I would add three machines, firstly a spindle moulder with a power feed, a Morticer and a two or preferably a three headed tenoner. If you’re making windows with say a curved head you will also need a bandsaw. Buying secondhand Sedgwick or say SCM machines is a chunk of change, but once you’ve made your project all can be sold again with no loss and possibly a small profit.
The nice thing is that the design of windows has changed little and although ironmongery has been updated the principles of making windows remains the same. There are any number of excellent books on traditional joinery used for windows construction. What has changed is sectional sized and the need for one, two, or three draft excluders built into the openings. Standard cutters for the profiles needed for the draft strips are standard off the shelf and consist primarily of either wipe and or compression seals.
When making new windows there is a whole bunch of ‘rules’ about designing windows to achieve minimum u-values, trickle vents, etc etc. Then your supposed to either have building control or a FENSA approved installer fit them.
I wouldn’t use oak unless its on show ie not painted and is important for the character of the building (eg chapel) . I don’t see the value in Accoya and in preference would select traditional redwood, Sapele or Douglas fir for the frames and Sapele for the cills. All will take paint well and if properly maintained and built will last more than a lifetime. Again just me, but avoid water based paint like the plague. You cant burn it off and it allows water to get underneath whilst maintaining a nice surface allowing rot to start. With new windows you can paint it with Linseed based paint which reduces maintenance intervals, prolongs the life of the windows and is cost effective.
Now, this is my approach, and not a recommendation! If I were replacing a few windows in an unlisted house I’d make them without worrying too much about the regs. I’d select a design from researching different profiles (a lot of company’s publish their profile detail) to select one that I felt offered good draft proofing, fitted the aesthetics I was after and I could make without too much specialist tooling. I’d opt for triple glazing unless it was sliding sashes and install them myself. In a few years, nobody will be nay the wiser, the windows will be a huge improvement over what I’d taken out and if I were to sell the house I’d be leaving something I’d improved significantly over what I had bought.
