The Prazi Beam Cutter
(a new attachment for an old tool)
The Prazi Beam cutter is seen here with the Borneman Layout Template ("big Al") set up as a guide for an end of tennon cut.
Although it requires firing up the generator the Prazi can be a useful tool at times (it should see more use when it comes to stress skin panels). It's basically a 12" chainsaw blade designed to attach to a wormdrive circular saw allowing the saw to cut a large timber in a single pass. It's a good deal lighter than firing up my Stihl 066 and the foot of the circular saw will hold the blade at any angle the saw is normally capable of.
Here are the results of my first Prazi cut on the frame. The cut was made from the far side of the timber. In the picture below you can make out the remains of the layout line for the end of tennon, as you can see the blade exited the timber near perfectly on the line. The chainsaw blade cuts in an upward stroke pulling the foot of the saw snugly to the timber, there was some deflection to the outside of the cut as the blade crossed through the harder wood at the center. I suspect the deflection would be less in pine.
The chain on the Prazi is comes filed for crosscutting and leaves a rough finish. I had a hickory sill that needed a long rip cut for a scarf joint but quickly decided not to even try the Prazi. To date it's only produced a few end of tennon cuts.