broken corner joint in maple

[R. Barker]

I'm in the process of building a built in linen closet in my newly remodeled bathroom and I'm planning on making the face frame out of 1x2 maple with FF biscuit joints. I made a couple of 90 degree test joints out of scrap stock about 12" long (end grain to long grain) and had some problems. The first joint broke with little effort when I applied pressure from both ends in an inward fashion. Turns out I did not get enough glue on one half of the biscuit and it didn't grab at all. With no biscuit to hold the joint the end grain side peeled a thin layer of the long grain off as the joint broke. I Remade the joint after cutting and jointing the surfaces again and this time it held strong while applying inward pressure. I thought I had it right but upon light outward pressure the joint split right apart again, this time taking a chunk out of the long grain side that encompassed the entire biscuit so the biscuit and surrounding wood were still fastened securely to the end grain side. I'm a little shocked at how easy this wood broke and I wondered if I'm expecting too much out of this type of joint. The pressure applied was by hand only and I'm no muscle bound weight lifter so I would not expect this to break like this even with a straight glue up and no biscuit. BTW, Titebond lll is the glue and it was clamped over night.

[George]

Check the expiration date on that glue.

I figured the biscuits were for alignment on a face frame. Nailing it to the cabinet was for strength.

[SonomaProducts.com]

Yes you need to glue it well but regardless, here are some other ideas.

1. When gluing endgrain you can do what's called "sizing" to add strength. You first put on a tin coat of diluted yellow glue, maybe 30% water added and let it dry, then glue the joint normally. This will add "some" strength.

1. Face frames do not typically endure much pressue to the corner joints.

2. In production shops we do not typicially use biscuits, just pocket screws and glue. You can use both if you wish. We use a commercial pocket screw machine that makes pockest at only 6 degrees, as opposed to the 12-15 degree pockets of smaller Kreg type pocket holers, so we don't suffer much rasing of the joint by the screw. A biscuit can stop this. Regardless, we use a clamp positioned mostly on the piece you are screwing too with just a lip over the piece you are screwing in, clamped down to the table. This keeps the pieces in enough alignment for minimal sanding for a flush fit.

1. Once attached to the cabinet the FF is very ridgid. We do sometimes use biscuits to keep alignment of the FF to the case but you have to be very careful with your layout. [Pointer, we keep a large number of pipe clamps on hand just for FF to case attachement. We use glue only so we have no Norm holes I mean nail holes to patch.

[R. Barker]

That's a great tip, thanks! In this case, the glue joint held just fine, though.

I was wondering if the pocket holes would be a better solution.

Thanks again for your input.

BTW, for the other poster who suggested checking the age of the glue, it's only a month or two old.