Gluing face frames
Is glue alone enough to attach face frames to 3/4-inch plywood cabinets? July 29, 2003
Has anyone tried gluing face frames on a cabinet built with 3/4 plywood? Seems to me this might be enough surface area to hold everything together... I'm tired of fighting nail holes/putty that won't take stain and turn out to be the same color as the wood. Any thoughts on the subject would be appreciated.
From contributor J:
I build my cabinets with solid wood face frames and 3/4 plywood for the carcass. I use biscuits and glue to attach the face frame to the plywood. It makes a very strong cabinet. I would not try to attach the face frame to the plywood with glue only, as the joint would not be strong enough. I do this for the reason that you listed - I do not want to look at puttied nail holes.
From the original questioner:
I don't have a biscuit joiner, but would consider one if I thought this was the ticket. I use biscuits primarily to edge glue solid lumber together, using my table saw or router with a tiny saw blade/biscuit cutter. I read the other day that I was wasting time and money for the reason that if the boards are glued up properly, you actually weaken the joint with a biscuit.
Anyway, about how many biscuits do you use per linear foot? What kind of biscuit joiner do you use? Tell me any tips that will help. I hate dealing with nail holes.
When you glue and nail your face frames to your plywood edges, you are basically using the nails as a clamp until the glue dries. The nails also may provide an insurance policy; however to say that the edge grain of plywood is not a good glue surface is absolutely wrong. Do some test pieces with just glue. Try ripping a 2 foot long, 8 inch wide piece of cabinet plywood and then edge glue it back together, just like you would with two boards. That would be the worst case glue scenario with plywood. Also end grain to side grain wood glue joints are much stronger than most people think, not that I would rely on those.
The above post is basically correct about the application described here until the joint is "put under a microscope," so to speak. End grain does not glue well unless precautions are taken that are not mentioned here. Plywood has alternating end grain, so gluing is not all end grain. Picture wood grain as a bunch of hollow soda straws with the open ends. The sap flowed through the grain "tubes" when the tree was alive. There is nothing to grab where there is nothing. Application of a glue size will bridge and/or fill these voids and then an assembly glue joint will be more consistent.
From contributor J:
I am fairly conservative on my use of biscuits (I build extra strong). I generally place biscuits 3-4 inches apart (center to center of biscuits) depending on the layout distances. I know that some folks would not use as many but I do not like to revisit (rework or repair) finished products. I use a Lamello Top 10 but if I were buying a biscuit jointer today, I would take a hard look at the offering by Porter Cable. Much lower cost and seems to be just about as good. I don't use biscuits to edge glue boards. I don't know if it weakens the joint (I would doubt that it does), I just don't think that it is needed. After I get the edge straight on my power jointer, I use a sharp hand plane to make the final pass on the edge. This provides an excellent surface for gluing and I have never had any failures of these joints.
Before I started using biscuits, I glued small glue blocks on the back of the face frame to the plywood cabinet for additional strength.
A lot of people have started using PUR hot melt for this application. It's extremely strong and very quick.
Jeff Pitcher, forum technical advisor
Using only glue will be plenty strong enough. As long as it is clamped properly and the surfaces mate well, you won't have any problems with it coming apart. Unless you take a hammer to it.
Another option is to use pocket screws on the outside of the cabinet. This eliminates clamping and also gives you a mechanical fastener. I use a Kreg machine, which works great and is fast. I would forget the biscuits and clamps.
From contributor J:
I tried the Kreg Jig and the pocket hole screw method because it seemed to be easier and faster. However, the quality (strength) of construction was not up to my standards (I had to replace a couple of cabinets). I have never had any problems (failures) of cabinets put together with biscuits. Please note that I only use the biscuits to assemble the plywood parts and attach the plywood parts to the face frame. I use mortise and loose tennon for assembling the face frames. I know that this is extra work but the quality is work the extra work.
From the original questioner:
I use dowel rods to build my face frames. I built the neatest little horizontal boring machine to do this with. It's extremely accurate and it drills one hole at a time. Great for a small cabinet shop.
The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).
Comment from contributor A:
I avoid nails at all costs. Whether to use just glue or glue and biscuits depends on several things, such as if a door is to be installed to the frame the size of the door, it's weight will play a big role in your decision. A pine door will weigh less than an oak door, so just gluing should be fine. However, a large oak door will apply more stress to the face frame when opened and biscuits should be installed. One of the major problems I see when someone is using just glue is that too much clamping pressure is applied, squeezing out the glue. Here is where some good glues get a bad reputation.
Comment from contributor B:
I've used Kreg's pocket hole joinery to piece together the face frames, then PVA glue-only to the cabinet. If glue has good contact and is clamped well, it should hold up. Especially if the frame is not under any stress.
Comment from contributor C:
At the risk of coming across as a dinosaur, the best and most foolproof method of attaching your face frame is to put a 1/4 groove in it, cut a snug fitting rabbet on the plywood and then glue and clamp. If you leave the face frame slightly proud, a few passes with a plane will bring it flush with the plywood. Takes a bit more time but you eliminate the "slipping and sliding" of the pieces when you glue up and strength is there whether it's a built in or a free standing piece.
Comment from contributor D:
I use the pocket hole jig for building the face frames and attaching them to the carcass in most circumstances. I find this to be strong and accurate along with not being too time consuming. I do not have callbacks due to weakness from the pocket holes. Not nearly the clamping time that is used for biscuits, and just as strong.