Splines

[David Mueller]

My son and I were wondering? We both are planning to build a workbench. I had thought of getting some pieces of 10/4 x 8" hard maple and spline them together for the top. He suggested birch ply as the spline material for stability. Has anyone an opinion?

[Jamie Buxton]

If you have nice mating surfaces for the glue, splines don't change the strength of the joint. They may help you keep the planks aligned as you crank the clamps in the glue-up, but that's about it. Because they're just alignment aids, it doesn't make much difference what they're made from -- solid lumber, plywood, those little biscuits, whatever.

[Philip Glover]

David,
I use hardboard, 1/8" and 1/4", or biscuits for alignment of stock when glueing table tops and bench tops. I expect birch ply would work too.
It, splines or biscuits, greatly reduces the amount of stock removal required from each side when running the workpiece through the widebelt sander. Because of the good alignment I usually take .015" or less off each side.
As mentioned, there is no added strength from splines, the glue provides that.

Regards,
Phil Glover

[Doug Shepard]

David,
I use hardboard, 1/8" and 1/4", or biscuits for alignment of stock when glueing table tops and bench tops....


Philip - Not to derail the thread, but I've been wondering for a while about using hardboard for splines across miter joints. I would think they would swell up like biscuits and lock the joints tight. Does glue cause them to swell? Are you using the standard hardboard? My guess is that the tempered (oil impregnated) stuff might not work very well. ??

[Philip Glover]

Doug,

I've used tempered and standard hardboard - whatever is handy at the time. The standard hardboard appears to swell more than tempered.
When glueing I prefer to use epoxy. I do use Titebond II and III and Unibond 800 as well.
When I use splines it's with thick stock, ranging from 1.25" to 4.00". Since the stock is thick there is no distortion on the outside surfaces due to swelling of the splines.
I do not use a tight/interference fit for the spline either. The fit is between .003-.005 loose. This leaves enough room for the glue to do it's thing.
I always cut the groove on the shaper as this affords the best control and cut quality. When cutting biscuit slots I use a Lamello.
If you're going to spline something thin, you should cut some test parts, glue them up, and see how it works.

Regards,
Phil Glover

[David Mueller]

David,
I use hardboard, 1/8" and 1/4", or biscuits for alignment of stock when glueing table tops and bench tops. I expect birch ply would work too.
It, splines or biscuits, greatly reduces the amount of stock removal required from each side when running the workpiece through the widebelt sander. Because of the good alignment I usually take .015" or less off each side.
As mentioned, there is no added strength from splines, the glue provides that.

Regards,
Phil Glover

Phil,
Thanks for the info. I was thinking that with a spline, it would a provide a greater surface area to react with the glue thereby providing a better bond to resist movement from the larger slab. The alignment issue was a side benefit but I guess I see your point. Since I have an 8" jointer and only a 13" planer, I wanted to minimumize the glue joints since I'll be flattening by hand. Plus less wood to mill. Not sure if quartersawn is avail in that size though so the planning continues. Son has a line on 8/4 x 16" quartersawn white oak but has to wait 1 year for it to dry.

[Gary Curtis]

Anybody heard of Tanseli Wafers? They're made in England and used a splines. A continuous strip that is cut to size and then inserted in a thin mortise.

They have the property of Biscuits in that they swell up on contact with glue. I'm trying to find an American source for them and will post it here when I find it.

Unlike a Biscuit, one size fits all because you cut off just what you need. There need be no excess slot at either end as with biscuits, so lateral alignment is somewhat more precise.

I'd be interested to learn more about this technology because I don't want to spend $700 on a Lamello, and the new Domino Technology coming from Festool will be about as costly. The Domino is a floating tenon made of biscuit material. Serves the same purpose.
Gary Curtis

[Philip Glover]

These Tanseli waffers look like a good idea.
I just looked at them here http://www.tanseli.com/


Phil Glover

[Roger Everett]

When I'm using splines, I generally stick to Appleply or hardboard, because when you get 1/4" it's 1/4", Birch plywood in 1/4" isn't , it's more like a heavy 3/16. And since I use a 1/4" flycutter, I want a snug fit for a more perfect alignment.
Roger