"Scooping" out foam

[cncproadwarrior]

I need to create a river bed about 3-4" wide and 2" deep between 2 mainlines. The mainline HO cork roadbeds are glued to 2" extruded foam. What's the best way of "scooping" out the foam?

 

[RIRRfan]

dremel with a sanding attachment. Get the flexable dremel cable. You'll have better control of the sanding bit.

 

[Davejb]

I'd just carve the general shape with a knife, then use a rasp to get the final shape

 

[kenw]

A dremel is going to create a monstrous amount of dust. I'd ditto Dave's carving then shaping with a rasp.

an idea: You could heat the knife to red, then bend it to form a curve and slice each 'shoreline" with that. Reheating the knife (tho not to red) will allow you to hot-knife cut the shoreline fairly simply, but realize that melted foam fumes can be hazardous.

 

[tankist]

A dremel is going to create a monstrous amount of dust. I'd ditto Dave's carving then shaping with a rasp.

can't agree more.

i used retractable, snap-off bladed knives, 12mm for the rough cuts, 9mm for final shaping. with not to much force blade can be bent to sort of undercut the material (just not to to much. it will snap otherwise)

 

[cncproadwarrior]

Ditto on the dust and fumes.

Perhaps a curved grapefruit knife? Will have to try that.

 

[ianacole]

This came from another thread ... not sure if you can use it for your purpose:

LINK