How to create a concave in wooden block

[nlpmaster1974]

Hi all,

Newbie here. I dont have many tools but I need to create a .5" deep concave in a piece of softwood.

Any ideas how I could do this or what tool I need to buy to do this (cheapest)?

Thanks,

Chris

 

[nstreet]

Angle Grinder; spoke shave; jig saw; coping saw; lathe.

 

[shaggy]

 

[Thermo]

is it an elongated concave depression or just circular?

 

[nlpmaster1974]

It is a flat piece of wood, 8" x 5" x 1.5" deep.

I need a circular depression in the centre of the wood that is .5" deep and measuring 3" from one side to the other. Is there some kind of addon for my drill that will allow me to do this?

Thanks,

Chris

 

[Jasonb]

A router with a core box or cove bit will be the best option, if it's a one off then a cheap router will do. You will need to make a guide to keep the groove straight or cut it before the wood is rounded.

http://www.wealdentool.com/acatalog/Online_Catalogue_Core_Box_202.html

Jason

 

[nlpmaster1974]

Hi,

That looks absolutly great! Actially I like the box set of different router components for different effects. Am I able to attach these to a standard electric hand drill or does it need to be an upright stationary type drill?

Thank you,

Chris

 

[nstreet]

It really needs to be a router. A normal drill will probably not have a high enough rpm and you wouldn't get the finish. It would also be tricky to guide a drill.

 

[Jasonb]

As nstreet says a normal pistol drill runs at around 1000rpm whereas a router runs around 20000rpm so a drill would be too slow. Drill stand will also not be suitable.

Jason

 

[petewood]

I used to have an Arbourtech, which was a disc for a 4" grinder with chainsaw-type teeth around the edge. This was superb for shaping and stock removal and it would do your job with ease, although not as accurately as a router.

 

[Panjandrum]

When you say concave, I think of a kind of saucer-shaped depression.
You can get one of those by careful use of a drum sander on a normal drill.
If what you really want is a 3" diameter cylindrical hole then you really need a router.