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CORBIN HYDRO-PRESStm

CHP-1 top panel The world's most powerful (and popular) hydraulic power swaging and reloading press, Corbin's Model CHP-1, has been again revised and improved, with even more reliable electronic position transducers, redesigned powder-coated steel cabinet with integral hydraulic tank and forced air cooling, and new features to interface with Corbin's automatic strip feeder/decoiler and other accessories.

The CHP-1 has been produced for more than 20 years, starting with the original Mark I. The prior version, Mark IV, is used by nearly every custom bullet making firm in the world today, outselling every other type and brand of bullet making press for commercial custom bullet manufacturing, military prototype work, research and development labs and short run test production at defense industries. Today's Mark V retains all the reliability and features that have made Corbin's Hydro-Press the world's leading design, with even greater freedom from maintenance and more functionality.

The CHP-1, Mark V, weighs 350 pounds, has a 22 inch by 15 inch floor space, and runs on either 120 volt 60 Hz standard household current (USA), or 220 volt 50 Hz standard overseas power (with optional A-220v kit). With a six-inch stroke length, and enough power to swage 1-inch diameter cannon shells, the Hydro-Press is a true multi-purpose machine. Some of the things it can do, with the proper set of dies, include: Corbin Hydro-Press, CHP-1

  • Bullet Swaging from .123 to 1.000 inch diameters, up to 3 inch long projectile.
  • Making bullet jackets from copper, aluminum, steel or brass tubing.
  • Re-manufacturing fired or pulled bullets to nearly new specifications.
  • Forming powdered metal tungsten and other exotic bullet constructions.
  • Drawing bullet jackets from flat strip, including long heavy jackets like the 50BMG.
  • Extruding lead wire, hollow lead tube, or lead came for stained glass work.
  • Making detonators, grenade primers, and other formed round tubular devices.
  • Reloading ammunition of any size with conventional or special reloading dies.
  • Swaging finned shotgun slugs with helical twist and hollow cavities.
  • Manufacturing fishing tackle, spinners, spoons, and bass lures from copper or brass.
  • Punching, forming, drawing, and other precision metal fabrication operations.
  • Foming pressure-linked plastic materials into sabots, tips, and other round shapes.
  • Swaging perfect round balls for muzzle loaders in any diameter.


The CHP-1 is the machine of choice for any custom bullet business, because it can do everything from making the lead wire to drawing the jackets, swaging the bullets, and even reloading ammunition with the bullets it just made. While it is a hand-fed press (with the one exception of automatic copper strip feeding with the CSU-1 strip uncoiler and JMK-2 automatic jacket drawing head), it is a perfect match for custom bullet business volume, bullet pricing, and limited capital investment. Often, a company will choose to grow by adding more Hydro-Presses rather than spending six figures on the next step up, automated transfer presses, since the Hydro-Presses can make any caliber within a few seconds of setup time, whereas the high speed automatics not only cost as much as twenty Hydro-Presses, but are dedicated solely to one product at a time and are very slow and expensive to change to another.

How It Works

The Corbin Hydro-Press is powered by a 1.5 HP electric motor within the cabinet, vertically mounted. The shaft of the motor fits through a mounting, which in turn joins the shaft of a two-stage hydraulic pump inside the lower third of the cabinet. The lower third of the steel cabinet is a closed hydraulic reservoir holding about six gallons of non-foaming Chevron AW-40 hydraulic fluid. It is designed with baffles and a top-mounted filler/breather just inside the front cabinet.

The oil is pumped to a three way solenoid valve, which controls the direction of oil flow. In the idle or normal position, the valve dumps oil quietly back into the tank through a sub-micron oil filter (spin-off type, similar to but much finer than your car oil filter). When you press the ENERGIZE and UP buttons on the top pannel, the solenoid valve switches to allow oil to flow into the bottom of a 3.25-inch bore by 6 inch long industrial drive cylinder. The oil pressure is regulated by an internal safety valve, and a top panel drive pressure set knob that runs a temperature-compensated pressure regulator valve. You can set the drive pressure anywhere from a minimal 100 psi to as much as 2000 psi. Drive pressure is translated into 8.3 times as much ram thrust by the cylinder, and internal die pressure is determined by dividing this thrust by the area of the swage die cross section. More than 120,000 psi can be generated in some dies, although a far lower limit is imposed by the breaking strength of a die in most cases.

A book(Power Swaging) which comes with the press contains a table of safe die pressures for a given cross section (usually the caliber, but not always...a core swage die can have a much smaller bore than the caliber it is intended to fill). A high grade, glycerine-filled pressure gauge on the top panel monitors drive pressure at all times.

Electronic dwell timing can be set to precisely control the length of time that pressure is applied, down to the millisecond. The Mark V includes dwell time controls for both the top and bottom of the stroke, so a delay can be introduced during ejection to allow sufficient time to break "air-locks" and eliminate the impact of a sudden reversal. The press can also be set, by means of simple toggle switches, to operate according to certain prewired cycle programs. With the pressure reverse switch turned off, and the position switch turned on, the ram travels up until it is detected by the top position transducer, which is on a standard to which three adjustable transducers are mounted. When the transducer detects the presence of the ram at your definable top setting, it stops the ram travel by moving the solenoid valve to the center position, holding pressure at the top of the stroke.

If the pressure switch is turned on, it passes over-riding control to a sensitive pressure transducer, which can be easily adjusted with a hand knob. This transducer monitors drive pressure, and causes the ram to stop when a pre-set pressure is reached. Thus, you can set the press to stop on reaching a certain position, or a certain pressure. One setting backs up the other to prevent accidents. Next to the pressure reverse control is a speed control so the ram can travel at any rate, from zero to barely creeping along, to 2 inches per second.

Because the press uses a two-stage pump with feedback control, the power consumption is very low while the ram is moving up and down. The only time there is any significant power use is when a bullet is actually being subjected to pressure, at which point the pump switches from high speed low pressure mode into a short burst of high pressure at low speed. The amount of energy used is a fraction of that required by a single stage pump without feedback, making it practical to run the Hydro-Press in any garage, den, or even trailer house, provided the wiring is at least 12 gauge copper with a 20 ampere breaker. The press itself contains a 20 ampere circuit breaker switch as the main power control, as well as a 5 ampere push-button breaker for the logic and control circuits.


The CHP-1 Mark V has a three position key switch that controls the power and functions. In the off position, only the fans and inspection lamp are functional. In the on position, the press can be run in manual mode only, stopping as soon as a hand is lifted from either the Energize or the UP button, except on the down stroke. In the Auto position, a red warning light comes on, and the press can be started in an automatic up and down cycle, with or without pressure reverse. It can also be operated in a one-shot automatic mode, where a person drops in the part, presses the Energize and UP buttons in the proper sequence, and then lets the press handle the stroke cycle while the operator does something else. The ram will then stop at the LOAD position, set by the center position transducer, on each stroke, and wait to be loaded again.

For safety, the key can be removed with the press in the manual or off position, preventing automatic stroke operation.

On presses made prior to August 1, 2011, at the rear of the press, a shunt plug fits into a socket that is intended as a sensor inlet so that the optional strip feeder can shut off the press, in automatic operation, when the 50 or 100 pound coil of strip runs out. This features was almost never used, so it has been discontinued.

On presses made on or after August 1, 2011, the shunt plug is not used, and the socket at the rear of the press top is connected so that it receives 115v from the logic and control circuits, limited to 5 amps, whenever the press is in the "down" stroke mode. The earlier shunt plug should not be used on these presses, as it will cause the 5 amp logic circuit breaker to open. Instead, the socket is used for an optional automatic jacket stripper, which can be purchased separately and mounted on the press head. The jacket stripper can be operated manually, or it can be shifted in and out of position to strip drawn jackets from their drawing punch, using the soleniod-operated power shifter. The power for the devices comes from this socket. When the press ram begins to go down, the solenoid shifts a stripper plate to catch the mouth of the jacket being drawn, and the punch continues down. This pulls the jacket from the punch automatically. When the ram reaches the bottom of the stroke, the power is removed from the solenoid and a spring returns the stripper plate to the "rest" position, ready for another jacket.

For full details and pricing on the Hydro-Press and the -H dies which fit it, see the Corbin Price list and read the book "Power Swaging". This book also comes with the press as an operating guide.

Building 1609, housing the advanced weapons lab. Not far from Parsippiny, New Jersey, is the Picatinny Arsenal, home to US Army advanced weapons research and development. Building 1609, a tin-roofed 1920's style barracks-like structure, houses an extensive laboratory which includes two Corbin Hydro-Presses which were used by Ph.D's during the development of the service-wide Green Bullet project. Corbin delivered and set up the presses in 2001 and 2002 for this work.
Dr. Deepak Kapur operating a Corbin Hydro-Press in Building 1609 One of two Ph.D's working on compounds for the Green Bullet project, Dr. Kapur uses a Corbin HydroPress to form lead-free bullets from powder metal mixtures in this 2001 photograph. Corbin's presses and dies have since been used by dozens of agencies and defense contractors to further the development of advanced projectiles, including special remote control models for assembly and disassembly of 40mm ammunition (the limit of the standard CHP-1 is 25mm).
A small portion of the interior of Building 1609 The exterior of building 1609 would scarcely warrant a second look, but this is a small portion of the array of sophistocated lab equipment inside! The ARDEC related development work done in this building would seem more likely to be housed in a gleaming glass and steel structure, not one where the sparrows sometimes enter through gaps in the ancient wood-framed windows.
Corbin Hydro-Presses used at Picatinny Arsenal, in early days of the Green Bullet project Corbin Hydro-Presses at the Picatinny Arsenal, during the early days of the Green Bullet project. The CHP-1 press and Corbin dies are also in use at Frankfort Arsenal, Oak Ridge, China Lake Naval facility, Eglin AFB weapons labs, and other research and development facilities.
Indoor firing range large enough for artillery, just across the street from the research lab Across the street from the lab, this indoor firing range is large enough to drive a tank into one end, and fire artillery shells into the backstop at the other end!

For a fold-out color poster, and brochure, send $1 to:
CORBIN
PO Box 2659
600 Industrial Circle
White City, OR 97503 USA





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