If you can put enough pressure down on your sled(?) you can avoid some tear-out on the slot. As for the teak, it is one splintery wood, and to top it off, the dark dust will fill in the pores in the oak. It's one of the reasons for not using dissimilar woods when making projects.

 

I cut splines slots on my table saw and they are nice and clean cut

 

The upcut bit is likely part of your problem. They will generally leave more tearout on the tool side of the cut (though they are better at chip evacuation). You can try the tape trick. But using a downcut bit may help. You will just have to go a bit slower to avoid burning.

 

What redoak said, a nothing fancy sled/jig made for the table saw is what I use and works well.

having a sacrificial fence or backing is key to help tear out.
If you try out the table saw you need a flat tooth grind blade, what happens when you forget…

Little angles are cut above the splines.

 

This is one of the simpler spline jigs I've seen.

 

I also cut the slots for splines on a tablesaw with a jig, like shown above, with an FTG blade.
I use a Japanese pull saw a ryoba or nokogiri to cut-off the splines, with a piece of painters tape there as a guide so the teeth dont mar the wood, this will leave the splines a hairs thickness proud, which will have to be sanded flush.
If you are going to match a wood like wengue or rosewood with an open pored wood like oak, or a light wood like maple, then you can seal the oak first with a sanding sealer or spar varnish or shellac, and that will prevent contamination, mostly.
You can clean up the issues with that box in photo #1 with a sanding board - that is, a piece of 3/4" melamine with sheets of cloth-backed sandpaper spray-mounted to it, like this:

I have four of these boards with different grits on each side.
The concept is, rather than taking the Paper to the wood, take the wood to the Paper.
Whatever board you use for this must be dead flat
3M 77 is good spray mount.
Once the paper is spent, just peel it off and put down new sheets.
The thing is to apply even pressure, and make the same amount of passes on each face/side, and keep going until the tear-out is gone, or mostly gone, keep checking for square on both axis as you progress to correct if your pressure has been uneven.

 

I also cut the slots for splines on a tablesaw with a jig, like shown above, with an FTG blade.
I use a Japanese pull saw a ryoba or nokogiri to cut-off the splines, with a piece of painters tape there as a guide so the teeth dont mar the wood, this will leave the splines a hairs thickness proud, which will have to be sanded flush.
If you are going to match a wood like wengue or rosewood with an open pored wood like oak, or a light wood like maple, then you can seal the oak first with a sanding sealer or spar varnish or shellac, and that will prevent contamination, mostly.
You can clean up the issues with that box in photo #1 with a sanding board - that is, a piece of 3/4" melamine with sheets of cloth-backed sandpaper spray-mounted to it, like this:
View attachment 3865502

I have four of these boards with different grits on each side.
The concept is, rather than taking the Paper to the wood, take the wood to the Paper.
Whatever board you use for this must be dead flat
3M 77 is good spray mount.
Once the paper is spent, just peel it off and put down new sheets.
The thing is to apply even pressure, and make the same amount of passes on each face/side, and keep going until the tear-out is gone, or mostly gone, keep checking for square on both axis as you progress to correct if your pressure has been uneven.

What redoak said, a nothing fancy sled/jig made for the table saw is what I use and works well. View attachment 3865496
having a sacrificial fence or backing is key to help tear out.
If you try out the table saw you need a flat tooth grind blade, what happens when you forget… View attachment 3865497
Little angles are cut above the splines.

I made a similar jig and cut my slots for the "keys" using a Dremel 4" table saw. the fine cutting blade and a spacer made for consistant slots. I used it on frames, a small cabinet door etc. It did impress my grandfather who looked at the 4" saw with skepticism.

 

I use a table saw for my splines with a backing which will eliminate the tearout. I have also cut the splines by hand when I want to use one that gives a dovetail appearence at the corner. Allow the glue to dry before trimming the waste of the spline then use a chisel to pear of some on the excess and sand smooth.

 

+ on the table saw method. You need to use a flat top rip blade but I think even with that you'll get less tear out. The other thing is you have to be rock solid when moving the jig. Any wobble at all is going to reflect in the cut.

What kind of saw are you using to trim splines? Best to cut about 1/16 proud and use a chisel or block plane to flush up. If you use a sander, you're going to have an issue over sanding the box b/c the splines are end grain.

The corner of the edges in the first and third pic illustrate what happens with sanding. Wouldn't happen if you hand planed it.

 

If you have a biscuit joiner, simple splines are pretty easy. I use them for picture frames

 

The spline jig shown works well, but can be simplified. Cut a 2x4 on the 45° and then flip one end over to form the V. Screw or glue to backer board and rip away. Harder is to get the splines exact thickness, especially if your blade isn't exactly on width. Here an Incra helps. I use a Freud lu86 tk blade that is dead on 3/32". With the incra, I can easily rip exact 3/32" +-0.002" thick strips.

 

Thanks so much for all of the tips! Always so much to learn.

I have concentrated on using the router because our table saw is old and lacking in modern safety systems, and I'm still learning how to use it. I'm much more comfortable with the router, so I will probably try using a downcut bit and better controlling the jig first. But the consensus seems to be the table saw is the way to go, so I'll pursue that as well.

I can see how planing would work better than sanding. And the tip about the sanding board is fantastic.

The good thing about these boxes is that they don't use much wood, so I can keep plugging away without bankrupting myself! Thanks again.

 

Best thread title of 2023...

 

Aww, it's only January! But I do my best. 🙃

 

If you want to minimize any tear-out with the router, try putting painters tape on the area needing the spline cut, before using the router.

Here's another method to consider Rockler Corner Key Doweling Jig | Rockler Woodworking and Hardware This jig requires a 6" long drill bit.

 

I cut mine on a router. I sometimes prefabricate my splines out of contrasting woods, so black white black or any other conbination. You can also have the grain going different ways as in 3 ply.

Sometimes I put a string down the edge. Route the corner after the splines are fitted to fit the string. Yes you need to seal any light open grained wood to prevent the darker dust filling the grain. I cut my splines as over size triangles with the grain running parrallel to the longest/inserted edge, and a tight fit before glue. I then use a notched piece of wood to tap/hammer them in.

 

Whenever I'm mixing dissimilar woods, which is always, I use my air compressor to blow dust out of the pores before sealing. You can also use a brush attachment on a vacuum with equally good results.

I'm also a fan of using painter's tape around the slot before gluing on the spline, just to reduce the risk of residual glue getting in the pores and affecting the final appearance. Like this:

 

Hi, folks! I'm working on some boxes, and I'm trying to really master mitered corners with contrasting splines.

This is my second try. The box body is oak. The splines are wenge. I cut the slots on the router table with a Rockler Spline Jig using a spiral up cut 1/8 inch router bit.

The result is not nearly as clean and sharp as I would like. I'm posting several pictures.

I was thinking for my next box I would try to make the slot edges cleaner by putting painter's tape where I plan the cuts to limit tear out. I need to make sure the spline is all the way in the slot - - there are a few little gaps at the edges. I need to do a better job getting all of the glue that squeezes out from the spline.

What else? I feel like I'm getting sawdust from the wenge into the pores of the oak. Is that a thing or am I crazy? Can I stop that?

And what's the best way to trim the splines? On one corner the wenge split as I was sawing it and broke off below the edges of the corner. For the rest of the splines I really snuck up on the cut, trimming it bit by bit and then sanding. I've got a small piece glued in the gap and will trim it very, very carefully. I don't own a flush cut saw so I used my duzoki saw. How can I do this better?

I know the best way to get better is practice, but any tips or advice would be incredibly helpful!
- Elizabeth
View attachment 3865466
View attachment 3865463
View attachment 3865464
View attachment 3865462

Hi, Elizabeth,

The pics show some tear-out on the exit side of your slots. You can try backing up your box with a piece of wood or hardboard on the exit side, essentially creating a zero-clearance backer. That should minimize the exit issues. Then, be sure to tap your glued splines into their slots. You’ll hear the sound of the tapping change as they seat in the slots.

Sawdust contamination is a common problem when using contrasting woods. If you flush up the splines with hand planes or card scrapers there won’t be any sawdust and that problem will go away. Another approach would be to fill the box pores with a pore filler (not wood putty) and brush on a coat of shellac before cutting the spline slots. Then the box pores will be filled and shouldn’t accept any of the spline sawdust as you sand.

An inexpensive flush trim saw is a worthwhile investment. UntIl then you might want to consider rough trimming them with a European saw instead of a Japanese one. The Dozuki cuts on the pull stroke which means you‘re probably pulling the spline fibers toward you as you saw. They’re unsupported in that direction so they break. A European saw cuts on the push stroke so the spline fibers will be supported by the box. Just use a spacer to make sure you don’t scratch the box sides. Then finish the job with a sharp chisel, cutting toward the box to make sure the fibers stay supported.

Hope that helps.

 

I also use a table saw jig to cut splines, but I made the jig to fit over the fence so it won't move sideways. And I always clamp my project to the jig. I can slip a back board on the backside of the jig, but usually I don't have tearout. Pics can probably explain better.

 

Looking at making anew jig myself.

 

I've always use a table saw sled for speed and consistence, but do want to try "styled" splines (dovetail, etc.) which means the router table.

Never had any issues with tear out since I always use a fresh backer in my spline jig. I typically will place tape over the cut area before using the jig as a way to take care of protecting from glue squeeze-out getting into the wood pores. A great substitute is to use paste wax over the area before cutting. Squeeze-out pops right off and the wax is removed with mineral spirits before finishing.
To trim the splines I'll cut close with the bandsaw, then even closer with the disc sander (while avoiding contact with the project surface). The last little bit is removed in the course of sanding the project surface.

 

Hi, folks! I'm working on some boxes, and I'm trying to really master mitered corners with contrasting splines.

This is my second try. The box body is oak. The splines are wenge. I cut the slots on the router table with a Rockler Spline Jig using a spiral up cut 1/8 inch router bit.

The result is not nearly as clean and sharp as I would like. I'm posting several pictures.

I was thinking for my next box I would try to make the slot edges cleaner by putting painter's tape where I plan the cuts to limit tear out. I need to make sure the spline is all the way in the slot - - there are a few little gaps at the edges. I need to do a better job getting all of the glue that squeezes out from the spline.

What else? I feel like I'm getting sawdust from the wenge into the pores of the oak. Is that a thing or am I crazy? Can I stop that?

And what's the best way to trim the splines? On one corner the wenge split as I was sawing it and broke off below the edges of the corner. For the rest of the splines I really snuck up on the cut, trimming it bit by bit and then sanding. I've got a small piece glued in the gap and will trim it very, very carefully. I don't own a flush cut saw so I used my duzoki saw. How can I do this better?

I know the best way to get better is practice, but any tips or advice would be incredibly helpful!
- Elizabeth
View attachment 3865466
View attachment 3865463
View attachment 3865464
View attachment 3865462

 

Hi Elizbeth something that my near 50 years of woodworking taught me in glue management is to be careful with the squeeze out and forget the water techique as water thins most wood glues and the combinatuion of the water thinning the glue and then wipping it away only drives it deeper into the wood. That is the cause of most contaminated finishes (white color) that has coated the wood pores. It is clear when it is wet and dries to a dull finish. The way I take care of glue squeeze out is removing as much as I can with a sharp tool such as a razor knife of chisel when the glue begins to cure to a soft non smearing substance. Following that I remove the residue using white vinegar wiping the surface. It is a mild acid that removes the glue residue and removes it ability to stick the outer surface giving you a cleaner surface. It will also remove alot of the wood dust however for the most of the wood dust it can be blown off if there is no glue sticking it in the pores. As a rule most of my joinery gets washed with a wet vineger rag after the glue removal with the chisel or sharp razor and before sanding. Hope this will help as I see alot of what is glue yet being looked at like it is wood dust. Don't worry the acid in the vinegar will not weaken your glue joint and or mess up your finish as from experience I have never had a failed glue joint and I have used most of the old and current types of finishes including automotive finishes including the candy apples and translucent metal flake finishes on wood.

 

Interesting about the vinegar.

 

I've never heard of using vinegar this way. I'm going to give that a shot tomorrow!

 

Back in 2011 I posted a spline cutting jig that I built. I'm using a skill saw blade that is 1/16" thick and 7 1/4" diam. These blades are available with 60 tooth count so they give nice smooth cutting.

My jig is here

Spline Cutting Jig

Spline Cutting Jig I have seen a few spline cutting jigs here on LumberJocks. I was trying to think how I would use such a jig. I ran across some Freud blades for a skill type saw that are 7 1/4 wide and 1/16" thick. They were made for the battery skill saws where you don't have a lot of...

www.lumberjocks.com

Good luck in your spline making hobby

Karson

 

I use my table saw with a sled that sits flat on the table top to cut splines (see the attached picture, not mine but representative of my sled's layout). The V-shaped boards hold the box and it acts as a zero clearance fence, since it doesn't change position on the table saw table, which greatly reduces any blowout. I can set up stop blocks to set the thickness of the spline/slot and if need be a spacer to get the width just right. If you want more than one spline, say 2" apart, you can create a spacer that is 2" so you can set the stop blocks once and then pop the spacer in when you are ready to cut the second slot. I prefer this over a jig that straddles the rip fence as I don't have to deal with moving the rip fence and having to come up with a solution for a zero clearance insert.

As for dark color wood dust getting in the pores of the light colored wood, I agree with the suggestions to seal the oak before you install the darker colored splines. Oak is very open grained so it has lots of little pores that can hold onto the darker dust. You can also try putting painters tape around the notch and doing all but the last little bit of sanding with the tape in place. I usually prefer to use a block plane to take off as much of the spline as possible. You want to plane toward the supported part of the spline, not toward the edge or you may cause a lot of blowout.

 

It is all about giving the wood around the cut some support.
To continue using you current method you need to put a piece of back up wood (tempered masonite is good) clamped tightly on each side of the cut but for certain on the exit side of the cut. The back up piece will support the wood fibers and eliminate tear out. Even with a table saw jig you can get tear out if the exit side of the cut is not supported.
This method is also used for router cutting dovetails or finger box joints. I often do the same thing on my chop saw and radial arm saw to prevent tear out and that is what zero clearance table saw inserts do. I have even gone so far as to glue a piece of scrap to the edges of square items I'm turning on the lathe and cutting them off when done.

 

@ElizabethL
You say this is oak but the the tearout look to me like an extremely thin surface veneer tearing out, like you would get with a plywood. Is this solid wood or plywood? Also, it doesn't really look like oak to me. It looks more like luaun unless it is some sort of oak I am not familiar with. Luaun veneer is very brittle and prone to tearout.

Another contributing factor may be that you cutting the splines across the grain rather than in the end grain. Depending upon the blade, you may get more tearout across the grain. Note that when gluing side grain miter joints (assuming it is NOT plywood with veneer), splnes do not add any strength so are only really for decoration in that case. Side grain glue joints will be plenty strong and spines really only add strength in end grain or plywood mither joints.