Fitting to a steel deck

You used 7018 to weld stainless acorn nuts to A36 plate?

PDW

 

Not stainless!
Mild steel nuts. I tried them with both 2.5mm 6013 and 2.5mm 7018. I had some issues with trapped slag with the 6013, very small pores over the point where it was tacked from the other side.
Nick

 

Many ways to attach hardware to a metal substrate. Thru bolt, drill and tap.... In the end you will have hundreds of fasteners driven into the metal.

To achieve good results these joints must be watertight...forever.

The best way to achieve this is to ensure that the mating surfaces of hardware and substrate are true and that each fastener bears to same load.

The best way to accomplish this is termed hardware bonding.

This is done when the boat is in primer stage

The hardware base is coated with mold release then adhered to the substrate with a bed of thickened epoxy. Only use one or few temp fasteners.

Clean up the squeeze out epoxy and let cure. Once cured, bore fasteners holes....tap or thru bolt...then remove hardware from its epoxy bed...sand and prime the new hardware epoxy bed.


subefotos

The hardware now has a perfectliy true base . All surfaces bear equal load..all fasteners bear equal load.

Final assembly with sika flex or similar. Plenty of compound on mating surface, inside the fastener hole and on the fastener threads.

Never use SLOT head countersunk fasteners outside. The slot wipes the bedding compound off the countersunk and more importantly the slot holds standing water in contact with the joint. Always use allen head countersunk.

No standing water is allowed on a boat deck


subir fotos gratis

 

Ah, ok, I've never seen anything but stainless acorn nuts.

Ignore what Michael said about attaching stuff to a metal deck. The best way bar none is to weld things down. Second best is to bolt them down to blind hole fittings as you're doing.

Any other way is a distant 3rd best because you're relying on some form of bedding compound to not deteriorate over time and not split away from the surfaces due to differential rates of expansion & contraction. Michael may be a yacht captain and that's fine, but I spent a lot of my working life on steel research vessels where we regularly added & removed equipment from the steel working decks. If we could weld it, we welded it. If we were changing stuff regularly, we'd set a frame under the deck with blind threaded holes through the deck and weld all around them, then make standard sized bases for winches etc so we could unbolt one winch and bolt down the next one.

Bolting stuff down except to blind holes in sub frames etc never worked over the long term.

PDW

 

This is interesting, I have a preference for slotted fasteners because they can usually be removed even if the slot is damaged whereas allen heads have to be drilled off. I hadn't thought about the water standing in the slot...and now that you say it, I have often seen the effect of the sealant being wiped off the wall.

I had to remove some winches on a boat I was repairing that had been bedded with Sikaflex and they were extremely difficult to get off.

 

Many ways to use sikaflex..if it is a large surface area and you are worried about an over strength bond you contaminate one surface...any contaminate will work...wd40. Mold release

I prefer to contaminate the hardware surface and let the sika bond to the substrate...some prefer the other way around.

Other techniques to make a bond break are mylar tape on the hardware surface.

I work with metal yachts for thirty years. These are the methods I have learned. The same with hardware bonding in epoxy .

The winch pictured has been mounted for twenty years. The cambered deck was leveled with high density epoxy filler under the winch base