Reproducing an old bow window

[Fitzroy]

Great write up thanks, I'm about to rebuild a sash dormer window, and I'd always planed a rod for the sills but I'm going to steal the idea of the ply sections. The 'epoxyfied' sill is an interesting idea. You've also made me much more comfortable over my choice of redwood for the window.

F.

 

[johnnyb]

The epoxy is American smiths clear penetrating epoxy sealer. (Cpes).
Available in the UK of course. It's thin and does indeed sink in nicely even on new wood. Sash case parts are all sizes so decide on the sash thickness(40/45mm for single glazed/vac glazed) and work everything back bearing in mind the sizes of commercial staff/parting beads. I always find traditional sash joinery complicated and confusing and I don't make enough to make it automatic hence I've got one made up to refer to. It's much easier to add the meeting rail after(hence sensible to choose thicker parting beads)

 

[johnnyb]

The ply sections are basically the map to the window. As the sections end up exactly the same(as there a template on the spindle and a rod on the bench. Also the critical sizes were marked on the full sheet of mdf that's my bench so I've also got square references.

 

[johnnyb]

Thought I'd finish this of by showing how I cut the glass and put tied the casements.
This is all slightly arcane falling somewhere between witchcraft and legend as new single glazing is not at all common but the act is both slow and satisfying and the result pretty durable on the whole.
Any way the first pic shows tools required basically a sharpie, a straight stick, and a glass cutter.
Measure the opening then take 3 or4 mm of and aim to cut that size. This is to make sure it fits and isn't to tight. Mark the size on your glass. Now I was using old drawn glass I'd brought from Liverpool which was far from flat. But it's still simple to cut. The biggest issue is removing the paint/putty/scratched edge. Mainly because it's a narrow cut.(at least an inch) this means it's hard to get purchase for the break. I use a batten with a saw cut.
The next step is to mark the glass using a ruler and sharpie dots. Then get the glass cutter and line the wheel up with the mark. Then smartly score going forward and listening for an uninterrupted zipp. Just once. Trying to make it edge to edge. Then put a small rod of wood under the score and carefully put pressure on both sides. It should snap! With smaller pieces the rod isn't necessary tbh.

 

[johnnyb]

Next onto the face glazing. This is the term used for finishing with a putty fillet hand applied. I use toupret putty which is a slightly less messy whiter version of the traditional linseed oil and whiting mix of old.
This requires the rebate to be primed otherwise the putty can crack as the oil is sucked out. Although old windows rarely have primed rebates(old stained glass doors seem to have a dark shellac primer)
Start by removing a lump of putty and kneading it to warm it up and make it pliable and homogenous. The old traditional putty can be far from ideal out of the bucket.
Then start to press the putty into the back of the rebate. Finally smooth it forward so its an evening thickness.
My putty knife is basically a polished straight scraper with a fairly robust blade. The ones sold as putty knives are trickier imho. The polish and round is most important.