Thursday, April 19, 2012

61, Joinery, part four, Window sash preparation.

The tedium of assembly line work has reached new levels with the commencement of the sash construction. 23 window frames equals 46 sashes equals 92 stiles and 92 rails equals 184 wedged, mortise and tenon joints!

The mouldings and rebates I machined on my old home made router table. It has performed a massive amount of work over the years and the table top is almost past it's "use by" date, hence the extra sheets of Masonite to stiffen up and true the surface!
I had originally formed a 12mm deep, glazing rebate in the sticks before I stacked them away, this being more than sufficient for single glazing with plenty of room for beading's. The finished thickness of the sashes was 42mm and with a 12mm moulding on the inside, 16mm was left in the centre for the joints. In more recent times, however, I have been considering the inclusion of double glazing. Despite being over regulated in most aspects of building in this part of the world, we still have no requirements for this "luxury", it's just a "nice to have" item. Unfortunately, standard double hung windows don't readily lend themselves to being double glazed. Their future conversion, once assembled and balanced is also a job that I would not wish to tackle.
I carried out some homework and researched a variety of insulated glazing systems. One method I came across, that can be found here; superspacer, seems feasible. The product is distributed locally, (well, within 200km!) and is available down to 4mm in thickness. It doesn't require any special machinery or tooling to assemble the units and seems reasonably priced.
Some years back, shortly before my Father-in-law retired from his position at Pilkington glass in North Geelong, he was able to procure for us a large supply of 4mm thick glass for a fantastic price. I took delivery of  of more than enough pieces for my needs and stored it all away in a sealed case, ready for this stage of the build. Using this glass and the 4mm superspacer, I could theoretically make 12mm thick, sealed units. This is not an ideal insulation solution, but it would certainly outperform any single glazing.
I toyed with the idea of increasing the rebate depth in the sashes to 16mm, they would then have enough room to fit these units. Very little space is left, however, for beading and I will need to rely on a bead of sealant to keep everything in place. I may need to do some more investigating on that.
I have opted to start heading down this path and ran all the pieces back over the router table to deepen the rebate. This then had the effect of reducing the joints to 12mm in thickness which, I figure, is still quite acceptable. The drawback of this action, however, meant that the joints would need be formed "off centre", creating more headaches with their construction.

My 'cheapie' chisel morticer, an invaluable tool for this sort of work. I have improved it considerably with the provision of a new base incorporating a two way, cross slide vice. To minimise "breakout" I cut the mortice's from both sides. The stiles did however, suffer a certain amount as, when drilling the first holes from the face, I set the depth stop a bit too deep, resulting in some splitting occurring on the outside. The mortice's were cut at 90deg. from the face, with the angled block being used when doing the back cuts to enable me to form the wedge shaped holes.

Stage 1 taken care of... 92 stiles with their mortice's complete.

Next on the agenda was the rails. I am currently the proud owner of three spindle moulders, the second two bought because each was better than what I already had and was offered for a "good price". At this stage, neither of the better two have been converted to single phase operation. The last bought machine, seen in the above photo, incorporated a slide groove in the table top and I opted to use this for the machining of the tenons.
The first thing to be done was the fitting of a router. The original spindle, which I had removed to lighten the load when bringing the machine home, was still separate. I turned up a new table insert to suit the router cutter, drilled and countersunk holes in it to align with tapped holes in the router base and then used this to clamp the router below the table.
That sorted, I knocked up a sliding table. This incorporated two separate right angle guides, each providing a different depth of cut, the price to pay for having offset joints. A fair bit of fiddling was required here, with various shimming sizes trialled until a balance was achieved for the two different shoulder depths.
To add to the headaches, a combination of 3 different window heights and 7 different cill lengths led to a total of 11 different window sizes.

Stage 2 over, the tenons complete. The meeting rails, in the foreground, were particularly fiddly to machine. The joints being partly cut on the bandsaw to allow the splayed edges to continue over the faces of the stiles.

Back to the stiles. The final thing to be completed, before assembly could be commenced, was to cut and sand the horns. There is a myriad of shapes and designs for these and indecision on my own choice was the reason for this being left until last.
I had scoured through all of my photo's and took a number of detours during my travels to identify as many different patterns as possible. I shortlisted my favourites and cut samples on some scraps. On presenting these to my wife, her choice actually matched mine when she selected the simple ogee, the same as on my original windows!. A couple of days of bandsawing and smoothing on my bobbin sander and the stiles were ready to go.

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