bbv 4 u

[squib]

I have uploaded the balance of the videos detailing the BBV MG for anyone who is interested in having a go at a build. I'd love to see what can happen with more imagination applied. I am practical to a fault and would love to see the "cool factor" buffed by people better at that kind of thing than me.
I am voluntarily omitting one of them here as it could technically violate a forum rule. Probably not, but I'm not keen on chancing it. At any rate, it shouldn't be hard to find. There are 4 video segments in total, the first of which has been posted previously in another thread.
I have recently finished a proof of concept build of a different type. I'll share that interesting little project soon. I would like to build one more BBV sub machine gun, then I have one more bb mg design concept to develop. My proof of concept was a smashing success but I put it on hold to work on the BBV, which took longer than expected ( not that I'm in a hurry lol).
Anyway, here you go. I'm sure there are plenty of things I should've included. I'll do my best to clear up whatever seems foggy.
Best of luck whatever your build.

[hectmarr]

I like your project! I am trying to understand well. It would help a lot, (for those of us who do not speak or read English fluently), simple weapon drawings, or diagrams.

[Doc j]

My proof of concept was a smashing success but I put it on hold to work on the BBV.

Sounds interesting.

I think I get it.
Sorta like a blowback but vertical.
The bb when in barrel causes back pressure for the diaphragm to close and grab a bb from horizontal feeder.
When bb leaves barrel,no back pressure. diaphragm pushes bb into barrel. Then so forth.
Then I lost how cycle starts.
If it relys on back pressure to cycle.

[squib]

Yes there is a "blow back" half of the cycle which retracts the operating pin. There is also a "suck forward" half of the cycle which punches the next BB into the breech. The diaphragm converts the alternating positive and negative pressure pulses into work. The BB does the switching.
Because the last thing that happens at the end of burst fire is that the BB exits the muzzle, and ends on the vacuum of an empty barrel, the diaphragm stops sucked in, unable to start another burst. This is the reason for the diaphragm return spring. One way you know you have a good build is when you tap the trigger repeatedly with an empty mag (the mag has to be in) and see the diaphragm suck in every time. I think that's what makes the BBV a bit different. People generally don't think of doing work with a vacuum when pressure is king.

[squib]

Now you all may be wondering just how the vacuum is being generated. In the case of the BBV it is exactly the same principle as an air brush. The air blown across the end of the lift tube creates the vacuum needed to draw the paint up out of the jar and into the air stream. So you may think "Why the diaphragm?". I did try a pure suction feed from the magazine but found the vacuum was not strong enough to draw the BB's into the breech. The diaphragm amplifies the vacuum and gives it mechanical advantage. This applies to the positive pressure side of the operating cycle as well. It also regulates the rate of fire at a more realistic rate than the "insane rate of fire" BB blasters are known for.
The next build I have recently completed does use a pure suction feed. I'll post that one pretty soon.

[jackssmirkingrevenge]

Here is my interpretation of the operating principle:



Good job fleshing it out!

[hectmarr]

Here is my interpretation of the operating principle:



Good job fleshing it out!

oh yes, now it is more clear the working principle after watching its animation.

[squib]

Yes, that is precisely how it works. You've included both halves of the operating cycle. In reality the diaphragm has travel limited to only enough to get clear so it is a bit asymmetrical regarding travel, but your animation is spot on. Very nice indeed, and thank you . What app do you use for the animations? I'd like to check one out. I'm basically a sledgehammer mechanic and don't have any experience with CAD type stuff.

[squib]

Ok, my last post wasn't as helpful as it should be. I was excited to see someone went to the trouble to make an animation The mechanical operation is animated great. The airflow is correct in showing the diaphragm blowing back and carrying the operating pin out of the way, so everything there is good. There is just one thing missing ; that the airflow is continuous. When no BB is in the breech or barrel air flow is still present generating the vacuum that sucks the diaphragm up and punches the next BB into the breech. You have illustrated the mechanical parts moving correctly so again, nothing shown is wrong. I would only add that the air flow remains constant and change the color of the flow indicating negative pressure when no BB is present in the barrel. This will help show how the BB is the actual valve that switches the diaphragm between suck-in and blow-back.
I appreciate the interest greatly.
It seems the vacuum stage is the hardest part to visualize. Perhaps it will make more sense if you consider that the BBV is really 2 devices in one. When there is a BB in the bore it is a BB gun. When there is no BB in the bore it is an air-powered vacuum.
When I replaced my water heater it was limed up past the drain cock. I made an air-powered vacuum to suck the water out. I had to throttle it back or it would collapse the hose lol.

[jackssmirkingrevenge]

I redid it to try and better visualize the vacuum:

What app do you use for the animations? I'd like to check one out. I'm basically a sledgehammer mechanic and don't have any experience with CAD type stuff.

In that case you will love my sledgehammer approach to animation.

I basically make each frame in Microsoft paint and then use an online tool like EZGIF to put them together.

I am trying to up my game though, I recently downloaded Blender and I am struggling to understand it. I think it will be worth it though, here is an example of what you can do from someone who mastered it:

[squib]

Ah, I might be able to work with something like paint. I've been messing with LibreCAD and not gaining much traction. I reckon blender is out of the question since I struggle with Gimp lol.