Biscuit joinery or just glue?

[jhelfer]

Assuming I can get my router to joint my edges well, I am going to put some boards together to create a 22" dia table top for an occasional table. 3/4" thick wood.

Considering this usage, do you think I need to use biscuit joinery, or can I just glue it up edge-to-edge?

Does the answer change if I include the fact that I'mout of biscuits and would have to go out and buy more?

Thanks for any advice.

[dwitzke]

Just glue it up. Unless you are going to use the biscuits to help in alignment, they are not needed.

[venkatbo]

Though its true (these days) that the glue in joints holds up better than the wood itself in breakage tests, biscuits are very useful in alignment, especially if slots are cut with an uniform reference along the length of the faces being joined. Any errors in slots alignment could be amplified when its time to join the boards.

Also, since the biscuits may not really add much more strength than the glue, you may want to leave the slots glue free, before placing the biscuits. This will give you sometime to adjust alignment before the glue starts drying up on you. Water in the glue makes the biscuits bloat and cause a tight fit in the slot.

/venkat

[LCHIEN]

I think the biscuits are primarily for alignment.
Strength enhancement is secondary.

[RayintheUK]

Let's not forget that biscuits are actually flat plate dowels, which is why biscuit jointers were initially (and are still correctly) called "flat plate dowelling machines."

The original intention of the machine was to cut a slot for a type of spline joint, but the inventor (Hermann Steiner, a Swiss cabinet maker) went on to develop the machine further, then founded the Lamello Corporation.

Flat plate dowels acquired the nickname "biscuits" owing to their wafer-like appearance, so the name of the machines that used them swiftly followed suit.

Long way of saying: "If dowels or splines add strength, so do biscuits."

Ray.

[jhelfer]

Ah - That's why Harbor Freigth sold me a "plate joiner" rather than a biscuit joiner. I always wondered.

[Ken Weaver]

I would take the time to use biscuits. Every glue up I've ever done has had a tendency to slip somewhere and they really do help the alignment. Another trick I've started using is to put two 3/4" dowels, about the length of the glue up, one on each side (see pic below, its a 30" long table top, the dowels are 24"). This puts the pressure point from the clamp exactly in the center of the boards being glued and there's less tendency for the clamping pressure to cause a bow in the glued up stock.

[drumpriest]

One more vote for biscuits, alignment is everything. The better the alignment of the glue-up, the less work for you to do after it dries. Also, consider taping the edges so help prevent problems with glue squeeze out. Especially if the wood is porous such as red oak.