J Weld Preparation

What is the best way to machine a "J" preparation with a 3mm radius for welding 10, 12 and 16mm plate ?

I am building a 10" dia boiler for a 6" Ruston Proctor and have a Sieg SX3 mill.

My first thoughts were to make a special cutter or to use a bull nose cutter and tilt the milling head.

Paul.

I find ball nose cutters quite slow at removing material as the periferal speed near the centre is very slow. You would be better of with a "radius" cutter these are like a 12mm Dia endmill but the corners are all radiused to 3mm.

As this is only for weld prep you may just as well take an old blunt 1/2" milling cutter and round off the corners on the hand grinder, you don't need them to be exact. I use this method quite a bit when fabricating parts from solid to get the look of a cast fillet in the corners

Can also be done with a flycutter.

Edited By JasonB on 17/12/2012 12:02:16

Thanks Jason,

Grinding the corners of an old milling cutter is a good idea.

Hi Paul, 'Fraid I just use the angle grinder. Ian S C

I've only seen J weld prep put on by machine on pipe welders. Don't really know how it's done but most involve rotating the tool round the pipe, or the pipe rotating. These machines have shaped form tools, and a lot of power. The few times I've done it I used an angle grinder, not for critical welds.