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Sentry Gun Project

This area is for the discussion of BB or airsoft sub machine guns, and or other small arms such as pellets.
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Unread postAuthor: jackssmirkingrevenge » Mon Feb 01, 2010 1:18 pm

POLAND_SPUD wrote:
if you vacu-form a plastic shell (like R/C car bodies) the weight will be negligible.
How do you do such things?


I've never done it large scale personally but there are online guides to doing it with domestic ovens and vacuum cleaners ;) if you could provide a mould I'm sure a local manufacturer could do it for cheap, if not there's fibreglass as a lightweight strong option too.

I believe it would be better to have one running on low pressures... your hpa setup might be ok for testing your prototypes but it would probably be a better idea to have something that can provide sustained fire


I could always buy a bigger tank ;) I was thinking of a semi-auto BTB QEV mod style valve coupled to a BBMG type chamber. For even better efficiency I could try to make a version of my ball valve strafer design. A decent paintball tank (remember mine is only 13 cubic inches, I can get a 48 cubic inch one relatively cheaply) at 200 bar regged down to 30 bar would last more than enough.

If its going to be a fairly permanent placement (i.e.- always around your residence), you could just attach it to an air compressor and tank with a feed tube from a large hopper. 20,000 BBs and someone will be waiting a LONG time to move before it runs out of ammo


That's also an idea, but I like damage and as you can see comparing 100 psi to 800 psi, you can't beat HPA :)
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Unread postAuthor: POLAND_SPUD » Mon Feb 01, 2010 1:56 pm

you can't beat HPA
lol just don't forget to turn it off when not in use... :D

I guess that with this kind of project it is quite likely to get shot at least once... not to mention that it would be a good idea to test it on yourself... there are really a lot of things that can go wrong so I'd preffer to play with stuff that can't kill seriously harm someone
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Unread postAuthor: jackssmirkingrevenge » Mon Feb 01, 2010 2:20 pm

POLAND_SPUD wrote:there are really a lot of things that can go wrong so I'd preffer to play with stuff that can't kill seriously harm someone


No doubt about it.

It will probably end up in my room with a fake gun and laser sight eventually, and any dangerous experimentation carried out in a strictly controlled environment.

A small financial update, so far the software, controller, cables and wiring, servos, camera and battery box have cost around 160 euros (about $220 US), all purchased online. The material cost of the mounting will be minimal. Assuming you already have a PC (you're on this forum after all) it looks like this thing can be put together for well under $300, maybe not what your average teen can afford on pocket money but hey, if you can afford playstations and xboxes...
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Unread postAuthor: MRR » Tue Feb 02, 2010 11:39 am

Building a sentry gun is a cool idea but its also "autonomous" = boooring, once you have set it up.
If possible you should build in a feature to take over manual control.

I've recently watched a video about a homemade "game gun" which is basically a gyroscopic mouse, a small lcd and a wireless gamepad. Combining your sentry and one of these would be pretty amazing IMO.

[youtube]http://www.youtube.com/watch?v=YZuzCpqVZ_c&feature=channel[/youtube]
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Unread postAuthor: POLAND_SPUD » Tue Feb 02, 2010 12:16 pm

I guess it wouldn't be that difficult to hook up a turret powered by step motors to the computer (using parallel port)

I've done some research and it seems that this is all you need

Image

of course you still have to write a simple programme that would allow you to control it with the mouse and vary pan/tilt speed

EDIT
ohh it seems I can travel in time... and post in the past.. hey how cool is that ??!!
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Last edited by POLAND_SPUD on Tue Feb 02, 2010 12:24 pm, edited 1 time in total.
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Unread postAuthor: rp181 » Tue Feb 02, 2010 12:21 pm

Very similar to Jimmy's setup.
This system was/is being made for IR tracking, and only IR. The infrared filter was removed, and a cut piece of floppy disc placed over the CCD to act as a rough IR pass filter:
Image
film lower part:
Image
and the program:
http://rp181.files.wordpress.com/2010/01/desk-1_023.png

like jimmy's program, it shows crosshairs, and the area around that point in the cameras field of view in the lower box.

This is the older version, but shows the crosshairs:
http://rp181.files.wordpress.com/2010/01/3.png
And on the 'tube:
[youtube]http://www.youtube.com/watch?v=XD4WNxY8iu4[/youtube]
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Unread postAuthor: rp181 » Tue Feb 02, 2010 12:22 pm

Weird, I also traveled in time and posted in the past....

EDIT: AAH!!! it happened again!
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Unread postAuthor: irisher » Tue Feb 02, 2010 12:27 pm

I guess JSR always has to have the last word. :)
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Unread postAuthor: rp181 » Tue Feb 02, 2010 1:44 pm

Thats weird because the "last post" is correct.
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Unread postAuthor: jackssmirkingrevenge » Tue Feb 02, 2010 2:02 pm

MRR wrote:"autonomous" = boooring, once you have set it up..


I doubt it to be honest :)

If possible you should build in a feature to take over manual control


I believe the software allows you to control it manually by clicking a point in the camera's view at which the gun will aim.

Combining your sentry and one of these would be pretty amazing


Apart from the prancing around your office in shorts part :)
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Unread postAuthor: jackssmirkingrevenge » Tue Feb 02, 2010 5:34 pm

rp181 wrote:Weird, I also traveled in time and posted in the past...

EDIT: AAH!!! it happened again!


Eeek! My use of a high speed camera must have somehow warped time!

lol.

Well, technically then this isn't double posting :D Here's vaguely what I had in mind for the "gun" portion of this project, basically what I was trying to do here (but using an airtight piston made from a syringe plunger so I can have a separate equalisation hole of predicatable flow) coupled to a vortex block BB chamber.
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Unread postAuthor: rp181 » Wed Feb 03, 2010 12:28 am

why not a solenoid valve?
It would be difficult to get a servo to push a schrader reliably. If your looking for lower flow, there are valves like these:
http://www.legoeducation.us/store/detai ... =0&t=0&l=0
Its used for lego pneumatics, that would be easier to actuate.
I have a couple, they work great.

If you put a little silicone grease in it and work them, the become very easy to move.
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Unread postAuthor: POLAND_SPUD » Wed Feb 03, 2010 1:07 am

stuff from lego pneumatics operates at a couple of bars max... he wants to use hpa...

but I agree that a solenoid valve could be used here

lol I just realized that jsr is responsible for some of the most spectacular fails around here and now he is building an autonomous turret.. heh.. what could possible go wrong?? :D
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Unread postAuthor: jackssmirkingrevenge » Wed Feb 03, 2010 1:11 am

rp181 wrote:why not a solenoid valve?


I imagine it's hard to find one rated for the pressures I plan on using

I have a couple, they work great.


... but would they take 800 psi? I think I will look into lego pneumatics anyway, they seem to offer quite a few interesting options for lower pressure projects...

I don't see why it would be difficult for a 6kg/cm servo to open a shrader, if it doesn't manage to open it directly you could always have the schrader operating a double action spring loaded trigger, though this would not allow full auto fire.

lol I just realized that jsr is responsible for some of the most spectacular fails around here and now he is building an autonomous turret.. heh.. what could possible go wrong?


LOLOLOLOL!

I'm going to shoot myself, aren't I?
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Unread postAuthor: POLAND_SPUD » Wed Feb 03, 2010 2:28 am

I'm going to shoot myself, aren't I?

I'd say it's almost sure...

just do not call it 'HAL 9000'

nahh wait that would be a pretty cool idea... you could replace that gay portal sounds with that of HAL... for example when you turn it off it says 'I'm afraid that's something I cannot allow to happen' :D
and 'I am sorry Dave' played in a loop when it fires

:twisted:
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