Spline joints Octagonal Clock Face Frame

WilliamHF | Posted in Joinery on October 22, 2002 07:10am

About 25 years ago I built a Wall Mounted “School” clock, one of those clocks whose frame is Octagonal in shape.

The 8 pieces of the Octagnonal Face Frame are glued up using mating half-blind grooves in the left and right ends of each of the Octagonal pieces. A SPLINE is glued into the grooves of the mating edges of each Octagonal piece.

Well now it is no problem to rip out 1/8″ splines in Cherry and Hard Maple for the two clock Face Frames I’m making.

But I’m speculating that 3 ply birch plywood might make a stronger joint.

I haven’t been able to locate any 3 ply Birch Plywood in the 1/8″ thickness required.

I HAVE located 3 mm thick 3 ply (and 5 ply) Birch Plywood.

The question arises, tho’—————:

The 1/8″ grooves created by my tablesaw’s blade are 0.175 mm wider than the (presumed) thickness of 3 mm thick 3-ply Birch Plywood.

I don’t know exactly how thick such material would actually caliper.

If I used Titebond to glue the 3 mm thick splines into grooves which are 3.175 mm wide, will I get a sloppy joint?

Or, will there be just enough swelling of the 3-ply Birch plywood to cause a tight joint (in a manner paralleling my biscuit joiners action) ?

Anyone out there who has actually used the 3 mm plywood to mate with a 3.175 mm wide groove (that is, a 1/8″ wide spline groove ?

Or, will Cherry and Hard Maple 1/8″ thick splines which I’d make myself be just as strong as the plywood splines?

Many thanks.

William

Florida

I make something, sometimes twice, each year.

Edited 10/22/2002 12:13:38 AM ET by William

Replies

SgianDubh | Oct 22, 2002 07:33am | #1
William, I think I'd just machine your grooves across the joint and machine a piece of solid timber to fit snugly, and glue it all together. Make the long grain of the spline cross the shoulder line of the mitre. The plywood is perhaps a wee bit too thin, and what will you do with the exposed edges? It's generally easier to make the female part, and fit the male part to suit.

And you'd probably need to buy a whole sheet of ply too. Do you have another use for the offcut? Slainte.

Some stuff I've made.

WilliamHF | Oct 25, 2002 02:20am | #2
I have no use for the offcut that I can forsee now.

Before you replied I decided to order the plywood.

I'll post something re what happens and which I wind up using.

Thanks, Richard.

William

I make something, sometimes twice, each year.

Splintie | Oct 26, 2002 05:22am | #3
William, i go through many sheets of so-called 1/8" BBP in a year; even from the same supplier, i've had it vary considerably in thickness from sheet to sheet, not to mention from the sheet edges to the center. Anyway, don't get excited and cut your grooves until you have it in hand if you intend to use it for that. I use it primarily as jewelry box bottoms that i line with fabric before glue-up, but this variation can make for some really snug fits in the groove even with the wiggle-room of the fabric.

I used to use it as exposed keys on miter corners on jewelry boxes, but i had to keep different "batches" of keys separate from one another and size the kerf to the key each time i made boxes. I finally decided it was no part of a labor-saving method and switched back to making my own on the tablesaw to tighter dimensions.

If your blade is too wide, perhaps you have a narrower kerf blade you can add a piece of tape near the arbor hole to wobble it enough to exactly fit the key. (Ducking now while Richard explodes....)