27 replies to this topic

[louiec3]

This is my homemade Semi-Auto nerf gun. It took me about two and a half weeks to design and build.

People I would like to thank
Captain Slug- For making the +bow which got me into homemades, l+l Cs, and for making the Diy: External Air Tank.
Forsaken_angel24- For making the Angel breech which made this gun possible.
Whoever owns McMaster Carr- If you don't know why I'm thanking them just leave now.

It started like this


Finished product

The gun next to a recon.


I didn't even plan that it just was a coincidence.


As you can see it's about the same size as a +bow.



The video was taken at 100psi and at the end I think it was at 70 so it is inefficient but who cares it's semi-auto.
Ranges are about 30-40 feet. So not that good, but it can be improved.
On a recent test at 120psi one dart went 60 feet

On to the Write up.

For version 2 of the valve see page 2.

*It is more of a guide, so you still need to be able to problem solve and figure things out yourself.

Materials
1)Brass
19/32
9/16 2 sticks
17/32
1/2
15/32
7/16
13/32
3/8
5/32
2)Tools
Pipe cutter For Tightening Rings Only!!!
Dremel or other metal cutting device that doesn't deform the metal.
Drillpress
Bits: 1/8, 9/16 spade, 5/32, 1/4, 7/64
Scrollsaw
Screwdrivers
Good ruler
Fine tipped sharpie
6-32 tapping bit and tapping handle
Safety goggles (So shit won't get in your eyes)
Dust mask
3)Other stuff
Goop
Magstrike trigger valve
Epoxy putty
Super glue
Hotglue gun
PVC cement/primer
Spray silicon lubricant
some scrap wood I used a 1x4
Solder/ soldering iron (I used a blow torch )
A eyehole or hook screw that wont bend easily.
1 1/2 bolt that wont bend ever.
Label paper print l+l Cs templates on it.
4)McMaster
If it has a * you can get it at a hardware store.
8580k28
4880k55 x2*
48925k95 only 1 FT*
85805k28
9654k921 or strong rubber band
51545K77
5012K36
5006k53
91780a131 x2
91780A133
90309a154 x2
90402a146
90402A144
9087K61 x2
5) Air tank
Either use a low pressure air tank like this one, or a high pressure like this one

Breech and Barrel construction.

1)Start off with your barrel make it like the picture.

I still need to experiment with different lengths and with or without the tightening rings. (I only used 4 rings)

2) Start cutting brass pieces so you have all the pieces in the pictures.


Don't worry about anything besides pieces that are square or rectangular and dont make holes yet.

All your brass pieces should look like this. (I forgot 1 half in piece)


3) Breech cover
-Flare out 1 end of the 4 1/2in piece of 19/32 with pliers

-Assemble it the same as an angel breech with the 19/32 from above, 1/2in of 9/16, 1/2in of 17/32, and the 4 1/8in of 1/2. The flared end should be away from the 9/16 and 17/32.

4)Breech pipe
-take the 3/8, 7/16, 15/32, and the 13/32 and nest them together like so.

-Glue them into each other so the finished product is this.


5) Breech piston
-Take the 4 1/2in of 17/32 1/2 of 9/16 and 1/2 of 19/32 and glue them together like so.

-The 5 in of 9/16 is the piston cover all you have to do is drill an 1/8 hole 1/2in from one end only go through 1 layer of brass; like the picture.


6) Now you need to bust out your scrap wood and make a clamp similar to this one to hold your Breech piston and Breech cover.

Solder those two pieces together making sure the flared end of the breech cover is away from the solder joint.

Edited by louiec3, 09 August 2009 - 07:23 PM.

[louiec3]

6) continued
-Here is the finished soldering job.


7) Sand down around the joint and drill the hole for the 1 1/2in screw that won't bend in the middle of the 19/32 on the breech piston not going through to the breech cover.

thats what it should look like. Then use your epoxy putty and reinforce the solder joint and screw. Don't forget to cover the end of the 17/32 with epoxy putty. Then fill the 17/32 with hot glue.

(yes I know I did that backwards.)

8) Take your two 1 1/2 PVC end caps and drill a 9/16 hole in the middle of 1 and a 1/4in hole in the middle of another.

-cement both of those onto a 3 in segment of 1 1/2 PVC.
-Goop the piston cover (5in of 9/16) into the endcap then reinforce the joint with epoxy putty.
[b]Make sur the hole in the 9/16 is away from the endcap and pointing to the side.

-Drill an appropriate size hole for your eyehole/hook screw then goop it in.

9) Cut a short piece of 5/32 brass and stick it in some 1/8in flexible vinyl tubing. I didn't write the length down but 8 in should be plenty and you can always cut some off.
-Super glue the brass and vinyl tubing onto the 1/8in hole in the 9/16 then reinforce it with some epoxy putty.


10) make a 1 1/4 x 1/2 piece of 1/4in polycarbonate. drill a 1/4in hole in the middle, then countersink a 15/32 or similar about 1/8in. Goop the breech pipe into the countersinked hole and the tubing that is attached to the piston cover in the 1/4in hole.


Shell Construction

1) Make poly carbonate pieces shown.



Finished pieces.
-Assemble like so

-If you want you can add 8x1 pieces of 1/4 poly carbonate to the top and bottom to provide more support and protect your barrel.

2)Make 2 trigger guards like so use the templates from the lpl Cs write up to start.


3) take a break from working and enjoy some pigs in a blanket.

If you don't do this your gun will explode the first time you use it.

4) Make the handles from the templates.
-Scribe out where the magstrike valve will be then cut it out and Dremel it until it fits snuggly.


-Make your trigger no real dimensions just make whatever's comfortable to you.

-The hole is 5/32.
-Assemble the handle similarly to the +bow using 3/4in spacers in the grip and 1/4in spacers in the trigger.
-Don't forget to attach the trigger guards.

Edited by louiec3, 06 August 2009 - 03:30 PM.

[louiec3]

5) Make a 3/4x 2 5/8 and a 1x 2 7/8 on 1/4in polycarbonate.
-Set aside the 1x 2 7/8. Take the other one and attach it to the trigger guards like so.


6) Make 2 body plates like the picture on 1/8in polycarbonate.

-The top right holes are where the barrel assembly attaches and the bottom right is where the 1x2 7/8 piece attaches.
-You can see where the trigger guards/handle assembly attach in the previous picture.

-Make sure you have the screw in at the top of that picture.
-Put the 1 in spacer at the rear like in the picture.


7) make two 12 x 1 pieces on 1/4 polycarbonate. Then attach them like the picture.


8) Now it gets hard to explain.
- make a 1 1/4 x 3/4 piece on 1/4. then drill a 9/16 half circle on one 1 1/4 side. Set that piece aside
- mount the breech pipe in using 1 screw on each side about 1/2 from the l shape on the back of the body plate.

-Cut L shapes in the back of the 12x1 pieces so the 1 1/2 pvc tank will rest comfortably.

-Epoxy putty the tank on.
-Take the half circle piece and glue (reinforce it with epoxy putty) it onto the piston cover, and screw it onto the 12x1 pieces with one screw to each side directly behind the body plate.

9) Insert the Breech piston and Breech cover.
-Insert the barrel and glue it in place.

10) add your tubing coupler and disconnect valve to the tubing on the magstrike valve.
-add another coupler to the other side of the magstrike tubing. Connect the coupler and the PVC with the 1/4 in hole with flexible tubing. Goop the tubing in the PVC.

Now your done. Slap in your clips and blast away.

If you have troubles with the breech system sticking sand down the breech piston, Breech pipe, and barrel.

Edited by louiec3, 05 August 2009 - 04:51 PM.

[Darken]

Great job. Can you quickly lay off a clip or does the breech system cycling slow it down?

[bookybabora]

Very nice, do you think you'll be able to get the Raider's 35 drum magazine working with it?

[Kid Flash]

bookybabora, on Aug 5 2009, 04:41 PM, said:

Very nice, do you think you'll be able to get the Raider's 35 drum magazine working with it?

It's the same as an ls clip...

So to make this more reliable you could do slugs backpack tank right? Then the pressure would decrease slowly... Once I get something that can cut polycarbonate and some brass I would love to try this out. Do you think that this could fit inside of a lonshot shell? Just curious since it's a pretty comfy shell. Does it seem sturdy when firing at 100 psi?

EDIT: I saw that you are using the large external airtank... How much air does this thing take? Is your external tank large?

Edited by Kid Flash, 05 August 2009 - 04:30 PM.

[louiec3]

Darken- Yes the breech system does slow down ROF, but the video shows the average ROF.

bookybabora- If you are asking if ls style clips fit in it you are blind, but if you mean it can use non-stefan modded clips then yes it can.

Kid Flash- Yeah the HPA tank would work much better because the shots would be more consistent and you could get off many more shots with it. I bet you could get this into a longshot shell with some slight modifications. They're pretty much the same size but you'd have to relocate the handle which is easy.

Firing at 100 psi it feels fine and I'm more concerned about the LPA Tank bursting than the actual gun.

Quote

I saw that you are using the large external airtank... How much air does this thing take? Is your external tank large?

You answered the second question yourself.
empty my tank holds 175 cubic inches and I can get it to about 120 psi

Edited by louiec3, 05 August 2009 - 07:41 PM.

[bookybabora]

louiec3, on Aug 5 2009, 06:05 PM, said:

Darken- Yes the breech system does slow down ROF, but the video shows the average ROF.

bookybabora- If you are asking if ls style clips fit in it you are blind, but if you mean it can use non-stefan modded clips then yes it can.

Kid Flash- Yeah the HPA tank would work much better because the shots would be more consistent and you could get off many more shots with it. I bet you could get this into a longshot shell with some slight modifications. Firing at 100 psi it feels fine and I'm more concerned about the LPA Tank bursting than the actual gun.

Quote

I saw that you are using the large external airtank... How much air does this thing take? Is your external tank large?

You answered the second question yourself.
empty my tank holds 175 cubic inches and I can get it to about 120 psi

Yes that was my question, sorry for not being more descriptive.

[randomnerfninja]

so can this use captainslugs backpack tank? Holy shit if it can

[balisticjoe]

Dude-freaking awesome. It is a version of the apb5k(or however it is spelled) that a person can actually build. Brilliant. Really good work.

[DartzDude]

This is pretty awesome if you could get ranges up to 80-90ft then you will dominate everyone. once again nice job.

[DartzDude]

Ignore

Edited by DartzDude, 05 August 2009 - 08:43 PM.

[Saber]

Have you tried using two+ pressure tanks (safely) to see if you can get any more range?

[Nerf Bros]

I don't get it... which is a good thing. Fascinatingly complex and well executed. Is the dart flutter in the video a result of wind or stock darts? I hope it's the second.

[spartan062]

Nerf Bros, on Aug 5 2009, 09:16 PM, said:

I don't get it... which is a good thing. Fascinatingly complex and well executed. Is the dart flutter in the video a result of wind or stock darts? I hope it's the second.

Most likely stock darts combined with wind. High power guns don't agree with stock darts.

[Norther of Heaven]

Freakin' sick man. Very nice work. I should make more homemades..

[Eboreg]

I really don't read entire writeups unless I'm following them. What's the basic principle behind the gun?

[Liam]

Looks awesome, and seems to funtion, but it seems like your darts are crazy fishtailing and just spinning out of control.

[louiec3]

randomnerfninja- Yes, it can with the proper fitting.

Saber- Using two tanks LPA tanks would just increase the air capacity, and the amount of shots I can make. To get more range I would need to increase the pressure, and with the LPA tanks I can't increase it more safely.

Nerf Bros-Spartan.062 was right I used streamlines in the video. Those darts would have fluttered like in any gun because they suck.

Eboreg- If your asking how the gun works there is a poorly drawn picture in the first post.

[Eboreg]

Ok, I can get how the breech closes but not how the air is delivered to the dart.

Edited by Eboreg, 06 August 2009 - 07:21 PM.

[louiec3]

I drew a picture on my poorly drawn picture to help.



Once the Breech is fully closed by the piston it passes over the hole for the tubing, which lets the air go through, into the breech pipe, then the breech cover, and finally to the barrel.

Hope that helped you.

[Chaos-blades]

Good work.

You probably know this but if you used converted streamlines (with weights) you would get rid of the fishtailing problem. If the problem persists, go heavier.

~Chaos~

Edited by Chaos-blades, 06 August 2009 - 10:59 PM.

[Eboreg]

Simple design, I like it!

[louiec3]

Well I've came up with another design. This one should decrease friction, be easier to make, eliminate the need for soldering, and be simpler all around.



This is the general new design. The piston and breech cover are made as one so you don't need to worry about making a straight solder joint. It still uses the same spring return method and the PVC tank at the back.



This is the brass parts list the barrel and the piston cover are exactly the same as Version1.
Everything else has changed a bit.



This is how everything looks when its assembled. It's all super glued together.
The piece of 7/16 is the one filled with glue.

This breech would require some changes to the construction of the shell, but this breech creates much less friction; with less friction the minimum operating pressure goes down.

Any more questions?

[SchizophrenicMC]

Shwow.

If I had any machining skill, I'd make me one. Looks pretty good, and I'm liking the exaggerated sound it makes.