35 replies to this topic

[PVC Arsenal 17]

I'm not sure what's up with that...

try this: http://s237.photobuc...nt=101_0004.flv

[pjotrkuh]

Makes a nice "plop".
It looks great, cant wait to see the gun with the mag firing!!

[Lt Stefan]

What are the shells made of?
And wow.

[PVC Arsenal 17]

What are the shells made of?
And wow.

The shells were originally supposed to be 5/8" x 1/2" clear Polyester tubes but I may change them to .527" bore steel. I was having issues with getting the shells to stay in the gun until they're supposed to be ejected. Instead of building some kind of mechanical detent that is prone to fail, I can make simple magnetic detents to hold the steel shells in place. The polyester was also too tight for most FBR, so the .527" bore will fit a wider range of darts, especially the Dennis brand that I prefer. This will add weight, but it may be necessary.

[Galaxy613]

What are the shells made of?
And wow.

The shells were originally supposed to be 5/8" x 1/2" clear Polyester tubes but I may change them to .527" bore steel. I was having issues with getting the shells to stay in the gun until they're supposed to be ejected. Instead of building some kind of mechanical detent that is prone to fail, I can make simple magnetic detents to hold the steel shells in place. The polyester was also too tight for most FBR, so the .527" bore will fit a wider range of darts, especially the Dennis brand that I prefer. This will add weight, but it may be necessary.

Plus because you don't exactly intend to use it in combat, weight shouldn't be much of a issue.

[MoonMaster]

Thanks for helping me over at spudfiles. As you probably realized I plan on making a semi-auto, it will be a nerf gun. Do you have the part number on mcmaster for that air cylinder or did you order it somewhere else?

[PVC Arsenal 17]

Thanks for helping me over at spudfiles. As you probably realized I plan on making a semi-auto, it will be a nerf gun. Do you have the part number on mcmaster for that air cylinder or did you order it somewhere else?

No problem. You have another reply from me in your thread over there with some more info. Check what I wrote about cylinders. The one I used is kind of uncommon as it is a spring-extend cylinder as opposed to a spring-return cylinder. The cylinders you'll find on McMaster are all spring-return, if I recall correctly.

A spring-return cylinder will extend when pressurized and retract when unpressurized.
A spring-extend cylinder will retract when pressurized and extend when unpressurized.

The name essentially refers to what the spring will do to the rod when the cylinder is unpressurized.

I ordered my cylinder from another site, I can find the item number if you like. As of now, do you have any ideas for a loading system? The type of cylinder you need depends largely on that.

[MoonMaster]

I think I have the loading figured out, a cylinder will push the bolt forward when the tank is pressurized, then when the dart is fired the air will leave the cylinder and it will reract the bolt, then when the tank is refilled the cylinder will extend again.

[PVC Arsenal 17]

You have another post waiting for you over there haha.

Looks like you're going with a projectile-pusher setup. Here's a video of one of my early nerf gun designs.

Things to note:

-will your bolt seal the breech opening well?
-where will the air enter the barrel? (Behind the projectile and in front of a solid bolt, or behind a flow-through bolt)
-will your darts pinch and jam against the breech opening when the bolt pushes them into the firing position?

I suggest chamfering the breech opening to reduce pinching.

Edited by PVC Arsenal 17, 26 August 2009 - 01:59 PM.

[cheesypiza001]

You have another post waiting for you over there haha.

Looks like you're going with a projectile-pusher setup. Here's a video of one of my early nerf gun designs.

The link does not work.

[PVC Arsenal 17]

Photobucket is having problems lately. Try this: http://s237.photobuc...nt=HPIM0762.flv

The video is unimportant anyway, it was just to help out MoonMaster.