Biscuits Or Butt Joints

High-quality, high-speed cabinet joinery techniques. October 20, 2004

Please clear something up for me. I usually build my cases out of ply with dados/rabbets. I have done butt joints, but thought they made it harder to align. Would biscuits help the assembly? I am looking for a way to speed up production, with quality, of course.

Forum Responses
(Cabinetmaking Forum)
From contributor D:
If you are looking for speed, I don't see biscuits as being a step in the right direction. Pocket holes with a production machine would be faster. Doing dadoes is not that slow if you have a dedicated machine like a table saw or a vertical panel router to run the dadoes.

From contributor W:
Dado is probably the fastest if you have it set up the right way. Take some lessons from the big factory guys.

From contributor E:
Butt joints would be accurate if you used confirmat screws and precisely drilled the holes for them.

From contributor J:
A little more history as to how your shop is set up would help. We cut our cabinet parts nested on a router and we have a Gannomat dowel inserter and a couple of case clamps and I don't know if it can be done faster. No screws - just dowels and glue.

From contributor K:
Dado is the fastest if you have a dedicated machine. Even if you don't have a dedicated machine, cutting all your cab parts first and then keeping the sheets of colored sticky dots by the table saw and putting a dot on the edge needing a dado is fast. By doing this, you will not be changing blades out often. (You will still end up doing at least one change-out, but this should take no more than 1-2 minutes.) Unless you have boring capability with a CNC, doweling doesn't make sense. I can pass plywood across a dado faster than putting the parts through a separate boring process, and while dowels and glue with clamps don't require screws or nails, using a staple in the blind areas is quicker than clamping.

From contributor M:
I biscuit my boxes and screw them (on blind ends). It works out nice - I wouldn't do it any other way. Just like dadoes and other methods, you can impose your own simple system and make very simple jigs to turn this into a very productive operation. Fine Woodworking had a pretty good article on using biscuit jointers about six months ago. It may change the way you think about using the jointer. I also find that boxes on a butt-joint system usually come out square with no hassle.

From contributor T:
I agree with the other replies about dados (actually rabbets) being quick.

A cheap contractor's saw can be set up for rabbeting the cabinet sides and leave it. We have tried a lot of ways - routers, shapers, etc - but dado blades in a saw seem to work best for less chipout on melamine and good results in plywood.

We leave 1/2" thickness after rabbeting: that way the tops and bottoms are cut 1" less than the cabinet width. The rabbet width is adjusted with the fence, the depth with the height of the blade. Actual dados would be more complicated, since you would have to change your dado blade setup for every change in thickness of material.

We use separate toe bases - that keeps it simple: no dados, just rabbets.

Butt joints and stapling, then screwing, is fast, but it takes me too long to line everything up. I know other shops that use that method and it works fine, but it is slower for me, and I like a glue joint.

Pocket screws would be very strong and fast, and cheaper to set up than confirmats or dowels. We just tried the manual Kreig jig for pocket screws, and with an automatic setup I think it would be very fast. Another local shop uses that method for cases, drawers, and lots of other joints.

Definitely CNC is the fastest, but probably just a dream for you like a lot of the rest of us.

From contributor D:
Over the years I've used butt joints, dadoes/rabbetts, biscuits, pocket holes, and now I dowel all my boxes together (including drawers). I use a 23 spindle horizontal/vertical construction borer. It's a fast, strong, and accurate method. Assembly is easy because the alignment of the parts is automatic.

From contributor E:
I think the bottom line here is to adopt one method and stick with it. If you can afford a construction borer and case clamp, great; if not, a dedicated craftsman saw with dado set is fine too. Most inefficiencies come from mixing and matching methods.

From contributor D:
Those that are using dados: are you also doing face frame cabinets or are you using dados with frameless as well?

Seems like the cabinet would not look right if you were edgebanding, as you would see the dado from the front, unless I am missing something.

From contributor T:
We rabbet frameless. Yes, you can tell that it is a rabbet joint instead of a butt joint, but I see that as a plus.

From contributor D:
I am leaning toward using dados for the stretchers and decks and pocket holes for mid-stretchers, etc. Seems that this may be stronger and easier then butt joints and screws. It would also leave the end of the cabinets free of any staples or screws and could be installed without a finished end if so desired.

Are most of you just using glue and clamps or are you also shooting a staple or driving screws?

Seems that several staples in from the top stretchers and in from the bottom through the deck into the side would probably eliminate the need for clamps.

I am also wondering how many are finishing the plywood before assembly. Also, does a pre-finish affect the ability of the glue to hold it together?

Am I also correct in assuming that most are cutting a dado for a 1/4" back or are you cutting a rabbit instead? If dados, what size backs are you using and how much are you offsetting the dado from the back of the cabinet?

From contributor T:
We build out of melamine with end panels to match door material. Staple through the sides into stretchers and deck. Fastest and easiest for us.

But when it is impossible to use end panels, we cut the rabbets deeper so we can staple through the stretchers and deck into the sides.

Pocket screw for mid stretchers. We used to use biscuits, but pocket holes are faster. Yes, we glue also.

From contributor R:
Before I started outsourcing my boxes, I used to cut dados for the deck, rabbets for the tops and backs. I glued and stapled. Finished ends are just glued and clamped. I pocket screw and glue the face frames. On melamine boxes I pre-finish the frames, finished ends and bottoms of the upper cabinets. I have pre-finished ply boxes before. When I do, I tape off any joints so the glue will hold.