Adjustable Dado Jig From Scrap Wood

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Introduction: Adjustable Dado Jig From Scrap Wood

This is a adjustable router jig I made from scrap wood and knobs from a old lawnmower.

Step 1: Building the Jig

The purpose for this jig was for me to be able to make mirror image dados for built in bookcases. I built mine to span two 11 7/8 inch side panels butted together but you can make it any size you need. The jig is made with six pieces of scrap wood i had left over from other projects. I chose MDF for the base of the guides because it is very smooth and would let the router glide on top. I took two 30 inch pieces of 1/4 x 8 inch MDF and glued them to two 30 inch pieces of 1/2 x 4 inch plywood. When the glue has set up choose which bit you will use for this jig and adjust the router. Use the router to cut the MDF to the exact width of the edge of your router to the bit. On one piece I drilled 1/4 inch holes on each side along a straight 2 inch line on my drill press. I then used a file to square up the sides of this groove in order to make a slot for the adjustment knobs. The side rails are made from 1 x 4 x 24 inch poplar. A machine screw is counter sunk from the bottom on one side of each rail for the the adjustment knobs. The other side of the rails are glued and screwed to the top guide so you end up with a permanent side and a adjustable side.

Step 2: Any Size Dado

With the jig assembled you can now use whatever stock you need a dado for to set the width of the jig. Here I used a 2x4 to set the width followed by a 3/4 inch piece of plywood

Step 3: Perfect Fit

As you can see from the pictures, since the piece of wood dictated how thick its own dado will be, the fit is always perfect.

Step 4: Measure Once Cut Both.

As i said at the beginning, this jig is used to cut both sides of the bookcase at one time, Just set the hight of each dado and clamp the edge of the stationary side to the line. Adjust the gap using the shelf itself and cut the dado.

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Woodworking Contest 2017

Participated in the
Woodworking Contest 2017

3 People Made This Project!

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6 Comments

0
mattcecile
mattcecile

Tip 5 months ago

For best results, use a up-spiral router bit. Clean cuts and good chip removal

0
mattcecile
mattcecile

Tip 5 months ago on Step 3

Note that your router base plate may not be centered. Always position the router in the same orientation

0
Bradscopegems
Bradscopegems

Question 7 months ago on Step 4

Am I right in thinking that you can use only one diameter of bit with this jig? Also, does the accuracy depend on the circular router base being exactly concentric with the bit? I am making a similar jig but have made a rectangular aluminium base plate screwed to the original circular base with one longer edge slightly further from the bit than the other. I always use this edge against the fence ( i.e. turn the router around when I am using the second fence. I am using a 1/4 diameter bit to start with, but your design is so good that I would be happy to make a series of jigs to suit a range of bits and make it easy to cut dados of all sizes with minimum number of passes.

0
DonM51
DonM51

Answer 7 months ago

Yes this is for 1 size bit. The jig was for making book case shelve dados.

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Kink Jarfold
Kink Jarfold

2 years ago on Step 4

This jig works great! I made a similar one and love its accuracy. I used it in my shadowbox bookcase. Great instructable.

KJ

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MrSaranac
MrSaranac

4 years ago

Very clever looks like it would work great and save time