15 replies to this topic

[voidSkipper]

I haven't seen this done at all, so I'm assuming there's a good reason for it, but I'm curious anyway.

Is the use of electronic motors to cock and advance a springer a viable option to make a semiautomatic blaster?

If so, is there some kind of equation I can apply to find the gearing and force required to cock a given spring?

I'm fairly interested in giving this a go, so if anyone has any experience with using electric motors in this way, could they please post.

EDIT: Is there an ethical reason behind the rarity as well? I hear the words "It's just not nerf" kicked around a lot when shooting down homemade ideas.

Edited by voidSkipper, 20 February 2008 - 12:06 AM.

[PC III]

There was a thread like this recently. it would be possible but the amount of force required to cock a spring is quite large, and would require a MASSIVE motor. All in all, cocking a gun is not too hard, not worth the time.
See what good searching does?

Edited by P.C. III, 20 February 2008 - 12:31 AM.

[BlackFox]

Yes, automatic airsoft guns use motors all the time. Granted, the spring is extremely weak, but it uses a tethered gear system to open and close a breech while the motor pulls back the spring.

I once had the idea of using a drill gun motor in a design which would pull back a nitefinder spring, but there were two main problems:

1. The breech needed to open further than that of the airsoft gun to fit larger ammo
2. The breech had to close before the plunger sprang back

It's just not a practical way to create a nerf gun. But mind you, I said practical.

Edited by BlackFox, 20 February 2008 - 12:41 AM.

[Thom]

You'd need a hell of a motor to cock a strong spring quickly. For example, cocking a 20 pound spring in one second would take about 90 W.

[Green Riptide]

When asking yourself how to make a semi-automatic blaster, use this simple process.

Step 1: Has Captain Slug already done/thought of it? If so, it can be done.
Step 2: If Captain Slug has NOT done/thought of it, it probably can't be done.


Seriously though? Theres been some use of solenoids to open valves and things, but that's about it. If you were going to bother to use enough juice to cock a spring-powered semi-auto... you might as well just try and build a railgun. Wonder if anyone has used electromagnets in a homemade yet.

[Thom]

Hey. Don't be discouraged just because CS hasn't done it. The worst case is you have an idea that doesn't work.

[aetherguy881]

You'd need a hell of a motor to cock a strong spring quickly. For example, cocking a 20 pound spring in one second would take about 90 W.

I don't know if you calculated that out. The stress on the parts would be pretty high and parts would be prone to failure, especially some stock parts. It seems that you would need to build one from scratch, and even so the spring compression via motor would still be quite the challenge.

If you do want to go the electronics route, I would suggest an air reservoir and a regulator and a QEV. If you wanted to make loading automated, you could use a stepper motor to bring the darts to the breech.

Anything is possible, you just need to think your way through it before you make it. It's also better to put it on paper or on the computer to see if it works (at least you have the idea up so far). Look into your idea and let us know what you think you should do.

Good luck.

[CaptainSlug]

Is the use of electronic motors to cock and advance a springer a viable option to make a semiautomatic blaster?

Maybe, but the final solution won't have a very effective reach, will have very heavy batteries and motors, will be extremely difficult to design and create, and won't be very efficient.
You waste alot of potential energy whenever you go from one form of energy to another. Having the energy converted from electrical energy, to mechanical, then to pneumatic energy will hurt your efficiency. This is why I'm only attempting semi-automatic systems that are powered by pneumatics alone. The resulting design is much simpler and has very parts to screw up.

ANY true semi-automatic is going to involve alot of designing and machining work. So far I'm the only person to accomplish a true semi-automatic blaster. And hopefully I can get the second one made sometime soon.

Edited by CaptainSlug, 20 February 2008 - 08:45 AM.

[Doom]

I think the idea's worth trying, voidSkipper. You might decide that a certain level of inefficiency is acceptable if you get a working gun.

CaptainSlug, I wouldn't say that you're the only one to make a semi-auto blaster. I made something that was semi-reliable semi-auto back in 2004, but very few people noticed. The only problem was that the shells were not made well enough to be ejected by gravity alone most of the time, but the project was nothing more than a proof of concept and use for leftover parts, so I was happy. There also is the RevoSemi that few here noticed. The RevoSemi duplicated Nerf's implementation of the Webley-Fosbery Automatic Revolver design (or at least the notch system). I have a plan to do something similar to the RevoSemi with a vertical clip and two valves (likely a piston assembly like my modification of Dr. Nerf's or two sprinkler valves). I'm sure that there are other things I haven't noticed as well.

[CaptainSlug]

Okay, fine. Here's the correction: I am the only person to create a completely working non-ugly semi-automatic blaster that was capable of firing successive shots without any user input aside from squeezing the trigger. And some time this year I will be the first person to finish one that is war-capable.

It's not like I care about being first. I was just pointing out that seeing one FINISHED is so damned rare because it's a very difficult task to accomplish. ABP5k took months of tweaking and refining because there's no real white paper information on the subject of pneumatic systems used to fire darts. There are also no off-the-shelf parts you can use to make such a device so I've been having to make my own valves from scratch.
There's tons of THEORIES out there, but theories aren't worth anything if you don't try to implement them.

Edited by CaptainSlug, 20 February 2008 - 03:50 PM.

[Doom]

You're coming across as more angry than I think I was intended. All I wanted to do was point out that other true semi auto things have been done.

Edit: I'll agree with you that something something finished is very rare. What I made, to reiterate what I said, was just a proof of concept I finished mostly in a day. I didn't add any ejector, but you can see where I wanted to add a spring loaded one in the second link I had. If I wanted to try that design more seriously I would do a lot of things differently and it would take a while to make. I decided that design isn't worthwhile because free bolts are annoying. The largest obstacle is breaking from the planning stage into the fabrication stage. As you said, there are a lot of theories, but less results. In my earlier mentioned design, planning and fabrication overlapped because I made it up as I went along, so that's why I had something fabricated.

Edited by Doom, 20 February 2008 - 04:02 PM.

[CaptainSlug]

Yes, I'm kind of cranky lately.

[PointBlank]

Still a cool thing to think about.

[voidSkipper]

If the answer is it can be done, but it's too clunky and inneficient for a war, I think I'll go through with it. There aren't any nerf wars in South Australia anyway.

[Thom]

You'd need a hell of a motor to cock a strong spring quickly. For example, cocking a 20 pound spring in one second would take about 90 W.

I don't know if you calculated that out.

I realize now that I divided force by time to get power. ; 10W is probably the most you'd need.

[umdlancer]

Erm, all the designs posted are NOT semi-automatics. Semi-auto is by definition one trigger-pull, one shot. If you have to actuate the breech manually to "chamber" another cartridge, then it's not semi-auto.