Building Prototypes Dan Gelbart part 7 of 18 Presswork

Summary: Presswork

The video explains how a shop press can form and stiffen sheet metal, while emphasizing that careless use can cause severe injury or damage.

Press safety

• Treat the press as a potentially dangerous machine. Compressed steel can store substantial energy. If a brittle or hardened part shatters, fragments may fly in multiple directions like shrapnel.
• Do not press brittle or hardened workpieces. Tooling can also be hardened, so there may still be a risk even when forming ductile material.
• Use a shield when appropriate. The presenter recommends a half-inch polycarbonate shield and says operations other than ordinary sheet-metal pressing should generally be shielded.
• Avoid concentrating the press’s full force on a small area. A small object can focus the load enough to dent or crack the press. For example, with a 100-ton press, a rough safety limit of 10 tons per square centimeter would imply at least 10 square centimeters of contact area if the full force could be applied. This is an illustration, not a universal rating.
• Center the work in the press to avoid putting uneven stress on the machine.

What a press is useful for

A press can straighten, flatten, and shape material. Paired with a water jet, it can also help make custom tooling quickly: cut the tooling from mild-steel plate, then use it to form sheet-metal parts.

Pressed ribs and folded or closed shapes make structures stiffer without adding much weight. A closed section is particularly effective at resisting both twisting and bending.

For ordinary structures, the presenter recommends steel. For high-performance parts, some stainless steels can be formed, welded, and then hardened with a heat-treatment cycle.

Forming methods demonstrated

• Forming against rubber: A male tool presses sheet metal into hard rubber or polyurethane. This is a quick way to make a rib, though the result is less sharply defined than with matching dies. The rubber should extend beyond the sheet; if it is too small, the sheet’s edges can wrinkle or snap.
• Using matched male and female dies: A rough shape formed against rubber can help locate the two halves of the tooling. Once aligned, the dies produce sharper details and can make deeper shapes.
• Deep drawing: Deep shapes may need to be formed in stages. The presenter describes drawing the material partway, annealing it, and then drawing it further. Trying to form the full depth in one operation can tear the sheet.
• Using lead as a backing material: Pressing a sheet against lead can produce a well-defined shape in one step. The lead can be reused by melting it. Sharp tool edges may cut or shear the sheet rather than simply form it, so the tooling’s edge shape matters.
• Making round end caps for cylindrical enclosures: Cut complementary tooling with enough clearance for the sheet metal. The example suggests roughly 1.5–2 mm of clearance for 1 mm sheet. Press the sheet into the die to form a lip that can be spot-welded around the cylinder, then finish the edges.

Main lesson

A press can produce useful, lightweight formed structures and custom parts with simple tooling, especially when combined with a water jet. Safe presswork depends on understanding stored energy, protecting against brittle failure, avoiding concentrated loads, and choosing a forming method suited to the desired detail and depth.

Speaker

• Dan Gelbart — presenter and demonstrator, identified from the video title and channel.