Working on a low volume (few hundred maybe) gutter end cap for an 8" commercial gutter profile. Will use 4140PH for upper and lower die and 4140 annealed for the rest. Depth is 1/2". Material is prepainted 0.027" aluminum "coil stock" like typically used for building flashings, gutters, etc. Press is 20 ton Harbor Freight with air over hydraulic jack for power.
Attaching cross section. Die plates are 1/2". Lower spacer is 3/4" thick and plan to have a removable front section that slides in to support the lower die plate, then pull it out to remove the finished part. Just above the lower die plate is a thin plate slightly thicker than the material with a cutout for the blank - this will locate the blank. Haven't figured out how I will hold the blank holder - the typical way is to use die springs but I am very limited on press force so trying to avoid that. I could use bolts around the edge but that is very time consuming and not really practical even for my low volume. Might work while developing the die and process. Plan to dowel and bolt layers together. For long holes though multiple layers is it feasible to used multiple shorter dowels? 4140 annealed is still fairly hard - how difficult will tapping be? Other choice is to through drill and use a nut, counter boring where needed. For alignment of the top and bottom die I plan to pin the lower plates to the lower die frame. Then fit the upper die into the lower with shim stock in multiple places to center it. Then drill and pin the top to the upper die frame. Due to the small radius of some of the corners I may draw to a larger radius and then stretch the corners slightly - have some tests to see how small a radius I can reasonably achieve.