Poor Mans Dovetail Spline Jig

Roy Millsaps

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399
Location
St. Mary's, Georgia
I'm going to show how I make a Dovetail Spline jig, but I'm making 2 of them. First one is for the main dovetail an the second one is for a Inlay Dovetail

First I pulled out a scrap piece of Baltic Burch Plywood 3/4 inch

I'm going to making (2) X 7 Inch rips on the scrap

Jig for Dovetail Splines 01.jpg

Next on each piece I'm going to make (2) 7 inch cuts an (1) 11 inch piece

Jig for Dovetail Splines 02.JPG

Next on the 7" x 7" pieces I cut a 45 degree angle on one side,

Jig for Dovetail Splines 03.jpg

As you can see in the picture there is a recess cut across the grain on the 11" piece. Here is why all corners on the project theses jigs are made for are sharp corners so I cut a recess in the center across the board I only went in about 1/8"

Jig for Dovetail Splines 04.jpg

Next on the C/L I marked out for (2) 1" holes these hole are 3 1/2" from the recess on each side

Jig for Dovetail Splines 05.jpg

Next thing I did I found some scrap Oak an cut some 45s for support latter in the thread

Jig for Dovetail Splines 06.JPG

Now for the best alignment for this jig is to take it to your project an clamp the 7" X 7" pieces to the corner top an bottom with the long end of the 45s touching the wood , bring it close to the corner

Jig for Dovetail Splines 07.jpg

While it is clamped check an see if the top plat sits nicely on the 45s, if not adjust until it does. On mine it looks great so I took the pieces off an put some wax paper on the corner an reattached the pieces

Jig for Dovetail Splines 08.jpg

Double check fit-up an adjust as needed, If you are ready put glue on the 45s an set your top plate on an brad nail it in place

Jig for Dovetail Splines 09.jpg

Jig for Dovetail Splines 10.jpg

Back in next thread
 
Now next thing to do is get your 45 degree pieces of scrap an glue then in place an brad nail them in place this is the added support

Jig for Dovetail Splines 11.JPG
Jig for Dovetail Splines 12.jpg

Now that I am making 2 of these I will make the other one on the other corner same way as this one

Jig for Dovetail Splines 13.JPG
Jig for Dovetail Splines 14.jpg

Now I leave them in place until dry
So be back tomorrow
 
Well it time to finish the jig, the next step is to find what size of my guide bushing since my router bits are Half inch shank so I am using 5/8 bushing , so I got out my 3/8 inch strait bit and set it up in my router table

Jig for Dovetail Splines 15.jpg

Jig for Dovetail Splines 16.jpg

As you can see I cut in a small run from one end to the first hole it helps me for setup an clean out when I cut the Dovetail Spline areas

Jig for Dovetail Splines 16-1.jpg

Next thing I did is set the bit height to the highest it needs to be. I set my digital gauge to 0 an lowered the bit to 1/4" above the table then set my center point with the fence. Next I ran 1 grove through the holes an turned it around an did the same I was off by 1/32 from center so not to bad, I raised it an did another passes until I reached my max height

Now I'm at the max height I need to make it wider so I marked where my fence is an moved the fence in small increment's until I needed to where I need to be for the bushing size

Jig for Dovetail Splines 17.jpg

Jig for Dovetail Splines 18.jpg

Now here is what the jig looks like after cutting the grove for the bushing

Jig for Dovetail Splines 19.jpg

Next I got out one of the test pieces an I set up the height of the bit an clamped my jig to the test piece, time to find out if its going to work for my project

Jig for Dovetail Splines 20.jpg

Next I do my cut , this is the first time the jig is used so I'm also cutting the jig to for the router bit an it looks good

Jig for Dovetail Splines 22.jpg

I removed the jig an checked my test piece

Jig for Dovetail Splines 23.jpg

No blow outs an nice clean cuts so this jig is ready for the project, but before I do anything I mark the top an size of the dovetail bit used for this jig. I plan on keeping this jig for future projects

Jig for Dovetail Splines 24.jpg

Now you can make this jig for strait bits also for splines for your bigger projects or an size of dovetail bit. Since I made 2 of these I will be making a inlay dovetail with the other one for future projects
 
Excellent posting, Roy! I love to make splines and have been wanting to make a better jig. This fits the bill. Thank you for taking the time to develop such a detailed tutorial.
 
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