Cabinet with rounded corners

[Temp]

So I've seen a nice bathroom sink/vanity unit that has rounded corners. Looks very nice but they want over £600 for it. The basin top is available on its own for £150ish so they essentially want £450 for the 60cm wide three draw base unit. Apart from the rounded corners its basically just painted wood, almost shaker style.

 

I figure next spring/summer I can buy a 50cm wide drawer unit and add dummy side to it and come up with something very similar for a lot less than £450. However I'm stuck on the best way to make the rounded vertical corners. They need a radius of about 40mm. 

 

* I've not been able to find any quadrant mouldings that big.

* I could plane down square blocks but it's time consuming and difficult to get perfect and errors would be very obvious.

* Don't think my router would take a big enough bit to make one?

* I thought about bendy plywood around (perhaps 3D printed) formers but the radius seems too tight for say 5mm ply. 

* Perhaps I could cut 80mm round into quadrants but all I can find that size are pressure treated fence posts.

 

I'm leaning towards laminating some very thin plywood as I've done that on model aircraft before but have i missed an easier way? Obvious source of 80mm round? Stair posts?

 

[Oz07]

When you're done it think you will wish you bought the off the peg one! Sounds time consuming and will you get as good finish paint wise?

 

A local joiners shop might be able to do you the corners on the spindle for a drink. I've used half inch router cutter does about 35mm radius was a bit of a beast

[Stewpot]

This stuff:

 

https://www.atlantictimber.co.uk/flexible-plywood.html

 

The idea is, you take two sheets of it, and glue it back to back, bending and clamping it to your desired curve. Once the glue has dried, it becomes surprisingly rigid, though it probably won't do as a structural element - I doubt it'd take a screw very well. And you'd have to experiment to see if it can deal with the small radius you have in mind.

 

I've seen the stuff made of pure plywood, rather than MDF with a thin plywood face. But it is certainly possible to make your own out of plywood, or even solid wood, if you have an accurate table saw. The closer the kerfs, the tighter the radius.

 

Maybe cut a drainpipe in half length ways to use as a former to clamp this into. And plenty of glue - you are aiming to glue all the thin strips together, as well as the two sheets to each other.

 

Alternatively, you can get especially flexible plywood, but by its nature, it doesn't have a lot of stability to it without support.

[PeterW]

You can get 38mm quadrant if you search for it but it may be a minimum quantity 

[carlb40]

You can do it with matching solid timber and a round over router bit. https://www.wealdentool.com/acatalog/Online_Catalogue_Large_Ovolo_187.html   

Bottom of the list is the largest one they do. You would need to use it in a router table, but a temporary one with a basic fence will take 30 minutes if that to knock up.

 

[SteamyTea]

Cast them out of resin, or get some vacuum formed.

3D printing maybe.

Edited December 23, 2019 by SteamyTea

[Temp]

Thanks for the ideas. For cost reasons I think I'm leaning towards laminating from thin ply around a former.