Taming twisted baords
Posted: Fri Feb 01, 2019 8:32 pm
There have been some lumber related posts lately and thought I would share my recent experience with taming some twisted lumber. I am not saying I did this the easy way or the correct way just saying this is how I did it and it worked out pretty well.
The back story is that I walked into the locally owned lumber yard a couple/few years ago looking for some straight grained oak boards. There was a pile of big white boards in the middle of the floor and of course I had to ask; “what’s up with this pile?” turns out that a contractor had special ordered True 2x8 – 12 foot long cypress boards for a specific project and rejected them when they came in. I asked, “how much for the whole pile?” and was told $200 to which I said, “if you help me load them, I will get them out of your way”.
Brought them home, stacked them in the “lumber area” of the garage and used a few here and there but mostly have been working around them for years because remember they are rejects. Most of the boards were cupped, some cupped and twisted. As a hobbyist, I just don’t have the big machinery to get these to a good usable state.
Recently I needed some beefy lumber for the “Upsized Cubby project” and although I thought about sourcing some hardwood, I decided to raid the “cypress pile”.
In the first picture I had just laid the 3 boards I needed out to find the best fit for the three.
I whipped together a table saw sled out of some scraps to run these through the saw to get a gluing edge. My strategy was to try and get the saw cut perpendicular to the average flatness of the board then turn the board around (not flip it) and use that side to run against the fence to rip a second gluing edge.
Once all three boards were ripped, I edge glued and clamped them as flat as can be reasonably expected.
Since these were true 2x8 boards or 8/4 boards for the guys that speak in board feet, I am totally ok with losing a little thickness to get flat slabs.
Next, I tossed the slab on the CNC and set up a 1/16th inch deep surfacing toolpath sorta the same as spoilboard surfacing. The slabs were heavy enough that I didn’t need to clamp them down, just clamped boards against all four sides to keep them from moving. On a couple of the slabs they were so twisted that I had to use shims to get them to lay solid on the bed.
After running the surfacing pass on one side, I flipped the boards over and ran it again on the other side. Most of the slabs – there were five in total, came out flat and true after one pass on each side. The slabs that needed the shims originally had to be run through the process twice, the second time with no shims required. So, that means a couple of the slabs are 1/8th inch thinner than the others, but for this project they are mounted 4 feet apart with rounded over edges, so I challenge anyone to “see” the difference.
While this may be old hat for some of the long time CNC’ers, this was a very eye-opening experience for me. It has totally changed the way I will look at lumber. What I would have previously considered scrap wood may now be bargain lumber.
I hope this is helpful to someone.
The back story is that I walked into the locally owned lumber yard a couple/few years ago looking for some straight grained oak boards. There was a pile of big white boards in the middle of the floor and of course I had to ask; “what’s up with this pile?” turns out that a contractor had special ordered True 2x8 – 12 foot long cypress boards for a specific project and rejected them when they came in. I asked, “how much for the whole pile?” and was told $200 to which I said, “if you help me load them, I will get them out of your way”.
Brought them home, stacked them in the “lumber area” of the garage and used a few here and there but mostly have been working around them for years because remember they are rejects. Most of the boards were cupped, some cupped and twisted. As a hobbyist, I just don’t have the big machinery to get these to a good usable state.
Recently I needed some beefy lumber for the “Upsized Cubby project” and although I thought about sourcing some hardwood, I decided to raid the “cypress pile”.
In the first picture I had just laid the 3 boards I needed out to find the best fit for the three.
I whipped together a table saw sled out of some scraps to run these through the saw to get a gluing edge. My strategy was to try and get the saw cut perpendicular to the average flatness of the board then turn the board around (not flip it) and use that side to run against the fence to rip a second gluing edge.
Once all three boards were ripped, I edge glued and clamped them as flat as can be reasonably expected.
Since these were true 2x8 boards or 8/4 boards for the guys that speak in board feet, I am totally ok with losing a little thickness to get flat slabs.
Next, I tossed the slab on the CNC and set up a 1/16th inch deep surfacing toolpath sorta the same as spoilboard surfacing. The slabs were heavy enough that I didn’t need to clamp them down, just clamped boards against all four sides to keep them from moving. On a couple of the slabs they were so twisted that I had to use shims to get them to lay solid on the bed.
After running the surfacing pass on one side, I flipped the boards over and ran it again on the other side. Most of the slabs – there were five in total, came out flat and true after one pass on each side. The slabs that needed the shims originally had to be run through the process twice, the second time with no shims required. So, that means a couple of the slabs are 1/8th inch thinner than the others, but for this project they are mounted 4 feet apart with rounded over edges, so I challenge anyone to “see” the difference.
While this may be old hat for some of the long time CNC’ers, this was a very eye-opening experience for me. It has totally changed the way I will look at lumber. What I would have previously considered scrap wood may now be bargain lumber.
I hope this is helpful to someone.
