Sunday, August 17, 2014

Paging Og...

Aliens!
Can anybody decode the dimples on the underside of the BG380 slide? Paging Neanderpundit...
.
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31 comments:

Anonymous said...

When I took the M&P armorers class the instructor explained that the dimples were a code to identify the specific milling machine the slide was machined on.

Corey

2:56 PM, August 17, 2014
og said...

Right in one. The specific milling machine (Top three dots means it was machined in machine three) the pallet (These are two pallet machines), bottom left dot on top means it was done in pallet one, and the bottom right dot means it was done on the bottom fixture. So, bottom fixture, pallet one, machine three.

3:49 PM, August 17, 2014
og said...

If you compare several side by side, you will also find there are subtle differences in the stippling of the grips that show which mold cavity the receiver came from. And there are also guns with no dots in the slide, which means I don't know what.

3:57 PM, August 17, 2014
Kristophr said...

"Help, I am trapped in a MiM cast factory!"

4:03 PM, August 17, 2014
Tam said...

Thanks, Og!

4:17 PM, August 17, 2014
Al T. said...

Og, awesome. Wondered about that myself.

6:47 PM, August 17, 2014
Tam said...

Dave,

Why would I do that when I could ask the guy who set up the machines that milled the slide in question?

7:10 PM, August 17, 2014
Don M said...

I guess one could ask the guy whose ears the earplugs came from.

7:18 PM, August 17, 2014
Anonymous said...

Gosh, and all this time I thought that it was Braille for "Buy a handgun caliber that starts with a .4"

- A Guy in The American Redoubt
(Where we encounter bears)

7:26 PM, August 17, 2014
Tam said...

It's almost like they made different kinds of guns for different purposes.

Mind. Blown.

7:36 PM, August 17, 2014
Anonymous said...

When parts are molded there has to be sprues that allow the metal to contract after it cools. That is why MIM triggers are hollow in the back.

These are probably sprues.

8:08 PM, August 17, 2014
Tam said...

"When parts are molded there has to be sprues that allow the metal to contract after it cools. That is why MIM triggers are hollow in the back.

These are probably sprues."

The internet never fucking fails to amaze me.

We just had the guy who helped set them machine up come and post what the marks meant, and people are still coming along and telling what they think the marks might mean.

Un-frickin'-believable.

10:10 PM, August 17, 2014
Paul said...

I thought they would help blind people reassmble the gun.

Otherwise I would go with what Og said.

10:52 PM, August 17, 2014
Mike said...

Hmm, sounds like someone doesn't know what a sprue is.

Hint: It doesn't look like a dimple!

12:20 AM, August 18, 2014
Cincinnatus said...

David is an evil man ... I like.

12:30 AM, August 18, 2014
Ed said...

Dancin' monkeys i can deal with.
It's the flyin' monkeys that give me the willies.

12:56 AM, August 18, 2014
Drang said...

Flyin' monkeys aren't so bad, it's the flyin' pooh-flingin' monkeys I worry about. I hear they carry and transmit ebola.

2:27 AM, August 18, 2014
Drang said...

Also, I wish the stock Blogspot comments system would let us do "Up/Down" votes on comments...

This is entirely selfless, considering that the average comment on my own blog is flogging fake Prada or Coach, or "male enhancement" products...
(Thank you, Blogspot's spam filters...)
(You'd think spell check would recognize "blog" as a word. And "Prada". And "Blogspot" and "blogger.")

2:31 AM, August 18, 2014
Ed Skinner said...

Braille "94" -- too bad it wasn't "42" - that would've been fun

9:58 AM, August 18, 2014
og said...

It is a very common industry practice to mark parts in the machine they came from. This practice was brought to you by W Edwards Deming. the marks are usually made by ball end mills because they leave a smooth rounded dimple that contains no sharp edges to act as stress risers.

10:36 AM, August 18, 2014
og said...

BTW Tam, check your Tamslick email for further information you might find amusing

12:26 PM, August 18, 2014
Will said...

Tam,
Part of the problem may be the time lag for the comment moderation you have instituted. Really screws up the flow of feedback. Gets sort of disjointed and frustrating. Feels a bit like going to a telegraph system. I'm guessing this was done in response to PB?

3:58 PM, August 18, 2014
Tam said...

Will,

Og's posts had been visible for hours.

On the internet, in comment threads or forum discussion threads, people only read along to the point where they feel like they GOTTA PROVIDE THEIR INPUT and no further. They see something in post #11 or a thread and immediately hit "POST REPLY" to add post #27 to the discussion, blithely unaware that somebody might have already said (or refuted) what they are about to type, 'way back in post #14.

(I'm not immune to it, either.)

4:03 PM, August 18, 2014
Sigivald said...

When parts are molded there has to be sprues that allow the metal to contract after it cools.

That's also not what a sprue is, anyway.

Sprues are the metal connecting the object being cast to the outside world, where the metal is injected or poured.

You cut them off, ideally pretty flush, and then machine/file flush as needed.

How you'd get an indent is beyond me.

(I know this kind of thing from doing artsy metal casting, not MIM machining, but the term's the same.)

(Further, as far as I understand the process, the hollow trigger thing, e.g., is simply to save weight and material (money), not because of shrinkage.

Every casting process I'm aware of that has shrinkage as things cool or compress is uniform or damned close to it... so why you'd have or end up with a hollow back to account for it is unclear.

I'm sure Og knows more about this one, too.)

5:54 PM, August 18, 2014
og said...

Im gearing up for a series of posts on mim and manufacturing.

6:22 PM, August 18, 2014
Jim said...

I'm an expert on "shrinkage". Old age and cold water tend to highly exaggerate the effects.


Jim
Sunk New Dawn
Galveston, TX

9:33 PM, August 18, 2014
Anonymous said...

I did not know Og did work for S&W regarding their CNC machines. Had I known that I never would have jumped in with my answer to begin with. I just saw the question hanging out their and thought, "I asked the same thing in the armorer's class, might as well pass along what I got told." Og's answer was much more informative and complete and I made a note of it in my armorer manual.

Corey

10:42 PM, August 18, 2014
Tam said...

Corey,

You were fine; Og hadn't answered yet. :)

10:56 PM, August 18, 2014
Windy Wilson said...

Just how many bloggers have blogposts and comment threads that contain not only the right answer, a sort of "folk etymology" wrong answer, and a number of pertinent and impertinent on-point jokes?
I love this bar.

12:15 AM, August 19, 2014
og said...

Corey: I'm very impressed they taught you that thoroughly. And you would be amazed how much many manufacturers do NOT manufacture their own stuff. You were dead nuts on.

12:26 AM, August 19, 2014
Anonymous said...

Thanks, Og. I have just enough experience in machine shops that as soon as he started to explain what it was I felt dumb for not having recognized them in the first place (one of those "oh, yeah now I remember" moments). That is also just enough time in machine shops that I am not at all amazed how many manufacturers don't actually manufacture their stuff.

As to the thoroughness of the training, this class was about 3 years ago and the same instructor said the accuracy problems with some of the full size 9pm pistols were an Internet myth, and the occasional dead trigger and early unlocking problems were impossible and could not ever happen even though I had personally seen both happen. Win some-lose some.

Corey

11:20 AM, August 19, 2014

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