Splined Miters - Table Saw or Router Table?

I'm working on a small box with mitered corners and I want to add splines for both strength and aesthetics. I'll need to build a jig and I know these can be done either on the router table or table saw but I was curious as to which might be the better choice. Since I have yet to build the jig I am open to either.

What might be the advantages/disadvantages to each method? Which is safer? Which is easier to control? Does using a router bit insure that you will have a flat bottomed grove?

What does the collective say?

I do mine on the tablesaw. For a flat-bottomed groove, just use a rip blade. Most rippers have a flat-topped profile.

Never tried it on the router table, but I guess I'd make a slightly different jig that'd ride across the table, against the fence, and be several inches wider than the stock being slotted. For the bit, I'd use a 3-wing cutter. Like I said, I've never tried it, but that's the way I'd envision doing it. Carol??

Jim DeLaney said:

Never tried it on the router table, but I guess I'd make a slightly different jig that'd ride across the table, against the fence, and be several inches wider than the stock being slotted. For the bit, I'd use a 3-wing cutter.

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Interesting approach. I had envisioned a jig very similar to one you would use on the TS and use a straight bit appropriate to the size spline I would use.

Tablesaw would be my first choice due to having a very repeatable fence. And the tabletop is usually bigger for good support of the jig. Hard to do thin splines with a router bit; much easier with saw blades and also less expensive.

My 2 cents.

I decided on the router table for doing my splines and I was going to build my own jig until I found the Rockler one. It is actually made the same way I would have made mine and I liked the way they did it, I had a discount coupon, it was fairly inexpensive, so I just got that one. I really like it and have used it fairly often, to add strength to the miters, for small boxes. I am going to be making a box for my wife's Mah Jong set and I will be doing splines on the corners for it, if I ever find the time to get too it.

Carol Reed said:

Tablesaw would be my first choice due to having a very repeatable fence. And the tabletop is usually bigger for good support of the jig. Hard to do thin splines with a router bit; much easier with saw blades and also less expensive.

My 2 cents.

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Surprised! The router lady is shaking the foundations of my woodworking roots!!! I agree on the fence and thin spline points. However...

Earl Rumans said:

I decided on the router table for doing my splines and I was going to build my own jig until I found the Rockler one. It is actually made the same way I would have made mine and I liked the way they did it, I had a discount coupon, it was fairly inexpensive, so I just got that one. I really like it and have used it fairly often, to add strength to the miters, for small boxes. I am going to be making a box for my wife's Mah Jong set and I will be doing splines on the corners for it, if I ever find the time to get too it.

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I had been leaning towards the router table option because I might like the ability to do dovetail keys. Impossible, I think, on the table saw. I looked at the rockler jig and think I could recreate it with stuff I have on hand.

You two have given me much to think about. This is indeed a problem of immense proportions on which to probosculate.

After looking at the Rockler jig, I'm thinking we may have different definitions of splined joinery.

My idea was to put the spline lengthwise along the miter to strengthen the actual joint. You and Earl seem to be thinking about decorative splines across the corner. If that's what you want, disregard my earlier post.

BTW, take a look at the MLCS/Eagle America spline jig for across-the-corner splines. It's similar to the Rockler one, and pretty easy to build instead of buy. I made one like it several years ago.

I don't see why you think the Rockler splines will only be decorative. I use mine to cut across the corners for added strength, the decorative aspect is just a bonus. On a small box, with 3/8's thick sides, there isn't enough material on a miter joint for it to have any strength. A spline cut across the corner adds much greater glue area and added strength. I know you already know this, so I don't know why you would say it can only make decorative splines. The Rockler can make about any spline you want, I can do dovetails, or straight cuts, or just decorative cuts of various designs on thicker material. I like the flexibility the router gives me, that is why I decided to use it instead of my TS for splines.

I confess to forgetting there are a couple of ways for a spline to run. For cross corner splines I've always used the table saw and a jig made from mdf that rides along the table saw fence. The Rockler router table jig looks pretty good for the money and gives you the dovetail option that would be hard to do on the table saw. If I were going to do a lot of splined boxes I'd pop for one.

Plenty of opinions offered already, but I'll throw mine in anyway. They only way I've ever done them (no matter which direction they went across the miter) was on the table saw.

Jim DeLaney said:

After looking at the Rockler jig, I'm thinking we may have different definitions of splined joinery.

My idea was to put the spline lengthwise along the miter to strengthen the actual joint. You and Earl seem to be thinking about decorative splines across the corner. If that's what you want, disregard my earlier post.

BTW, take a look at the MLCS/Eagle America spline jig for across-the-corner splines. It's similar to the Rockler one, and pretty easy to build instead of buy. I made one like it several years ago.

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Yep, I could have been more specific. I'm guessing that my less than adequate description is also led to Carol's recommendations.
I am looking for the cross grain solution that adds the decorative touch.

Rennie Heuer said:

Yep, I could have been more specific. I'm guessing that my less than adequate description is also led to Carol's recommendations.
I am looking for the cross grain solution that adds the decorative touch.

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Actually I was thinking of the decorative spline. That said, I looked at the Rockler jig. Yikes! $80! Not unless that's the only thing you plan on doing! And poorly designed as well. IMHO. Too many pieces. Too hard to adjust, let alone readjust for repeatability.

Go to YouTube. There are some simple but very effective jigs shown there.

As for tables vs, router table: either way you need a straight edge (fence) to run the jig against. A jig that saddles the fence is most effective and easily adjusted. No reason to not build one for both tools. Just a little plywood or MDF, some glue and a few screws.

Though I'd still lean towards the tablesaw. Only would consider the router table for dovetail splines.

Lots of good advice from all - thank you!!

Jim DeLaney said:

take a look at the MLCS/Eagle America spline jig for across-the-corner splines. It's similar to the Rockler one, and pretty easy to build instead of buy. I made one like it several years ago.

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This one is more what I had in mind when thinking of making my own. Could not understand why the Rockler jig used a sled that went perpendicular to normal travel on the table. Why ignore a perfectly good miter slot and also necessitate the full removal of my fence?

Carol Reed said:

Actually I was thinking of the decorative spline. That said, I looked at the Rockler jig. Yikes! $80! Not unless that's the only thing you plan on doing! And poorly designed as well. IMHO. Too many pieces. Too hard to adjust, let alone readjust for repeatability.

Go to YouTube. There are some simple but very effective jigs shown there.

As for tables vs, router table: either way you need a straight edge (fence) to run the jig against. A jig that saddles the fence is most effective and easily adjusted. No reason to not build one for both tools. Just a little plywood or MDF, some glue and a few screws.

Though I'd still lean towards the tablesaw. Only would consider the router table for dovetail splines.

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The Rockler jig is interesting, but $80 is out of reach for me right now. That being said it also appeared a bit 'flimsy' in the videos. Might be completely different in person, but I'm not willing to part with the $$ to find out.

Lots of ideas on the web, for sure. Found a few so far that are promising. I have some MDF and plywood scraps hanging around and a few inches of T-track. I'll come up with something!

I am pretty sure they can be done with either piece of equipment but thought a 'picture' might be worth those 1000 words. Two types or directions of splines:


One is parallel to the joint, the other perpendicular.

Parallel can be done on the table saw with blade tilted 45 degrees with a miter gauge and stop blocks. Or on a table saw with a sled that holds the wood 45 degrees to the 90 degree blade position.

Perpendicular can be done on the table saw with a jig/sled that holds the assembled joint at 45 degrees. Straight cuts can be done with a rip blade as stated by others. Dados can be made by tipping the straight blade but some additional chisel work is required.

Perpendicular can be made on the router table, possibly with the same sled if miter bar locations allow for it or if it can be adjusted. Use straight bits or dovetail bits. Lots of bit options

If you make a jig/sled, consider replaceable inserts where the cutter will come through. Give you better control/zero clearance for chip out control I don't see these in the store bought version.


Lots to think about for sure.

Great idea on the replaceable inserts, Robert. I need to add those to my jig.

Ted Calver said:

Great idea on the replaceable inserts, Robert. I need to add those to my jig.

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Excellent idea. Too late for me though. I just finished building a jig (I'll show some pics later) and did not use the replaceable inserts.

May I contribute to this thread with a video from Steve Ramsey of Woodworking for Mere Mortals.

https://woodworking.formeremortals.net/2017/07/super-strong-splines-miter-joints/

My recent mitered splines were like picture #1 in Robert's post #14. I made a jig to ride in the miter slot to hold the previously mitered boards at 45 degrees while I cut the slots for the splines. Then I used my Delta Tenon jig, positioned so as to cut cross grained splines from the end of a board. The spline was actually cut from the surface of the board, so I could flip the board horizontally and make another spline from the back surface of the board. Then I flipped the board end for end and cut two more splines on the other end of the board. Using a stop set on my miter saw, I then cut the splines free from the board at just the right width. What is usually the resulting tenon on each end of the board became scrap. Since I am making four boxes, I needed to go back to the Unisaw three more times to get enough splines for all four corners of all four boxes. The tenon jig worked perfectly, making splines with very parallel sides and exactly the same thickness every time.

For "across the corner" splines like shown in Robert's second picture, I have usually used a shop made jig in my table saw to hold the box corner down while cutting across the corner with the table saw,with the box and jig held against the fence to cut in the correct position. Then I rip thin strips of usually contrasting wood the thickness needed to fill the saw cuts.

I recently saw that Infinity tool has redesigned the original " Kehoe Jig" for making tapered dovetail cuts in box corners and the mating tapered dovetail splines and I am considering getting one of these sets. I'll probably just buy the smaller set, since I can't comprehend me ever wanting to do these in every possible position on large boxes and I can just move the jig over If it doesn't prove to be long enough. . https://www.infinitytools.com/complete-tapered-dovetail-spline-systems

Charley

after giving it some thought, why not build a sled to hold your work at the right distance, and tilt the tablesaw blade to 45 degrees, and cut them that way?

When I was making a lot of boxes I used a ripping blade for flat bottomed grooves to hold splines of contrasting wood. I tried doing the same thing with router bits of differing sizes and had differing levels of success. Sometimes the router bit would chip out the wood when exiting the cut. Usually this happened when the wood was highly figured.

I also did dovetail splines which gave the impression of a fake through dovetail joint. This requires you to cut tapered splines that match the profile of your dovetail bit. I found that it was necessary to clamp the box into the jig firmly to hold it against the jig to prevent chip out. I used a good quality flush cutting saw to trim the splines close and then finished them the rest of the way with either a plane or random orbit sander. Be sure to plane in the right direction if you use a plane.