16 replies to this topic

[catmods]

Last fall, I got several of these on sale.



Let’s get to work.



Remove these screws. Pry off this cover.





Notice the small hole? Drill it bigger, about one size down from the ½ inch drill bit.





Much better. Grab a ½ inch cpvc coupler, and shove ¼ inch of cpvc in there. Glue the end that you blocked on the hole. This will be where your barrel will go.



Now twist off the rear handle. ½ inch cpvc fits perfectly.



I ran out of t joints here, but I’ll put a bolt through the coupler later. Then, glue the t joint to your six inches of cpvc. Slather the cpvc in glue, and shove it where the handle was.



Here is my horde. Now, you may be wondering about the ranges. But first, I would like to explain how these things work. They have no springs. They work by putting the dart/ barrel on before pulling the plunger back. The airtight seal means the minimal amount of air in there reverse compresses the air, time the large plunger draw, means that when you release the plunger, the reverse pressure pulls the plunger, pushing that small amount of air forward, flinging the dart 50s-70s flat, without a spring, or helping push the plunger forward! I will have a video up as soon as youtube works for me. There you go, a water gun you bought for 1 dollar, that with little work done, hits almost as far as a 30$ Pas, although less accurately



Questions, comments, or flames?

[death by cheez]

That's pretty creative, and I have that same set of screwdrivers.

[moosa]

I have a hard time understanding how creating a vacuum in your air chamber would prove beneficial.

That being said, 50-70 feet can hardly be called a failure. Good job.

[Broderick]

Right, I've seen these around. I always laughed at these since they're just a 3 foot long rod when fully extended. I'm surprised to hear you're only getting a maximum of 70 feet... Even if it is cold where you are I thought you'd be breaking 100' easily. I understand that you said the plunger pushes itself back into place from the reverse pressure built up, but can you manually push it for more air? I just think if you could to so, then a longer, looser fit barrel would work well if it releases a monstrous amount of air.
Also, why replace the back handle with a T-joint? I would just keep the existing handle. Even so nice mod, and thanks for sharing this with the community.

[catmods]

Broderick, on Feb 14 2010, 05:46 PM, said:

Right, I've seen these around. I always laughed at these since they're just a 3 foot long rod when fully extended. I'm surprised to hear you're only getting a maximum of 70 feet... Even if it is cold where you are I thought you'd be breaking 100' easily. I understand that you said the plunger pushes itself back into place from the reverse pressure built up, but can you manually push it for more air? I just think if you could to so, then a longer, looser fit barrel would work well if it releases a monstrous amount of air.
Also, why replace the back handle with a T-joint? I would just keep the existing handle. Even so nice mod, and thanks for sharing this with the community.

It is warm here,( in Arizona) but my back yard is about 70 from door to wall, and it lands just at the base of the wall. Although, it is hard to aim with no handle and a 3 foot plunger moving forward. I have tried pushing the plunger forward, but I've noticed the human hand is slower then reverse pressure alone. But, you do have to fire it quickly before pulling back the plunger, there is a slight leak with my tightest darts. I have also noticed the handle has weak plastic, and the screw thing gets damaged, and gets released slower than a t joint. Community, you are welcome.

moosa, on Feb 14 2010, 03:48 PM, said:

I have a hard time understanding how creating a vacuum in your air chamber would prove beneficial.

That being said, 50-70 feet can hardly be called a failure. Good job.

Especially on sale 50 cents a pop.

Edited by catmods, 14 February 2010 - 09:40 PM.

[bourbon]

Are these those things you stick into a pool, pull to fill, then fire?

You can't rely on the vacuum created by pulling the plunger back to fire the dart. Basically you're firing the air nerfers call "dead space", nothing more. Put some bungees on it, and find a way to stop it from creating a vacuum when cocked. 50 cent BnA.

To put it into perspective, cocking a Nitefinder then somehow removing 90% of the air in the plunger tube is what you've done here. You've got a plunger draw length of over 12" on here. You should be getting absolutely ridiculous range. Trust me, it will work much better, and if for some strange reason it manages to defy the laws of physics and doesn't work, you're out 50 cents.

Edited by bourbon, 15 February 2010 - 01:40 AM.

[catmods]

bourbon, on Feb 14 2010, 10:36 PM, said:

Are these those things you stick into a pool, pull to fill, then fire?

You can't rely on the vacuum created by pulling the plunger back to fire the dart. Basically you're firing the air nerfers call "dead space", nothing more. Put some bungees on it, and find a way to stop it from creating a vacuum when cocked. 50 cent BnA.

To put it into perspective, cocking a Nitefinder then somehow removing 90% of the air in the plunger tube is what you've done here. You've got a plunger draw length of over 12" on here. You should be getting absolutely ridiculous range. Trust me, it will work much better, and if for some strange reason it manages to defy the laws of physics and doesn't work, you're out 50 cents.

Yes, they are. Did you honestly think I would stop here? Just like every other nerf gun, there is still much more that can be done. I'll have to costum order a spring though. Anyone know any sites? I'll be mounting one on Giygas soon, and the added weight will add accuracy, and something that shoots 100-150 does sound good.

moosa, on Feb 15 2010, 03:59 AM, said:

Bourbon has said exactly what I would have said. Sure, it is kinda neat how you've found that creating a vacuum will propel the plunger enough on its own to launch a dart 70 feet. And honestly, I'm a little baffled at how you could be getting that much range with this kind of method, though I do believe you. You should understand though that Nerf blasters work by creating air pressure to propel the darts. A vacuum is the exact opposite of air pressure, meaning you're working against yourself. Even though it does "work" as you have it, you're not nearly using the blaster's properties to their potential.

I'm starting to repeat what's been said, but you'll see that I also agree. Instead of using that massive air chamber to create a big vacuum, fill it full of air, then use another method to pressurize and force it out with your dart. If you want the spring back effect rather than manually pushing it forward, then attach some bungees to it and you're good to go. Don't bother with springs, that's too complicated. A loose fitting barrel should not only work well with that kind of air delivery, but I imagine it would also fix the vacuum issue as well, allowing the chamber to fill properly. For that much air you'd probably want a pretty long barrel too.

I did find it interesting that you managed to propel a dart that far using this vacuum method, something I didn't know was possible, but I think it's only an effect of the chamber being so large and don't believe it to be a truly useful method.

I do wish I could find some of these things for 50 cents.

1. I just put on a bungie, and tested range out in the backyard. Many will be disapointed.
Dart 1:tight fitting dart= I pulled half way back, and the plunger slipped out of my hands. that would normally be okay, but the really heavy shaking made it so that it shot at an angle. Again, normally wouldn't be so bad, right? I mean, it was only at half pull. You could not be more wrong. It shot over the fence, 70 feet away. I didn't even see it shoot, but I heard it land in only 2-3 seconds. In reference, most guns shoot flat in 1-2 seconds, 45 at 5-7, and up in 10-15.
Dart 2, a middle dart, this time, I waited for the air tank to fill halfway, and I got it some what steady this time. It did not make it to the wall. It was close, I would say the 60s.
Dart 3, loose dart fit: I filled the tank all the way. Not very shaky, but It shook down, and only went to the 2nd wall section, between 30-40 feet. Ill have to overhaul it.

The big green one was on sale for 1 dollar, the others were 50 cents each. As I said earlier in the write up, I got these in fall, Immediatly after summer. Get them during the summer, and its 3 dollars a pop.

Edited by catmods, 15 February 2010 - 11:18 AM.

[moosa]

Bourbon has said exactly what I would have said. Sure, it is kinda neat how you've found that creating a vacuum will propel the plunger enough on its own to launch a dart 70 feet. And honestly, I'm a little baffled at how you could be getting that much range with this kind of method, though I do believe you. You should understand though that Nerf blasters work by creating air pressure to propel the darts. A vacuum is the exact opposite of air pressure, meaning you're working against yourself. Even though it does "work" as you have it, you're not nearly using the blaster's properties to their potential.

I'm starting to repeat what's been said, but you'll see that I also agree. Instead of using that massive air chamber to create a big vacuum, fill it full of air, then use another method to pressurize and force it out with your dart. If you want the spring back effect rather than manually pushing it forward, then attach some bungees to it and you're good to go. Don't bother with springs, that's too complicated. A loose fitting barrel should not only work well with that kind of air delivery, but I imagine it would also fix the vacuum issue as well, allowing the chamber to fill properly. For that much air you'd probably want a pretty long barrel too.

I did find it interesting that you managed to propel a dart that far using this vacuum method, something I didn't know was possible, but I think it's only an effect of the chamber being so large and don't believe it to be a truly useful method.

I do wish I could find some of these things for 50 cents.

[bourbon]

Ok, here is an idea.

At the front of the plunger tube, like right behind the coupler, drill a tiny hole in the side and put a check valve on it somehow. This way, when you pull the plunger back, it will be able to draw air in, but when firing, all of the air will leave the barrel.

If I understand correctly you are having a hard time getting the air into the plunger tube with the barrel on, and this would fix it. Most Nerf guns have their plunger heads designed so that when cocking, the O-ring slides forward a little so it doesn't seal and draw in air through the barrel. When the plunger moves forward, the O-ring returns to it's seat and seals again.

One last thing to consider is, how long is your barrel? It appears to be like 4-5". If this is true, it makes sense that you're getting NF ranges. Crossbows and shit have 12" or longer to utilize the full volume of air. You may also want to try a looser barrel material. If this plunger has a fairly large diamer, it probably has a fast, low pressure air release (like the Expand a Blast) and you'll want to use a looser barrel material.

[Draconis]

The seal on these things is terrible. I would suggest using a slightly better version like the Stream Machine.

[catmods]

bourbon, on Feb 15 2010, 02:58 PM, said:

Ok, here is an idea.

At the front of the plunger tube, like right behind the coupler, drill a tiny hole in the side and put a check valve on it somehow. This way, when you pull the plunger back, it will be able to draw air in, but when firing, all of the air will leave the barrel.

If I understand correctly you are having a hard time getting the air into the plunger tube with the barrel on, and this would fix it. Most Nerf guns have their plunger heads designed so that when cocking, the O-ring slides forward a little so it doesn't seal and draw in air through the barrel. When the plunger moves forward, the O-ring returns to it's seat and seals again.

One last thing to consider is, how long is your barrel? It appears to be like 4-5". If this is true, it makes sense that you're getting NF ranges. Crossbows and shit have 12" or longer to utilize the full volume of air. You may also want to try a looser barrel material. If this plunger has a fairly large diamer, it probably has a fast, low pressure air release (like the Expand a Blast) and you'll want to use a looser barrel material.

Right before checking the thread again, I put on the 12 inch barrel. 6 wasn't enough. I put in the loosest dart I have. Put on the best bungie for it. I fired off some shots, then realized I was only pulling half way. I pulled 3/4 the way, and lost grip. The entire gun shook really heavily, but still fired flat, to the left of whhere I was aiming, adding an extra 10+ feet to the wall. It seemed the dart was out for blood. The wall was 80 feet away from where it started. It hit chest hieght. I was holding it shoulder hieght. The dart wanted more. It bounced off the wall, itno the next. now its stomach. Then, I felt a pain in my elbow. the gun shook so much, the t joint hit me. I am probably one of the few here who has been bruised by a t joint. By the time I looked back, the dart had fallen out of the air. Next fall, I'm getting 10 of these things, after I over haul it. Then, these will be on the arrow holders of Giygas.


Draconis, I think the one you got was a dud. The plunger is 100% airtight in all of mine.

[moosa]

I would try an even longer barrel. But I think you've figured out that getting the barrel length right is important here. That thing is surely putting out a LOT of air. I'll be interested to see how much you can get out of it.

[nerfer63]

Very nice, very nice, and I have those exact set of screwdrivers.

N63

[Draconis]

catmods, on Feb 15 2010, 03:41 PM, said:

Draconis, I think the one you got was a dud. The plunger is 100% airtight in all of mine.

All four that were on the peg? Seems unlikely, but I'll give you the benefit of the doubt. Regardless, the tubes are made of blow molded polyethylene, and may prove difficult to get any adhesives to bond with.

[moosa]

There's no reason to think he could be wrong or lying about that. It could simply be a small change in the manufacturing process. Just because the product has the same name and same brand doesn't mean it'll always be exactly the same. Nerf makes tiny changes to things in their blasters all the time and they aren't going to bother changing anything on their packaging to reflect the fact.

On another note, why do people here always point out the fact that they seem to have the same screwdrivers as someone else?

[thedap]

they are made to shoot water and depend on the water to lubricate the seal. you might want to lube it somehow, to make it move easier and hold up a little longer. (don't want you to go and waste all that money)

I picked up a smaller douchy version of those things, maybe a third the length and with a tip shaped like a crayola. pretty much seized up just dry pumping it. one of these days it will run through the bandsaw for a postmortem.

P.S. I scratch my asscrack with a set of screwdrivers EXACTLY like that. in fact, you better sniff them and make sure their yours.

[Draconis]

thedap, on Feb 16 2010, 01:13 AM, said:

P.S. I scratch my asscrack with a set of screwdrivers EXACTLY like that. in fact, you better sniff them and make sure their yours.

You've piqued my curiosity... What sort of epidermal malady could a person be afflicted with, which would coerce them to apply the business end of a screwdriver to themselves? Seems as though it would be horrible, and I suggest you have it inspected by a physician.