straight crown molding

[markos]

hi, I´m begining a small bussiness, I´m making crown molding for arquitectural decoration , I´m using xps foam 16 kg/m3, the problem is that the cuts are not straight, the profile and surface are very good, but some cuts are not. I´m using cnc at 20 in/min, and the cut lenght is 4 ft, this machine is home built, I have a foamlinx 3920foam cutter, but the problem is the same.
I think that the problem is the internal stress of the foam, but I´m not sure and I don´t know what can I do, could some one help me please?. thankyou

[harryn]

Hi - any chance you can post a picture of what you are seeing ?

There definitely is internal stress in some foams. I have seen foam being marketed as "stress relieved" - probably some kind of heat treatment prior to cnc work.

[markos]

thank you for your help Harryn, unfortunatly my digital camera is not working, but the center of my molding has a curve about 1/8 inch separate of the straight line, The material is expanded polystyrene(eps), and sure you are right, the problem is internal stress because the corners are perfect whitout deformation. I will try to get information about internal stress, and foam stress relieved, thank you.

[skippy]

Markos, check your pm box

Skippy