3d printed body with Lathe turned pressure chamber?

[devilzcall]

So I've been thinking about which parts of an autococker could be replaced by 3d printing, allowing for endless customizability on a budget. Turns out the cocker has most of its pressurized parts fairly close together and I believe you could get away with a single lathe machined part and 3d print the remainder of the body.

We have seen pipe bodies before, but I believe they can be simplified even further.

• Everything beyond the firing valve really doesn't need to be airtight, just close enough is fine, however to improve your seal and durability, you could make use of a second machined upper tube for the barrel threads and bolt o-ring contact surfaces.
• The entire body around the hammer doesn't need to be metal so the lower tube can be kept short which should drastically reduce material cost.
• The VASA can be moved to a mini-style front block, so all other operations on the tube can be performed on a lathe and a drillpress.

Here's a rough concept of what said lower tube would look like:

This is probably gount to ruffle some feathers, but please let me know what you think especially regarding the safety aspect. Only piece I could see failing would be the firing valve, and it might be worth to move to a standard cocker valve with retaining nut instead of relying on the valve set screw that seats partially in plastic.

[OpusX]

Reminds me of Spanky bodies with the tube inserts. As I recall they did not stand the test of time, but they did work for a minute.

[Alexndl]

Mini body from spanky where less prone to leaks at the lower tube
Full length body where a different story
But fishbone have such a cool look

[devilzcall]

Alexndl that's what I'd think. Mounting the VASA through the body into a tube suddenly requires two seals instead of one and seems like asking for disaster.

[jokers]

Does anyone know how a spanky fishbone regularly failed and for that matter how they were made? Was the tube just cold press fit in and glued? Was it hot pressed and glued? In my mind I see the body being drilled out undersized. the tube milled with all the fittings needed and slightly oversized. The body heated and the tube chilled and then pressed together. I may be over simplifying it a little.

As far as 3d printed if you were to build the lower tube and upper tube outside the body and then 3d print a clamshell that can go over the tubes kind of like a tippy that may get your desired results. I would make sure that there is enough meat on the front so that the banjo bolt is threaded on the print and the tube so that it is held in with more than a friction fit.

As far as safety i would make sure and have the two tubes welded together and made of a material strong enough to take 4500psi or 310 bar. The valve retaining nut would have to be in the metal and as you stated the barrel would need to be attached to the tube. The banjo bolt and mini front block would need to be metal. I would put in a couple of locks on the valve retainer and the banjo bolt so that they are less likely to back out.

Keep in mind that the hammer tube even though it does not have to be metal is still supporting pressure from the springs / ivg and that the hammer is moving very fast through that pathway so it can not catch on anything otherwise it would self destruct.

I hope this helps and does not cause to much strife devilzcall keep me updated on your progress i think this is a cool idea.

[devilzcall]

Good feedback. I don't think welding the tubes is necessary, if some air could escape on the path from the valve to the bolt, that still wouldn't cause a leak and just slightly decrease efficiency.
I'd go for an off-the-shelf front block and banjo bolt. I'll definitely make the switch to a 9/16th cocker valve and retainer, that also gives a bit more meat on the tube and should form a solid, self contained unit.
I really don't worry about the hammer catching, but making sure the body is free of printing debree should be a given. Also since the hammer is cocked by the low pressure ram, I'm not too worried about it failing. The worst case would be the ivg breaking loose and that would just mean no more shooting for the day.

I don't think any marker can take 300 bar tbh, but 800 psi should be sensible.

[jokers]

In going with a mini block you already have a decreased air volume, and any leaks would decrease your velocity. What about using a gasket or oring between the two pieces of metal.
Speaking of valves why not the 11/16th valve that would give you a larger air chamber and make the connecting point less critical. My comment on the hammer was more to do with the idea that it would be open air and if you were to do something like the fishbone but were able to see inside it would need to be free of points that the hammer could catch on.
800 makes sense i was just thinking of a mass failure of the tank reg and the hpr.

[devilzcall]

good points. I thought about wedging an O-ring between the two tubes, but that would be painfull to install, you could print a body with grooves to seal around the tubes in front of and behind the air passage but that seems Overkill.

Good point with the hammer, should'nt be too hard to avoid

[SignOfZeta]

Isn’t the whole point of a cocker that you have this inherently strong monoblock body?

This seems like a contrivance to justify 3D printing and depending on how cost/labor intensive the final product is…it would only be cheaper in very specific settings.

[devilzcall]

The idea is that If i wanted to design my own body or just get one on the cheap I could do so with this fairly cheap to manufacture part and my 3d printer, requiring no further access to machine tools. I guess it's somewhat like 3d printing an emek body, more for cosmetics than actually a cost cutting measure since you'd still need to source everything else.
Cheap autococker bodys are usually only the generic ones and new ones are bespoke custom products, while everything else from the bolt to pneumatics are available as spare parts.

[MuddyBloodyFactory]

Ive sketched up some plans for this and discussed them a bunch with some friends. Also always browsing mcmastercar and figuring out good parts we can use. Figured first step is a frame! So I designed a printed frame! Also designed a feedneck! next is body! Really excited with what we can do with the feednecks with these lol.
For body sleeve, I was was also looking at freak inserts. You can fit an 11/16 valve and hammer in them pretty nice. Idk just an idea.

[MuddyBloodyFactory]

East Coast Anarchy also did a concept where he chopped off the valve part, for SLS printing matched with a machined lower chamber.

[Ecapnation]

Giving away all my secrets......lol

Eventually I'll finish up the machining part of this concept.

I'm even debating just whacking off the valve chamber of a test body I have

[MuddyBloodyFactory]

ahhh i dont want to give away your secrets sorry lol

and do it
Chop that sucka
and then reattach it lol

[Jordan]

Isn’t the whole point of a cocker that you have this inherently strong monoblock body?

Nah, the whole point is to have an auto cocking Sheridan with a removable barrel.

[devilzcall]

MuddyBloodyFactory Here's what I mocked up from the files on zdspb.

[MuddyBloodyFactory]

nice! what do you need to make that real?

[devilzcall]

I have a friend in a machineshop, It's the remaining mini cocker bits I'd need to source (i'm from germany, so these are just a bit harder to come by), I only own a trilogy and that doesn't have a front block and a sad excuse for front pneumatics.