This post appeared on the original Woodhaven site, and I'm reposting as I've been told that a number of readers found it useful.
After lots of requests for help, here and elsewhere, on the practicalities of making my own external bifold doors I finally made a decision to go for it last autumn. This was primarily after having a quote for £9500 for 2 sets of 3 bifold doors, supply only. The ones in the showroom were admittedly very nice - but £9,500? Plus fitting? Then I went to see some that had been made locally in a neighbours house. When I looked at them I was not impressed and thought that I could do better. The decider came when he said that he had been having problems with them and when I suggested that he call the manufacturers back in under guarantee he told me that it was worthless as they had ceased trading within weeks of the installation.
I had already shown an interest in the laminated approach to door making as described by Keith Smith, and had a practice making a new back door, as shown in this post. This seemed to be pretty painless so became the basis for my bifold door build to fit in the space shown in our new kitchen extension.
I started with the frame. These are big chunks of iroko and were not easy to manage on my 8” table saw, so I invested in a Festool TS55 track saw. Brilliant piece of kit, although strictly speaking the TS75 would have been better for ripping 50mm iroko. I started with the threshold into which a groove has to be cut for the base track, using the router table.
To cut the slope for the sill I made a simple jig which attached to the thicknessing table on my SIP p/t. Initially I tried to hold it in place with clamps but found that to be a hopeless task. Fortunately the SIP thicknessing table has a “lug” at either end with a hole in it so I bolted the jig to these as shown. It was now rock solid ...
...... and the way the slope on the sill is cut is clearly shown here
And the slope can be cut in easy stages until it is jsust short of the base channel.
Here is the door head and sill dry fitted and ready for a glue up, having remembered only just in time to cut the groove for the Aquamac 21 door seal first!
The jambs are made from 175mm x 45mm solid iroko and, again, are hefty pieces of timber to surface plane and thickness using my 10 x 6 SIP, but with a roller stand fore and aft and some running about we had a workable system. Now time to try a dry fit.
The finished frame is 2600mm x 2175mm so it’s not the sort of thing you can assemble in the average garage, so yet again I worked outside. Initially trying to get the frame square with the sill and head was a nightmare and I tried all sorts of methods using spirit levels and a bevel box held to a post with a clamp, as shown here.
Then I scribed the angle of the sill onto the jambs ...
... and it fits quite nicely.
However, I found the whole process a “bit of a faff”, so when I made the second set of frames, I simply used an offcut from the sill, held it square with the jamb using a set square and just scribed the lines for the cuts onto the jamb. So much more simple, and the end result was just as good.
The joint with the top of the jamb didn’t involve any angles other than 90 degrees so they were simple. So, now I had 2 sets of frames which were stored away until they needed to be assembled prior to fitting. Just as well we have a couple of spare bedrooms.
So now for the doors (x6). These were laminated up from 3 layers of 100mm x 20mm iroko. I wanted the internal faces to have chamfered edges where they meet the glass and I dislike the “routed out” look that you so often see where a hand held router is simply run around the inside edge of a square frame, so this involved cutting the chamfer prior to assembly.
First I ran the edge of the first layer past a cutter on the router table until it was just short of the 45 deg line I needed for the corner of the chamfer.
Then I cut a piece of scrap at 45 deg using my SCMS and held it onto the side of the workpiece with a clamp and trimmed the face using a razor saw.
Having done this for all 4 pieces they fit nicely and are “indexed” with a 6mm domino. Not strictly essential I guess, but when you’ve just invested in a “dom” you find any excuse to use it!
A word now about accuracy. The tolerances on bifold doors are quite tight. Not only do they have to be absolutely square, there is also little room for error on the dimensions. I’m making a set of 3 doors. The gap between each one is 4mm and this is dictated by the size of the hinges which are surface fixed. This is therefore not adjustable after the event. The clearance at the jambs is 7mm, and the only adjustment possible is on the attachment hinges for the first door at the jamb which enables you to move the door along the frame left or right by a few mm. All 3 doors have to be exactly the same if they are to fold back squarely, so it makes sense therefore to assemble each door on the same jig. I chose to make each door 1mm wider than the precise figure calculated to allow for a final trim when complete.
Whilst it would make sense to assemble the first layer face down so that the next layer can be glued on top, I wanted to be able to see that the corners where the chamfers meet had pulled in tightly, and I couldn’t be certain unless they were visible - and so this is why I chose to assemble the first layer face up. Here it is after gluing and after the clamps have been removed. The new kitchen is making a useful assembly area.
Then lift the first layer up and turn it over - it should simply drop back into the jig precisely - after all we have made it accurately haven’t we? Weather starts getting cold now so I’m able to get away with continuing the glue ups in the dining room. Here’s the next layer going on.
These doors are clearly going to be heavy, and they’ll have to carry 25kgs of sealed unit. I decided that rather than rely 100% on the glue (TB3) I would drive 30mm stainless steel screws through layer 2 down into layer 1 to strengthen the corners. The screw heads will be hidden by the 3rd layer and they’ll never be seen again - or will they - watch this space. But I digress - here’s what I mean.
Now for layer 3. I’ve cornered the market in Axminster F clamps. I now have about 30, and if I had more I’d have used them.
One door down, only 5 more to go! The frames had been stained and treated with Sikkens Filter 7 ready for storage, and now it’s time to assemble them. These have to be square to within +/ – 5mm across the diagonals - I managed +/- 1.5 mm which I’m well pleased with and once assembled attach a diagonal brace from corner to corner to hold everything square. Time to install them in position.
The frames are suspended from the flitch beam with a piece of stainless steel threaded rod at each end and in the middle which goes right through the beam. This enables me to fine tune the fitting with a spanner from the top. Packing pieces are put between the frame and the beam where necessary so that it is held tight to the beam. Then the intermediate positions are attached with stainless steel coach screws. The side is attached to the galvanised steel post with 5 hefty self tapppers.
The frame has to be precisely vertical if the doors are to slide nicely. I decided that a plumb line would be more accurate than a spirit level, so made a little “carrier” that sits in the top channel ....
.... and the plumb bob is aligned with a line drawn on a piece of tape that is 18.5mm from the centre of the bottom channel. This ensures that the doors will hang vertically
.
Next the doors are hung. I left these unfinished as I thought that they may need a little “fettling” to make them fit. Having made each one 1mm over width I took a final measurement from the installed frame and them trimmed each one to size using the TS55 and a guide rail. The finish from the 48 tooth blade is so smooth that it is ready for sanding. I’ve no photos of the installation of the doors as both SWMBO and I were needed to fit each one, but here they are, fitted but unfinished.
The sliding action is just beautiful, and having taken a lot of time to ensure accuracy they fitted without any adjustments being required. Time to take them down again for finishing.
The doors are held closed with a recessed bolt. The slot for them was cut using a router up against a straight edge.
And “bingo” - we’ve found those hidden screws again!
Fortunately, although I hadn’t anticipated this at the time I made the doors, I did spot the problem before I cut the recesses and used an old cutter, and increased the depth of cut with 2mm increments and it barely noticed it, although it’s taken the edge off the cutter!
I had originally planned to glaze the doors before fitting, but I felt that the weight would make them too unwieldy at 45kgs per door, so elected to rehang them unglazed and then glaze them in situ. Two of these were invaluable.
Here’s the end result, with only the posts waiting to be clad in wood.
The sliding gear is Centor E3 top hung, which came in at about £500 per set of doors. Glazing was £550 in total for Planitherm Total+ with Argon fill. Iroko was about £1200 as far as I can tell as it was part of a larger order to include the windows - tho’ that’s another story. Locks/handles etc came to £260. Add in sundries like Sikkens, glue etc and the final bill was i.r.o. of £3200 for 2 sets of bifold doors, fully fitted, so a saving of £6,300 plus fitting. I’ve not included the purchase of a TS55 or a Domino in the costs - but these are toys that will serve me for many years.
Why did I choose to laminate? Several reasons really. I don’t have a spindle or a morticer. Also iroko is a b***** for movement and I felt that laminations would be more stable in the long term. Obviously if you had a spindle you’d probably use it! What I set out to achieve was a major cost saving and a better end result than I saw locally. Also I like a challenge - and it was a very time consuming project - but also very satisfying. Do not under estimate the time you’ll need, or the space that is needed to assemble and store all the components - although not everyone will be making two sets of doors simultaneously.
.............and just to prove that these are "foldy slidy" rather than "sticky binding" here's a quick video of them in action!
https://youtu.be/sFW7Ln61XeY
Anyway - if you’ve got this far - thanks for reading, and I hope it’ll be of some help to anyone else tempted to have a go. Finally a huge thank you to Keith Smith (Woodsmith) who provide lots of advice as well as a copy of his magazine article on laminating doors, and to jonnyd whose post on foldy slidy WIP provided some much needed inspiration. Thanks Jon - you’ll have noticed where I pinched some of your ideas.