So the time has come around again for our Continuous Arm Windsor Chair Class at the Melbourne Guild of Fine Wood Working. Alastair and I have been teaching this class for a few years now and have put an enormous amount of preparation and time into it, but what never ceases to amaze me and impress, is when a student comes up with something else to improve the process.
We have had people from all walks of life come and make chairs with us. Teachers, solicitors, dentists, and carpenters, vets and Doctors, and even a few other furniture makers looking for a change in pace and its that sort of cross section of the community that brings fresh ideas and approaches to the chair making process.
Some of the ideas are interesting and others so simplistic in their answer to the problem at hand that you wonder how you could have possibly not thought of them beforehand. Today for example there was a 2 minute adjustment to a drilling jig that made sighting and alignment a breeze. Followed by a suggestion on how a small change to our 6 degree reamer could almost eliminate the need for sighting lazers.
I guess sometimes you cant see the wood for the trees ( or chair legs ), but it's this continuous improvement and working out solutions to make us better at our craft that I enjoy about chair making and wood working in general. Add to that, sharing of ideas and advice and it makes for a happy experience all round.
So with that thought in mind it's my turn. Now this isn't ground breaking stuff by any stretch. But when it comes to solving a small problem that always seemed to catch out at least one or two students every class, this one is a simplistic beauty.
After drilling the mortises in the legs of windsor chairs the side and centre stretchers need to be measured, insitu, including the exact distance into both leg mortices. Now while this is not brain surgery it does require accuracy and measuring a distance between two internal surfaces and if to be really accurate, inside the mortices of those internal surfaces. So that rules out ( excuse the pun ) tapes, most rulers and even the wooden fold out rulers with the slide out extensions.
Previously we had used a couple of steel rulers, one large and the other a small 6" steel rule that would fit into one mortice hole. Then there would be some adding of measurements plus the extra mortice that the large ruler didn't fit into etc etc. Suffice to say there wasn't a simple solution. By the time that final measurement was transferred to the stretcher there was usually one or two mistakes, usually in the addition phase and the stretchers were cut too short. End result, wasted stretchers, new stretchers to be turned and plenty of time wasted. So...
Bar head gauges. Made by Veritas they are a simple brass and plastic fitting that you add some fine timber beams to, to make a sort of adjustable 'story stick.' I think they are made mainly for checking the square-ness of drawers etc. But for our purposes I make the beams so that they are about 40mm longer when fully extended than the usual length of a stretcher. The ends are then tapered to slightly less than 5/8", the standard mortice size. I then measure the exact overall measurement of the gauge when closed. I then mark on the face of the gauge 'mm' increments starting with the closed measurement. So in this case starting at 280mm and through to 410mm.
To use it, simply loosen the knurled brass locking nut, extend the gauge into the mortices on both legs until they bottom out. Then just read the accurate measurement on the gauge. Better still, if the gauge does not rotate smoothly inside each mortice hole then it means that your legs are not located in their correct alignment. When the legs are adjusted the gauge will rotate smoothly and you've got guaranteed aligned legs too. We haven't lost a stretcher since and they are 'mm' perfect.
Provided you've marked the increments accurately on the gauge you now have an accurate measurement gauge, no adding, no more balancing two rules and a nice tool to add to your chair making kit too! Make the beams out of something nice too. There's a bit of birds-eye maple in this one. I'll post a photo of them in use when we use them this Thursday. Cheers.