[keebler303]

How strong should a permanent magnet chuck be?

I just bought a walker ceramax 6x18 and Its not as strong as I was expecting. I never used one before so I have no real idea what is normal.

Should I be able to move a 1-2-3 block when its on the chuck?

Thanks
Matt

[Dr Pete]

First off make sure that everything is clean & dry.
Are you putting the 1-2-3 block across the magnetic in the long direction?
In other words 3" parallel with the 18" direction on the chuck?

You want to be across the fields with your steel.
I can move a 1-2-3 block on our 6" X 18" mag base.
Put a piece of 1/8" or 1/4" steel on the chuck.
Some steel holds better than others.

The mag base on our Blanchard grinder depending on what steel you put on and the direction you can either move it or you can't get it to move without a hammer if you wanted to.

Not sure if this helps.

[Geof]

The grip on a magnetic chuck depends on the surface area of the part in contact with the chuck. Your 1-2-3 block has holes (probably) that subtract from the surface area so I think it is not surprising that you can move it.

Magnetic chucks are for grinding where the DOC is measured in thousandths of an inch; they are not often suitable for milling unless you area dealing with a large area.

To some extent you can compare magnetic chucks with vacuum tables; you have a fixed maximum hold-down force per square inch, the only way to increase the grip is increase the area.

[keebler303]

Thanks guys.

The chuck is for a surface grinder I just acquired. It sounds like the chuck is ok. The 123 block does have holes and the 2 direction was parallel to the long axis of the chuck.

Matt