Tuesday, August 21, 2012

Oxymoron: Softwoods can be Harder to Work than Hardwoods!

     This is a discussion that I'm sure many other woodworkers have had.  It seems as if the opposite should be true but you'll find that it may be more difficult to cut softwoods cleanly than it does to work with hardwood.  This is especially true when it comes to hand cutting joints or mortises for hinges.  At our last Sin City Woodworkers the focus was for the members to bring in various jigs that they had either bought or made and share them with everybody.  One of the members brought in a very complicated and technical jig for routing the recesses for butt hinges and although it did the job, getting there was definitely not half the fun!  Anyone who's ever used small butt hinges knows how temperamental that process can be.
     As luck would have it, the Urban Ranch series of boxes I'm working on now need those small, brass, butt hinges.  They are 1" wide and since the pine I'm using is 1/2" wide there is very little, if any) room to make a closed mortise.  This is where the frustration set in.  No matter how I went about scribing the outline of the hinge, the thin piece remaining towards the inside of the box would split off.  Marking gauge, sharp chisel, marking knife ---- made no difference.  I gave in and decided to just mortise all the way across but since I'm using inexpensive hinges from Lowe's they're pretty thin so there isn't even 3/16" of depth required.  By the way, I discovered all of this on scrap pieces of pine.
     Combined with my frustration and the memory of the hinge jig brought to the meeting I recalled how we'd make a "quick and dirty" jig to hang doors when I worked construction in the 70's.  At that time it wasn't real common to have pre-hung doors so we'd make a quick U- shaped piece, tack it on the door and jamb, then use a router to rough it out.  Figured that should work equally well for this operation.  Here's what I came up with:

Hinge Mortising Jigs

     I'm using 1" and 1 1/2" hinges so needed both sizes.  In the foreground is my test piece and it shows I need to lighten the cut just a little to increase the gap between the lid and the box.  The first step was to hold a piece of MDF upright and cut the opening for the hinge on the table saw.  Here I'm almost done, notice the hinge laying there?  That's used to make the opening exactly the correct size, carefully make your cuts as you sneak up on the measurements.

Tablesaw to Cut Opening
      I used a piece of Walnut to attach the jig to, any scrap of wood will do.  Before that though, I cut the piece of MDF so there was the same amount of jig on both sides of the opening, in this case I used 1 1/8" as the distance I wanted to attach the hinge from the edge of the box.  This way, if the edge of the jig is lined up with the outside edge of the box they'll line up during assembly.  You could also draw a center line for the hinge and then use center lines on whatever project you're making to line them up.  When you attach the piece of MDF to the strip of wood, position it where you want the hinge to be on the box.  If you're cutting the mortise completely across the box it doesn't matter as long as you can cut the entire thickness of the box.  If you're making a housed mortise you'll need to calculate where the mortise will be located on the edge.  I used a brad gun and a spot of glue for that step.
     Here's how it all works together:

Jig in Use

     First line up the edge of the jig with the edge of the box.  Then cut the mortise with a short, 1/2" straight dado bit with a top mounted bearing or any other size you have.  Since the box and lid were made as one and then cut apart you can be assured the hinges will line up.  If the hinges were of Brusso quality you'd probably be better off making more than one pass to cut the recess but these inexpensive ones aren't mortised very deep at all.  The only down-side to this jig is that you need one for each different size of hinge.  Since most of us probably use the same style and size of hinges for what we usually build that shouldn't pose too big of a problem.

No comments:

Post a Comment