Getting ready to epoxy in some self tapping A4 SS inserts into a solid carbon fuselage on my AFS foil. Saw that a high density adhesive filler is recommended for bonding the inserts in (per westsystem video), question is, can I use some regular hardware store/ Walmart two part slow setting epoxy with that filler? (the kind that comes with dual syringes, see pic.) I do not need much epoxy/filler, maybe an ounce max.
Thanks

Now is not the time to go cheap.
Buy real epoxy.

LeeD said..
Now is not the time to go cheap.
Buy real epoxy.

Edit, contacted west systems and marinetex, someone there will know what is the best product for this application.

okay LeeD you have a good point, thanks
so what about this, small amount of thickened Gflex epoxy? $25 for this versus $5 for the Loctie. Or what about the second one, sounds perfect for my needs, and do not have to add filler, right?

Sandman,

Use the Six10 thickened epoxy. It has the structural properties of their epoxy with the thickener already added. I probably have used 20 tubes over the years. I even have used it for small board repairs because it will wet out several layers of fiberglass. When you use it fill the holes completely and let it sit for a few minutes to make sure it has saturated cloth on the sides of your holes. Maybe use a nail to force some of it into the hole sides. Most likely when you screw the insert in the excess will squeeze out around the side of the insert. If you find there is too much resistance back out the insert and remove a bit of the epoxy before reinsertion. I am still a proponent of over drilling the hole size and setting the inserts using a fixture like I previously described in you other thread. Before you commit to your threaded plan I would install the inserts dry and check to see if the holes in your wing still line up. Thread a nut onto the screw and lock it against the insert so you can back it out. You always have the option to drill the hole larger and set the inserts without the threading them into the existing carbon.

Since you wont use the whole tube you can save the remainder by replacing the caps. Only the mixing nozzle will need to be discarded. You can buy 2 extra new mixing nozzles for under $5.

Good luck and take your time getting the setup correct. You only have 1 chance to get it right once you mix the epoxy!

Not to digress but the Chicago bolts (barrel screws) that were recommended in your other thread would be another good option if the threaded inserts don't work. McMaster sells them in 316 stainless with an M6 thread in a variety of lengths so you can come close to matching your fuselage thickness. You would have to drill the through holes fairly accurately. You could use your wing as the drill template. They are only 7.5mm in diameter and you could set them in epoxy to fill the annular space and ensure the surrounding cloth is thoroughly saturated.

McMaster is also a good source for your replacement hardware.

Awalkspoiled said..

The Scotch-Weld product below is very strong and resists cyclic vibration every well, which is the big issue. Pay attention to cleaning everything first - I use acetone - because the metal parts will often have a thin layer of oil on them.




"Toughened epoxies, such as 3MTM Scotch-WeldTM Epoxy Adhesive DP420 and DP460, actually incorporate elastomeric regions which absorb impact, and thus provide the highest shear, peel, impact, vibration and fatigue resistance; and hence are chosen for the most demanding end use applications. In general, however, epoxies require rigorous cleaning of oils from metal joint surfaces for room temperature bonding."

Good point Awalkspoiled, I have acetone, but would not of thought to clean the new inserts in it-thanks! Will also check out the Scotch-Weld, Do you know if the Scotch-Weld DP 420 is thickened?

www.bighead.co.uk

Designed specifically for composites, Bighead fitting are used extensively in auto, space/aero & marine industries. I've found them to be light, excellent quality and bond astoundingly well.

Brent in Qld said..
www.bighead.co.uk

Designed specifically for composites, Bighead fitting are used extensively in auto, space/aero & marine industries. I've found them to be light, excellent quality and bond astoundingly well.

Brent, looked at them, they would have been great if installed in the layup.

Mark _australia said..
JB Weld or similar.

If using the syringe systems they never dispense equal amounts due to air bubbles so mix way too much, if you see one stream stop due to air, start over again with a new mix

Rough the inserts really well with a dremel or similar, soak in acetone for an hour, blow off and repeat. That's the only way to really ensure no oils...

Mark and Awalkspoiled, good points about the inserts needing to be clean and rough. I saw some carbon in the cutting groove of an old insert, put pressure on it with my finger nail and it slide right out, so the carbon did not bond to the inserts, just molded around the threads. New inserts have deeper threads, but maybe an acid wash to clean up the A4?

Read that you can etch stainless steel for epoxy adhesion with muriatic acid for 15 min., followed by rinsing with hot distilled water and then hot air to dry.

Brent in Qld said..

Sandman1221 said..

Brent in Qld said..
www.bighead.co.uk

Designed specifically for composites, Bighead fitting are used extensively in auto, space/aero & marine industries. I've found them to be light, excellent quality and bond astoundingly well.

Brent, looked at them, they would have been great if installed in the layup.

Bigheads can be retro fitted with a bit of detailing & glassed over. Main thing is they bond well & have the mechanical shape to avoid spinning or pulling out which, from my experience, is half the battle getting metal parts to stay put within composites.

Thanks Brent

Looks like I will not have to fill in the holes and drill, since the old grooves are still there and it looks like the new inserts have the same thread pitch, but slightly larger OD, so they will cut in deeper into the same grooves and that means aligning the wing should not be a problem.

I use this product. It is white, so does contrast with carbon fibre. The great thing about it is it is very think, dries fast, can be sanded and is polystyrene safe. Norfill White Epoxy Filler - Norglass Paints and Speciality Finishes.

And note that while SixTen epoxy can be put under load after 24 hrs per instructions, it continues to harden. So I did not use the first mixed epoxy that came out of the mixing tip, and after 24 hr it was hard but also flexible, now after 72 hrs it is not nearly as flexible, so it is continuing to harden.