Introduction: Mortise and Tenon Bunk Beds
The following Instructable is my dive into mortise and tenon joinery. I am not necessarily a newbie when it comes to woodworking, but I am far from an expert. Mortise and tenon joints were always something I found extremely intriguing but daunting as well.
I was recently commissioned to make two sets of bunk beds for a client of mine who is furnishing a lake home nearby. This is a second home for the client and it is mainly used as a family and corporate retreat, so the name of the game is piling in as many people as can comfortably fit in every room, hence wanting two sets of bunk beds in one room. So I was tasked with making the bunk beds, each with full size mattresses on top and bottom, which would allow for 4+ adults easily in the same room.
With all of this in mind, I grabbed a pencil and paper and went to work...
- Woodworking Tools: Compound miter saw, table saw, hand saw, plunge router, rubber mallet, hammer, chisel, drill, brad nailer, disc sander, 4" angle grinder (with flap disc), etc.
- Wood Glue (lots of it!)
- 1/2" Dowels
- Wood: 2x6's, 4x4's (I used rough sawn pine) and 1x4's
- 3" Lag Screws
Step 1: Plan It!
So my first step was to hit the drawing board. I started with what I knew I had to work with and worked back from there. I knew the size of the room gave me certain size constraints I had to work around, mainly for the height of the beds. I also knew I wanted to make them with full size mattresses for both the top and bottom bunks. I also knew the client wanted some sort of rustic look, not too clean.
The lower bunk ended up just a few inches off the floor which allowed for adequate headroom for those on the lower bunk, while also giving the top bunk enough headroom, given that the ceilings in this basement room are only 7 feet high.
After a little bit of research, I made the decision that mortise and tenon would provide the strongest joints to make this bed last. I didn't want to have any exposed screws, I wanted everything to have an old school look, so i decided to use dowels to in addition to the mortise and tenon joints. Full disclosure, I did end up using screws in just one aspect of the construction of the beds for the sole purpose of being able to deconstruct the beds to move them in and out of the room, but more on that later.
I contacted a local saw mill for the wood for this project. They were able to cut me some rough sawn pine that had actual dimensions of 2" by 6" by 12' and 4" by 4" by 12'. This differs from most 2x6's and 4x4's that you can get from your home improvement stores that typically have an actual dimension of 1 1/2" by 5 1/2" and 3 1/2" by 3 1/2" respectively. The 1x4 slats I used for the bed supports were from the hardware store and those do have an actual dimension of 3/4" by 3 1/2". Keep that in mind when reading through my process and my measurements. All this means is that you will have to adjust your numbers to fit the lumber you have on hand.
After lots of tweaking the numbers, I finally had all my measurements. I then took the rough lumber and began cutting my boards down to size. This part was relatively quick, and the only thing that took some time was figuring out how to maximize my cuts out of the 12' boards to have as little waste as possible. I made sure to add 3" to every board that would have tenons to leave room to make the tenons at 1 1/2" on each end.
Now it was time to really get to work...
Step 2: Setup: Mortise Making
The actual construction of this project isn't too hard, it was really the mortise and tenon making that was very repetitive. Once you've figured out how to make the joints, everything kind of just falls into place (no pun intended). Like I said, this was my first foray into mortise and tenon joinery, so the learning curve was what took the most amount of time on this project for me. Setting up my tools and jigs took some time and patience, but in the long run, they will save you a lot of work and headaches.
**Pro Tip: One thing I learned in researching this technique was to always make your mortises first, then fine tune your tenon to fit.
The first objective was to come up with a jig that would work for the plunge router to make the mortises. I needed something that I can clamp onto different size thicknesses of wood (2" and 4") and make two different size mortises (1"x2" and 1"x5", both at 1.5" deep). I made the main part of the jig to fit centered on 4" thick pieces, large enough to make a 1"x5" mortise. Then I made an insert out of 1/4" MDF to block off a portion of the router plane to restrict the router to make a 1"x2" mortise. Next I made an attachment to the fence underneath the router plane that, when inserted, would allow the jig to sit centered on a 2" thick piece. This allowed me to quickly adapt the router jig, which would save me a lot of time.
**I didn't bother to give the dimensions of this jig I made because it will all be dependent on the size of the router you are using, the size of the lumber you are using, and the size of the mortises you are trying to make. Most likely this jig will not be used very much after this project, however, it was still well worth the time it took to make it.
When it came time to make the mortises, I used a 1/4" up-spiral bit to make the cuts. I had to make a number of passes to complete the full depth of the mortise that I wanted to make. One rule of thumb I used when doing this was to never go deeper with the plunge router than the width of the bit. Since my bit was only 1/4" wide, I made sure not to go further than 1/4" deep for each pass. Once I routed out the perimeter of the mortise, I used a zig-zag motion to route out the center, then I would drop the router bit another 1/4" and continue until I completed the full depth of the mortise.
Obviously using a round bit in the router created a rectangular mortise with rounded corners. Ideally, most mortises have square corners. What I could have done was take my sharpened chisel and shaved out the corners to square them off, but that would have taken a lot of what I considered "unnecessary" time. Instead, the path of least resistance" to solve this was to slightly round off the corners of the tenons instead. Speaking of tenons...
Step 3: Setup: Tenon Making
When making the tenons, I used my sliding miter saw, a hand saw, and a chisel for clean up. A feature I discovered on my miter saw is something I came to find a few years ago which is a depth stop. I'm not sure how frequent this handy feature is on other miter saws but it sure saved me a ton of time when making the tenons.
Basically, a depth stop does just what it says, it prevents the blade of the saw from going down all the way, stopping it at a height that is set by the user. All it is on my miter saw is a small black lever on the right side of the blade that, when pulled out, will stop the blade from dropping completely.
I made a test cut just about a blade width into the piece on both sides to doublecheck the thickness of the tenon it would make. Also note that when my blade has the depth stop in place, the blade will not slide all the way back causing my cut to be incomplete (see pictures). To get around this, I used a scrap piece of lumber clamped to the fence of my miter saw to act as a spacer.
I was able to use this to set my blade to cut approximately 7/16" deep on both sides of my 2"x6" the leave a tenon that is a little more than 1" thick that runs the full width of the board (6'). The extra thickness gave me plenty of shave down the rest with a chisel by hand, to ensure a tight fit. Next I needed to cut approximately 1/2" off each end of the tenon to give me a final tenon dimension of 1"x5". I tried a few different techniques for cutting the edges of the tenon off but ultimately found that the easiest thing to do was to cut it with the hand saw. I used a piece of tape on the saw blade to give me a depth gauge of a little less than 1/2" to be sure I didn't cut too deep, then once again, I shaved down the excess with a chisel by hand to a tight fit.
As I've already mentioned, because the mortises had rounded corners, I need to round off the tenons to match. This was as simple as using the hand chisel to shave off the corners. Again, this was much easier and less time consuming than squaring off the corners of the mortises.
And just like the mortise making, "wash, rinse, repeat"...
Like I've said previously, the construction of this project is not terribly difficult. The biggest thing for me on this was repetition and discipline. I did find a few ways to save time on certain processes without cutting corners and sacrificing quality. When it came down to it, some things were just tedious and took time. But it all paid off in the end.
Step 4: Rails and Slats
The rails were pretty straight forward. I single 2x6 board that runs down the length of the bed for both the bottom and top bunk. In efforts to keep the bed frames as small as possible I cut an L-shaped notch from the top of the wood on the rails that would allow for the beds to sit recessed into them by about 1 1/2" and was a 1/2" wide.
At this stage it was time to add some support pieces that ran the length of the bed as well that would support the 1"x4" slats that hold the mattress. I ripped down the 2"x6" pieces in half to make a piece that was approximately 2"x3"x75" that was the same length of my rails. I then attached them to the rails at 3/4" below the notch I made, since the 1"x4" slats I was using had an actual thickness of 3/4". This would allow the 1"x4" slats to sit flush with the notch i made. As pictured, I made a simple spacer using a couple pieces of scrap wood that helped me set the correct spacing all the way down the rail.
A full size bed is 53" wide, so I cut the slats to 52", this plus the 1/2" notch on the rails on each side would give me a full 53" for a nice fit for the mattress. These slats would be set aside and would later be set in place during the final assembly process.
Step 5: Dry Fit and Glue Up
After all the mortise and tenon making, I emerged from the heaping pile of saw dust and wood shavings, ready to start putting things together. I was close to glue up but wanted to dry fit all my pieces before drilling out holes for the dowels. Once I was confident a joint fit tight, I used a 1/2" drill bit to drill two holes through the post and through the tenon for joints on my 2"x6"s and one hole for my 2"x3"s.
With this design I decided that both the foot and the head of the bed would be completely assembled and glued up and that the rails that ran the length of the bed would be put together once everything was finished and moved into the room.
Once I had everything dry fit and drilled, I took it all apart and began the glueup. I made sure to place a generous amount of glue on the tenon and inside the mortise before joining the two pieces, then I squeezed some glue into, and inserted dowels into the pre-drilled holes for pins that were intentionally left about 1/2" too long, to be trimmed later. I used a rubber mallet to ensure the dowels were seated properly.
On some pieces, particularly the ladder end of the bed, I had to pay special attention to what order I glued these pieces up. Some of it takes a bit of reverseengineering to figure out. Be sure to pay special attention to this when looking at the design you decide on. Then all that was left was to let the glue dry overnight.
Step 6: Sanding/Distressing
This step is completely optional based on the look you want. I didn't want things to look too clean. I decided I would distress the wood to take away all the clean edges and corners. But, there was a lot of surface area to be distressed.
The method I chose to use to do this was to use a 4" angle grinder with a 60-grit sanding flap disc. Using this aggressive of a grit eats away at the soft pine pretty quickly. The key to this was to keep the grinder moving in quick back and forth motions of about 4"-8" with the grain across the surface area of the wood. Doing this led to a very "hand-scraped" look that was happy with. I also did a bit of hand distressing by using the edge of the flap disc wheel that would put "gouges" in the surface, and also hit it with a few different tools like hammers, pry bars or large nails and screws. This is the part where you can get creative or use a distressing technique that you're familiar with. You can see the effect this gave in the next step when the product was finished. There is no shortage of posts online that can give you some techniques if you run out of ideas.
I was also able to cut off the excess on the dowels now that the glue was dry. I still wanted to dowels to sit a little proud of wood posts, but I needed them to all look the same. I didn't trust myself to be this precise with as many dowels as I had. What I did to get a consistent look was rip a thin piece of excess material to about 1/8", which is how far out I wanted the dowels to set. I drilled a 1/2" hole (same size as the dowels) into the ripped piece, then used that as a guide for my hand saw. I simply slipped the thin piece over the dowel, and used the hand saw to cut all the dowels at the exact same length (as pictured). Definitely a time saver here as well!
Step 7: Stain and Finish
After testing out a few different stains and combinations of stains, I ended up settling on Puritan Pine by Minwax. It gave a nice natural tone to the wood that would go well with the interior of the room I was working in. Also, because this room was dimly lit and without any exterior windows, I did not want to go with anything too dark.
**Pro Tip: One of the best ways I've come to learn to apply stain is using a stain sponge. Whether I'm dipping the sponge into the stain to apply it, or brushing on stain and using the sponge to wipe, I find it easier to use than a rag.
I used a water-based Polyurethane from Varathane to seal the wood. I really like using the water-based formulas from Varathane. They are very easy to apply and have some of the fastest drying times when it comes to poly. I finished this project with three coats with light sanding in between coats.
Step 8: Final Assembly
Once all the sealer was dry it was time to move all my pieces in and start assembling. Since the head and the foot of my bed was glued up into one piece, there was a total of only 8 pieces to this bed that needed to be assembled (the head, the foot, 4-2"x6" bed rails and 2-2"x3" top bunk rails). Assembly was pretty straight forward, put the square peg into the square hole.
I wanted the joints where the rails attached to the foot and head of the bed to be durable but not permanent. After all, I imagine the beds might not stay in there forever. Because of this, they were still joined using mortise and tenon joints, I just skipped the glue, and instead of dowels, I countersunk some 3" lag screws to hold them in place. Because I wanted a cohesive look with the other glued up joints, I countersunk the lag screws in about 3/8" into the 4x4's with a 1/2" spade bit that would allow me to use my 1/2" dowels as plugs to cover up the heads of the screws. The dowel plugs stay put pretty well without falling out, while also are not too hard to pull out if you need to get back to the screws again. This ended up being the perfect way to hide the lag screws.
After the frames were built, I needed to lay in the slats. Now, all I had for the the slats were a a support piece that would hold them up, but not in place. My solution for this was to drill a hole through the slats at the head and foot of the bed into the supports. I glue the dowel into the support piece but did NOT glue the slat in place (again, I want to be able to disassemble this in the future). I then evenly spaced all the slats down the length of the bed and ran two strips of vinyl webbing across the tops of the slats and stapled the webbing to each piece using 5/8" small crown staples. This was a great way of holding all the slats in place, but if they need to be disassembled, the slats can all be rolled up together.
All that was left was to put the mattresses in place and some staging.
Step 9: Conclusion
What. A. Project.
As I mentioned at the beginning of this Instructable, this was my first dive into mortise and tenon joinery, and what a dive it was. I learned a whole lot while doing this, but I'm so glad I did it. There's nothing else like the feeling you get when you are finally ready to tap that tenon into place and everything sits perfectly. It wasn't all perfect, but I'm proud of myself. And let me tell you, these beds are SOLID. I'm so glad I decided to learn this new-to-me technique.
Most of what I learned was by researching, watching tutorials, and trial and error. If you have some techniques you like to use, please drop them in the comments below. I sure appreciate some constructivecriticism. Just be nice, and remember this was my first go at it, so let all the readers know what you wish you knew on your first go around with similar projects.
Thanks for reading, until nexttime!
Runner Up in the