I was planning to use epoxy for spot welding but after reading some posts on using CA glue I am having second thoughts. I can find CA glue at my local hardware store such as Titebond. I read a post that Titebond CA glue is recommended by Nick Schade. That is the only brand I have ready access to without driving to a big box store 30-40 minutes away. I assume I should use medium? With an accelerant? I also read to not use Gorilla glue.
I sort of see my SW Dory as an epoxy and fiberglass learning progression. You learn to mix and thicken epoxy on puzzle joints. You get a little better at it with tack welds. You get a little better at it with fillets. By the time you get to glass you have a fairly solid foundation of experience to build from.
Super glue (cyanoacrylate glue, CA glue) is all the same chemically but comes in various viscosities. CLC sells CA for boat building, but it is just repackaged medium Insta-Cure+ (purple label) manufactured by Bob Smith Industries. I personally use BSI for both boats and RC airplanes but I don’t think that it really matters as long as it is medium viscosity. You should also buy some accelerant which sets the glue instantly and prevents runs on vertical surfaces.
Sounds like you are planning to tack the entire boat with CA instead of epoxy? Can’t say that I would recommend that for a Chesapeake build. The Petrel Play that I used only CA to tack is build with 3mm ply and has four external forms that hold the boat shape. The Chesapeake uses 4 mm ply (harder to bend) plus shear clamps without any forms. As a result, there is a lot more force on the wires, especially in the bow and stern. I am not certain that the CA will be strong enough in those high stress areas.
In my current build, I used epoxy for the keel line and chines in the center of the boat, and CA for the more vertical seams in bow and stern. My technique with the epoxy is to use a popsicle stick to spread very lightly thickened epoxy between the wires. It does not take much. Another technique is to use a syringe.
I agree with everything Mark Nye says. I like to use CA (medium, with accelerant) just as much as possible. Much faster, easier to apply and cheaper, and CA tacks suffice in almost all situations. But where I know the stitches are holding a whole lot of tension I’ll use some small, between-stitch dabs of epoxy. The dabs don’t need to be big (if worried, make the tacks longer, not thicker) - makes fileting over them easy - but even small dabs of epoxy are much stronger than the CA.
Mark,
Thank you for your continued and valuable help. I’ll do the epoxy method then. I thought I could tack weld with CA glue in warmer weather but not if it won’t hold the 4mm ply as well. I actually have been saving popsicle sticks so I am set to start tacking early tomorrow morning before it gets too warm.
Rob
+1 on the popsicle stick (or a putty knife) for applying the tacks. That lets you force the epoxy putty into the gap between the workpieces as well as making a smooth transition that allows minimal fillet sizes. It also avoids having to fill and clean syringes.
Laszlo
Jon,
Thanks for the reply. I think I will use the epoxy method instead of CA glue as per Mark’s warning about using CA glue to tack 4mm ply. This will be my real first epoxy/fiberglassing project.
Rob
Your choice to do as you like, but I would give CA some consideration and test both. You won’t know if you don’t try. Then you can make an informed decision.
FYI I built my first boat (NE Dory) with 100 percent epoxy tacks, laid in too big (now I realize), resulting in thick filets over the wires and big bumby tacks. I built my fourth boat (a Rhode Runner - really thick ply in many areas) with 90+ percent CA tacks, laid in probably 10 times faster and much cheaper than epoxy, pulled all wires prior to fileting, and made filets neat and only as thick as they needed to be.
Laszlo,
Thanks!
Rob
Jeff,
Sounds good. Thank you!
Rob