Sentry Gun Project

[inonickname]

I had a 2mm barrel for a small gun I made a while ago, and that was fun to use. It would fire several bbs at a time through a coke can. A bit less KE is probably good incase it decides to shoot at something you don't want it to.

[USGF]

Get servos big enough and you could sit in the turret and ride along.

USGF

[jackssmirkingrevenge]

I had a 2mm barrel for a small gun I made a while ago, and that was fun to use. It would fire several bbs at a time through a coke can.

2mm would probably have been more practical, if anything exponentially better than 1mm, but I wanted to go as small as I could.

A bit less KE is probably good incase it decides to shoot at something you don't want it to.

If there was a serious risk of that I shouldn't be doing it at all

Get servos big enough and you could sit in the turret and ride along.

If only I had the space

I had a play with the IR sensitive camera, good for low light but useless in bright sunlight...

The gun itself is in progress and curing as per the diagram below, I didn't bother with vortex blocks because the porting is so wide relative to the projectiles that it seems unnecessary, we'll see how justified my mindless optimism is it should be safe for HPA testing on Monday.

[iknowmy3tables]

Only testing will prove it's actual effectiveness, but I fear that you might damage your valve especially during moments when the opening isn't large or small enough

[inonickname]

The valve will be farily strong, and the bb's wont have accelerated too much by the time they reach the valve so it shouldn't be too much of a problem.

[jackssmirkingrevenge]

The valve will be farily strong, and the bb's wont have accelerated too much by the time they reach the valve so it shouldn't be too much of a problem.

This is what I'm betting on, I'm not really worried about this in this case though it might be an issue with my larger 0.177" version.

Here's a mockup of the system as it cures:

[jhalek90]

JSR, your ghetto-ness, and excessive use of epoxy always please me. 8)
But i must ask... where the heck do you get all those darn syringe tubes???

[jackssmirkingrevenge]

JSR, your ghetto-ness, and excessive use of epoxy always please me.

What can I say, it gives you an incredible amount of flexibility compared to using standard fittings and it's cheaper that a machine shop

But I must ask... where the heck do you get all those darn syringe tubes???

Joys of working in a pharmaceutical laboratory but I imagine you can pick them up at your local drug store.

[jimmy101]

But I must ask... where the heck do you get all those darn syringe tubes???

Joys of working in a pharmaceutical laboratory but I imagine you can pick them up at your local drug store.

Or, try a farm supply store. They usually have plastic syringes from a couple cc up to about 60 cc for a buck or so each. They'll also have sharp and blunt largish bore (smallish gauge) needles.

[jackssmirkingrevenge]

I gave it a whirl and EPIC FAIL

The BBs are so fine that they clogged up immediately, this clearly isn't going to work. Plan B is to build a conventionally laid out minature vortex block with the valve feeding into the chamber as per my original idea, even when half open the 1/8" ball valve has over 12 times the flow of the 1mm barrel so performance should be just as good.

[iknowmy3tables]

did you try it upside down too, unless the problem is that bad,
I can imagine this vortex block, probably just a thin sheet of plastic or metal, unless you plan to epoxy it too, to get the 1mm bore exit

But I must ask... where the heck do you get all those darn syringe tubes???

Joys of working in a pharmaceutical laboratory but I imagine you can pick them up at your local drug store.

I can beat that, my dad is a respected engineer for the marine corps, where do you think I got my magnalium alloy laptop
I also got my syringe tubes among other things for being a teacher's assistant for the head of the tech ed department

[jackssmirkingrevenge]

did you try it upside down too, unless the problem is that bad,
I can imagine this vortex block, probably just a thin sheet of plastic or metal, unless you plan to epoxy it too, to get the 1mm bore exit

Upside down the BBs will just fall into the remote line...

I will probably use a bit of 6mm tubing or something similarly tiny, I also ordered a couple of paintball fill nipples for a lighter setup, so this will be a couple of weeks yet. Still waiting on those darn servos anyway. I'll amuse myself with the 4.5mm variant in the meantime

I can beat that, my dad is a respected engineer for the marine corps, where do you think I got my magnalium alloy laptop

In that case your projects aren't as impressive as they should be

[jhalek90]

JSR. A cheap range finder can be made from a laser pointer.
Or, u could buy an ultra sonic range finder.


Matter of fact, i once made a simplistic range finder from the lego mindstorms infrared led emitter and receiver.

With the addition of a laser range finder, one could predict the exact range to the target, and account for things such as gravity, and projectile speed loss over distance, and even for things like projectile height.

Just a thought 8)

I am watching you.

[SEAKING9006]

I've been working on a concept in my mind recently, since I've been working a lot with the PICAXE IC chips. The PICAXE ultrasonic rangefinders are accurate enough to detect a broom handle at 3 meters, and by using two of them in concert with a servo harness, you could in effect make a scanner system suitable for use indoors. A little bit of clever algebra and you can lock onto a target, and fire an airsoft mini at it.

PICAXE chips on their own are fairly inexpensive for use on their won, about $3USD for a PICAXE 14M (14 pin chip, 80 lines of memory. Not great for projects outside of a classroom.) and a bit more for the PICAXE 40X2.

If you get a finalized design that you might wish to mass produce (a PIC controlled shell fuse, for example), to save money you can get a programmer from Microchip for around $50 and just buy the blank PIC's that they make PICAXE chips with.


As some on the forum already know, I've also been searching for a light, cheap laser rangefinder that i can use with a PICAXE for years. Any way i could build one for up to $30 and without having to resort to more expensive microcontrollers would be grand.

[rp181]

See: http://www.seattlerobotics.org/encoder/ ... vision.htm