Scarf joint

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Model T Ford Forum: Forum 2005: Scarf joint
Top of pagePrevious messageNext messageBottom of page Link to this message  By galen west on Sunday, February 03, 2008 - 04:17 pm:

I am doing a scarf joint and I am uncertain on which glue to use in the joint.I would appreciate some opinions on it.
Thanks, Galen


Top of pagePrevious messageNext messageBottom of page Link to this message  By Thomas J. Miller on Sunday, February 03, 2008 - 05:22 pm:

Elmers now make an exterior carpenters glue that I've tried and it works great. I've also tried the Gorilla Glue with good results but you have to wet the wood and clamp it securely because the stuff expands as it cures. I like the gorilla stuff for mortise and tenon style joints for that reason. Also, If you buy the gorilla glue, buy the smallest bottle because it has a short shelf life even if you squeeze the air out of the bottle.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Sunday, February 03, 2008 - 05:39 pm:

Thomas:

Something I learned about PE glue (Gorilla, Excel and other brands) is that you can keep it for a VERY LONG time by putting it in the refrigerator. You also can FREEZE it without hurting it if you need to store it for a REALLY long time. And finally - if the glue skins over on you - the glue underneath the skin is still totally OK to use so long as it is still liquid. It is NOT like paint in that regard. I vote for PE glue for any exterior application and you really do not have to wet the surfaces unless you know there is no moisture present in the items being glued. As long as there is some moisture - the glue will cure. I don't think you can dry out a block of wood dry enough to prevent the curing of PE glue. Moisturizing is a precaution but I have never done it on my wood projects built at 55% relative humidity in my shop. Some PE glues dry faster than others. I for one like EXCEL brand the best because it has a very slow drying time which works best on large projects where you need time to get everything lined up.

Just my .02


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Mikeska on Sunday, February 03, 2008 - 05:55 pm:

John,

Thanks for the tip on storing the glue in the refrigerator. Maybe now I won't have to buy a new bottle every time I need some.

Paul


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Sunday, February 03, 2008 - 06:11 pm:

Resorcinol is a powder mixed with a dark liquid that is FAA approved. There are federal specs for glues, and when I asked a manufacturer, they (Gorilla?) would not admit their poly glue did not meet the Fed spec; they just refused to answer.

FAA AC 43.13-1B has a thorough description on how to make scarfed joints, including the doublers to use.

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/MainFr ame?OpenFrameSet

Go to Advisory Circulars by number, and it's yours for the downloading.

What are you scarfing?

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By galen west on Sunday, February 03, 2008 - 06:49 pm:

Thanks guys for your help. Galen


Top of pagePrevious messageNext messageBottom of page Link to this message  By Doug on Sunday, February 03, 2008 - 10:20 pm:

Abatron Inc of Kenosha Wisconsin makes two compatible products. Liquid wood and wood epoxy. Mix the two together for the best all around joint "glue". Good Luck.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Sunday, February 03, 2008 - 11:03 pm:

What's the name of the Kwik Poly stuff the Carnegies sell?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Michael Snyder on Sunday, February 03, 2008 - 11:28 pm:

Tight bond III got the best strength score in Fine Woodworking Mag.
Mike Snyder


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Sunday, February 03, 2008 - 11:33 pm:

And I bet there was a Tite Bond ad just two pages after that. Would magazines do that? Nah.. The articles are there just to separate the ads. That's why they never print articles all together.

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck on Monday, February 04, 2008 - 12:52 am:

I use Titebond II on all my wood projects and see no reason to change to anything else. Excellent water resistance. Bonds wood to outdoor concrete wet with Louisiana rain for seven years now.

Seth


Top of pagePrevious messageNext messageBottom of page Link to this message  By Noel on Monday, February 04, 2008 - 03:06 am:

Rick,
AC 43.13-1B is not a living document. When I retired as an FAA Inspector over 11 years ago it was in the process of being rewritten for the previous 5-10 years. However the FAA hasn't the quality aviation experts now that it had 30-40 years ago. The drafts were absolutely bureaucratic and junk.
The section on wood working and 7:1 scarf slopes is good stuff. But the glues specified are really obsolete by todays glues. For the latest on glues I suspect the Experimental Aircraft Association, EAA, has a lot better info on glues.

Regards
Noel


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Monday, February 04, 2008 - 09:01 am:

Thanks for the info, Noel. "AC 43.13-1B; 9/27/2001; [Large AC. This includes Change 1.] Acceptable Methods, Techniques, and Practices - Aircraft Inspection and Repair."

Chapter 1 is on wood, and, no, at a glance it does not seem as complete as my old -1 copy, which I cannot find right now. Heck, I was thinking a 10:1 scarf was required. I actually did one on an aileron spar for my Bellanca Cruisair.

Regardless, polyurethane glues do not advertise they meet any Fed specification. I have a "new" bottle of the stuff I bought last week that I'm taking back to Lousey's because it was skinned over on top, and is too thick to pour.

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Weir on Monday, February 04, 2008 - 09:30 am:

Rick; I heard the only thing holding a Bellanca together was the termites holding hands.

From an oldtime Mooney driver. :-)

Jim Weir


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Monday, February 04, 2008 - 10:36 am:

Apparently yours wasn't one of the wood wing Mooneys, Jim.

"If God had meant for Man to fly in aluminum airplanes, She would have grown aluminum trees."

Aluminum won't even float; how can it possibly fly?

It takes a good man to fly a triple-tail Bellanca ... handling 3 pieces of tail.

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Jeandrevin on Monday, February 04, 2008 - 10:46 am:

No matter what the hype, the advertisments, the research done.....here is years of experience in the furniture business. If you are gluing wood, you won't find anything stronger than
tite-bond II!

I have glued hard woods, soft woods and everything in between. The bond is stronger than the wood itself. If the joint is proper clamped and allowed to cure, excess stress will shear the wood grain next to the glue joint before the bond lets go.

That is my overly experience old body's opinion!

Tim


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck on Monday, February 04, 2008 - 11:24 am:

Tim,

You be the man! IMO, Knute Rockne would not have been killed in that Stinson Tri-Motor crash if there had been TiteBond II in those days.

Seth


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Monday, February 04, 2008 - 11:25 am:

What's the difference between II and III?

I don't know about your furniture, Tim, but the wood furniture in my house isn't exposed to much shock, vibration, and never rain, hail and freezing at 18,000 feet. Even automotive service is much more severe than furniture ever sees.

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Scherzer on Monday, February 04, 2008 - 11:50 am:

Here's their [titebond] website on their product line with a break down for uses. Bob
http://www.titebond.com/IntroPageTB.ASP?UserType=1&ProdSel=ProductCategoryTB.asp ?prodcat=3


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Jeandrevin on Monday, February 04, 2008 - 12:56 pm:

Basically, "II" is water resistant, and "III" is water proof. But even "III" can't be submerged, so I think it is really the same thing.

Tim


Top of pagePrevious messageNext messageBottom of page Link to this message  By Warren Mortensen on Tuesday, February 05, 2008 - 08:20 am:

I believe the Fokker Trimotor that Rockne died in had a rotten section in a wing. Even Titebond won't work well with bad wood.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck on Tuesday, February 05, 2008 - 08:30 am:

I heard that moisture trapped inside the wing had loosened a glue joint, but that may be more "urban legend".


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Tuesday, February 05, 2008 - 08:55 am:

Per the Titebond site, it is not to be used for structural applications. Resorcinol, OTOH is:

"DAP® Weldwood® Marine Resorcinol Glue
A two-component glue ideal for exterior structural applications. 100% waterproof and weatherproof. Meets MIL-A-46051 (Type I, Grade A)(Type II,Grade C) and MIL-A22397 (Grade A). (2-Compound Can)"

www.dap.com.

"DAP® WELDWOOD Waterproof Resorcinol Glue is a high performance, two component adhesive designed to provide the strongest, most durable bonds in severe service application. Once cured, Resorcinol withstands continuous salt or fresh water immersion, outdoor exposure, tropical or sub zero temperatures."

"Suggested Uses:
DAP WELDWOOD Waterproof Resorcinol Glue is designed to laminate structural wood beams, also
provides durable bonds on a variety of porous and semi- porous materials such as wood, particleboard, leather, cork, concrete (cured) and crockery (unglazed)."

I use a variety of glues, but when it's for a serious application, I use resorcinol.
rdr


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