We posted a short video flattening some walnut and
got a lot of questions there about how to set this up on the CNC with a cupped or twisted board.
So I figured I’d go into that setup a little more on this video. Basically I’ve got these
walnut pieces sitting here, and cut off the piece that I didn't need.
I’ll save that for a
future project. You can see how bad this piece is cupped. There's also a bit of a twist to
it and I’ll show you how I deal with that. So we'll take it over to the
bandsaw and rip it down the middle, as removing the material like this would remove
way too much and leave me with basically nothing. Bandsaw works perfectly for this because it
doesn't pull the pieces like a table saw would or bind at all. So it doesn't really care
about any of that.
So now we're left with two boards and you can see just how much
material was saved there. But we still do need to deal with that twist that is in the board.
So I’m setting up a fence here on the CNC. This will just be for something to put some pressure
up against, and you can see that twist there. So basically I’ll shove a shim underneath it
until it doesn't rock anymore.
That just puts some pressure around. And then we'll use some side
pressure with just a few pieces of scrap plywood and some brad nails into the waste board. And
this piece isn't going anywhere. It's being held in nice and tight. So we can pick up the
RC-2255 flattening bit. This is a three-wing insert carbide flattening bit. We'll zero off
of the highest area and then do a full pass, just removing anything just to make sure
that I don't have any unexpected high areas and end up crashing the CNC or anything like that.
So you can see it just skimmed that top and removed those high points. And then we'll do
steps down until we end up with a perfectly flat top surface.
So essentially as long as the piece
doesn't move the head of the CNC is parallel with the waste board. So it's going to create a flat
surface. You could definitely do this with like a jointer and a planer in a shop. Unfortunately I
don't have one so this is the way that I do that. So we'll remove those from the CNC, get
everything cleaned out underneath, and then get them put back down to flatten the other side.
We don't need any shims or anything since the other side is already perfectly flat.
And again we'll take steps down until we end up with a nice flat surface.
So we can end up with two parallel surfaces. I had a little bit of fun with the dust collector
on the CNC going around picking up all the extra dust.
But anyways as you can see here there are
a couple areas that I missed, but I only need a three inch wide board so this will work great.
This is another way to do this if you don't have a CNC. This is just a router flattening jig, and
it's essentially the same principle as a CNC. So I can just hold everything down in place and
then I’ll use the same RC-2255 flattening bit and we'll go through and make passes, going across
the grain since this is a really wide piece. You essentially have the same thing as
the CNC. You have two parallel surfaces; the router’s riding on one and creating that
parallel surface with the slab that's sitting there, since everything is moving
nice and square with each other. So anyways that is another way to
do that and it works really well if you don't have a CNC.
And you can see
the results here are pretty spectacular as we have a perfectly straight piece.
So I’ll show you a quick version of doing that on another one. We'll hit all the high spots.
We'll get everything going down at a step a time, and then we'll end up with a nice flat piece. So
we'll flip it over and do the exact same thing. So the walnut grain is absolutely beautiful. So
it's always really cool to see. As you can see there are no ridges on the piece at all. Those
are the lines that are created when going back from climb to conventional cutting, similar to the
lines that are created when you mow your grass. Hopefully that provides a little bit
of insight on how you can get pieces flattened on the CNC as well as on a router sled.
But hopefully you guys enjoyed it.
We'll catch you guys back out here in the next
one. Have a great day everybody..