Precise bullet seating and crimping using computer control

[sam007]

[sam007]

I am designing an ammo assembly machine that is computer controlled. I want precise bullet seating and crimping for ammo accuracy

[Hans Gruber]

To do it right you'll need a lot of money and...


... lasers, lots and lots of lasers.

Other than that, I've got nothing Good luck!

[J-cat]

I trim my brass to the same length, that way the crimp is consistent. I use my case expander with its plug backed out to final seat bullets, so they are all the same OAL. You don't need special machines, lasers, or alien technology to do this.

[fairfaxjim]

There are a couple of ways to go, none of them all that easy and cheap. I would recommend that, since the crimping force and seating depth are both actually controlled by the amount of insertion into the dies, that a servo motor be used to control the depth of insertion into the dies. That will definitely work for the bullet seating. The crimp "force" is not going to be directly measurable - unless you are asking for a the amount of force used to press the cartridge into the crimping die. I don't see where that would be a direct correlation with the amount of crimp applied, as different cartridge case thickness, length, etc. could require a greater amount of force to get the same insertion (which may or may not give the same crimp tension on the bullet.)

I think if the cases are selected and prepped properly, i.e. as uniform as possible, then the insertion depth would be the best way, and that is actually what happens with a conventional press. A Servo (or stepper) motor w/gearbox could possibly be used in conjuction with an inline strain/force gauge that would allow the cartridge to be pressed into the crimping die until a specified force is reached and then stop. That would require a force gauge, probably a force gauge signal conditioner (to amplify the low voltage from the force gauge to the analog input to the computer), a servo motor or stepper motor, a servo or stepper motor amplifier, and a motion controller card for the motor control. The motion card will usually have software available with it for programming the control. You will also need an analog input available on the motion control card for the strain gauge input, and you will need some digital/discreete inputs (and possibly outputs) for some safety limit switches.

A couple of servo/stepper sources;

http://www.galilmc.com/products/overview.php

http://www.applied-motion.com/

A motion and control system is pretty complex if you are looking for any degree of accuracy, repeatability and robustness. A possible solution would be these guys, they have programmable controllers that have a Web based HMI (Human Machine Interface) That puts all of the control on the controller, you program it and operate it from a web browser based application.

http://www.ctc-control.com/info2.asp?gclid=CI6u9pPApZoCFRIcawod4EeU9Q

There are some motors with controllers included in their design with some software programs that can be used also, look for Smart Motor (in the SF Bay area I believe)

I've done a lot of motion control projects, but all of the Programmable Logic Controller (PLC) or stand alone programmed controller based. I do not find the PC to be a very good platform for direct machine control (some do for certain applications.) PC's are used for programming, and are also used for the HMI portion (although I usually use a machine mounted touch screen that interfaces directly to the PLC and let the PLC handle the motion control or communication with the motion control components.) There is a product called "Soft PLC" that may have all of the required control software components. http://www.cmccontrols.com/index.html There are also some CNC machine type controls that are available for PC use - a search for them and a look on Ebay would be useful - I'm not reallly up to speed on what's available there.

You are venturing off into a very complex area of automation. Sizing motors, gearboxes and motion systems is key to getting a working system. Determining the amount of force needed, and the mechanical resolution required is going to be your first task.

BTW, most of this stuff is not cheap, but you can often find some pretty cool stuff on Ebay. The problem is making sure it will work with the rest of your setup.

Good luck!

[Beelzy]

Just run over to Olin and pick up one of their used ammo machines out back
and throw some gizzmos on it.

[mattman]

Why not measure the diameter of the round where it was crimped to determine how much crimp was applied.

[waterworld]

I have been in the hydraulics business for 35 years; everything you asked about can be done very effectively with hydraulics. However as fairfaxjim stated it is not cheap.

One question I might have is when you use the term “accurate” what do you mean? A half thousandth?

[waterworld]

I am relatively new to reloading however I think you can measure crimp force. The built seating die performs 2 functions A) push the built into the cartridge to a predetermined depth. B) Crimp the cartridge around the built.
I believe if you had 2 seating dies one could be set to push the built into the cartridge to a predetermined depth with no crimping at all. On the second die the stem could be backed all the way out if necessary so as not to touch the built at all but could be adjusted to perform the crimp operation.

The difference in pressure between the blind end and the rod end of a hydraulic cylinder is force. These can be measured with a pressure transducer. You could reasonably expect achieve force accuracies to within a few ounces I believe. These forces can be mathematically calculated given a cartridge diameter to produce a crimping force.

However I doubt this is what is significant. The term “accuracy” in motion control is rarely as important as repeatability.

[30Cal]

If you're going this far for accuracy, you'd be shooting good bullets (in which case, you probably shouldn't be crimping).

[bohoki]

it woudl be cool to have some kind of electric eye to seat bullets to maximum oal instead of the ogive differental seating depth that often happens

[jwest]

Interesting thread.

Reading this begs the question, "What do the commercial ammo manufacturers do?" Have any of you toured any of the commercial ammo plants - what do they do? They must have some decent automation to churn the ammo out. I would like to watch how .22LR is done - think about how many rounds of that stuff that has been produced in the history of history.

[sam007]

If you're going this far for accuracy, you'd be shooting good bullets (in which case, you probably shouldn't be crimping).

I don't know much about reloading and am new to the subject. I read that for really accurate ammunition u want the force required to separate the bullet from the case to be of a value so that they separate when the gas pressure has reached the value required, optimum. So I want to have an assembly machine that can create a precise tension so that the bullet and case will separate at the desired force\pressure.

[sam007]

jwst, there is very little info available about how commercial ammunition manufacturers do things. not sure why not as ammunition making isn't new technology. The camdex site has a liitle info and a few videos and utube has some videos. sometimes some of the guys who work in the ammo making business use these gun forums and provides some info, thats what I am hoping

[Josh]

Is there a reason you want so much automation?

Is this for production?

Pretty much everything you have been asking for is currently able to be done in some way by traditional methods.

They have micrometer seating dies and with neck turning of the brass along with the appropriate neck sizing bushings you can keep seating tension consistent. Adjustable crimp dies allow you to vary the crimp pressure.

And with the variation between components you would need to calibrate the system each time you change anything. And you need to test each combination of settings for different components to see how accurate they are for your rifle so you need to adjust them anyways to find the sweet spot. Once that spot is found you just leave the setup alone anyways.
Granted im no expert on reloading, i just do it for fun. But i cant see any advantage to this unless its on a production scale.

i dont think it would be too hard to do what youre asking but integrating it into a reloading setup would be the main issue.

A transducer in the seating die or in a mechanism that controls the ram can sense the level of pressure required to seat the bullet. And a linear position sensor built into a modified seating die can be used to measure seating depth of each round if placed in the station after the actual seating die.

Then a stepper motor hooked up to the seating die could adjust seating depth automatically.

But all this can be done manually right now for 1/5 the cost of building this CNC loading machine. And you will not see any improvement in ammo consistency.