Cabinet Door Construction: Doweled Corners or Nailed Corners?

      For a high-end custom product, is it worth adding dowels to the joinery for strength and reliability? January 19, 2011

Question
Unlike most of the shops we compete with, my company builds all of our own cabinet doors. Most of these doors are shaker profile but some are ogee or ovolo. We have always added a single 3/8 dowel to each corner of the door. The purpose of this dowel was to provide a more positive connection between the end grain of the rail and side grain of the stile. Would we be equally well served if we just pinned the tenons with a nail from the back side? We've been using a product called Raptor Nail by Composite Plastics for our end panels and are wondering if this would work for doors. Dowels definitely produce a stronger corner. Would nails produce a strong enough corner?

Forum Responses
(Cabinetmaking Forum)
From contributor G:
I haven't doweled or nailed a cabinet door in 15 years and never had a failure. As far as I am concerned, nailing the door is only because you don't have enough clamps. You need 20 clamps to keep a rotation going. Two clamps per door, six minutes to assemble the door, ten doors an hour which is more than long enough for typical yellow glue to dry more than hard enough to have a secure joint.



From the original questioner:
What got me onto dowels originally was some doug fir doors with shaker style profile. The doors were properly glued up but over time (couple of years) the lumber fibers apparently shrank enough to make the tenon not match the groove. It could have been the tenon that shrank or the stile. In any case the joint didn't have much integrity. Never did notice this with an ogee profile or any other material that had more area for side grain adhesion.


From contributor G:
I don't think I have ever made a cabinet door out of fir. All of the shaker style doors I have made have 1/2" tenons. I make them on the tablesaw with a tenon jig and a dado. I make them .003" smaller than the slot. Any closer and when you add glue it swells enough to make it hard to assemble. When I was working in the first shop I got a job in we had a two hole borer and we would use two 3/8"x3" dowels in the doors. It was pretty quick to do with the borer, but I think it is total overkill.


From contributor I:
Iím with Contributor G. Yes your doweled door is stronger, but one without dowels is more than strong enough. Think about how many doors are made every day by the big guys like Walzcraft, Conestoga, etc and none of them are doweled and few if any fail. I have never doweled a door, and I have never had a joint fail. Pins wonít give you any strength, they will just hold it till the glue dries. I would think your fir was probably not at a suitable MC if that kind of shrinkage occurred. Pins would not have held that together.


From contributor V:
To dowel or not would be completely dependent on the length of your tenon. As an example, if you were making your doors with a router cope and stick set that yielded a 3/8Ē stub tenon. I think that a dowel is good insurance against failure as there is not a lot of glue surface area. The tenons on my Conestoga sample doors are 21/32Ē long, thatís nearly 11/16Ē. In my opinion, dowels used here would be a complete waste of time and resources, and add additional cost that isnít necessary.


From contributor F:
I have always been taught that a properly executed glue joint will never fail - the wood will give before the glue. Doors are tough because if you apply too much glue and have squeeze-out it might glue the panel tight and cause it to split from the corner with climate change. The tendency then is to starve the joint for glue to eliminate the squeeze-out which will cause the joint to fail. If your tenons are too loose there will be an excess of glue between the wood members of the joint and the glue will fail. If your tenons are too tight, too much glue is squeezed out to make a good joint and it will fail.

The nails you see that some shops use through the tenon are not for strength, they are just to hold the joints in place until they are clamped. A mechanical fastener is never as strong as a glue joint. If you have to dowel your doors, you are not machining the parts correctly or you are not gluing the joint properly.



From contributor A:
What would one glue joint failure on one joint of a door on a hundred door run cost? I am talking about a call back three months later. What would ten call backs a year cost? Put the dowels in.


From contributor G:
I agree with most of the others, dowels are not needed. I also agree you had a moisture content issue with the fir. A few years ago we made quite a few fir cabinet doors and have not had an issue with them or any of the other thousands of doors we've made over the years. I remember reading one of your posts a few years ago where you referred to using dowels in the door joints. I thought then as now that it was a waste of time.


From contributor O:
Your fir was not dried properly. If wood is properly dried, there is no reason for failure. Why the concern about the stick/cope joint failing? There are how many steps to making a good cabinet and door, making a good house, making a good anything? You do a step wrong and you are going to have a failure. We've made over a million doors, almost none of them in low-end subdivisions. There are about 25 steps to make a door. Do a step wrong and there will be a recall, or at least extra work in the shop. A longer tenon is better than a short tenon (cope), but 3/8" is suitable if everything else is done right. 1/2" or better is what you should strive for. You should be buying doors. I would bet a paycheck that you are putting a ridiculous amount of labor into making doors.


From contributor UD:
I only dowel mitered joints where profiled stock does not allow for conventional stile to rail joints. It takes at least twice as much time to cut the miters, bore both sides of the miters, glue and insert dowels, and then clamp from two directions simultaneously.


From contributor K:
Although I have purchased thousands of cabinet doors without dowels, and don't dowel my own doors when we do make them, I'm going to come to the defense of the questioner here. I have at least one joint break on every single cabinet job. On a square cope and stick profile, I might have several. It has nothing to do with glue failure, but with wood failure. The joint splits, it does not come apart. This can happen on the hinge side, or on the handle side. I have had it occur simply from drilling for hinges. A 1/2" tenon is not as strong as you think. When this happens, we deal with it by putting a 3" screw through the joint and plugging it.

Years ago, Decorative Specialties put 1/2" by 3" dowels into every cope and stick joint. I don't know when they stopped this practice, but I assure you that was a higher quality door back then. I would pay for this added service if anyone offered it.

The questioner prides himself on building a classic style of cabinetry that will withstand the test of time. He builds all of his own doors, allows his wood to climatize before construction, joints all the wood flat, builds almost exclusively flush inset style cabinetry, and uses true mortise hinges. If he wants a flat door that will never, ever break, then my advice to him is to stick with dowels.



From contributor G:
I have seldom heard of this happening much less so often for the same person. Is there a chance something is happening at your shop such as poor handling, lumber mc, or shop humidity? One door or more on every job is unacceptable and unusual.


From contributor K:
Any door that is over-extended against the hinge will break. If anybody states that they've never had a door split at the joint, then they're customers have never bothered to call them. I assure you, it happens with regularity. I have ordered doors from Decorative Specialties, Meridian Products, Consestoga, Brentwood, Design Craft, and Sunriver Industries. They all make a good door, and they're all susceptible to splitting. If you run a screw into the joint while attaching a drawerfront, it might split. If you pound a hinge in, it might split. If a door gets slammed, it might split. If a stile has some end checking in it, it might split. I assure you, we do nothing unusual in our handling.


From contributor D:
I agree with the others that a pin is not going to add any significant strength to your doors. I also make my own doors and have not had any failures as of yet - about nine years. I do believe some mass manufactured doors are inherently weaker. Not sure if it's the glue, or how they're clamped or something else? I was surprised to find I could disassemble other manufacturers doors in the past to re-size them for clients. A couple taps with a deadblow and the joints separated. I cannot do that with my doors. If you feel the need to use dowels then I say stick with it. It can be a sales point that differentiates you from the rest of the pack. Maybe focus instead on a way to increase the speed of the doweling itself?


From contributor G:
Bad door joints do not happen with any regularity for me or any other shop that I network with. Why would you over-extend a door joint? Why pound a hinge in, why run a screw into the joint?

It should not happen with any regularity at all if the doors are handled correctly. If this a reoccurring problem for you I think there is a way to solve it. I'm not saying it has never happened to me but I can probably count the times that it has happened in the last ten years on two hands. My customers would let me know if it did happen because we give a lifetime warranty for construction with our cabinets.



From contributor G:
I think a lot of the door manufacturers will only put glue on the tenons and not on the whole joint. This is why they are not as strong as a self built door. The nails will add a small amount of strength to the door. If the glue joint fails the nails will hold the door together until the wood fails, which shouldn't be too soon after.


From the original questioner:
Based on the responses I have read here I think I will stay with dowels and just focus on getting better at the doweling process. I have an extra boring machine that could be situated next to the cope station and this would make door parts flow better from cope to stick. The last time this was timed as a stand alone event it added two minutes per door. I'm not sure what this time would be in a bucket brigade approach. We recently built a run of 30 doors with three people in the pipeline. It was interesting to see where the bottlenecks were when the doors were being processed in one piece flow. It was also useful to note that we could have utilized a fourth person.

Building things in a bucket brigade format turned what could have been a very tedious day for one person into a social event that only lasted a couple of hours. It is also very easy to identify where you could use an inexperienced or part time person in this process. With people pushing to you or pulling from you it is hard to not keep up a fast pace. With limited responsibilities it was also easier to maintain quality and accuracy.

I want to make more use of bucket brigade strategies. To make this work well the processes need to be simplified and the work stations need to be arrayed in a way that can absorb several people but still be staffed by just one when conditions require smaller batch sizes.



From contributor G:
Two minutes sounds like a long time to punch a few dowel holes using a boring machine. It should be on the order of about 15-20 seconds per piece (two ends). Without knowing what boring machine you use, I can't really gauge how quick it should take. If you are counting the gluing and inserting of the dowels then I agree that it will be about two minutes per door.

For me, it takes about six minutes to glue up a door. That includes getting the two clamps, placing them on the surface, getting the five parts of the door, applying the glue to the four ends using an acid brush, assembling the door, clamping the doors checking for square, adjusting if necessary and putting the clamped door out of the way and then starting the process over again. I hope you are using a dowel glue applicator as this would make it much quicker and as soon as you figure out the glue amount it will eliminate squeeze out too.



From the original questioner:
I like the compartmentalized way you think. The first thing your last response made me think of was the annual pricing survey that Cabinetmaker magazine puts out each year. They spend a lot of resources discussing bid differentials in different parts of the country but there's not much you can do with this information. It really doesn't matter how much you can sell something for without understanding what a loaf of bread costs in Manhattan, NY vs. Topeka, Kansas.

What would be useful in a survey like that would be exactly what you just offered up. I am far more interested in how long something takes to produce and the underlying method to get there than I am how much I can sell it for. For what it is worth, we've used acid brushes for many years, up until my greenhorn daughter demonstrated that one inch foam brushes were way faster.



From contributor G:
How is the squeeze-out when using the foam brushes? I find a difference between cherry doors and hard maple doors. I can easily control the squeeze out on a cherry door, while I have problems doing it on a hard maple door. It must be the tighter pores in the HM that push the glue, rather than incorporate it into its structure.


From the original questioner:
We've been very fortunate in the past several years in that we just about only work with paint grade material. Poplar is our wood of choice. I would suspect that the porosity of poplar is more like that of cherry. Now that you mention it we do pay a bit of attention to glue absorption when laminating lumber. We glue the staves on just one side then press them together light for about a minute before we tighten the clamps. This gives the wood a moment to drink in some moisture before squeezing all of the glue out of the joint.

I would guess that hard maple does not want to receive glue so readily. All of this became really apparent back in the days when we built a lot with Honduras mahogany. We used a glue that had an additive that showed up under black light. We did this so you could find any excess glue before staining. The individual staves of mahogany were stitched together about 1/8 inch both sides of the joint. Capillary action pulled the glue into the joint. It looked like a Christmas tree under the black light.



From contributor G:
I use to do a lot of poplar doors and it was much easier to glue because the glue stayed inside the joint instead of being squeezed out. Because I use lacquer for my coatings, I had a problem with the grain telegraphing through. I switched over to soft maple for those jobs. I also noticed that the soft maple has a lot less reaction to the humidity changes during the seasons than poplar does. So a lot less call backs for doors that have expanded beyond their face frames. It is great for a hand painted doors though.


From the original questioner:
Our jobs just about exclusively end up brush painted. The paint is typically Benjamin Moore Satin Impervo. It is usually delivered with a spray gun then hand brushed on the final coat. Sometimes the raw paint is delivered with three inch paint rollers, also to good effect. Assuming that there were no brush strokes, do you think you would get more or less telegraphing with enamel vs. lacquer?


From contributor G:
There is a lot more telegraphing with lacquer. With lacquer you only have four mil thickness to hide the grain. With brush on, it is much thicker. And you could put 20 coats on if you wanted. Lacquer is usually limited to four coats of primer and topcoat combined.



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