The Top Secret Project

[DocsMachine]

Is no longer a secret.

Watch 'til the end, there's a twist.

Doc.

[scottieb]

I notice some shrinkage there.

[Ecapnation]

50 cal sniper?

[Jonnydread]

Hmmmmm

[Glovebox Operator]

Finally. A proper mini cocker.

[scottieb]

Brilliant response.

[ThatBobbyjoe]

First time I’ve been subtly reminded to subscribe and actually checked to make sure I was.

[tko33]

OMG!! Why was watching that video sooooo satisfying!!!!!!

[Jonnydread]

Yeah it felt very zen, like machining ASMR

[Swedgin!!]

I had to watch that video a few times🤘🏽. Hells yes!!

[Daltech]

Very well produced video. Very cool product.

[William the Third]

[DocsMachine]

Spoiler:





Not done yet, that pic's a month old so there's been more progress, but I've mainly been focusing on getting the backlog of customer work off the table. But yeah, a 3/4-scale, fully functional .50 Sniper.

Completely pointless, of no real marketable value (especially for what it'd cost ) but man has it been fun to make.

Doc.

[Swedgin!!]

Not pointless at all 😎

[Glovebox Operator]

Absolutely awesome. We'll need a shooting video soon. Then a 3/5th scale 43 cal sniper.

[GattoDiavolo]

Micrococker!

[DocsMachine]

Absolutely awesome. We'll need a shooting video soon. Then a 3/5th scale 43 cal sniper.

-Two things: One, air and the valve don't "scale" well. I'm already worried about the 3/4 valve- the scale hammer isn't 75% the weight, it's more like half thanks to inverse square.

(Stock hammer is about 38 grams, the reduced one is 17 grams.)

Ditto the travel, which is 25% shorter. And I know from direct experimentation that adding .100" travel to a 'Cocker sear adds velocity/allows reduced spring pressure. I'm confident this gun will work- aided of course by the fact the ball doesn't need as much energy to get up to speed- but I may have to use fairly stiff springs.

All of which gets even worse if we try to go down to .43, which is just about 2/3rds scale.

The other thing is, all my machines are too big for this stuff.

That's why I spent some time just a month or two ago upgrading my Rivett- that precision Hardinge X/Y slide is the best thing I have for weeny little precision parts like this. I go down another step or two, I need to buy a friggin' watchmaker's lathe with a microscope!

Doc.

[LightArmsJXF]

Yes. Scale it UP and fire ping pong balls!

[William the Third]

LightArmsJXF I can think of more "entertaining" ways to launch ping-pong balls...

[Blackmagic71]

I’m on board for a ping pong ball launcher 🤣

[DocsMachine]

And for those of you that prefer the build-blog format, of course I took pictures!

If the video wasn't clear- or you're not a paintball player for some reason - I'm building a 3/4-scale pump-action Sniper. It'll shoot .50 caliber paintballs rather than normal .68 caliber- 50 ÷ 68 is 0.735, or 73.5%. Reduce all the original specs by a nice even 25%, and we have a scale marker shooting scale paint.

It's a straightforward task- I'm just copying existing parts. But, as we'll see, it gets a little tricky when calculating things like O-ring fits and thread sizes- and, of course, there's the fact I have to make everything. The body, the grip frame, the barrel... the valve, the cup seal, the hammer...I gotta make a 3/4-scale ball detent fer pete's sake!

Why am I doing it? Because I friggin' can. So, let's get started....

The body was simply blanked by the usual quick trip through the bandsaw- the date was the day I semi-officially started the project:



I set up the angle plate and bolted the body directly to it rather than going through the trouble of mounting and dialing in the vise, as shown in the video. The indicator made sure everything was true and square...



The centers were found, and the bores spot-drilled...



Then deep-drilled...



And the RVA tapped.



The full size adjuster is 3/4"-16, so the reduced version should be 9/16"-20. That's actually available as an off-the-shelf-but-nonstandard tap, but it's also a sixty-dollar tool and I'm not quite that pendantic. I did have 9/16"-18, so that's what I used.



Flipping it end for end, the front got a similar treatment. The pump rod is normally 3/8"-24, and .375" x .75 is .281". That's too big for 1/4", but lo and behold, I actually had a 9/32"-32 tap! 9/32 is... .281"! Technically the thread count should be 30 to be proportionally correct, but even McMaster doesn't carry that caliber....

So, I calculated the tap-drill size (turned out to be .250" even) and drilled and tapped the front of the body.



Dunno where I got that tap, probably in one of the miscellaneous tool scores I've made over the years, but that, too, saved me $60 plus shipping.

Then the breech area of the body was milled out to clear the barrel...



Bored with a 21/32" endmill I picked up off eBay, to save the hassle of having to set up the boring head...



Then tapped with another close equivalent.



Again, the factory barrel thread is 15/16"-20. Technically that should convert to .703"-25, but that caliber doesn't exist either. The closest match is 11/16"-24 (.6875"-24) which it just so happens I'd also ordered from McMaster a week or two before.

And that was as far as I got in the first go-'round.



I'd of course been trying to think a little ahead on all this, and I'd been working up proper drawings (though no CAD yet) so I wasn't flying entirely by the seat of my pants.

Been having a blast with it, simple as it is, and can't wait to see it working.

Doc.

[Swedgin!!]

Doc, yous a Badass🤘🏽

[tyronejk]

Damn, no CAD is wild. I would've botched this six ways to Sunday by this point without having drawn up a CAD file beforehand.

[Jordan]

Will it be run on 8gram CO2 cartridges?