Time to put them thinking caps on...

[ThunderCactus]

The mod looks solid, eliminates pressure between the barrel and hop chamber.
To make that specific design work, I agree the hop and barrel would need to be billet, but aluminum would work fine. I'm not sure a 3d printed plastic part would be able to handle those stresses.

[lurkingknight]

you can 3d print in metal as well but the issue is that 3d printing metal and even plastic means it's not as strong as. the metal uses a binder between layers of material, so it's not solid metal.

3d printing is for prototyping a piece, it's not meant to be very strong. In some cases though like modelmaking and prop making, it's fine, but something that has a lot of forces exerted on it will not last as if were cast in the same material, injection molded or cut/carved out of a billet of the same material.

[ThunderCactus]

Depends on the 3D printer, I always assume people aren't talking about the million dollar ones that fuse metal together with lasers making sintered metal parts lol
Even those aren't as strong as billet, but should be tough enough for airsoft.

[lurkingknight]

a guy on YT made a home made kiln and melted aluminum cans with it... he made some pure ingots and poured them into a mold... I believe it was a wax cast buried in sand or something, it came out pretty good... wonder if the aluminum is strong enough. lol

It wouldn't take much to cast the hop up parts... the casting materials are available at most hobby stores, create a mold, cast it in wax and cook up some of your very own aluminum... or even buy a chunk of billet and melt it down. Only issue is that there is some sort of size difference in casting stuff.. .as I understand it the final cast part might be as much as 3% smaller than the original.

[e-luder]

I have packed the spaces between the 2 pieces on my 5-7 with rtv silicone and have not seen an issue here yet. I have a feeling the creation slide and the rtv mod will move the stress points around. The inner portion of the slide is the front end which the creation slide can replace, but it butts up against the BBU and the rest of the guts housed in the slide. The guts float inside the slide and are tension clipped in by the outer slide. The front and inner halves are only merged by 2 tiny screws (might only be 1) just under the ejection port. I think the BBU might be anchored through the outer by the rear sight, but even then there's not a whole lot that weld the inner and outer slides together. But after 2 seasons of use, I have not had any parts of the slide or BBU fail.

RTV won't cut it.
The bond it creates is too soft. Thus the force will just dispurse amongst it's stronger surroundings.

It needs be basically welded together kind of bond.
So just like you, I JB Welded the Creation inner to the outer. I figure use the WHOLE slide to brace to impact.

My worry is the muzzle end. The Creation inner rest right on the two tabs right above the muzzle. I'm kinda scared that if the JB Weld Fails, the Creation inner will destroy the front end of the slide.

The other option in terms of a redesign is that you would somehow split the hopup differently or include a portion of an outer barrel that extends out from it, then you thread the outer barrel on, but that would need to be a full kit.

This wouldn't be ideal either, i feel like. It would just move the breakage point to another site. It would depend on how the two would fuse together. Either by screw barrel or by pins.

The issue is the recoiling power. it would still yank on the barrel.
The most ideal scenario is the eliminate the force that's yanking on the barrel. Or disperse it elsewhere. Which is what my mod was suppose to do.
To be quite honest, I don't know exactly where that force is coming from. THe return or the charge? Or both? I figure it's the return stroke since the barrel breaks almost the same way each time a repair of these guns came across my my table. THe barrel always broke (or the lug holes to be more precise) towards the bucking and not away. Which means, something is pulling the barrel and not pushing it.

I love this gun when I owned it. It lasted a while when I owned one. It's too bad so many operators have so many issues with it.

Originally Posted by lurkingknight

I don't think the slide itself could take the entire recoil shot. If it was solid metal, sure, but they wanted to sleeve it with plastic like the real one, so it halved the thicknesses pretty much of both materials. That's why you get the front of the slide cracking at the weld.

I don't think the creation slide does much for the plastic outer slide, renegadecow on asm/asf/arnies also ran this and his slide still cracked.

I have packed the spaces between the 2 pieces on my 5-7 with rtv silicone and have not seen an issue here yet. I have a feeling the creation slide and the rtv mod will move the stress points around. The inner portion of the slide is the front end which the creation slide can replace, but it butts up against the BBU and the rest of the guts housed in the slide. The guts float inside the slide and are tension clipped in by the outer slide. The front and inner halves are only merged by 2 tiny screws (might only be 1) just under the ejection port. I think the BBU might be anchored through the outer by the rear sight, but even then there's not a whole lot that weld the inner and outer slides together. But after 2 seasons of use, I have not had any parts of the slide or BBU fail.

I have however gone through a hop up unit already. both lugs sheared off, even with extensive rtv to merge the outer barrel into the hop up.

There was an effort by someone to 3d scan the hop up unit and try and get out there for people to play with, but I have not heard of any progress on that front. Ideally you'd cast it in steel or have it CNCed but to achieve that it may need a redesign as the precision around the lugs might not work.

The other option in terms of a redesign is that you would somehow split the hopup differently or include a portion of an outer barrel that extends out from it, then you thread the outer barrel on, but that would need to be a full kit.

[pestobanana]

I feel like the chamber lugs breaking may just be from the recoil spring and washer hitting the stabilizing O-ring and pushing the barrel forward. The barrel that I have looks like it was under forward pressure, not rearward. Its a decent impact each time, and I imagine it would fail just like the feed lips of gas mags break if you allow the follower to slam upward enough times.

I feel like that fix should fix the barrel lug issue since it won't put the forward force of the spring and washer on the barrel.

[SuperCriollo]

You could always cast a much stronger piece in urethane resin after printing the prototype. Not as strong as metal, but comparable to most plastics.

[lurkingknight]

unless you're printing off another design you can cast the original in resin, however I don't think the resin will be as resilient as the pot metal. Maybe the elasticity will prevent the pegs from shearing but I don't see much benefit.

I don't think the lugs are as likely to shear with a stock outer barrel. The silver barrel is much softer and that ends up shearing before the lugs. Only when I went to the steel outer from mag did it just pop the lugs right off the hop up unit.

Granted my 5-7 was modded from day 1 so I didn't even shoot it with the stock outer in it.

I think what happens is that the barrel also torques up during the recoil The torque travels down the barrel and to the point of least resistance which is the lugs and the half centimeter or so of mating surface between the outer barrel and hop up unit. If you redesigned both, you could lengthen the shelf the outer barrel sits on, as well as increase the size of those lugs.

[e-luder]

unless you're printing off another design you can cast the original in resin, however I don't think the resin will be as resilient as the pot metal. Maybe the elasticity will prevent the pegs from shearing but I don't see much benefit.

I don't think the lugs are as likely to shear with a stock outer barrel. The silver barrel is much softer and that ends up shearing before the lugs. Only when I went to the steel outer from mag did it just pop the lugs right off the hop up unit.

Agreed.

the pegs themselves will sheer off because of the outerbarrel is much stronger in this case. It's a case of soft vs not soft material.

I think what happens is that the barrel also torques up during the recoil The torque travels down the barrel and to the point of least resistance which is the lugs and the half centimeter or so of mating surface between the outer barrel and hop up unit. If you redesigned both, you could lengthen the shelf the outer barrel sits on, as well as increase the size of those lugs.

I don't see any evidence of that though.
The barrel design is non tilting design as well. So I can't see how it can torque itself up.

The only evidence i see is from broke barrels. It always sheered towards the hop unit suggesting that the force pulls on the barrel.

Anyways, i'm gonna brave it.
I gonna test the fucker to the T.

Also Lurking, the mod that you did to the muzzle end to fill the gaps...
How did you pack it?

[lurkingknight]

when I installed the creation slide I just packed the front and then put it together with a squeeze in the vise to get the inner to sit into the outer, then I used a pin to smush the rtv into the gap and smoothed out the gaps by scraping off the excess. The engine gasket makers stay goopy long enough to work on it, it can be messy so try not to get it everywhere, it will come off when it's wet with some work. lol. Let it set for 24 hours.

[pestobanana]

Message to e since I wrote some shit up and your inbox is full

So I did some 5-7 tinkering today, and I think found some ways to improve the durability. Correct me if I'm wrong, but here are my findings:

1. What stops the slide on the rearward stroke is not the stopper in the frame, but actually the front of the Creation slide hitting the hop up chamber.

2. The hop up chamber is not flush with the inner slide, all the impact force goes on the top and sides because the inside of the creation slide is rounded, not square like on the original slide. This probably contributed to the cracking of my first slide.

3. The barrel O-ring never touches the spring washer during operation, and both are there to center the barrel in the slide.

What I did:

I sanded the front of the hop up chamber to be closer to the shape of the inner slide, which will hopefully do a better job of dissipating the shock. and prolong slide life. I also put the O-ring and washer back on, and used a thin neoprene pad to cushion the impact between the hop up unit and the front of the slide.

I also found that I can fit an O-ring inside the hop up unit, between the hop up chamber and the spring. It cushions it a bit, and it stabilizes the outer barrel a bit. I don't think it will reduce the forward force on the barrel much, but it does reduce the play and makes it wobble less.

I plan on taking some sorbothane and spacing out the stopper on the frame to take some of the impact of the recoil, hopefully that will alleviate stress.

Also, the left side safety blew off lol. Time to put the original controls back in.

-Z