...but I do need a better under-pinner.....don't I?

Sarah Winchester

CGF, Certified Grumble Framer
Joined
Nov 6, 2004
Posts
186
Location
Michigan
I've been gluing my corners, letting them dry and then fastening with a manual v-nailer. I've read the threads about the different v-nailers, but I'm trying to make a logical decision. The pneumatic v-nailers seem to drive the nail in with temendous force, and I wonder if that would disturb the glue jont ??? With the manual I can eaaasssseee the v-nail in, in any kind of wood. My neighbor says I want one that has some teeth to push, under the rabbet into a corner brace, and a device that comes down from the top to hold the moulding in place, regardless of it's shape. I'm going to Atlanta, but would like to get some opinions before I get there. Thanks in advance.
 
A pneumatic underpinner will take the place of the clamping (for the most part). You will glue and v-nail at the same time. It saves on time and space.
What will be confusing is that all the distributors for the various underpinners will tell you that theirs is the ideal one for your purposes, as will any number of Grumblers. You're going about it the right way by attending the show and checking them out first-hand.
After you have spent Friday scoping them all out, come to the Omni Bar and we'll do our best to add to your confusion, err, help with your decision.
 
Sarah, if you're going to the trouble to glue corners together and to allow the glue to set up, you don't need an underpinner at all. There is no good reason to insert mechanical fasteners into a glued joint and a lot of reasons not to. A miter joint does involve endgrain but only 45% and with modern glues and time to set up, it's stronger than any joint reinforced with mechanical fastners. If it fails, it'll be because it fell from some distance or was pulled apart, not likely events. But when a joint without metal fasteners fails, it's a lot easier to repair than one with fasteners. The v nails are intended to make joining corners faster, not to make them stronger. If you are already spending the time to make a good glue miter joint, there's no advantage to using v nails. You're right, the v nail will make the joint weaker because no matter how gently you insert them, they will weaken the joint around their positions. They actually cut through the area of the stronger glue joint they occupy. Get a good v nailer when you need to speed up the joining process. Warren
 
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