Tube punches come in many shapes and sizes. Circular punches are necessary when the diameter of a circle is less than one inch because it is not possible to bend steel rule. The smallest punch is 1/32”. Sizes vary up from there on 1/4” increments. Punches come in different bevels. Center bevel, inside bevel and outside bevel are the different profiles. Inside bevel punches are best for cutting thick stocks because they do not deform the substrate. They are also best for mitres when a cutting rule must butt up to the punch.
Punches eject in many different ways. The majority of punches eject with springs or silicone rubber. Side out punches are typically used on thicker materials and the slugs eject through the side of the punch and a routed trough in the die. Feed through punches allow the scrap to push through the punch. The smallest punch with a spring is 3/32”. Punches smaller than that would be side out. Many people think that the springs are to eject the slug from their material. Although this may happen, any form of ejection is solely to rid the punch of any scrap. If you must eject the chad from your paper, side out is your best choice. Be aware that your press may be lifted by the scrap holes. Amazingly only a small amount of paper pulled into the punch will blow the steel punch apart.
Custom punches come in many shapes, sizes and ejections. Custom punches are machined out of tool steel. Custom ovals, slots, and stars are examples. Metric punches may be custom if they have to be exact. Punches can sometimes be confusing. Please give us a call to make sure you get the right punch for your project.