How Important are V-Nails for joining corners?

Mercury Mercurius

Grumbler in Training
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Mar 30, 2004
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Columbia, MD
I am an artist who frames my own artwork, so I don't need to complete huge volumes of framing like a framing business. Nonetheless, I'm trying to decide upon type of frame vise I want to purchase....A plain one, or one with V-nailing capability. My understanding is that V-nails are useful for stabilizing frame corners until the glue sets up, but that ultimately it is the glue that does the bulk of the work for structural integrity of the frame. Is this true? Or should I invest in a more expensive vise with v-nailing capability?
Thank you for your help,
-M
 
My understanding is that V-nails are useful for stabilizing frame corners until the glue sets up, but that ultimately it is the glue that does the bulk of the work for structural integrity of the frame. Is this true?
That is a subject for debate. We’ve all seen frames brought to our shops where the corners have separated i.e. the glue has dried and lost its grip, so to speak, and the V-nails or brads are the only thing keeping the corners from falling apart.

There is a fairly new adhesive by 3-M (sorry, I haven’t used it and don’t know the name of it) which is said to be stronger than the wood surrounding it. I have heard that it is quite impossible to break the corner bond without splitting the wood. The set time may be a few hours, though. Again, I don’t know the specifics.

If you’re only doing a few frames at a time, buying even a hand (non-pneumatic) V-nailer may not be cost effective.

I would suggest a standard right angle vise, woodworkers glue, a drill and brads for stability. With a good collection of Amaco® nail hole and corner fillers (they are cheap and mixable up to a point) you should be able to hide just about any hole.
 
Your understanding about glue & nailing is backwards.

Unless the nailing can be completed very quickly, before the glue begins to set up, the corner should be left to dry/cure undisturbed in a vice. Nailing a freshly-glued corner after it has begun to set up actually weakens the bond.
V-nails, Thumbnails, and some other fast fasteners, which are installed before the glue begins to set up, are OK.

The real benefit of nailing the mitered corner is to prevent catastrophic failure later, when the glued joint fails.

Whether you choose v-nails, Thumbnails, ordinary brads, or something else, it is very important to have a mechanical fastener in each miter joint. Most of the modern frame glues, when applied & viced properly, will outlast the wood to which they're stuck.

But that doesn't mean the corner won't come apart. There's always the possibility of impact or twisting that could break the glue joint loose. But if the frame is perfectly built and perfectly joined with only glue, it will still fail, eventually.

The problem is that wood fibers, like all things hygroscopic, expand & contract constantly with changes in temperature and humidity. The glue in the miter expands & contracts too, but differently, which stresses the bond. Eventually the fibers stuck to the glue will separate from the rest of the fibers, and the corner will come apart.

Note that in this scenario, the glue doesn't fail -- the wood fibers attached to it do.

The 3M glue Bill mentioned is Mini-Weld. Yes, it is very strong, but 3M has discontinued the product. For those of us who have invested in the application tool, the glue cartridges will remain available from our usual sources for some time. But if you're looking for a new glue, that's not the one to get into.

So, the short advice is: Glue & nail your frame corners, and do it right. V-nailing is good, but not the only way. Other fasteners can do the job adequately, too.
 
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