortex

Dan

[oregon wind]

Thanks all for the tips.