Thread: Miracle dinghy loose nails.

U,

Nails compress surfaces and fix relative positions to allow adhesion between the glued surfaces. The right choice depends on the extent that these needs can be met by the selected combination. You could achieve compression with clamps, weights or even cords. Occasionally, I have used dowells to fix relative positions (new work)


My preferred method is to use nails but to protect the surface with a pad of scrap plywood covered with packing tape to prevent surplus glue sticking to it. When the glue has dried, I split the ply with a chisel, pull the now exposed nail head and insert a cocktail stick covered in epoxy. It looks good and my tools are protected, should a repair be required later.

You might consider rehearsing your assembly, particularly the positioning of any cramps, wedges or packing pieces before mixing glue or drilling a single hole.

Good luck.

Are these copper nails or clenches? I dislike nails of every kind, even the twisted ones, which work considerably better than smooth shank styles, but not as well as screws (or machine screws or bolts), which is what I prefer. If the screws or other fasteners are temporary, then a technique much like what Ross has described is wise. I use little plywood pads and drywall screws most of the time for these temporary fasteners, as they're cheap, easy to find in bulk and have good holding power.

I wrap the pre-pilot hole drilled plywood pads with plain old packaging tape, like that used on cardboard boxes. Goo doesn't stick to it and it's fairly easy to remove. I also wrap tools with this stuff as well as plastic bags or sheeting to protect them from globs of goo, that might want to cling to them. In fact I have a goo drill, specifically used for this task, covered in plastic sheeting and taped in place. When it's covered in goo, I just peel off the tape and plastic and apply more.

The same is true of clamps, backing pads/blocks and anything else that may come in contact with goo, during assembly, that needs not become part of the final assembly. This same packaging tape trick can be used to refine areas you want epoxy, keeping them separate from other areas. A good example is a deck I just made, that needs to land on some beams and stringers. I taped off these contact areas, but pre-coated and finished the rest of the deck pieces. When cured, I peeled the tape off and reveiled raw wood to bond the deck down to the beams and stringers, which will happen later this week.

As to nails, the only time I use them at all is to lightly take something temporary. I'll use finish or concrete form (double headed) nails for this, but (again) not very often, because they tend to move and pull if the attached pieces are stressed.

Originally Posted by PAR

In fact I have a goo drill, specifically used for this task, covered in plastic sheeting and taped in place. When it's covered in goo, I just peel off the tape and plastic and apply more.

Cool.....Very cool

Thank you for your input chaps.
I have found that the loose nails are (were) holding rubbing strips on the floor/sole so have worked loose with flexing (as their bonding has failed over time. I have now learned enough about epoxy that I can glue these down, temporarily screwing them to hold them whilst it sets. Thanks for the tips on epoxy, it's all new to me.

I agree with PAR about nails & would reach for screws any time. I don't know much about boatbuilding and there are circumstances in ither It's a leap of faith to jump from traditional fastenings to epoxy though..

There are other nails, which I don't think are loose, that are clenched, Having exposed these, the shanks haven't corroded so I can re-clench these IF necessary, but I think these are still tight as they are in stronger parts of the structure.

I think we had our summer last week & it has rained most days since then, stopping play as this is on my drive. When it stops, I can work out what & how much epoxy etc I need.
Cheers
J

Clenched nails can loosen, actually they usually stretch and/or open up at the bent over portion of the fastener. If the clenches are of substantial diameter, you can often "buck" them back down, tightening things up. Sometimes this doesn't work out as well as refastening, mostly because you can't examine the fasteners for fatigue. I usually just assume the fasteners need to be renewed and yank them all wholesale, if any or a reasonable percentage of, show some sort of fatigue, corrosion, bending, breakage, etc.

I did some tests a few years back and found that machine screws hold better than wood screws, if in good holding power woods or in bonded holes (an epoxy thing). This kind of surprised me a bit, but after some thinking it does make sense, much like a fine thread bolt being able to tolerate more torque than course threaded. When I have an option I use machine screws in bonded holes, instead of wood screws, for this extra holding power.

FWIW

Thank you.
That is interesting about the clenches - I'll inspect them thoroughly.
Trouble is, this dinghy was bought to be a family hack & I'm wary of getting drawn into a total rebuild - rather looking for "keeping it going". Obviously I don't want to do some work, get it all painted up & have something spring apart. Things will fail regardless of whether I hope they won't, but I need to assess the balance of probabilities, and on the basis of what I want the boat for (eg she doesn't have to stay in class & I'm not looking for concours condition).

The clenches are in structures that are sound, so I can't just dismantle & re-glue. With the machine screw approach, do you drill a snug hole then drop in epoxy before screwing the machine screw in? Can you undo these at a later date? What grade of s/s do you use?
Cheers.

I have a set of pilot and clearance hole sizes I use, some species dependent, while others are application dependent. Yes, you can remove and reinstall the machine screws. If the screw is waxed before bonding in it's hole, it'll come right out. On the other hand if the fastener wasn't waxed, you can use a soldering iron to warm the fastener to about 150 - 170 degrees and the epoxy will loose much of it's grip and you can back it out.

For more about fastener bonding with epoxy, download the free "User's Guide" from Westsystem.com or the "Epoxy Book" from Systemthree.com.

Thank you for that additional info about the machine screws. I think I'll go down that route.

I had already downloaded the 400+ page West book & am wading through it, printing off bits as I go for a bit of bedtime reading - I'll get there in the end...
Thanks for your help.
Cheers
J