Milled strip bending after milling problem.

[Arnak]

Hi,

I am building a Virginia but am having a problem with milling the connecting rods between the wheels.8-((

Using mild steel, the drawing calls for the rods to be reduced in thickness on one side but doing that in the mil causes the rods to bow after milling.

Can anyone give me some advice to stop this from happening, perhaps how to straighten them?

Thanks,

Martin

 

[Jasonb]

Use hot rolled (black) bar rather than cold rolled (bright) bar as the cold rolling induces stresses which become unbalanced when you cut one side only.

You can also heat your bright bar to red heat and hold it there to remove the stresses before machining.

 

[Arnak]

Hi Jason,

Thanks very much for the advice, I'll get some black material and use that.)

Martin

 

[clockworkcheval]

Small addition: stresses in the material tend to prefer the surfaces, even some residual stresses that remain after the suggested heat treatment for stress relieving. So it is good practice to machine both sides, one side for stress relieve say 1 - 2 mm deep, and the other side for final dimensions.

 

[Jasonb]

Indeed but it does not work if the part is not symmetrical

"drawing calls for the rods to be reduced in thickness on one side"

 

[Harglo]

Use hot rolled (black) bar rather than cold rolled (bright) bar as the cold rolling induces stresses which become unbalanced when you cut one side only.

You can also heat your bright bar to red heat and hold it there to remove the stresses before machining.

There is stress relived steel for this purpose.
haglo

 

[clockworkcheval]

Sweet memories of the different points of view and ensuing discussions between designers, manufacturers and purchasers!