After reading the detailed and insightful thread posted here by Lee Martin on bullet making, I was encouraged to start a thread on my current .264" jacket making project. I've always been keen to swage my own bullets but the biggest barrier in my way was sourcing jackets here in Australia. It was during a Covid lockdown last year that I decided to give jacket making a red hot go.
Step 1: Research
I began researching the deep drawing process and anything related to bullet jacket manufacture. A lot of the information was for high volume mass production especially large press tooling. I needed to gather all of this up and shrink the whole thing down to a small, manual benchtop process. I settled on C12200 0.7mm (.027") copper sheet which can ordered fully annealed. Deep drawing of copper is based around a basic set of rules. The first cup draw has a maximum limiting drawing ratio (LDR) of 2:1. The cup punch diameter is no less than half of the blank disc diameter. The subsequent drawing stages then have an approximately 22% reduction ratio. Lengthening each draw requires "ironing" and I settled on a 17% ironing ratio to form a 1.4" long final jacket. This is controlled by the punch diameter. A larger punch diameter increases the ratio.
The calculated forces needed were about 1.13 ton for blanking and under 0.25 ton for the drawing operations. To reduce the required force of blanking, I designed the punch with a slight 1.5 degree angle face. This "shear angle" reduced the force down to 0.2 ton.
Step 2: The Press
I ordered a 2 ton arbor press online and set it up on a work bench in my spare bedroom. The reason for using an arbor press and not a large compound lever press was simple. The force needed for deep drawing is constant through the whole stroke not at the end of the stroke like an O frame press. The quality was average for a Chinese made press but would be just fine for my prototype tooling. The plan was to make "proof of concept" dies and punches and see if it works.
Step 3: Prototype tooling
My background is in consumer product design and I've worked in manufacturing for over 30 years. My main tool of the trade is CAD so everything was drawn up digitally so prototype parts could be CNC machined straight off my files. The dies looked like big versions of Redding neck sizing bushes. These inserts then dropped in an off the shelf shaft guide block. Punches were made by ordering HSS drill rod blanks and grinding an end radius. The dies were CNC machined by a prototyping bureau in 1018 mild steel. Stripper plates and die mounting plates were cut from scrap steel. So far nothing fancy.
Step 1: Research
I began researching the deep drawing process and anything related to bullet jacket manufacture. A lot of the information was for high volume mass production especially large press tooling. I needed to gather all of this up and shrink the whole thing down to a small, manual benchtop process. I settled on C12200 0.7mm (.027") copper sheet which can ordered fully annealed. Deep drawing of copper is based around a basic set of rules. The first cup draw has a maximum limiting drawing ratio (LDR) of 2:1. The cup punch diameter is no less than half of the blank disc diameter. The subsequent drawing stages then have an approximately 22% reduction ratio. Lengthening each draw requires "ironing" and I settled on a 17% ironing ratio to form a 1.4" long final jacket. This is controlled by the punch diameter. A larger punch diameter increases the ratio.
The calculated forces needed were about 1.13 ton for blanking and under 0.25 ton for the drawing operations. To reduce the required force of blanking, I designed the punch with a slight 1.5 degree angle face. This "shear angle" reduced the force down to 0.2 ton.
Step 2: The Press
I ordered a 2 ton arbor press online and set it up on a work bench in my spare bedroom. The reason for using an arbor press and not a large compound lever press was simple. The force needed for deep drawing is constant through the whole stroke not at the end of the stroke like an O frame press. The quality was average for a Chinese made press but would be just fine for my prototype tooling. The plan was to make "proof of concept" dies and punches and see if it works.
Step 3: Prototype tooling
My background is in consumer product design and I've worked in manufacturing for over 30 years. My main tool of the trade is CAD so everything was drawn up digitally so prototype parts could be CNC machined straight off my files. The dies looked like big versions of Redding neck sizing bushes. These inserts then dropped in an off the shelf shaft guide block. Punches were made by ordering HSS drill rod blanks and grinding an end radius. The dies were CNC machined by a prototyping bureau in 1018 mild steel. Stripper plates and die mounting plates were cut from scrap steel. So far nothing fancy.
