>every lower 80 blueprint online is different by up to .100 thou >on some prints the fire pocket width is plus minus .002 thou, some its plus minus .010, some say its .680 some say its .700 >every dimension is like this >unending frustration because of this, and retards that aren't machinist trying to make a fucking print with rulers and shit >get a finished bear creek lower, put it in a vice and indicate it in to 0 >edge find every single dimension, use radial gauges on the inside corners, depth mics on the pockets >do this twice to repeat the numbers and guarantee accuracy >all instruments I used are accurate within .001 >print I have come up with is completely fucking different than any print ive seen online by nearly .250 thou in some dimensions >this lower is straight from the factory, not modified, been fired and is in working conidition
what the fuck is this shit? why is this so goddamn hard? just give me the goddamn dimensions so I can make the part. is this part of the lower so wide open that all of these wide range of dimensions are considered in tolerance? this is the blueprint I came up with using modern CNC measurement equipment so I know for a fact its going to work but i just want an answer on why the FUCK every print out there is different?
Because it really doesn't matter a couple thou on the pocket dimensions. Hell, I hacked out an 80% lower with a fucking dremel lmfao as long as the pin holes are within a couple .010thou and the safety is pretty spot on, you're good to go. The hammer can be off a full .1" and still fire fine you know?
Really it's not that important. That's why things like picrelated can exist
The dimensions of the lower aren't all that important in an AR as long as they aren't dramatically wrong.
The upper is where the tolerances really matter.
Cooper Butler
>bear creek what are you even doing
Austin Brown
The majority of the measurements are totally meaningless. As long as these are correct relative to each other the rest requires very little precision: -takedown and pivot pin location -trigger pin location -threads for receiver extension
Like the other user said, the things that matter are in the upper, and even then the critical part (headspace) has nothing to do with the upper itself.
John Myers
How can you pretend to know anything about machining and metrology, and be that oblivious to critical vs. non-critical dimensions?
Snowflakes and it's not even winter.
Logan Miller
People here are shitting on you like they always do, but I appreciate the work you've done, OP.
David Ortiz
Post toolbox faggot. I know more than you. If you're an anal autistic retard about dimensions you'll never fuck up. Kill yourself
Jaxson Davis
This user knows what's up?
Luis Smith
Just use the step by step from a forge pdf or get an 80% rig Both should be easily accessible
Jayden Kelly
for what its worth dont the different generations and models of ar lowers all have diff dimensions?
Grayson Jenkins
Pocket depth, trigger hole, and pin locations are really the only vital ones. The rest is just clearance.
Brody Martin
>asking why there is non-conformity in "good enough" measurements >spergs the fuck out on the user pointing out that the "good enough" measurements are non-critical dimensions
FYI this is why people who actually do tooling and work hate engineers
Well if you try to handhold-drill it of course you’ll fuck it up
Leo Collins
Mine looks like that and it works fine. FCG pocket is 0.850 in places and the trigger walks out of position, but it also walks out from my retail lowers too.
Oliver Clark
Why don't you just look in the technical data package, my dude? You're not going to get anywhere measuring random lowers, it won't tell you the acceptable tolerances. Here you go friend spee.ch/@Deterrence-Dispensed:2/M16TDP Download links are at the bottom.
Bentley Sanchez
Oh, and the part you want will be in the .pdf on page 63, 64 and 67.
Oliver Diaz
Does anyone here have a 80% lower cad file in metric?
Anthony Murphy
This. The tolerances in a lower are actually pretty loose for the most part. Almost all components which benefit from being extremely precisely machined are components of an upper receiver. If you can bolt an upper that costs $1800 before optic onto a lower that costs $40 without any loss whatsoever in performance, that should tell you something about the nature of AR lowers.
Henry Ross
>being this autistic about dimensional variation among lowers that are all out of spec for the purposes of legal distinction
Anyone have the design pack for that sheet metal ar15 lower? The flat spot guy sold it to someone.
Thomas Watson
>spee.ch/@Deterrence-Dispensed:2/M16TDP thanks user, this is pretty cool. any CAD file can be in metric if you convert it. Just get the 3D file from FOSSCAD or the ar/k/, and in your 3D space convert the model to metric.
