When are biscuits appropriate for joints?

[Ksu93dlv]

I'm building an activity table for my son that stands about 20" high so he can play with his wooden trains on it. I'm sure there are a million different ways to build something so simple, but I'm following a set of plans I found on the web that calls for #20 biscuits for the joints on the table legs. Having never used biscuits before, I was intrigued and decided to give it a shot by borrowing a friend's buiscuit joiner. I finished it over the weekend and it seems to have worked just fine, but I'm wondering if it was really worth the trouble. Would it have been just as good to use long screws for the joints? Is there a rule of thumb as to when it's appropriate to use biscuits?

[B a r r y B u r k e J r .]

My personal rule is anytime I can use them to save time, and a traditional woodworking joint is unnecessary.

If I'm making a traditional piece, I pass on the biscuits, and use whatever "real" joint would be appropriate. I find biscuits strong, fast, durable, and easy to use. I just finished some ash radiator covers and between biscuits and pocket screws, they went together incredibly fast.

Barry

[Edwin Pawlowski]

Biscuits make alignment easier. If you are gluing end grain, it makes the joint stronger also, by giving a glued surface on the "side" grain inside the cut out.

Woodworking did well for centuries without them, but they can make some jobs easier and faster. Ed

[Brian]

I hear this from time to time, and don't really get it. How do biscuits make alignment easier? I tend to avoid biscuits for the most part, and ESPECIALLY where alignment is critical because there is at least 1/16" of play when dealing with biscuits.

What am I missing or doing wrong?

Brian.

[B a r r y B u r k e J r .]

The slots cut by my machine normally have play side to side, as in the length of the biscuit, but no movement in the thickness direction.

That's a plus, as the actual centering of the tool can be a tad off when cutting the slot, but the joint will match (or have the desired reveal) on the other plane, as long as the tool is referenced off the correct faces of the parts.

Am I helping or talking in circles? Sometimes I can't tell.

Barry

[Nova]

It sounds like you own a Roybi.

-- Jack Novak Buffalo, NY - USA (Remove "SPAM" from email address to reply)

[Swingman]

I also avoid biscuit joinery, but often use it in lieu of splines on miter joints, where it appears to be just as effective as splines, and much quicker. I've had a 557 for a while, but finally tried biscuits on a three board wide shelf glue-up the other day just to see what the fuss was about. I don't know whether it was the biscuits, or the Bessey clamps, or a combination thereof, but it was one of the flattest, easiest, hassle free glue-ups I've ever done. So I'm thinking all this talk about biscuits and alignment is more about alignment perpendicular to the plane of the biscuits, not parallel to it.

[Bridger]

yep.

[George]

Biscuits provide shear resistance, and, especially with modern glues can be used as a substitute for a tenon. Where they really stand out is when working with plywood. Just finished a Normesque set of shelves for book boxes and medium-term storage, using only biscuits and glue along with good loading in joints.

[Jeff Cochran]

Edge joining is a natural point, I also use them in MDF. No real proof, but for me they just seem to be stronger than a screwed joint on MDF. I have a tendency not to use them when a screw would work fine, but tend to use them over a mortise/tenon or dowel joint when I'm working quicker.

Jeff

[Roland Hart]

Do you have any tips on gluing up 1/2" red oak to a width of 20" wide. I was thinking of using bisquits for this. Can you use bisquits for 1/2" material? The panel is for the center of mission style armoir door FYI.

Thanks, Roland

[Swingman]

Sorry, can't really help you as I've not used biscuits that often for wide glue-ups.

My gut feeling would be that in stock that thin you would run the risk of the biscuits "telegraphing" on the surface of the stock.

That said, I've done plenty of glue-ups of 1/2", and much thinner stock, with NO biscuits and never had a problem. You do need to be careful about thin stock bowing under clamp pressure, so use cauls, duct taped bricks, or other heavy objects (my dedicated mortiser gets called into play on large panel glue-ups quite frequently) to keep your panel straight.

It sometimes helps, with thin material, to do the glue up in stages, but you will still needs cauls, etc., IME.

[Roland Hart]

Thanks

[Phisherman]

Probably the best joint for attaching an apron to a table leg is the the classic mortise and tenon joint. It is truly difficult to make a stronger, more reliable joint that this. Bicuits do not have a lot of strength, but are very good for alignment. It's the glue that gives the holding power. Using screws to hold a joint--well, perhaps buying furniture at BigLots is easier.

[Rumpty]

classic mortise and tenon joint. It is truly difficult to make a stronger, more reliable joint that this. Bicuits do not have a lot of strength, but are very good for alignment.

I have built over $1,000,000 worth of tables using biscuits in the apron to leg joint. I offer my customers a lifetime warranty on my work, I have yet had to repair this joint for a customer.

[Mike G]

Whether it is biscuits, dowels, spines, mortise and tenons, dovetails, dado's, etc. A properly made, glued, and clamped joint is almost always a better, stronger, and longer lasting joint then what you will be able to achieve with screws or nails. Take a trip to your nearest furniture store and see how many nails, screws or staples you can find in their better grade dining room furniture. To save you the trouble, you won't find any even though, with the working hypothesis that time is money, they are a faster way to fasten two pieces of wood together for the maker. There is a reason there and it isn't because the stock holders don't want to make more money per unit..

I guess that that would make the rule, don't use screws or nails if you can use a traditional joint.

[B a r r y B u r k e J r .]

I agree. If "traditional" joinery is called for in the piece.

BS! I've used biscuits here with excellent success, as well as dowels, and pocket screws through a 45 degree brace behind the aprons.

They're all STRONG if done right.

Barry

[Rich Coers]

Roland, I like to put an 1/8" slot cutter in the router and cut slots along the boards. Cut some 1/8" spline stock and glue in. If the strength of the spline isn't really critical I use 1/8" hardboard. This method really makes for accurate alignment. I've even glued plywood end to end this way. The base of the router runs right along the stock. If the board or plywood has a slight bow, the router stays right on the surface.

[Bob Timmons]

I like the idea of biscuits if you're trying to make the joinery 'hidden' and not so obvious (as a screw will do, even if you're plugging the holes). I had a chance to use mine today to fix a stair that had split.

As far as the 'play', I don't think it's necessarily a bad thing, so long as you make sure you're straight & aligned before you let the glue set...

[Dan]

On Wed 31 Dec 2003 02:39:05p, [e-mail] (g) wrote in news: [e-mail]:

Great article! That one's in my woodworking folder. :-)

I'll also add two things:

1. SWMBO wanted a shelf in the nightstand door, placed at the right height so she could reach it easily from the bed. We found the height and I marked a straight line, put the shelf on it and marked for three biscuits. Removed the shelf, cut the slots in the shelf board, flattened the fence, carefully cut the slots in the door. Glued fence, clamped with caul. Everything aligned perfect. Rock solid joint, no screws. Love that biscuit cutter.
2. I remember a thread here from about a year or so ago where somebody was asking how he got dips in the table top, and they all seemed to be right where the biscuits were. Couldn't prove it conclusively but it looked like he'd sanded the top too soon after glueing. I think he sanded about twelve hours after the glueup and the biscuits were still swollen from the glue. The next day they returned to normal size, and since the table top was flat before they shrank, it caused the dips. I usually wait at least 24 hours before finishing those panels but now I have more incentive. :-)

Dan