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Any thoughts as to adding some pre-hardened inserts (0-1, H-13, ETC.) On to the faces of your forming tool? These could be screwed & doweled/pinned on using flat ground stock. John
Started the process of rough milling the Die which is a slow process with a lot of material to be removed. The Die blank is 2-inches wide by 1-3/4-inches high by 12-inches long
Quote from: Ye-Ole Steam Dude on October 07, 2018, 08:40:56 AMStarted the process of rough milling the Die which is a slow process with a lot of material to be removed. The Die blank is 2-inches wide by 1-3/4-inches high by 12-inches long That would be a large piece to quench, more than I would want to do. You have to prepared for the material to move on a heat treatment which is why stuff is usually ground afterward. Small solid shapes are more stable, but that longer shape carries some risk of moving about imo. For brass and AL I'd skip heat treating, safer and no warping. You'll bend a lot of material before wearing it appreciably and even if you did you can resurface. If you are really worried about a wear, I'd make it out some prehardened chrome moly - tough and somewhat hard but still machinableSecond point, whats the angle in the bottom die? it looks like 90. Most of the time in a brake you're air bending and the bottom die has to be less than 90. the material doesn't really contact the sides of the bottom die and you over bend to account for spring. Maybe you're an experienced press hand and i'm telling the choir how to sing...but if not, it'll save you some pain. With an air bend, much less force is required and afaik the most common approach, vs coining or bottom bending. Bend radius is a function of material, bottom die width and top die radius. You also need a radius at the top the V on the bottom die finished to very smooth surface - that's where material will get pulled over the die and that soft stuff will easily scratchIncidentally you can fabricate a bottom die with round bar welde to the top of V block like shapes made of 1/2 plate every few inches. We've done that to get special jobs done. If you used tompson shafting or such you'd start with the bend surface hard and smooth. Probably how i'd go at it.EDIT, for what its worth the above is from experience with steel, I've only done AL and brass in a finger brake, so perhaps I'm not the best one to advise on AL/brass die design....but thats what works with steel
Hi Thomas, I was just playing with Cincinnati calculator (https://www.e-ci.com/press-brake-tonnage-load-calculator/) and those tonnage calcs look a little light in comparison but I'm following what you saying. The cinci calculator is for air bending and is close but a little higher than your numbers. Bottom or coin bending will take 4x the force or more, so am I safe in assuming your numbers are based on an air bend?What I was getting as is to get a 90 degree bend with air bending, you net to bend past 90 (it springs back to 90) so the bottom die V opening is always less than 90 degrees. btw, the DIY bottom die I was trying to describe is sketched below. Its a bit 'quick and dirty' compared to your design which is more solid and how commercial dies look, but it does make for a ready made smooth and hardening opening radius if you use hardened and ground shafting (thompson shafting). Yours is tradition die shape and probably the right way to do it, just offering this up as an another approach. Mike
Please keep the pics coming. I still cannot see you could get an air bend of 90 without the bottom die being less than 90, but you seem well in control so I look forward learning how it all comes together. There seem some slight differences in nomenclature, around here everyone it calls this a press brake and the dies are commonly called upper and lower, vs. die and punch. I think you are more technically correct, I just mention it in case it created confusion; me using the local vernacular.Here's a shot of my brakes, press and finger....big one at the plant and little I made in the garage. If I had one, I like the small hydraulic press idea like you are making....much more capacity than the finger brake I made. The big one is a 16' 300 ton cinci, I've used it but mostly the guys keep me away from it.....they have the impression that anyone from the office will surely destroy it if given half a chance cheers
Hmm. All that work just to fold a dollar bill?
Looks great!We'd each like one...!