Biscuits,dowels,or both?

[ken masoumi]

If you were to glue up a long and wide table top would you rely on biscuits for alignment or dowels for both alignment and strength?
The tabletop is made of 6 pieces of Ash,6.5' long ,2" thick,5.5" wide.

The way I'm planning on doing is:since all pieces are straight and jointed/planed,I would use #20 biscuits for alignment,glue up 3 pieces at a time ,let the two wider pieces dry,then do the final glue up.

Would you also add a few dowels for strength just because the top is long,thick/heavy or would you agree that gluing with some help from the biscuits should be plenty strong and there's no need for dowels?

[Judson Green]

You're table top will be plenty strong with none of the above, but with the biscuits it'll be easier to glue up, so that's what I'd do.

[steven taggart]

I use both. On large glue-ups I use the biscuits to align the boards, and glue and clamp. The next day I use those really long drill bits, with the 2' extensions to drill a 3/4" hole through the piece and insert an epoxy covered dowel. Overkill for sure but I never have callbacks on my tops.

[Loren Woirhaye]

No strength gain in either, but they do work for alignment if you don't have clamps that can do it, like a Plano press. Wire nails with the heads clipped off also can be used for alignment, preventing boards from slipping on wet glue as the clamps are closed.

[Phil Thien]

Neither are required for strength, and cauls do a better job with alignment than biscuits. So I'd use cauls.

[Mike Henderson]

Neither are required for strength, and cauls do a better job with alignment than biscuits. So I'd use cauls.
I agree.

Mike

[HANK METZ]

If used simply for alignment, I use the smallest biscuit, a #0 almost exclusively. Although not needed for strength in a well- crafted edge to edge joint, the shear resistance of a simple #20 has to be put to the test to be believed. I will agree with other viewpoints however, that it is not the best device for all furniture constructs.

[Phil Thien]

I agree.

Mike

Well you would, I learned about the cauls from your tutorial. ;)

[Rod Sheridan]

None, just glue..............Regards, Rod.

[Ed Wood]

I would go with the biscuits

[John T Barker]

I use both. On large glue-ups I use the biscuits to align the boards, and glue and clamp. The next day I use those really long drill bits, with the 2' extensions to drill a 3/4" hole through the piece and insert an epoxy covered dowel. Overkill for sure but I never have callbacks on my tops.

You are gluing a dowel crossgrain? A 3/4" diameter dowel?

[Shawn Pixley]

Just glue, clamps and cauls.

[Rick Lizek]

Curved cauls are all you need. I have glued up four by eight panels single-handed in one piece with curved cauls and never had to do more than scrape down the glue beads. Curved cauls are quick and easy to make. In 40 years I have done this with perfect success every time. I would never even considering using dowels or biscuits for doing this.

[steven taggart]

Yes. with epoxy. The reclaimed softwood I mostly use has a tenancy to move significantly with moisture and temp changes. Most strips I can salvage of any length are only 2-3 inches across. So I biscuit, and dowel.

[Peter Quinn]

Neither are required for strength, and cauls do a better job with alignment than biscuits. So I'd use cauls.

This. I've glued up hundreds of tops. Biscuits wont give perfect alignment, not as good as cauls, the only time I use them is to add a thick edging to plywood where two different thickness items are being joined and cauls wont easily work. Biscuits just aren't tight enough or robust enough to work out any slightly out of flat conditions in the boards, and boards are rarely perfectly flat after milling. If the biscuit slots don't go in perfect they can actually force two boards out of alignment, so it still takes careful clamping and a little english. Grease pole to frustration IME. Forget dowels, they are really for butt joint intersections to replace tenons, no reason to add tension across the grain like that , too tricky to get perfectly aligned by hand. Once you learn to make and use cauls (i.e. flatten some junk from your scrap pile of appropriate dimension and length, maybe bow it slightly on the jointer for the top cauls) its very liberating. Take boards, add glue, cauls and clamps. Done. A belt sander and card scraper, you can make a conference table should you choose.

Maybe practice with something small scale like a little cutting board from the drops, try using cauls, you will throw our biscuit joiner out the window....

[Jim Matthews]

If you make a properly "sprung" joint that is match planed, clamps and cauls are sufficient.

There's so much long grain surface in a proper joint, that anything mentioned
is more likely to weaken the joint over time, fail during assembly or get in the way.

I like dowels for long grain to end grain joints, as they hold things together when clamping corners.

For table tops, not so much.

[ken masoumi]

Thank you all for your comments,I forgot to mention that I am going to use clamps/ cauls as well ,,considering 7-9 minutes of TB-III open time,the biscuits are mainly used to quickly align the edges and to limit the slippage during glue up.

The last time I glued first of 4 legs for the kitchen island I was building ,(each leg:2pcs of 4" X 2"X 48" to make 4"x4"x48" using TB III,and lousy clamps), the glue acted like a lubricant and the two chunks of wood were hard to align and kept sliding over each other,for the next 3 legs I used two dowels and that problem was solved.

That's why I thought if I prepare the newly acquired k body clamps and the cauls ahead of time ,I should use a few biscuits just to sort of tame the long/heavy pieces long enough to quickly clamp them together.

[Wade Lippman]

I agree with everything said (well almost everything, I am not so sure about adding dowels afterwards).
The important thing is to carefully face joint the boards and glue them up before they have a chance to unflatten.

[Keith Hankins]

In my opinion if you want to use them for alignment go ahead. Not going to give you any extra strength. If it breaks it won't be at the glue joint. I've done quite a few tops and not used anything other than cauls. Waste of time and effort IMO.

[ken masoumi]

Alright,thank you Wade,Keith and all for your opinions,I'll update later on,and ask for your guidance .

Ken.

[John A langley]

The next time you have to glue up two pieces try a sixpenny nail in each end It will keep it from sliding around for you and you can pull out after , but the nail at 45 close the joint