Tired of a mundane air mattress, we wanted a nice futon for guests and as a daybed. We also hate having free floor space.
(I’ll upload better pictures at a later date)
(Click the arrows to expand)
Project Timeline
I felt it may be helpful to start including project timelines in these project write-ups. After milling, I spent most mornings before work and weekends to get this project done quickly.
- 18 June: Wood purchase (SL Hardwoods). Had it delivered and let acclimate to the shop for a bit over a week.
- 28 June - 7 July: Milling. Process took about a week on and off.
- 7 - 14 July: Arm rests
- 15 - 19 July: cutting and fitting the horizontal beams
- 20 - 25 July: finishing touches and oiling
Design
We didn’t like most of the futon frame styles out there, but after some browsing we found this wonderful concept from Karup designs. To fold flat, there is a hook integrated into the armrest that flips around and becomes another leg to support the mattress.
I really liked most of what is going on here, but there were many tweaks I wanted to make:
- the structural members are a bit boxy, I’d incorporate heavier fillets and chamfers as in some of my previous projects (Shelf, coffee table)
- it’s designed to be flat packed, which necessitates visible bolts. I wanted to get rid of those.
- there’s hierarchy between the back rest (it’s inset) and the rest of the frame, but not much between the front beam and lower beam running between the legs. I inset those and added fillets rather than chamfers
- the arm rest is not in line with the hook
- there are lines cut into the arm rest. I wanted mine to look like a continuous piece and maintain a sense of hierarchy
- make it in ash rather than pine.
As with recent projects, I drew my redesign in Fusion 360. I find it’s conducive to iterating over different proportions and measurements and modify designs throughout the process.
There was probably a much easier way to do this, but I went a bit overboard with my sketch of the legs/hook/armrest to get everything to line up as I wanted.
Thanks @njhansen for your feedback on my redesign!
Dimensioning Timber
I used two 2" thick boards of ash appx. 240mm x 3m acquired from SL Hardwoods. As mentioned in the timeline, I let them acclimate in the shop for a few days before milling. I decided to try flattening one end of the board on the CNC machine rather than the planer, really to try something new mostly.
Then off to the planer for jointing and thicknessing. The rollers were game changing here, contrast to my setup in shelf
I don’t have photos of the process of marking out and cutting my boards, but this super easy to decipher cheat sheet based on the CAD drawings was very useful. I spent an entire morning figuring out where I wanted to make my cuts in a way that left the least amount of waste, considered grain patterning, and color variation. After marking out the boards, I cut them down to rough size a bit larger than what I wanted to end up with.
Then back to the thicknesser to get the components to the exact width and thickness.
Arm Rests
The plan for these was to make up two arm rest blanks, then either route or CNC them to their final shape. I made sure to add blocks in the corner to allow for the gradual curves in my final design. I could have avoided having to add in the blocks had I used wider pieces for the legs and arm rest, but that would’ve been a lot of waste.
One of the problems I had to think through was how to get those blocks to have nice, tight, square contact between the beams in two planes. I did this by attaching the blocks to each of the legs first, gluing, cutting, then squaring up each assembly before attaching both to the armrests. Drawing this out and writing down the steps helped to arrive at the final order of operations. The piece of paper I’d made up for my cut list was hugely helpful as well.
Planing one edge of the blocks flat.
Attaching the blocks to the legs. Dominos helped with alignment.
The glue-up for the legs.
After the glue dried, they were roughly (pretty accurately, but rough for my intent here) cut on the tracksaw.
Using a plane, square, straightedge, and protractor, worked the face flat and square and at the exact angle I wanted.
Dominoed the join here to help with the glue-up. Measured the two frames against each other to ensure the inside edges of the legs were the same size.
The glue-up went pretty smoothly.
I was considering making up a series of router templates, but ended up going with the CNC. I didn’t have much extra margin when cutting these out, so I spent a lot of time aligning the frames and screwing in some blocks to help ensure proper alignment. Since I couldn’t cut through those blocks, I only cut through half the thickness of the blanks, with the intent to use a trim bit to finish it off.
Cutting the excess away on the bandsaw.
Using the router and a trim bit to make it flush. Remember to be careful and take lighter passes on curves!!
The hooks (made later) were done on the CNC using the same process.
The setup for making the hooks flush. Again, being careful when going around sharp corners.
Next up was insetting the horizontal beams. It was very important that this went in parallel to the bottom of the legs, and at the exact same height on each leg. This was also the point where I made the judgement of which armrest would go on which side. To do this, I referred to my model, took measurements, and marked the placement of the beam on one of the legs with a knife. after some testing to confirm I was happy with those marks, I aligned the two frames and transferred the knife marks. That way I knew that both would land in the same place relative to the bottom of the feet.
While the beams were fixed into position as in the above picture, I clamped pieces of MDF with squared edges to the point where they met the legs. I then removed the beams from the frame (leaving the MDF guides in place) and routed a groove with a bearing bit to establish an edge.
Here they are after a bit of cleanup and routing to make the surfaces flush and to the depth I wanted
This probably wasn’t necessary, but for added strength I sunk a large screw into the area that the hook pulls against to keep the backrest up. I covered it with a wooden plug and planed flush.
The ends of the cross beams would’ve been just fine trimmed square, but who am I kidding, of course I made up some templates. For this is was important to make two corresponding templates offset by the kerf of the laser cutter for a nice, snug fit.
The template attached to one end of the beam. I cut these on the router table, but had some nasty kickback that chewed the end of one of the curves. Luckilly, it happened in a non-visible spot. Always be careful of curves when routing!!
A dry fit to help place the template used to inset the beams.
Next up was routing a fillet on the horizontal beam. You can also see the slots cut into the legs, as well as the (near) final shapes of the beams.
I ran a chamfer along the edges of the legs/armrests.
The hooks were chamfered to the same depth to match the arm rest. As is tradition, I used threaded inserts as well.
Here’s everything dry-fit immediately before gluing the beams onto the armrest/legs.
How I learned to stop worrying and love the Stop Block
If you look closely, 3 of the 4 horizontal beams are different sizes. The one in the front of the seat is the longest, the rear beam is inset a bit by arm rest cross brace, and the back rest beams need to be shorter by the width of the vertical beams. We can cut and tenon all of these accurately using stop blocks! Here’s how it works:
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Measure the distance from the saw blade down the bench that corresponds to the length of the longest beam. Clamp a stop block there (the piece of mdf):
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Make up an object that fills the the relative difference in length between the long beam and the shorter ones.
For the rear seat beam, I shimmed a block to fill the gap between the frames when they were clamped together. For the back frame, I used the width of the vertical posts themselves -
Cut the long beam against the stop block. Then to cut shorter pieces, place in the block, push the beam against it, then cut.
Notice the vertical beams against the clamped block.
or here, the setup for the rear seat beam.
These stop blocks also came in useful when cutting the tenons all to the same relative size. Here’s the general setup on the spindle moulder:
And how they turned out. Thanks to @riggerz for reminding me that I could use a knife to score where the spindle moulder would cut to avoid tear out; it worked better than the tape.
Marking out the vertical bits of the back frame.
The mortises on the back frame were done on the morticer:
I cut the curve on the bottoms of the frame out on the CNC rather than make up a template.
For the armrest mortices, I cheated and just did them on the CNC rather than mess around with trying to get them square by hand. Jokes on me though, I managed to cut them the wrong size so had to do them by hand anyways.
To get nice, tight fits, I used chisels and the router plane to shape the tenons into a nice, snug fit. I hadn’t used the router plane before, it was very fun to use!
Gradual test fits helped me fine tune.
Glue up
Before the glue-up, I did a final fit check with each leg/hook/back, and made a couple of necessary adjustments. I ended up widening one of the holes for the hooks and had to clip off the corners of the hooks.
At this point I was very pleasantly surprised that the stop block technique had worked so well and everything fit together square.
Glue up of the back frame. I bolted two sash clamps together to get them to fit. Unfortunately, they weren’t long enough for the seat frame…
So I ended up using ratchet straps which worked just fine. if you look at the back and right side of the table, you can see the boards I used for alignment during the glue up.
During the glue ups, I made sure to use winding sticks to identify any twist as well. The back frame was bang-on. The seat frame required a very small shim to get square.
Final assembly and Finishing
There were a couple of miscellaneous steps to take care of before final fishing.
Did a post-glue up assembly to check the alignment of everything.
There was almost no gap between the frame and the backrest, I needed to route small slots to get the washers to fit in.
Setting the router depth.
Here’s the template used with the palm router. The depth was set such that the washers are ever so slightly proud of the surface.
I inlaid a small circular plug in a contrasting wood (walnut)…
…as well as routed a light chamfer around the end of the hook that contacted the arm rest. I routed a corresponding chamfer into the arm rest as well. This helps to hide any misalignment between the hooks and the arm rests, and is similar in concept to the shadow line used in the coffee table I made.
The slats and rails were cut up from a couple of leftover boards that @lewiss had left over from a project. Thanks Mark!
Using a stop block to cut all of the slats to size.
Fitting the rails. For now, I held them in place with only few screws and pre-drilled holes for more. The rails would be removed for oiling.
Marking the positioning of the slats. Accuracy didn’t matter too much here, so rather than measure every single line precisely, I cut a block to a calculated size and used that to quickly mark them all up.
I didn’t need to spend a lot of time sanding on this one. Depending on the particular surface, I either sanded by hand directly with 240 grit paper, or with a light pass of 180 followed by 240 grit with the orbital sander.
Touching up the back frame. I planed the top of the vertical beams flush with the horizontal beams, then routed a fillet along the top edges of the frame.
Touching it up with a plane.
I routed a light chamfer around the frame to break any sharp corners.
I cut a small aluminum tube to sheathe the bolts used for assembly. The thought here is to prevent the bolts from digging into the frame, as well as allow them to turn more freely.
This was almost a disaster. If I’d made it about 1cm longer, it would not have physically fit into our flat. Thanks to @unicornstrike for helping me move it.
Here it is prepped for oiling. Did two coats of Osmo Raw applied with a microfibre cloth. 24 hours between coats.
After the oil dried, here it is with the rails and slats screwed in.
Mistakes
One of the beams on the back frame was a few mm narrower than the others. This would’ve caused problems with getting consistent tenons using the method I used. To fix this, I glued on a strip of scrap sapele and sent through the thicknesser to get to the correct size.
While routing an edge of one of the horizontal beams in the leg assembly, I accidentally clipped the edge as the bit was winding down (don’t do that!). I cut the chewed up bit out with the router, glued in a piece of walnut and planed it flush. You can also see the chewed up end of the beam from the router table.
I didn’t have the best setup on the spindle moulder for making my tenons; the extension guide I screwed on was flexible. This meant that a few of my tenon cuts were a couple mm out. All but one of these gaps were either internal or small enough I could fix with a chisel. However one was on the front of the front horizontal beam. The easiest fix was to glue in a scrap of veneer, then break it off.
