Originally Posted By Happygilmoresar:
New to the site here. I am going into production of upper and lower receivers for the first time. So far I have been unable to find an acceptable blueprint for the upper receivers. Mostly what I need is tolerancing on the critical sizes for universal compatibility of all mating components. If anyone has a link to help me out that would be great. Thanx.
You need a probe.
Budget priced ebay probe
If you say you don't need a probe, then please put me on your 'do not sell product to' list.
Okay ... I'll explain.
Anything you attempt to manufacture, will not be what you actually end up manufacturing, except, X percent of the time.
While you will design the part dimensions to be exact, the machine, the cutting bit, the time of day, the operator, whether or not
the operator got laid last night, the material, the temperature, the position of the sun in the sky, whether or not Obama is
golfing or drinking that day, etc. will all conspire against you, and the part you attempted to produce with exact dimensions,
will not be the part the machine cranks out and ends up in your hand.
This is why manufacturers have quality control processes in place. You will need to remove X number of parts from every batch of 100 or
so and probe them to make sure that your machines are actually producing the components within the allowable tolerances.
In addition, you'll be sending these parts out for coating / anodizing etc. You'll have to measure X number of each batch that returns
from the coating subcontractor, or department if you do it yourself.
You need to monitor the dimensions of the actual parts produced on a continuous basis, unless you plan on sticking your head in the sand,
pretending they are all perfect because "they look real nice," and letting your customers via feedback tell you when your processes have
drifted out of spec.
Screw 1 customer because you failed to perform QC and they'll tell the entire internet you suck, and it'll be on the internet for forever.
Make 10 customers really happy, and consider yourself lucky when 1 of them tells the entire internet your part was acceptable.
As an extreme example, I used to work for a well known soft contact lense manufacturing plant. They would plan a production run to center
on whatever prescriptions they needed according to inventory, but in each production run, X numbers of lenses would hit the target, and Y
number of lenses would land entirely in other prescriptions. They then used a special laser machine and measured each and every single
contact lense after hydration, and recorded its parameters before placing it in inventory, because they are not able to control what they
actually produced. It's not nearly as bad with AR components, or parts machined from aluminum in general, but you get the idea.
This is standard manufacturing industry practice.
Statistical Process Control
I would say 'Good Luck', except, I just explained how to remove luck from the process.
Making a few parts, does not equal, operating a manufacturing business successfully.
ps. This was focused on customer satisfaction. I didn't mention what could happen to you financially or even
criminally if your components explode while a customer is using them, you failed to perform quality control, and
cannot provide data to prove that you produced the parts properly.
I'll let your imagination run wild with the consequences.
While you may not actually be at fault, without data to show you are not at fault, you may very well end up
learning the definition of the term 'scapegoat' the hard way. All it takes is 1 accident, and an attorney who
has more time and money than you do, and you'll be closing shop, and flushing all your hard work down
pps. In addition to a probe, you may want to plan on using X-ray or ultrasound to verify that there are no
voids internal to your materials that would create a weakness. Probably more expensive than $200, but
without performing this quality control check, your pants will still be down around your ankles.
Then there will be surface hardness testing, color testing, finish abrasion / corrosion resistance testing,
dye penetrant inspection, etc, etc, etc.
Looking forward to reading on your website the great lengths your company goes through to insure the
highest quality components.