[old Steve]

I will be making some Oak boxes with mitered corners. I want to add some splines on the corners. I will be using a sled on my router table to cut the 1/8" or 3/16" groves. I am thinking that a spiral up cut bit would be best for this application...am I correct?

 

[Cherryville Chuck]

Are the miters to hold the corners together or through the corner horizontally? If vertical holding the mitered corners together I would say it should be a pretty good choice as the upcut gets rid of chips better than a straight bit. It may rag the edges a little but most of the grooves will be hidden in the joint. I would use a scrap piece butted to your good piece where you exit the cut to avoid blowout if possible. That would be hard to hide.

If they are horizontal splines that show on each face then the upcut may leave a rough edge on the slots that might be hard to hide.

 

[Nickp]

Are you talking about splines on the inside of the miters or visible across the miters on the outside...?

If on the inside, the tearout can be cleaned up and hidden...

If on the outside, a table saw spline jig would be better...

Using the router table for an outside spline, even with a spiral bit, you may experience some tearout and need to find a way to use a backer board.

Whether router table or table saw, the jig would look similar...

see https://www.google.com/search?q=spl...xt_gAhUST98KHa26B0YQ_AUIDygC&biw=1280&bih=579

 

[old Steve]

They will be on the outside corner, I have a jig for my table saw now so I guess that I need to purchase a flat tooth blade. I wanted to make some the splines 3/16" I assume that I have to run them thru the saw twice.

 

[Nickp]

They will be on the outside corner, I have a jig for my table saw now so I guess that I need to purchase a flat tooth blade. I wanted to make some the splines 3/16" I assume that I have to run them thru the saw twice.

Agreed...I don't think it's worth the aggravation to try to set up a dado arrangement...not sure you can get the dado down to 3/16 anyway.

Make the first cut on all the corners (1/8"), then go back and make the 2nd cut. This way you only need to adjust the fence once.

 

[malb]

An option for a table saw based key would be a set of the finger jointing blades that some suppliers have. Twin blades with offset teeth, stack in one sequence for 3/16in cut, stack in the other sequence for a 1/4in cut, produce a flat bottom cut either way, a single pass gives you the required finished dado width quite accurately. Most likely dearer than a quality 3/16in spiral router bit, but capable of giving you the slot you want with a single pass, whereas a conventional saw blade would be multiple passes for width, or a router bit would be multiple shallow passes for depth.

https://www.amazon.com/Freud-20T-Joint-Cutter-SBOX8/dp/B000ASGV1E