Should I use one large spline or multiple smaller ones for a miter joint?

Question

This obviously depends on the thickness of the wood. When you see multiple splines on a join they use contrasting wood colors to create a nice effect. But is that the only reason? Consider the following picture:

Spline Join

^{Image from CanadianWoodworking}

Would it be preferential, for the strength of the joint, to have one large spine that spanned the space between the outer splines of the picture above?

score 8 · Accepted Answer · edited Apr 24 '15 at 15:16

8

Joints increase in strength with the cross-grain surface area. This is the sides of the spline.

That means more splines is better.

However, too much of a good thing is bad. At some point the cuts you need to make for the splines will weaken the wood too much.

edited Apr 24 '15 at 15:16

Matt

20,188
41
99
202

answered Apr 24 '15 at 15:01

ratchet freak

4,674
3
18
35

1

Is it possible to take that logic too far? Using the same splines in the picture I could easily double the splines that are there. Not that it is realistic to do – Matt Apr 24 '15 at 15:07
1

Along the lines of your edit, I would think once you get past the point of the cross-grain surface area being beyond 1/2 the thickness, you've gone too far. – Pᴀᴜʟsᴛᴇʀ2 Apr 24 '15 at 15:12

score 2 · Answer 2 · answered Apr 24 '15 at 15:11

2

As rachet freak said, the primary reason for splines is to increase the gluing surface area. So having 3 small splines is going to give you more surface area to glue than one wide one, the wide one will give only slightly more area than a small single one.

answered Apr 24 '15 at 15:11

bowlturner

15,982
6
42
92

2

And most of the area you get will be end-grain, just the same as if you didn't have a spline. – ratchet freak Apr 24 '15 at 15:16
@ratchetfreak very true! – bowlturner Apr 24 '15 at 15:33

Should I use one large spline or multiple smaller ones for a miter joint?

2 Answers2

Linked