Another Biscuit Question

[lago]

After reading thread from Sweet Willy about using biscuits, thought I better see what options I have to use instead of biscuits in my next project. I starting working on the Curio Cabinet(Wood Mag 11/03) for our daughter. I have most of the pieces cut out, except for the legs, and ready to start jointing/planning to desired size.

The legs are laminated and are 1 1/2" sq. The back, front, and side rails for the upper & lower shelf at attached to the legs with #20 biscuits.

After seeing the comments on his thread, I think that a 3/4" tenon would definitely make a stronger/sturdier cabinet than the biscuits would.

Opinions?

Lago

Sketch of cabinet
ccsketch.pdf

[cabinetman]

After seeing the comments on his thread, I think that a 3/4" tenon would definitely make a stronger/sturdier cabinet than the biscuits would.

Opinions?

Lago

That would be my suggestion.

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[durango dude]

One of the woodworking sites did a joinery torture test -

Biscuits did not fare that well. I don't have the details - but I'd bet a dowel or pocket screw would be stronger than a biscuit.

The hands-down winner was the mortise and tenon joint.

[JimD]

Mortise and tenon are a good choice. If you do not have a dedicated mortiser, a plunge router is another easy way to make the mortises. If you are shaky on tenons you can cut two mortises and use a loose tenon.

The main drawback of the mortise and tenon joints is they take more time to make. If that doesn't bother you it is the way to go.

Jim

[All Thumbs]

One of the woodworking sites did a joinery torture test -

Biscuits did not fare that well. I don't have the details - but I'd bet a dowel or pocket screw would be stronger than a biscuit.

The hands-down winner was the mortise and tenon joint.

Biscuits actually make for very strong joints and have done well in the joint strength tests, especially considering those "shootouts" typically use a single biscuit when there is clearly room for two or even more.

Here is some interesting reading on plate joinery strength:
http://www.woodworking.org/WC/GArchi...abstract1.html

[durango dude]

Here's the video I recall

http://blip.tv/dave-at-wood-magazine...re-test-116591

See also test results (from a vendor that makes dowel jigs)

http://www.dowelmax.com/jointstrength.html

[Sweet Willy]

Frankly I wouldn't use biscuits for any cabinet (including tables and chairs) that is free standing like your curio cabinet. They get moved to often for cleaning, etc. Many times they have wheels on them. I would use M&T for that kind of cabinet. Clearly, M&T joinery has stood the test of time.

[JimD]

I have a curio cabinet a lot like that built using plans from Woodsmith. I don't remember at this point what joints I used but it is likely to be biscuits due to the time frame in which it was made. I was using a lot of biscuits then. It doesn't get moved much but did make a move from PA to SC. It has held up fine.

If I were to make it today, I wouldn't use biscuits at the bottom and might not use them at the top either. At the bottom, the quick and dirty way to join the pieces would be pocket screws. You would not see them because of the bottom of the cabinet and they are as quick or quicker than biscuits. The big time adder for mortise and tenon is the setup, however, so I would probably just mortise and tenon the whole thing.

Jim

[cwsmith]

I wouldn't use biscuits for anything that is "stressed". Table legs and any kind of shelving, fall into that catagory, at least from my perspective.

I do like biscuits for joining solid boards for making table tops and seating, like in window seats, side panels, etc. Between the biscuit and the edge glue, I've had nothing of this sort crack or open on me. Biscuits are also great for attaching trim, making corner moldings, etc.

For heavy tables, work supports, etc. I very much prefer mortise and tenons, and have always cut my mortises by hand with a chisel. For the tenon piece, I use the router and table saw. Tenons for my use are always "shouldered" so as to hide any rough edge on around the mortise.

For attaching legs to aprons on tables, the easiest course for me is dowels. I don't like to use metal fasteners for this kind of thing unless it is really just a quick throw-together utility table. Dowels do work really well, are strong enough under most conditions and you don't need any elaborate equipment. I just use those little dowel pointers (I forget their "official" name"), you know the little aluminum or steel cap-like things you place in the dowel hole in order to prick-point the mating surface.

The place I use screws (if I can't avoid it) is to fasten the top to the table apron, in a matter so it will float (expand and contract). I do also use screws for fastening drawer glides or channels... that way they can be adjusted or replaced.

CWS

[cabinetman]

I just use those little dowel pointers (I forget their "official" name"), you know the little aluminum or steel cap-like things you place in the dowel hole in order to prick-point the mating surface.

Dowel centers.

The place I use screws (if I can avoid it) is to fasten the top to the table apron, in a matter so it will float (expand and contract). I do also use screws for fastening drawer glides or channels... that way they can be adjusted or replaced.

CWS

Here's what I do...
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[JimD]

My favorite way to attach a table top is to put a dado that ends about an inch down on the aprons. I cut scrap in a convenient size to have a little tenon to fit into the groove loosely and I screw it to the table top. The scrap piece is not bottomed out anywhere so the top can move. C'man's idea is at least as good but it requires a little larger scrap pieces for the cleats.

[cabinetman]

C'man's idea is at least as good but it requires a little larger scrap pieces for the cleats.

It also stiffens up the apron.

.

[phrog]

I quit using biscuits several years ago when I saw a report that biscuits that had been done in the early days of biscuit joinery were causing the wood to cave at the sites where they had been used. (I don't remember where I saw this.) Just wonder if anyone else saw this report or if anyone has had this experience.

[jking]

I quit using biscuits several years ago when I saw a report that biscuits that had been done in the early days of biscuit joinery were causing the wood to cave at the sites where they had been used. (I don't remember where I saw this.) Just wonder if anyone else saw this report or if anyone has had this experience.

The explanation I have read & heard from at least a couple of sources that might look like this is biscuits swell after being wetted with glue. They will shrink back down some after the glue has dried. If sanding is done too soon after gluing, when the biscuits shrink back down there can be slight depressions visible.

I think the reason using biscuits for edge gluing boards became popular was because Norm Abram used this method frequently on NYW. As C-man pointed out already, they are not required for strength. I have even heard people saying biscuits might weaken an edge glued joint. Not enough to make any diffierence, mind you.

[cabinetman]

The explanation I have read & heard from at least a couple of sources that might look like this is biscuits swell after being wetted with glue. They will shrink back down some after the glue has dried. If sanding is done too soon after gluing, when the biscuits shrink back down there can be slight depressions visible.

I think the reason using biscuits for edge gluing boards became popular was because Norm Abram used this method frequently on NYW. As C-man pointed out already, they are not required for strength. I have even heard people saying biscuits might weaken an edge glued joint. Not enough to make any diffierence, mind you.

The affectation for biscuits is based on what is thought of as a quick easy method. I'll throw pocket screws in that hat too. Biscuits can shrink in place, leaving a divot, or they can swell, and leave a bump. As for any strength, their intention was to help keep parts from pulling apart. They provide little axial strength.

They aren't uniform in thickness, and can vary from brand to brand. With their shape, and shape of the cut, there is not much more than a "tab" resulting in a gluing surface. They have an allowable movement factor when used, and don't insure alignment. In a multiple use project, their positioning can get offset, and not allow a mating of the two edges.

For where ever a biscuit can be thought necessary, a spline would serve a better purpose. It can be made with a specific species of solid wood or plywood, better fit, and more surface gluing area.

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