What´s the best tool to make the corners of planks rounded:

From enter image description here

To this

enter image description here

  • Is that plank pictured face-on, or top-down? Graphus answer is very good if it is face-on. The portion of Peter Knego's answer discussing a router, straight pattern bit, and corner template covers the case if the plank is pictured top-down. Mar 2 '20 at 21:39
  • @CharlieKilian, well that was a very good question because it appears this is actually about how to round the corners. The original wording was "Making edges of wood planks rounded" -_-
    – Graphus
    Mar 3 '20 at 8:17
  • Carlo, you need to edit the Question, in part to make it more specific. There's never one best way to do anything for a start, so that's never a good way to ask it, but what radius? How thick is the wood? What type(s) of wood? And perhaps most importantly what tools do you currently have?
    – Graphus
    Mar 3 '20 at 8:18

Now that is has been clarified that you mean the corners (not the edges or arrises) my Answer needs to be completely revised. It still depends on the radius you want.

Very small radii
If you want to just round your corners slightly, say to a radius of 1-3mm arguably the easiest and simplest method is just to sand them (or by filing if you use files). You have to be careful if you want a very uniform result regardless of the method used but in general you can do this successfully by eye.

It's fairly easy to do this sanding by hand sanding using a block to back the abrasive paper. You can also do this by rotating the piece against a disk sander (one of the most common uses for this tool). This is also possible using a belt sander but much more care needs to be taken as it's very easy to remove more wood than intended, or to end up with an asymmetrical curve which looks terrible.

Larger radii
If you want a larger radius it's a very good idea to mark the workpiece to give you lines to work towards, unless you're using a method (e.g. a router template) that automatically creates a radius of a fixed size. Woodworkers are rather famous for just grabbing something round in the workshop and drawing around it, washers, bottle tops and spraycan caps all being favoured for this purpose.

For these larger radii many methods are available. You can still remove the wood entirely by sanding if you want, but this is only really practical using power sanding. Even doing a sizeable radius many owners of disk sanders or horizontal belt sanders will remove all the wood by sanding it off.

In the absence of a power sander the most common method today would be using a router and a template of some kind. Templates can be made in the shop but there are numerous commercial versions, and as you can see they can be used on the router table or using a handheld router:

Round corner router templates

Note the Woodpeckers template shown isn't for a fixed radius, it has replaceable inserts that cover a wide range of radii. This template is retired however, but a version of it returns to production periodically. So it may or may not be available when you read this!

This is a lot of wood to remove in one pass using a router, it wouldn't be a bad idea to cut a 45° off the corner prior to routing to ease the load on the bit. Just be careful not to cut too much off!

A bandsaw or jig saw are also possibilities for cutting round corners, but there's often a definite limit on the safe size of the workpiece that can be tackled on a bandsaw. You'd normally sand to refine the surface after either operation.

Using hand tools, the traditional method for removing the wood is to chisel down vertically, see image in this previous Answer and this is still a viable method, if a bit slow in thicker and harder woods. Your chisel needs to be very, very sharp. Although in the past the slightly faceted surface created would often have been left as it was these days it would be normal to sand to fully smooth it.

You can also rasp the bulk of the wood away (being careful initially to rasp off the edge towards the end grain, never the other way around or you'll get terrible splintering), then switch to files to complete the smoothing followed by scraping and/or sanding to create the final surface.

  • It is face on. I thought of using a router, thing is I have plenty to make, so was looking to optimize times somehow.
    – Carlo
    Mar 6 '20 at 6:48
  • Sorry your Comment didn't show up on the top strap for some reason so I only saw this now. "was looking to optimize times somehow" The router method is the optimal route for many people! I think a belt sander could be faster with a coarse enough belt (although the post-shaping sanding might end up making this method take longer overall) but those are less common than routers. Anyway, you pretty much have to pick a method that suits the tooling you have right? So you just have to put your nose down and get to it, and it'll then take as long as it takes (like lots of tasks in woodworking).
    – Graphus
    Mar 7 '20 at 8:19

For rounding the long edge of a board to a small diameter (aka taking the edge off)): use handheld router with a round router bit that has a stopping bearing: something like this.

For rounding the short edges: use a handheld router with a straight pattern bit and a corner template.

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