Mortising Jig

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I didn’t write much about the mortising jig production process but I will lay out some of the details of the jig itself.

Overall Shots

I had a large scrap panel made from laminated 3/4 plywood from my old flip-top table that is the majority of the jig.  The other pieces are left over cherry from my past table project.  Here are some rough overall dimensions (18″ long x 14″ tall).  The base is probably taller than it needs to be, but I like the length.

T-Track is for the fences and the dovetail slots are for the mircojig clamps to lock the mortised piece in place.

Overall Dimensions

The four lower bolt holes are to allow this jig to be bolted to my workbench.  I have two rows of T-Track in my bench.

Overall Dimensions

I should have made the top surface a couple of inches wider for a more stable base.  This picture also shows the guide that the router slides in and constrains in both directions.

Top Ledge

I had to cut some recesses in the fences to allow for the clamps to reach the work piece properly.

Overall with Fences

Router Sub-Base

The sub base is made from 1/4″ MDF.  It is roughly 12″ x 12″ square.  I started with the small hole for the router bit below, but increased the size to be very large later on so I could see the entire area to be mortised (~3″ in diameter).  I used an existing router base to lay out the holes.

The slots on the sub-base were cut on the router table.  The “runner” block has some holes drilled for 1/4-20 threaded inserts.  I could have used hanger bolts as well.  The black knobs have a bolts ran into them from the top.

Router Plate With Slide

Below you can see how much larger I made the center bit hole to see the whole mortise

Should have Jointed

Below is a shot of the jig before cutting any dadoes or dovetails.  The one thing I should have done at this point was to run the top surface across the jointer to ensure it was perfectly 90 to the large vertical face.  While I was using the jig the first time, the pieces were not perfectly parallel with the top after clamped into place.  

Jig Mounted to Bench

Jig Profile

The profile of the jig starting from the bottom.

  • The lower ledge sits in a dado and is glued in place.  It bears most of the weight and transfers it onto the work bench.
  • The piece on the left is the fence.
  • The large upper cherry piece is glued onto the plywood.
  • The short horizontal plywood is glued and pocket screwed into the vertical plywood.
  • The small cherry piece on the far right is only screwed from the bottom  to get the best fit of the “runner” block.
  • The whole jig and sub base had 3 coats of shellac applied.

 

Jig in Use

Some photos with the Jig in use.  I am able to use the jig with dust collection which is awesome

The jig is pretty straightforward to use.

  • Lay out mortise on first piece
  • Use the router bit sized for the mortise (1/4, 3/8, 1/2, etc)
  • Adjust the fence so the work piece is flush with the top of the jig
  • Set the distance from a reference edge using the knobs on the router base
  • Set the mortise depth on the plunge router
  • Start cutting mortise with multiple passes
  • The rest of the pieces can be marked with only a start and stop line since the distance from the edge is consistent
Results

The Jig in Action

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