Just some thoughts on sash templates and scribing that might help you Steve. I have studied this subject for many years, and carried out all sorts of experiments to work out how, or even if, these templates were used. It's my experience that possibly about 90 percent of the templates I have examined (probably running into hundreds) look to to have had very little, if any use. They do appear to have been around for a long period of time, probably from at least 1800, and possibly a bit earlier, so they were not rare. What is interesting to work out is if they were not using them, how did they form the scribes accurately? I'm sure they were firstly cutting a mitre, then using this as a guide line to cut the scribe. The problem area for them was how to cut the glazing bar scribe. In todays workshop it is easy, we can just use a coping saw, but coping saws don't seem to make an appearance in joiners kit until some time after about 1910. So what were they using to cut the scribe? I'm absolutely sure they used scribing gouges. This is easily done on the scribes between the rails and stiles, but when it comes to the bars it is not so straight forward. The cut must be supported to prevent breakout. There were special gouges produced with a built in wooden stop, but these are relatively rare. I made a discovery in an abandoned workshop one day that may shed light on at least one method used. Laying on the bench was a piece of 1" softwood which had a reverse profile of a sash bar worked into it. at one end, a screw had been used as a stop, and at the other end of the board was evidence of hundreds of marks where a bench knife had been driven into the other end of the glazing bar to hold it firm. I strongly suspect this board was used to support the bar while the ends were scribed with the appropriate gouge. I still have my grandfathers tool chest that was originally put together by a previous joiner in about 1870. it contains a set of scribing blocks complete with the number 1, and 2 sash ovolo planes, also a matching scribing gouge. It is interesting to note that the planes, and the scribing blocks appear to be virtually unused, while the scribing gouge has seen what looks to be many hundreds of hours use. I cant help but feel the scribing templates were mostly a tool merchants sales ploy, and experienced old time joiners just used the methods they had refined over a couple of hundred years.