Lynn Kasdorf
03-24-2005, 3:42 PM
Well, on my barn fixup project I'm getting into some real timberframing. Last weekend, I cut scarf joints on 2 6x8x15' white oak timbers. I made a template out of 1/2" birch ply screwed this to the side of one timber at the end where the splice goes. I hogged out the bulk of the wood with my prazi chain-saw beam cutter on a skil worm drive saw.
Then I used a top bearing pattern bit in a router to cut exactly to the template. Repeat this on the other side of the timber. Then, lots of chisel work cleaning out between the 2 sides. Then, repeat for the other timber.
Fitting these things is a real bear. Since each timber weighs something like 400lb, you don't just pick them up and shove them together. I picked up one piece carefully with my skid steer and forks and gently maneuvered it into position. Then, I pull the joint together with come-along and chains.
Of course, the joint needs refining- I kerf the joint with a hand saw. Pry the thing apart with a big pry bar, remove wood here and there with a chisel. Pick up with the skid steer and try again. Repeat about 3x. You get the idea. Pull the whole timng together, run a string from end to end to verify they are lined up, then drill and peg the joint.
This weekend I'm cutting 8x8 white oak posts with big tenons on the top that go into mortises on the beam.
I'm planning to cut the 8"x2" through-mortises with a router, a guide bushing and a template. I have a 1/2" diameter straight bit with a 3" long cutter. I bought this at a woodworking show from one of those no-name $5/bit vendors, and I've never seen another that long. Perhaps it is too dangerous because you could easily over stress such a long cutter and break it off- I don't know, but it has proved very handy.
I figure I'll cut as deep as I can go from one side, then mount the template on the back side and go as deep as I can. Then drill and chisel out the remaining in-between wood. Obviously, I'll have to take these cuts in many passes of ever increasing depth.
The posts get pegged into the beams, then the spliced 22' long beam with 3 posts will get lifted into place with my backhoe and forks and some sturdy helpers.
Working with these huge timbers is challenging, but really fun, and a great excuse to buy more tools (beam cutter, huge chisels, etc).
I'll post pics tonight.
Then I used a top bearing pattern bit in a router to cut exactly to the template. Repeat this on the other side of the timber. Then, lots of chisel work cleaning out between the 2 sides. Then, repeat for the other timber.
Fitting these things is a real bear. Since each timber weighs something like 400lb, you don't just pick them up and shove them together. I picked up one piece carefully with my skid steer and forks and gently maneuvered it into position. Then, I pull the joint together with come-along and chains.
Of course, the joint needs refining- I kerf the joint with a hand saw. Pry the thing apart with a big pry bar, remove wood here and there with a chisel. Pick up with the skid steer and try again. Repeat about 3x. You get the idea. Pull the whole timng together, run a string from end to end to verify they are lined up, then drill and peg the joint.
This weekend I'm cutting 8x8 white oak posts with big tenons on the top that go into mortises on the beam.
I'm planning to cut the 8"x2" through-mortises with a router, a guide bushing and a template. I have a 1/2" diameter straight bit with a 3" long cutter. I bought this at a woodworking show from one of those no-name $5/bit vendors, and I've never seen another that long. Perhaps it is too dangerous because you could easily over stress such a long cutter and break it off- I don't know, but it has proved very handy.
I figure I'll cut as deep as I can go from one side, then mount the template on the back side and go as deep as I can. Then drill and chisel out the remaining in-between wood. Obviously, I'll have to take these cuts in many passes of ever increasing depth.
The posts get pegged into the beams, then the spliced 22' long beam with 3 posts will get lifted into place with my backhoe and forks and some sturdy helpers.
Working with these huge timbers is challenging, but really fun, and a great excuse to buy more tools (beam cutter, huge chisels, etc).
I'll post pics tonight.