Epoxy for Scarf Joint

I am using a scarf joint to make long strips for my Shearwater's deck.  The manual calls for these to be epoxied.  Is there any reason not to use the Tightbond wood glue for this joint?  After all, the adjacent strips will be glued to it as well and the whole thing will be glassed.

 

Thanks 


10 replies:

RE: Epoxy for Scarf Joint

I used gorilla glue, works great. made myself a form to lay the strips in to make sure they are keeping strait and used crocodile paper clips to hold the strips together until dry. (15min) The form could hold 5 strips at a time. Will see if I can find picture of contruction.

RE: Epoxy for Scarf Joint

I'm having one heck of a time with both epoxy and titebond in my wd12h build....I first used epoxy (because the manual called for it) and I let it dry for two days to make sure it was set.  When I started to bend the sheer strip into place the epoxy gave way.  So, I figured I'd use Titebond II and see if I have better luck.  Well, after my second go-round with that I'm at a stand still and don't know what to do next.  I was going to start my own thread but I figured this fit the bill fairly well.  Any and all help will be greatly appreciated.  I would like to get going on this so I can actually get it in the water before it hardens up here in WI!

P.S. The titebond actually held better than the epoxy

RE: Epoxy for Scarf Joint

Did you thicken the epoxy?  It should be much stronger than the wood.

Paul

RE: Epoxy for Scarf Joint

The epoxy was thickened with wood flour to the consistency of mustard..just like tha manual said.  Anyhow..I'm trying gorilla glue now that I read flyingdutchman's post..It's suopposed to be set in an hour...I'm going to wait 'till morning to make double sure.

RE: Epoxy for Scarf Joint

Blacklab,

Houston, we have a problem!  Epoxy and Titebond don't work?  Clean up or recut that joint.  PAG is correct.  If the epoxy was thoroughly mixed, the wood should have broken around the joint, not at the join.  Sounds like something is contaminating your joining surfaces.

RE: Epoxy for Scarf Joint

If you do use a glue instead of epoxy, don't use Gorilla Glue for scarfing. Use Titebond 3 or some other waterproof carpenter's glue. GG is weaker because it foams and expands. The holes in the foam do absolutely nothing to help with the strength, and I've seen reports from carpenters warning that if too much GG is applied it can expand enough to force the joint apart.

In the meantime, what ootb says is absolutely true - either of those bonds should have been much stronger than the wood itself.

Laszlo

 

RE: Epoxy for Scarf Joint

How long are your scarfs? They need to be long (like 4" or more). A shorter joint doesn't have enough glue area, and creates more of and end grain joint. End grain does not make for a good glue joint.

One reason to use epoxy is that is has much better gap filling properties than PVA glues like Titebond. Titebond would probably work if you can cut a perfectly flat & straight scarf joint.

You could also try locating your scarf joints away from the middle, where the most extreme part of the bend will be, if possible.

RE: Epoxy for Scarf Joint

Alright, so i spent the morning making some extra long scarfs  (all over 4.5").  And the thickened epoxy is drying as I type.  I spent a solid 5 minutes mixing the epoxy to make sure it sets correctly.  If this doesn't work there may be a partially built WD12H for sale in the near future...lol.  Not really, but it is extremely frustrating at this point.  Between work and these glue set-backs it's been about 2 weeks of messing around with 4 tiny strips to get me going on the deck.  Thanks for all the input everyone!

RE: Epoxy for Scarf Joint

I suggest you go to the "Builders Tips" section and watch the videos of Nick Schade making and gluing scarf joints.  Gorilla glue is a terrible choice for most any wood working project.  I know of no one who has ever bought a second bottle.

RE: Epoxy for Scarf Joint

I went back and looked at the manual for the 2 Shearwater hybrids I built. It says to use a 8:1 scarf joint, which is a 6" long joint in a 3/4" wide strip!

Cheers,

Pat

 » Return to Forum Topics


Please login or register to post a reply.