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innovate, v.:
To annoy people.
(Score: 0) by Anonymous Coward on Monday November 16 2020, @05:09AM (4 children)
> and plane the surface.
Why use a plane to flatten the surface, that's the hard way.
If you don't have access to a really wide jointer (which makes a plane surface), then there is a trick I learned from an ace pattern maker* -- once you have the benchtop all glued up, tack on dead straight 1x4 or similar on the two long sides with the top edge an inch or so higher than the bench top. The 1x4 should be a little longer than the length of the bench. Move the 1x4 up and down as necessary so that the 2 top edges are in the same plane and roughly parallel to the bench top, I leave it as an exercise to the reader to work out this detail (there are several methods). When this step is complete you have established the tops of the 1x4s in a true plane surface.
Step two is to take an ordinary router and mount it on a very long & stiff base, 2x+ as long as the width of your bench**. I happen to have a piece of 3"x3" aluminum angle extrusion for this, but anything stiff that you can bolt the router onto is fine. By now you should see where this is going--lay the long base across the 1x4s and set the router depth a little deeper than the lowest point in the glue-up. Route (it's analogous to end milling) the top flat. The surface won't be great, but it will be dead flat (in one plane) and you can smooth with a sanding block, or if you prefer the clean look of a cut surface (without any grit in the surface), then take really thin cuts with a hand plane.
A neat thing about this technique is that it works on end grain too -- I tacked router supports to the side of a big tree stump and routed (milled?) off the top perfectly flat. All set to take a table top without any rocking back and forth.
* Al worked at a boat company and later Bell Aircraft after WWII. Among many other things, he built the full scale mockup of the Bell X-1 supersonic plane from wood. Back then it was common to build a full size wood version of the plane to lay out all the wiring, plumbing, etc...since they didn't have 3D CAD to check for interference between parts.
** It can be shorter, then you mount the router off-center and have to turn the router base around to do the other half of the top. I prefer to do it all in one setup with the longer router support.
(Score: 2) by c0lo on Monday November 16 2020, @06:18AM (3 children)
https://www.youtube.com/watch?v=WmUloHQjvOw [youtube.com]
Because I need to get used with a plane anyway.
Otherwise, why using hand tools when you can build/buy a CNC?
https://www.youtube.com/watch?v=aoFiw2jMy-0
(Score: 0) by Anonymous Coward on Monday November 16 2020, @04:41PM (2 children)
That would be one big CNC router to mill a workbench flat on top! The low cost ones (for wood working--like cutting out kitchen counter tops) never looked that stiff to me. I'd ask carefully to see how flat (planar) they can hold on a large single surface. My 3" aluminum angle is stiffer than the bridge on most of the lower cost CNC routers that I've seen.
I've done the hand work to resurface a maple butcher-block workbench (3x6 feet) and it took a long time. If I'd been able to "machine" it planar using this router approach (which I learned later), then I would have been able to focus on the hand cabinet-scraper work that generated a lovely surface.
(Score: 2) by c0lo on Monday November 16 2020, @09:32PM (1 child)
If I were to have a CNC that big, I'd barely need a workbench. A flat surface for sanding/assembly the pieces would mostly suffice in most of the cases.
In any case, the "planing by router" is equivalent to building a CNC table/gantry then move the router by hand - the flatness of the surface will be as good as the stiffness of frame/bridge you build in this one-off fashion; if those two are stiff enough, you can use the same for a full DIY CNC build.
https://www.youtube.com/watch?v=aoFiw2jMy-0
(Score: 0) by Anonymous Coward on Tuesday November 17 2020, @02:29AM
Earlier I hadn't looked at the video you linked, which I just did. Thanks! It looks like the router sled has caught up with my old toolmaker, who built his supports directly onto the work. That's what I did for the tree stump, which wasn't going to be moved! As you say, the router box & sled are the core of a CNC 2D router setup. Since I moved the router (with a smaller bit) freehand on my long bridge, I didn't get nice straight cuts, in fact I "mowed in spirals" on the high spots first. Hardly matters since there is going to be a secondary smoothing process.
In your link, and also another one, both of those guys relied on another flat surface, rather than checking that their guide surfaces were in one plane: first guy relied on his floor being flat (not always a great assumption) and the second one relied on having a flat work table (but it didn't look very stiff). Since they were making decorative tables (and not a work bench), that was probably flat enough.