What do I use to produce a nice curved corner in wood

[Daydreamer]

If I was doing the same, I think I would make a faceted version of the curve with perhaps three or four faces, using strips of solid cherry (because that's what my joinery is). The joints would be essentially butt joins at the appropriate angle (cut with the router using a simple jig to raise one side of it to set the angle), with a groove to take a spline of 3mm plywood. Then when it was all glued up and set, I'd hand-sand the facets into a curve with 80-grit paper on a foam block

This method is called coopering and this looks like a practical way of creating a one-off. Such joints only look good if done with high precision though. You can buy 22.5deg and even, I discover, 11.25 deg router bits which would be a good start.

100mm radius is a big curve. If a smaller radius (25-30mm) were acceptable then a suitably sized square post could be rebated on two corners and a satisfactory radius could be hand planed on the corner.

 

[JumbleDuck]

In the early summer I fitted 2 new fresh water tanks to increase our usable capacity. One of these 2 tanks is visible so I want to make it appear to be a nice mahogany (faced plywood) locker / table. The top and the sides are sorted but that leaves one visible corner. I don't want this unit to look like a box so would like the 'corner' to be rounded. The curved 90 degree bend is just under 60 cms high and I'll need to produce a 100mm radius. The bend will be a total 90 degrees with a 25mm straight at each end to attach the piece which will ideally be 12mm thick to match the rest of the hardwood faced ply.

Any thoughts about a material to use ( I can laminate to make up the thickness if necessary ) and where I can actually buy a practical material to do the job bearing in mind the 100mm radius?

Roger Ball (rogerball) has done some stunning work along these lines in his quest to produce the ultimate Westerly Centaur. Have a look at www.agentlemansyacht.com, starting with the posting for Sunday 18th January 2015.

Basically he cuts lots of grooves in the back, fills them with epoxy, bends the thing into a curve and leaves for the epoxy to set.

 

[prv]

This method is called coopering and this looks like a practical way of creating a one-off.

Cheers, that's a useful technique to add to the mental toolbox.

It's not quite what I had in mind though - I'd be using thicker and wider pieces of timber, and fewer of them. The inside would not have a nice curve like that chap needed for the inside of his knife box, but that's fine as it would be invisible on the OP's boat. The thickness would vary substantially with quite a lot of material planed away at the corners.

You can buy 22.5deg and even, I discover, 11.25 deg router bits which would be a good start.

That's definitely easier than my plan, if the angles work out . When I was making saloon speaker housings last winter, with similar odd-angled butt joints, I made a jig with two different-height rails so that with the router resting on top of the rails it was tilted at an appropriate angle. Then a straight bit would cut the equivalent angle (or its 90 degree partner) on the work in between the rails.

Pete

 

[cygnusv]

Hi JumbleDuck

I've actually done the curve using this method using 8mm ply. I used a bench saw with a 2mm thick blade and cut 6mm deep at 6mm centres. While assembling my jig I left the ply to soak for an hour in cold water and bent the 100mm 90 degree radius (nearly 600mm long) with no problem at all. I actually wanted to finish with a 12mm thick piece of ply but it looked too much like hard work (with limited equipment). I'm simply going to step the vertical end supports with a router to allow for the difference in thickness. I can't see that fairing the curve and adding a veneer will be a problem.

I have to say that to get to this point (a satisfactory curve) has taken about 4 hours so far. The only cost is my time. I may post a pic when the piece is fitted. Very pleased.

Roger Ball (rogerball) has done some stunning work along these lines in his quest to produce the ultimate Westerly Centaur. Have a look at www.agentlemansyacht.com, starting with the posting for Sunday 18th January 2015.

Basically he cuts lots of grooves in the back, fills them with epoxy, bends the thing into a curve and leaves for the epoxy to set.

 

[JumbleDuck]

I have to say that to get to this point (a satisfactory curve) has taken about 4 hours so far. The only cost is my time. I may post a pic when the piece is fitted. Very pleased.

Roger Ball's pictures of the end product are very impressive indeed - it looks like a very good technique.

 

[rogerball0]

Roger Ball's pictures of the end product are very impressive indeed - it looks like a very good technique.

cheers man

My Galley module. (50mm radius in 12mm ply)

How i got the curve.

Finished job.

The former the ply got bent over.

I like this method as Its quick and easy although it took a little while to perfect so you dont end up with a faceted curve, theres where the magic lies, i found taking a scoop with the router out of the immediate backside of the curve makes almost any material floppy and therefore a piece 'o' piss to bend.

 

[Sticky Fingers]

.... You can buy 22.5deg and even, I discover, 11.25 deg router bits which would be a good start...

If you want to use this method, setting a table saw to the desired angle is more flexible (any angle you like), much quicker and cheaper (and quieter)... rip a long length on the desired setting both sides, then cut your segments to length from it

 

[Sticky Fingers]

cheers man

My Galley module. (50mm radius in 12mm ply)

How i got the curve.

Finished job.

The former the ply got bent over.

I like this method as Its quick and easy although it took a little while to perfect so you dont end up with a faceted curve, theres where the magic lies, i found taking a scoop with the router out of the immediate backside of the curve makes almost any material floppy and therefore a piece 'o' piss to bend.

Man that's impressive for home woodworking, lovely job

 

[rogerthebodger]

cheers man

My Galley module. (50mm radius in 12mm ply)

How i got the curve.

Finished job.

The former the ply got bent over.

I like this method as Its quick and easy although it took a little while to perfect so you dont end up with a faceted curve, theres where the magic lies, i found taking a scoop with the router out of the immediate backside of the curve makes almost any material floppy and therefore a piece 'o' piss to bend.

Thats a nice job but will only work when the grain goes around the bend. If the grain runs along the bend the wood would split as I found out . A different method needs to be used as shaped vertical glued strips and routed to shape.

 

[Daydreamer]

If you want to use this method, setting a table saw to the desired angle is more flexible (any angle you like), much quicker and cheaper (and quieter)... rip a long length on the desired setting both sides, then cut your segments to length from it

Yes, I know.

The point about the angles 22.5 and 11.25 degs is that they are half the external angles of an octagon and a hexadecagon respectively. This ensures two faces at right angles to give lead off surfaces to match flat side panels. This sort of geometry is the traditional, ancient even, way of laying out joinery and stonework using simple tools such as straightedges, squares, compasses etc.

 

[cygnusv]

Hi Rogerball0

Very impressed with the bend, how deep did you go with the cuts in the 12mm ply? Did you bend dry or wet the material first and what quality ply have you used?

 

[rogerball0]

Thats a nice job but will only work when the grain goes around the bend. If the grain runs along the bend the wood would split as I found out . A different method needs to be used as shaped vertical glued strips and routed to shape.

Why not veneer it to the grain pattern you want afterwards?

 

[rogerball0]

Hi Rogerball0

Very impressed with the bend, how deep did you go with the cuts in the 12mm ply? Did you bend dry or wet the material first and what quality ply have you used?

Cheers, I personally wouldn't use water on plywood to bend it seeing as how poor the quality is nowadays, i use heat to bend ply and lots of it whilst cranking it over a former like the one above especially if the radius is tight, i use steam / water on various different hardwoods but it comes down to the application as to how much and for how long and if the piece is decorative or not.

With regard to the depth of cut it depends on the dimension of the radius, for the above i went every 3mm and 11mm deep so you're almost into the last (outer) lamination of the plywood;

what i found necessary to accurately repeat the cuts many dozens of time is one of these (a zero insertion plate);

Google it, they're dead easy to make, that one above is made for my ryobi site saw its 12mm thick and way stiffer that crappy plastic one the saw comes which you could deflect about 8mm when applying downward pressure pushing your stock through the saw so no good when trying to repeat the same depth of cut every time.

Hope that fleshes it out abit more.

 

[GrahamM376]

Google it, they're dead easy to make, that one above is made for my ryobi site saw its 12mm thick and way stiffer that crappy plastic one the saw comes which you could deflect about 8mm when applying downward pressure pushing your stock through the saw so no good when trying to repeat the same depth of cut every time.

And hope the man from HSE doesn't visit The standard fit steel plate on my saw has wide enough gap for a dado blade which the arbor won't take and we're not supposed to use this side of the pond (in an industrial location) anyway. I too use zero clearance plate most of the time and can't remember when I last used the knife or guard as cross cuts normally done with a sled.