Taming twisted baords

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Taming twisted baords

Postby WNC_Ed » 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.
twisted 1.JPG
Three boards laid out before gluing
twisted 2.JPG
Saw Sled
twisted 3.JPG
After glue up
twisted 4.JPG
Shimmed the slab on the CNC bed
twisted 5.JPG
After 1st pass - this one needed 2 passes to get it flat
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Re: Taming twisted baords

Postby gkas » Fri Feb 01, 2019 9:51 pm

+1. On planing boards.

That's also why I decided I don't need a jointer. I clamp the boards down, set zero to the spoil board, and get the spindle close to the board edge. Then I pencil the edge, turn on the spindle, and manually make thin passes with the controller until the edge looks good. For as little as I need to joint stuff, this works great. I don't even have to mess with the table saw.
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Re: Taming twisted baords

Postby scottp55 » Sat Feb 02, 2019 3:51 pm

Glad you shimmed the first side correctly:)
Once you have a true face on your spoilboard, you've got it made!
A lot of people just clamp it down, and of course when unclamped it will spring back, and muck up your second side as well.
Just going to post this Shopbot vid of flattening log slabs, as he goes into that;
Oh...WAS looking for his "Flattening a warped Board" tutorial as it was more relevant...but it was missing from New Shopbot training vid site:(

Yup, pretty soon you'll be going through cutoffs,short bins, and even firewood piles like me :D
You'll never pass a tree crew,woodpile, or furniture out for trash without at least glancing at it:)
FIREWOOD 2 3 4 5.jpg



Look at how well your Project turned out with "Rejects" :D

A lot of people pay through the nose for S4S dimensioned wood, when if time isn't the most crucial factor(hobbyists like me now), you can do a better, more accurate job on your machine.
Thanks for posting!!
"Never time to do the job right the first time,"
Always time to do it again.
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Re: Taming twisted baords

Postby WNC_Ed » Sun Feb 03, 2019 2:51 pm

Thank you for sharing the video Scott, that makes me want to take the chainsaw out to the log pile.
I wish I would have seen it before, the ramping in from off the edge makes total sense.

Gkas, I may be giving your jointer method a try - thank you for sharing.
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