42 replies to this topic

[Carbon]

Ah! Just realized that I've been thinking of this thing as a constant, with the only variable change being the dead space. Like you were saying, SHA, the clip is now an extension of the PC, and all of the pressure is now able to directly act on the ball (because of getting rid of the reducing bushing). I am without a doubt am getting less pressure with all the dead space, but the increase in airflow is able to overcome it. So, a shorter inline will probably increase my range, because of better airflow.

I think I may need to buy that bucket of balls after all.

Edited by Carbon, 23 October 2007 - 10:10 PM.

[Carbon]

Time for some Gun Porn.

I've given this gun a proper name. Going back to the whole bumblebee thing, I had the name Stinger lodge in my brain. So, this is the SNAP-1 Stinger.





A new method in gun painting - transparent adhesive film printed in a Xerox. Gun wallpaper, if you will. I tried this way mainly because spray painting is rather inconvenient, what with living in a hirise apartment. That, and this method will allow for some crazy detailed paints in the future. Although, I think I'll still spray the couplers. That, and I need to redo the trigger cover (it's done in etape right now).

Edited by Carbon, 30 May 2016 - 04:59 PM.

[nerfturtle]

Wow, that's beautiful. I'm going to have to try out that decal method, but that would only work on guns with flat surfaces. I could swear that that is the Berkeley High School hornet that you put on the front there.

[Carbon]

Yeah, the decal stuff doesn't like to bend at all, but it covers tubes beautifully. It even tucks into the endcaps pretty well.

As far as the hornet, yeah, I think it's a pretty common mascot. I grabbed that off the Stevensville High School web page (which turns out to be in Montana.)

[penguin807]

Carbon, let me the first to say, bow chicka bow wow. Seriously though, The Pain would be all over you.

Edited by penguin807, 26 October 2007 - 09:26 PM.

[SHADOW HUNTER ALPHA]

If only you could upgrade to a bigger one. Double the length and watch as others cower in fear of your balls.

(I'm sure someone's gonna quote that at one point or another).

Edited by SHADOW HUNTER ALPHA, 26 October 2007 - 10:40 PM.

[J cobbers]

You should slap that ball barrel onto the end of a cheap paintball gun like the old brass eagle talon/saber/blade. It would provide a lot of power and many shots.

[RaZeR ShArP]

Shadow, I quoted that, it really made my day.

Carbon, where else can you get those balls? I want to try this with a titan, do you think the same setup would work, or would I have to modify it so they don't all fire out at once?

[Carbon]

RaZeR_ShArP, on Nov 1 2007, 09:33 AM, said:

Shadow, I quoted that, it really made my day.

This project has brought out my giggling inner fourth-grader. I had just used some silicone spray on the plunger, and saw a nice increase in range. So I told my wife that lubing up makes my balls shoot further.

Quote

Carbon, where else can you get those balls? I want to try this with a titan, do you think the same setup would work, or would I have to modify it so they don't all fire out at once?

K-Mart is my source for balls.

Hold on.

*smacks inner fourth-grader*

The pack I got was $4 for 6, but they also had the bucket-o-balls (50) for $20. I'd imagine that most golf shops would carry the same thing.

The same setup would work on a Titan. Just experiment on how much you have to carve down the 1.25" coupler, to take best advantage of the air pressure you have to work with. As far as double shots, I don't think that would happen, even with a Titan, because of how loose the balls are in the 2". Maybe if you were firing at a steep downward angle, but even then I doubt it.

[RaZeR ShArP]

Carbon, on Nov 1 2007, 12:21 PM, said:

I had just used some silicone spray on the plunger, and saw a nice increase in range. So I told my wife that lubing up makes my balls shoot further.

That's also going into my signature.

Wow, $4 for 6 is kind of steep, buying in bulk seems to be cheaper here.

[Carbon]

At least the foam golf balls are cheaper than the Nerf brand balls.

More updates for tonight. But first, an important safety notice. I managed to forget one of the prime rules of homemades, and forgot to screw the endcap back on after I colored it. So, while I was testing it tonight, the whole plunger assembly exploded out of the rear of the gun, under force. I forget just how much power is stored in these springs....anyway, I got off light, just a few nasty pinches and a broken handle, but safety first: glue it down or screw it down. [/soapbox]

Back to tonight's news: remember the sanitary tee I mentioned earlier? I decided to try it out. Here it is, with a TTG as a size reference:



Almost sidearm size now. The tee adapter lets it carry about 7 shots. A smaller capacity, but it also helps range. The effect on power is noticable. I haven't been able to consistently test range yet (because of the ?@#$! handle) but I've definitely gained some range, about 5' or so (reaching about 35').

Edited by Carbon, 30 May 2016 - 05:00 PM.

[Blasphemy]

I, personally think that it's good someone finally made a ballgun. I've recently learned a great appreciation for balls in a victory I engineered around them, in the current war(s) I'm in balls are worth 2 or 3 points when they hit, so they're still valuable to me.

EDIT: Now that I look back upon what I just said I realize it sounds kind of disturbing.

Edited by Blasphemy, 01 November 2007 - 08:44 PM.

[SHADOW HUNTER ALPHA]

Now the next step up would be to make a magazine-fed breech for the gun, so 100% of the airflow is to the single chambered ball. This eliminates dead space in the magazine as potential area for pressure diffusion, and will increase ranges yet again. Brilliant work so far.

[Carbon]

SHADOW HUNTER ALPHA, on Nov 1 2007, 08:46 PM, said:

Now the next step up would be to make a magazine-fed breech for the gun, so 100% of the airflow is to the single chambered ball. This eliminates dead space in the magazine as potential area for pressure diffusion, and will increase ranges yet again. Brilliant work so far.

Something along the lines of a removable barrel breech should be possible...pull it forward until a ball drops in, and then push it all the way back. I'm just not sure about how round the space is in the sanitary tee.

Blasphemy, on Nov 1 2007, 08:42 PM, said:

I've recently learned a great appreciation for balls in a victory I engineered around them, in the current war(s) I'm in balls are worth 2 or 3 points when they hit, so they're still valuable to me.

My inner fourth grader is still giggling.

[frost vectron]

I love the font on that paintjob! Outstanding.

[Carbon]

More experimentation to report.

I don't have a method to create a true breech and seal off the magazine, so I did the next best thing: I used a follower to reduce airflow to the empty mag. 1.25" endcaps have a near perfect fit in 2", but still slide easily. So, it's a perfect follower: load the mag and drop in the endcap. As the ball level drops, the endcap will reduce airflow to the empty mag, resulting in increased range. Right?

Wrong.

Ranges from the non-follower shots were consistently better, by about 5 to 10 feet. What's more, the last shot of the non-follower mag usually had the best range.

Here's my guess about how this is working. Currently, my friction ring around the balls requires a certain PSI to fire the ball. When the total barrel/mag volume is reduced, critical pressure is reached before the plunger is at full stroke - in essence, wasting air volume (which seems to be a good guess, as I can hear the plunger hitting harder with the follower mag). Slower, low pressure/high volume is better than faster, hight presure/low volume.

So, I could thus make a new barrel with a tighter friction ring which requires a higher PSI to fire...but then the balance is in making it tight enough to take advantage of higher pressure, but not so tight as to overcome my plunger seal.

More experiments!

Edited by Carbon, 03 November 2007 - 10:58 AM.

[Carbon]

Time to drop some science.

I've been wondering about the relative pressures involved in the Big SNAP since I was working on it last weekend. I was attempting to make a new barrel collar, and I tried one which was a bit too tight. The pressure created by the gun with an empty mag was enough to blow the couplers apart. A relatively small change in volume of the gun is causing a decent change in pressure. So, I decided to crack out the math to figure out how much.

(I'm showing all the math here just for the helluvit. Anyway, these calculations could also be used to determine operating pressure at the base of a dart in any plunger gun.)

In a closed system, volume and pressure are inversely proportional to each other. In other words, when a given volume of gas is made smaller, pressure gets higher. In a formula, that's

P1V1 = P2V2

Where P=Pressure and V=Volume.

Yes, the Perfect Gas Law. We know the starting pressure and volume, and we know the ending volume. So, we can solve for final pressure.

Time to gather some measurements.

Variables:
P1=Before firing air pressure (atmospheric pressure)
A tire gauge is a relative pressure gauge. As you can see, our equation would break down if P1 was taken to be zero. So, we need absolute pressure measurements. Atmospheric pressure is often measured in millimeters of mercury. Standard atmospheric pressure is accepted as 760 mm Hg. I'm going to work in SI units, so I used Google to convert. 760 mm Hg = 101,325 Pascals (where 1 pascal is a unit of force, 1 Pa = 1 Newton/Meter^2)

P1 = 101325 Pa

V1=Volume of pressure chamber with plunger primed
Volume of a cylinder = Pi(r^2)h

I'm just going to calculate the pressure as a simple addition of two cylinders, since this is pretty rough anyway.

PC depth:
Primed: 18 cm
Fired: 9.5 cm
radius: 2.6 cm

Magazine depth: 15 cm

Magazine volume
V=3.14(2.6^2)15
V=318.4 cm^3

PC (primed)
V=3.14(2.6^2)18
V=388.0
V1=706.4 cm^3
V1=.000706m^3

P2=After firing air pressure (unknown)
What we're solving for.

V2=Volume of pressure chamber with plunger extended
The magazine pressure is constant, so I just need to figure volume of the lower cylinder with the plunger extended.

V=3.14(2.6^2)9.5
V=201.7
V2=201.7+318.4
V2=520.1cm^3
V2=.000520 m^3

P1V1=P2V2
(101325 N/m^2)(.000706m^3)=P2(.000520m^3)
P2=137568 Pa

Using Google to do some conversions to PSI:

P1= 14.7 PSI
P2= 19.95 PSI

Since P1 is atmospheric pressure, we subtract is from P2. So, the plunger is creating 5.25 PSI.

This will figure out pressure for firing the last ball. But what about
the first? We calculate the volume of a ball, multiply by 5, and
subtract from the initial volume.

A ball has a diameter of 4.4cm. So,

V=4/3Pi(r^3)
V=44.6 cm^3 per ball.

Four balls in the mag (one is acting as the stopper of our closed system, so we won't count it) = 178.3 cm^3. So, how does that decrease in volume affect our working pressure?

P1V1=P2V2
(101325N/M^2)(.000706-.000178 m^3)=P2(.000520-.000178 m^3)
(101325)(.000528)=P2( .000342)
P2=156431 Pa
P2 = 22.7 PSI

So, a working pressure of 8 PSI

The pressure stays pretty constant, but is definitely higher. The last ball usually fires better than the first, so lower pressure seem to be where it's at for this gun.

These calculations could also be used to determine operating pressure at the base of a dart in any plunger gun.

[ultra920]

Wow, looks like you got your calculations strait. It would be good, considering the dropage of range, they should be an automatic out if hit. my only problem if this becomes usable are the "war" stories that would come of it.

* I got hit in the balls with balls.

* I was cornered, so i made a last stand and whiped out my balls.

* My balls are sagging, will they perform well?

you get the idea. Its getting kinda hard to type. resist urge to hestericly laugh...