Can you fix a warped disc?

[Pukmeister]

Fourth visit to the surface grinder,one of the other blokes pointed out that it was a magnetic table,and every time he put the disc on it,the magnet pulled it flat,so he was grinding a flat disc anyway.Turn the table off,and disc has warp again

It's amazing just how much metal objects can distort in a magnetic vice, I had the same problem with a cast iron fridge compressor cylinder head in a Shipman-Jones surface grinder. The trick was to only apply just enough bite with the magnet to hold it rather than clamping it down as tight as possible. Second pass was perfectly flat.

So how exactly do you hold a stainless steel disk in a magnetic vice then ????

 

[Vern]

With a mounting boss on top of it

 

[JayC]

Think I'll just get my coat....

 

[(RIP) Arkwright]

Sometimes the mounting bosses need to be milled flat when they have warped, without touching the disc.

And sometimes the wheel mounting bosses have to be milled flat after the disc has chattered on it!

 

[thornley]

It's amazing just how much metal objects can distort in a magnetic vice, I had the same problem with a cast iron fridge compressor cylinder head in a Shipman-Jones surface grinder. The trick was to only apply just enough bite with the magnet to hold it rather than clamping it down as tight as possible. Second pass was perfectly flat.

So how exactly do you hold a stainless steel disk in a magnetic vice then ????

Some stainless steels are magnetic. Depends on them being Austenitic or Martenistic. (Probably got the spelling wrong) 400 series stainless steels are magnetic. Generally stainless steels used in brake disc manufacture are laser or water jet cut from low nickel/chrome grade plate and are magnetic.

 

[Vern]

Mounting bosses are ground flat chunks of steel in all kinds of pretty shapes, that you make to do different jobs with, but I guess that no one has ever had a big chunk of cast ally on a surface grinder before

 

[Rusty Bolts]

Mounting bosses are ground flat chunks of steel in all kinds of pretty shapes, that you make to do different jobs with, but I guess that no one has ever had a big chunk of cast ally on a surface grinder before

Please Sir, I have. When I used to work for a pastic bottle manufacturer in MK. We had Aluminimum Alloy moulds that were 800-1100mm long that needed grinding.

 

[Bendy toy]

Discs should not warp with no reason. Check the disc mounting face is flat and running true. If its only a tiny fraction out, the disc will wobble and one side will heat more than the other. Eventually that will cause it to warp. Also check the wheel bearings are not getting slack.