Mechanical Fasteners

[Walt M]

As I'm reading this thread, it just dawned on me how modular home manufacturers build walls from the inside out. they lay gypsum(good face down) on a large table, then they lay the framing members on top of the gypsum on edge they nail the bottom shoe and the top plate to the studs.
They then fasten the gypsum to the studs using expanding foam. the foam dries very fast.Buy the time they install the electricity and apply the gypsum to the face of the wall thats left, the expanding foam is dry and they can lift the wall and place it in the building. No mechanical fastners at all. this is a prett quick wall scene you can move ahead to about 2:00 http://www.youtube.com/watch?v=c3AD46HRW2A

[angib]

Everyone is either being 'sensitive' or they are assuming that everyone else builds like them.

There are two key things to consider:

- What glue is being used. There are weak glues, strong-but-brittle glues and strong-and-ductile glues. Which you use makes a huge difference.

- How good your workmanship is. Glue joints require a good accuracy of fit-up to be strong. There are photos on this forum that range from "you can't get more than a feeler gauge through the dry joints" to "you can't get more than a finger or two through the dry joints".

If the fit-up is in the 'finger' category, then mechanical fasteners are essential as gluing will never be strong enough (though a filled epoxy would come close).

If the fit-up is in the 'feeler gauge' category then mechanical fasteners come a poor second in strength to a good glue and add nothing (except maybe ease of building).

Andrew (ducking and covering)

[Walt M]

Hey andrew, I beg to differ. I think this thread was asking about different methods of construction using mech. fasteners or adhesives. your points are well taken about quality of craftsmanship. I did build a woody and I didn't want any brads,staples,or screws to show or that I would have to cover up. I chose to glue the inside and outside skins on,But I recognize and appreciate different design ideas. I trust and believe in adhesives. thats all. although I don't like the fact that it takes two days for the urethane glue to come off my hands. Angib, was it you who put together the design library? if so nice work, well done. cheers, Walt

[Lou Park]

There is absolutely no reason you couldn't build using just glue. Homebuilt
airplanes have been built this way for 100 years and they are subject to
100mph winds and torsion constantly. It does however require the right adhesive with the right materials.
Lou

[kennyrayandersen]

Everyone is either being 'sensitive' or they are assuming that everyone else builds like them.

There are two key things to consider:

- What glue is being used. There are weak glues, strong-but-brittle glues and strong-and-ductile glues. Which you use makes a huge difference.

- How good your workmanship is. Glue joints require a good accuracy of fit-up to be strong. There are photos on this forum that range from "you can't get more than a feeler gauge through the dry joints" to "you can't get more than a finger or two through the dry joints".

If the fit-up is in the 'finger' category, then mechanical fasteners are essential as gluing will never be strong enough (though a filled epoxy would come close).

If the fit-up is in the 'feeler gauge' category then mechanical fasteners come a poor second in strength to a good glue and add nothing (except maybe ease of building).

Andrew (ducking and covering)

Andrew,
Your points are well taken, though I have to say that if the gap is finger-wide, even the mechanical fastener might not save you as it puts the fasteners in bending which they really weren't designed to do.

I must admit I was thinking in terms of how I build and some naturally build to tighter tolerances than others. My dearly departed father couldn't get a straight board if you handed him one. My mother on the other hand... lets just say she was a BIT of a perfectionist. No matter what method you use, quality construction pays dividends in looks and strength.

[mikeschn]

I have always built with glue AND screws.

I have peace of mind while driving down the highway, knowing that if for whatever reason my glue joints no longer want to hold, my screw joints will.

Of course if you are a kayak builder or something similar you'll scoff at screws, but for the rest of us, I think screws are good insurance.

Mike...

[alftinc]

Thank you all for the help. I have built a Cubby already but covered it with aluminum so screws were ok. My next build will be a Woody and i really did now want a lot of trim work to hide screws and nails. I have built two Ocean Kayaks of wood, and epoxy, with cloth and not a nail or screw in them. They hold up to the winds on top of my truck and take a beating in the ocean, no problem so far. Thanks again.

[Mark McD]

Instead of hiding the fasteners maybe you could accent them with a different specie of wood plugs?

[kennyrayandersen]

Mark, one thing is even if you use the same species, if you use a standard-type dowel to plug the hole, the end grain takes finish differently and it will look like a different color anyway (darker). If you want a really strong contrast you can use a different wood.

[Mark McD]

Kenny,
Another solution would be to use cross grain plugs, instead of end grain plugs. Easy to do if you have a plug vutter. Of course, HF sells a cheap plug cutter set.

[kennyrayandersen]

Mark,
True dat, but in my little engeering mind I was thinking the standard plugs would add to the strength of the attachment. The cross grain plugs are more stealthy, but are only cosmetic as there is no shear strength when the are oriented in that direction. If you are just covering screws then it wouldn't mater which you are using, but if you used those lin dowel-like plugs you wouldn't even need screws.

Still, the standard way would be to use a screw to suck it up and followed with a cosmetic plug which could be any of the above depending on the look you're trying to achieve. I like your first idea of using a different wood, or just using an end-grain plug which will accent the joinery.