Mitred corner splines - Why?

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Forum topic by KnickKnack posted 738 days ago 971 views 0 times favorited 7 replies Add to Favorites Watch
View KnickKnack's profile


971 posts in 2190 days

738 days ago

Topic tags/keywords: splines question

I’m building my very first “thing” (it’s not a box, but if you think box you’ll be fine) using pure 45° joints. And, of course, I’m thinking of deploying splines like this…

(this image nothing to do with me, just copied from here)

I understand the need for, and the potential beauty of, the splines – this isn’t my question.

Every video I’ve ever seen, every book I’ve ever read, every blog I’ve ever digested, every jig I’ve seen about adding these splines consists of …
  1. Glue box together
  2. Holding your piece at 45° with some form of jig, cut the slots for the splines
  3. Add splines

I don’t have a table saw, and, even if I did, us Europeans aren’t supposed to make that kid of cut, so I’m going to be doing it with my 45° jig on the router table – basically a similar idea as with a table saw.

I can, and have, loaded the two pieces that will go together into my jig, before I’ve glued the thing together. Applying only brain cells and zero actual experience to this problem, I can’t see what might be wrong with cutting the slots first. If anything, it seems this will help me when I glue the things together – at least the joints won’t be able to slide sideways.

However, it’s late so “work” is suspended for today, and I thought I’d ask – any reasons not to cut the spline slots first?

Thanks in advance.

-- "Do not speak – unless it improves on silence." --- "Following the rules and protecting the regulations is binding oneself without rope."

7 replies so far

View ShaneA's profile


5285 posts in 1222 days

#1 posted 738 days ago

I have only done it on a TS with the joint(s) already glued, I have seen it done with a hand saw as well. Never tried it before gluing, but I guess if you keep everything perfectly aligned, you would be ok, but it would have to be dead on.

View Nicky's profile


636 posts in 2716 days

#2 posted 738 days ago

Cutting the slots first can be done, just need to be very precise. You also risk a greater chance for tear-out of the end grain fibers.

Cutting slots after the miter is glued gives you a better chance at a perfect fit for your splines and less of a chance for tear-out.

I’ve installed the splines with nothing more then a small handsaw.

-- Nicky

View Woodwrecker's profile


3580 posts in 2199 days

#3 posted 738 days ago

Shane & Nicky have both hit the high points.
(Plus, I think it’s just easier doing it after the glue up.)

-- Having fun...Eric

View NormG's profile


4088 posts in 1627 days

#4 posted 738 days ago

They may not line up and then you have additional choices to make

-- Norman

View Gene Howe's profile

Gene Howe

5499 posts in 2052 days

#5 posted 738 days ago

Why not use a dovetail bit to cut your slots?
As to cutting them first, I see no advantage.

-- Gene 'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton

View a1Jim's profile


112008 posts in 2201 days

#6 posted 738 days ago

We all do things in our own way so get it a try and see what you think. My guess is it’s easier once the boxes are put
together. That’s the way I have done it, but what ever floats your boat.:)) You are great at making very unique projects so I anxious to see what you come up with.

-- Custom furniture

View Dustmite97's profile


430 posts in 1844 days

#7 posted 738 days ago

I have had my nightmares with splines. I have tried cutting them first but wasn’t careful enough and wrecked the wood. I have only ever completed one box with splines. I cut them with the miter joints already made. They can be done first but I agree with Nicky, you have to be very careful. Good luck and I’m looking forward to see how it all turns out :)

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