I can help you out with some 4140 shaft. I'll have to check what diameter I have in the shed.
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Sounds good, let me know if u find something,

So im trying to fit a standard pnuematic tjuntion fitting to the top of a co2 bottle, im haing troubles cause the thread doesnt match anything standard i can find, so should i try retapping the bottle with a 3/4in standard thread, is that what you other guys have done?

i think what most people do is have a short single feed from the bottle to a reductor/expander and then the new fitting... kinda like this

[====]-------------==============<<<<<<<
|bottle| single feed|reductor/expander|new fitting

just make the feed from the bottle really short than that way you havent got any likelyhood of the new thread interfering with the bottles seal on top of that with a standard thread it meens it can be re-filled with co2 later on (assuming you re-use the bottle for something else)
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as a shadow is seen and not heard i am here
-Waddy the phoenix

I guess you are trying to connect to the paintball bottles pin valve? If so then the have an American standard CGA320 fitting which has a .825-14NGO thread while I am guessing your "standard" fitting has a BSP thread. Fittings are always a pain considering every country has their own standard. Always keep in mind that paintball gear comes from the US so use their standards.

Woody has some good stuff on his site: http://www.teamonslaught.fsnet.co.uk/co2_info.htm . But don't believe the stuff about a 1/2"BSP nut fitting on a CGA320 fitting. I tried and couldn't get it to work.
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Secretary of the Queensland Robotics Sports Club inc.

What im wanting to do is to remove the brass fitting / paintball thread / pinvalve and replace it with something else which would be say a t-bar with a 3/4" bsp male thread on it, as opposed to trying to fit something onto the pinvalve part which seems to have an extremely non standard thread, if i cant get it to work i can look into another vessel for a buffer tank, something that alrdy has a std fitting.

ill see what i can figure out

quote:

---

Originally posted by kkeerroo:
I guess you are trying to connect to the paintball bottles pin valve? If so then the have an American standard CGA320 fitting which has a .825-14NGO thread while I am guessing your "standard" fitting has a BSP thread. Fittings are always a pain considering every country has their own standard. Always keep in mind that paintball gear comes from the US so use their standards.

Woody has some good stuff on his site: http://www.teamonslaught.fsnet.co.uk/co2_info.htm . But don't believe the stuff about a 1/2"BSP nut fitting on a CGA320 fitting. I tried and couldn't get it to work.

---

Oh. In that case you will need a 5/8-18UNF fitting.
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Get Some!!!

Secretary of the Queensland Robotics Sports Club inc.

I tap and tread my own connections to the paintball bottles, and 1/2 bsp fits nicely. Drill a hole 17mm bore 18mm deep , turn it out to 17.6mm (smooth walled, its to seat the oring). Widen the top 11 mm to 19mm bore, and tap it with 1/2 bsp.


What doesn't fit is a 1/2 bsp nut on a normal CO2 bottle.

K well big update i spose, It all seems to be comming together a bit now,

My electrics are a pair of red wheels on bunnings drill motors powered by mikes homemade speedos prolly only running at 12v and ill try to get some nice lipo packs to put in there. But all of this side of things im leaving basic for now till i can get my weapon running. I have a plank of 5 ply driving around so its all i need for now on that front.

I got my pnuematic setup pretty good now, im quite happy with it, i have my 12oz co2 bottle with my palmer pursuit female stabaliser regulator attatched. After putting a nice coat of machine oil on the plunger in the regulator it seems to be performing much better in a horizontal position so i can now consider lying it down in my final layout. This then runs into a buffer tank which is another 12oz bottle with a gutted 'on/off' valve acting as a T peice. This then goes onto my 2x 3/2 valve and then my 63mm bore x 150mm stroke ram. This should all be running at around 100psi. I might look at some quick exhaust valves for my ram to help performance.

Today i finally got around to welding up a prototype 'rack' for my rack and pinion mechanisim, the basic idea is the ram pushes and pulls the rack which in turn rotates a sprocket and shaft which my axe is attached to. The rack is made from two M16 fine hexnuts welded together to allow for screwing onto the rams shaft, this is then welded to a 150mmish peice of 20mm box steel and then a 150mm peice of roller chain is welded onto one side of the box. I then have a 17tooth 6B (.375in) pitch sprocket running on the 150mm rack, this translates to about 270° rotation which will make for an interesting axe swing.

Now i need to design some form of mounting to hold the shaft in place and look at designing the axe and frame. I have my 25mm ali plate which i think will be good for making some mounts, but i need to get my hands on a drill press or some such...

Getting some progress done, might do up a cad sometime, i spose i should to try to work out some design flaws before going to far with things.

Pictures to come if i can get hold of a camera.

For now any constructive comments would be appreciated i spose, also any tips on mounting motors and shafts to 20mm box.

Got any pictures mate, it sounds interesting.
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Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.
Albert Einstein.

As far as mounting drill motors to 20mm box section is concerned, it is very easy. Two dodgey ways are hose clamps or saddle clips.

They both work because of the flat edges on the nose of the gearbox are around 20mm long, and seem to be a good spot to clamp down.

One suggestion i would make about either of those dodgey methods is that you should mount the motor and gearbox below the box section.

As far as mounting to shaft, i would get something thicker and flater, mount the shaft to that, then mount that to the box section. The walls of the box section are notoriously thin and bendy.

Hope that helps in some way.

Update time,

Iv been pretty slack last month or two on the robot front, but plane tickets to robowars have been booked so its time to get my ass into gear.

I have made some progres but at the moment my currently growing concern is weight.

Iv made up a frame for my robot out of 20mm box, picture below.



It currently weights like 5kg and i need to put some mounting brackets on it for my ram, gas tank and such.

Iv got my weapon mechanism setout, its explained in previous posts but heres a picture, the 'wood axe' will be replaces but the idea is that its bolted to the big sprocket which is turned via the little one via the rack setup.



Last picture is the overveiw of the whole setup with all my parts positioned.


Putting all this on the scales reads about 12.5kg

So i need to reduce alot of weight, from the frame, the big sprocket, maybe drill out the shaft, might look at a smaller bore ram but that will be expensive.
[edit] any tips on how big holes and how far apart i should put them when drilling out the 20mm box?

Then i need to add onto the above weight with mounting brackets for shaft and tanks, the weapon and armour

I was waiting till i have some better idea of weights before i jump in and get my weapon built so i can make it as heavy as possible but i need to get it done soon, any ideas on numbers for suggested size / weight of my axe would be helpful.

With armour, i calced that i have 4800cm^2 to cover (minus floor) and with ali at 2.7g/cm3 then 2mm thick ali armour will weigh about 2.5kg, any ideas on if 2mm will be fine or maybe i should look at 1mm
my current plan is to take a bunch of armour plates and keep pop riveting them into place this at least seems cheap, easy and light, as opposed to trying to weld or mount such thin metal.

more to come...


Constructive critacism welcome, i need all the help i can get to finish this in time.

Looks like it's coming together nicely
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They say that he crossed the fine line, from insanity to genius.

So im needing to source some co2 for the event, I dont have any refilling equipment so i just normally goto the local paintball place, but i dunno if thats viable during the event or what.

So im looking to see if anyone who plays with co2 can help me out, bring some gas or some such or if any locals to the event would know a paintball place i can goto.