Inconsistent tongues for shaker style doors

[Joshua Bass]

I made a bunch of drawer fronts in a shaker style and had a lot of problems getting making a consistent thickness tongues.

I first jointed and planed all stock to equal thickness. After cutting to size, I cut the tongues with a dado stack using my Incra 5000 sled. Each piece ran across the dado twice, flipping to ensure centered tongues. I had carefully set the depth and width of the dado cut on a few pieces of scrap.

I cut the grooves using a 1/8" dado blade on the table saw, running the stock through once then flipping it to ensure centered cut.

After all of this, the tongue thickness seems to be all over the place. Some are too tight, others too lose. The tight ones are easy to fix with sanding blocks, the loose ones are kind of a problem. I am curious what could be causing the discrepancy. I made sure everything was locked down and align during each cut, yet the inconsistent thickness proves something went wrong.

[Dave Richards]

Flipping the stock as you did will result in centered tongues/tenons but thickness variations can result. Check the thickness of the stock. It probably varies very slightly.

It's better to use a single face as the reference for cutting the tongue with a jig like this one (https://youtu.be/0XXftwASnK8) to create the tongues.

[Dan Hahr]

It is most likely due to not using a very tight featherboard.

[Ray Newman]

Do believe that Dave Richards is onto it. I found that good feather boards holding the work tightly down and into the fence are the answer.

[Wayne Lomman]

If your stock is thicknessed to the same size, this is not the problem. All you had to do was run everything through on the same set up. If you have a vernier calliper this makes checking thickness easy.

Accurate stock means working from both faces is ok. The problems will arise from the process. Is sawdust between the table and the work piece? Is your dado stack sharp? Slightly dull cutters cause inaccurate machining. And then there is the issue the other guys identified. Is the stock held firmly in place when machining? Feather fences help with this.

The problem will be in one of your machining steps. To fix the loose ones, glue a sliver to each face of the tongue, let it dry, trim and machine again. Cheers

[johnny means]

I run everything through twice. Eliminates including inconsistencies due to lifting or chatter.

[Jim Becker]

Featherboards are essential to insure the material stays flat on the saw table and tight to the fence...and running through twice like johnny mentions can be helpful.

[Bill Adamsen]

The one's that are too thin I'd be inclined to fix by either ...
1) making new rails or
2) gluing on additional material and recutting
I see nothing wrong with the second alternative and have done similar things many times. One of my mentors once wisely said, "it often comes down to how we fix the mistakes we make."

[lowell holmes]

If I had this problem, I would cut the tongues a bit fat and use a block plane to work the to the proper thickness.

[Bill Adamsen]

If I had this problem, I would cut the tongues a bit fat and use a block plane to work the to the proper thickness.
I cut tenons on a shaper carefully shimming to close to the right thickness. Final fitting typically requires just a few passes with a plane (I use the Lie-Nielsen rabbet block plane). Too thin is another matter altogether.

[glenn bradley]

I also vote for stock control issues. The material has to be held tightly to the reference surface, in this case your sled, in order for the dimensions to be accurate.