Reproducing an old bow window

[johnnyb]

Thought I detail the reproduction of an 1900 bow window. It's an odd beast as it's the only window in the house that's like this and was a show window. Most other windows were venetian sashes with a single 45 degree bay. It was basically a flawed design having a lead roof that didn't protrude far enough to protect the transom which was a poor design having a nailed on moulding almost designed to trap water. After taking plenty of measurements and patterns I had a fair grasp of what was needed.
The last photo is of next doors identical window.

 

[johnnyb]

Now the radius was basically 9 foot and circular work always requires accurate patterns to be made and I rigged up a long router compass to make the pair of patterns one for the head/transom(3 1/4)and a wider one for the cill (6 1/4) I normally drill a 30mm hole and use a guide Bush.

 

[johnnyb]

The first photo is the templates or more accurately half templates as the window horizontals were split into 2 parts centrally. The second photo shows sections of the frame members. The cutouts in the back of the frame members are to locate staff beads used as a water bar behind the casements. The horizontals having curved fronts but the backs being straight to seal against the casements

 

[johnnyb]

Anyone whose made old windows knows the timber sizes can be very large. For instance the depth of the frame section was 3 1/4 inch which requires 4×9 sections for the outside frame uprights(I ended up using 3×9 and gluing a 22mm bit on as 4×9 isn't the easiest section to find )
The head and transom half's could just be got from a 9×3 using a single saw cut to separate. The cill was a good fit in a 9×3. These were bandsawn just off the line so they could be pattern cut on a bearing on the spindle.

 

[johnnyb]

When selecting redwood for normal windows and doors I select the deals that are mostly heartwood and those can often have pith unfortunately this wasn't possible as I would be using the whole width. Normally I'd only be using half(so could saw down the pith and lose it when planing) having the option to sort through 15 or 20 allows you to find the better ones. I've also used 3 inch instead of 2 inch to make doors if it gives most heart. There's a lot of wood in these about 12m 9×3 and 6m 9×4. Plus 1 inch par to make the internal staff beads (12 curved 12 straight) each 9×3 was £56. I can get it cheaper but I prefer to pay more and select. Total timber costs are maybe £300. I dread to think what timber costs would be in accoya! And the weight in hardwood would be crazy. This is another reason I love pine, my machinery isn't the most heavy duty and whilst it can work these section it wasn't built for it. Sapele can be really heavy(it's not just my machinery I'm not as heavy duty as I was!)

 

[johnnyb]

The first pictures shows the half template set up to lines squared on on my bench at 7 foot(overall width) 3 foot 6 inch(overall width of half cill)
And probably the most important measure 325mm for the depth of the chord this was marked on the centreline. It's important because it's the measure that makes the window fit. The radius doesn't need to be a perfect match. The second pic shows how the frame section look on the cill. The final photo shows the fixed positions of all the frame members on the transom/head and the cill patterns.

 

[johnnyb]

So I'd bandsawn these slightly oversize so what remains was to pattern cut the large chunks on the spindle. I use an 80mm spiral cutter from wealden with a bearing. This turned out to be fairly straightforward and passed without issue but I was so busy focusing I didn't take any snaps! I did get one of the pile of bits including a compass plane I used to dress the inside curve a bit.

 

[johnnyb]

Now in my poor demented mind having done what I considered to be the "hard bit" I thought that was easy of course I was nowhere near half complete. I began to machine up the straight verticals the outside ones were an interesting shape derived from the angle the bay sat in relation to the wall. The transom and the cill were pitched at around 6 degrees to shed water. How was I going to achieve this I pondered if I could do it by tilting the spindle on the ring fence...to dodgy. Eventually I figured the drop at the front required the put a rebate to that point as a guide I also marked the flat bit that needed to be in line with the mortices. I then used my power hand plane to lose the bulk then finished with a jack! Actually real simple if not as perfect as spindle moulding. I'd also morticed the curved bits. A task not helped because the cill only just fitted in the machine. That's 16 mortices all placed according to a single half rod marked on one side then the marks transfered over to the other using a square so it could be flipped over.

 

[Jacob]

Looks good!
An odd beast as you say.
I've done several of the normal 3 bay bay windows, but not bowed.
Nearly got the job on a Georgian shop bow which had curved timber and curved glass to match but mostly missing and replaced by flat. Had to research the bowed glass and found it could be done to order but not cheap, unsurprisingly. They went for maintenance and repair instead.

 

[johnnyb]

Here's a video of the frame mostly complete. Next it's all the casements. Which thankfully are straight!

 

[johnnyb]

The casements were relatively straightforward if not quite time consuming to make in particular the 6 pane ones. I ended up using that cogged joint on the glazing bars. These needed a tunnel to stop them chattering as there quite small. The importance of size and marking can't be overestimated when making this.
I glued the top of the frame up then shot the casements in(of course the sides were angled at 7 degrees)

 

[johnnyb]

I made a curved base for the belt sander to allow the sanding of the inside curves which worked really well.

 

[johnnyb]

Just to reflect on this(I haven't fitted it yet) the scary bit before doing it was pattern cutting on the spindle and moulding on the ring fence. But these turned out to be straightforward operations on the whole. The hard bit was getting all the aspects in the right places. Also the sizes of the components made handling a challenge. I ended up "putting right" some of the fudges that were made in the original. The curved staff beads were made deeper in the original as when they were made at 7/8 ths they were to thin across the centre(these were made at 1 inch). The side rebates were left at 7/8ths leaving a large gap. I made the sides an inch meaning I had to reduce the size of the front beads slightly so the casements would not stick out.
The plant on mould on the transom I've just left off.

 

[Ollie78]

Nice work, I remember having to do some bow shaped 8 over 8 sliding sashes, there was some head scratching to get that right.
I quite like this sort of job once in a while keeps your brain working.

Ollie

 

[johnnyb]

I always figure its like a jigsaw and when you get everything right boom look at that it's just the same. As oppose to imposing your style window on the house. Which ventrolla did with dire consequences. Never seen such poor work.

 

[johnnyb]

BTW the vintage compass plane worked OK. It just didn't smooth the surface enough only having limited bearing. The stanlel ones must be superior in that respect. The ward iron was super.

 

[Ollie78]

I always figure its like a jigsaw and when you get everything right boom look at that it's just the same. As oppose to imposing your style window on the house. Which ventrolla did with dire consequences. Never seen such poor work.

I used to work for them many years ago. Some guys were actually good but equally some were proper cowboy idiots. Its a franchise so very dependant on where you live what quality of work you got. Our original boss retired (a top bloke) and sold the franchise to the neighbouring one ( a rat bast*rd ).

 

[johnnyb]

To insure against rot waterlogged I'm gonna show how to impregnate the cill with epoxy(clear penetrative epoxy sealer) first finish shaping and sanding the cill and vac the dust off.
Mix the epoxy 1 to 1 (more than you think as it disappears) then liberally apply on to the item. Leave it the apply again and again. Once it gels then leave to penetrate. Only use on bits that are badly exposed(cill in this case)
After 24 hours(more if colder) then paint the finish of your choice straight on top. So this is after the solvent has disappeared but before it's cured. That way the epoxy and paint bond together giving a great primer coat. It works with most paints as long as the solvent has gone.

 

[johnnyb]

Here's the wet cill before full penetrative.(oh err)

 

[Jake]

To insure against rot waterlogged I'm gonna show how to impregnate the cill with epoxy(clear penetrative epoxy sealer) first finish shaping and sanding the cill and vac the dust off.

Which epoxy do you use for that Johnny? I've done similar in the past but for different applications (a reeded mdf edge which seemed a bit fragile, and some exterior bendy ply) but kind of improvised using normal West stuff I had in stock and their solvent so not really ideal).