I just got back from an intorductory Timber Frame workshop at Foxmaple (foxmaple.com). I really learned a lot. The first day was in the classroom going over design, trigonometry, joint design etc. Then inspected our timbers for our project. We looked at the characteristics of the timbers, marked the crown side of the timbers and did a preliminary determination of where each would be used in our frame design. Our design was 4 bents. 3 of the bents spanned 24 ft via king post trusses. The 4th bent spanned 20 ft and was a hammer beam. Once we had evaluated our timbers, we set up cribbing and layed up the timbers in bent order with posts, then king post, then rafters. The tie beams for bents 1-3 were cribbed outside of the shop due to their length. We then discussed layout techniques. First we started with pencil to determine if any bad knots were in the way etc. We learned how to check our squares and tape measures. The preferred tape was a 25 foot Stanley. When laying out, we always used the 10 inch mark to start and not the end of the tape. The end of the tape could be used a sanity check before scoring, but is generally not going to be as accurate as the 10 inch mark method. If our preliminary layout on the timber showed a mortise or tenon located on a defect, we could then re-lay it out shifting it down on the beam. Once we were confident, we then did the layout again, this time marking with a tile knife by making tick marks. These ticks are definitely more accurate than the fat width of a carpenters pencil which could cause you to be off by a 32nd or more. Another thing I forgot to mention is that we determined which faces would be out outside faces (reference faces) and marked them big in crayon. All measurments were based upon these faces. We scored all cut lines with the tile knife. By placing the kife blade in the tick marks and then butting the square against it, allowed for more accurate layout. We also tilt the knife to the cut or scrap side. this rounds over one side of the score. This allows you to place your chisel into the score line later when parring the final way, and there will not be any gap between the chisel and score line on the good side. This leaves a very sharp accurate edge on the face of your shoulder or mortise. We then learned good techniques for using a 7-1/4 circ saw, squaring the blade, adjusting the depth and cutting 1/16 to 1/8 away from your score line. We also used 13" and 16 inch beam saws to cut off ends of timbers. We first cut with the 7-1/4 saw, cutting both sides of the beam, and used the kerf on one side as our guide for the big saw. We also used the 7-1/4 circ saw to make cuts for removing the majority of material for our tenons. Then we used our chisels and mallets to chisel and pare by hand to our final score line. We learned technique for using the chisel to par a flat face on our tenons, shoulders, and mortises. I also learned how to sharpen my chisels. It's not that hard and you don't even need a holder as long as your main angle is already correct. It can be time consuming though if the flat face of your chisel is not flat. By mid of the 6th day we started fitting the bents together, tweaking some joints on the fly, and by the end of the day we had the frame erected on a temporary site. I learned a lot and cannot begin to convey it all here, and now feel confident to design and attempt my first timberframe. My photos from the workshop are at:
My timber frame workshop album (the first picture of the sketch was not part of the class).
Brad
