Using a Magnetic Chuck to Mill a Round Bar Square

 
Magnetic Chuck Round Bar

Workpiece Material: Hot rolled 8620 Steel

Raw Workpiece Size: 5”diameter x 20” long

Magnetic Chuck:  DM-MC-70SP-0406 (16 x 24”)

Top Tooling: DM-MC-BP70-5 BACK Parallel

Milling a round bar square on a magnet may seem daunting to the uninitiated, but as the following data shows, if managed with the right top tooling, is quicker and more accurate than most conventional methods.

The Back Parallel shown provides an accurate and square rail, that not only serves as a locator for the part, but also transfers magnetism to the faces, thus providing a second “line” of clamping force.

OP1

Using the back parallel as a “Y” stop and following location of the bar, ensuring two lines of contact, cut direction was into the parallel and a milling pecking depth of 0.25” was taken at 40” feed/min. until the desired width was achieved.  At the largest width, around

OP2

Rotating the bar against the Back parallel and using 2 x ½” dowels to raise the bar off the surface of the magnetic chuck to ensure squareness, further 0.250” depth cuts were taken until the desired width was achieved.

OPS 3&4

The bar was rotated each time for the remaining faces at similar depths and feeds.