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Tennis Ball Mortar

Step 3Firing

Firing
Safety first: Lighting the mortar without a stand (like I did in the first shot of the video) is asking for trouble. A simple and fast stand can be made from PVC pipe and coat hanger as demonstrated in the photo. If no stand materials are available at least lean the mortar against something (bench, rock, etc.) so it isn't at risk of falling when you are trying to light it.

Tip: 3" PVC pipe will fit perfectly around Pringles cans with just the right amount of duct tape on them. A hole can be drilled through the PVC and cans for lighting. This provides extra structural reinforcement to the cans lessening the chances of a blowout.

Tip 2: Use a barbecue lighter, or like in the video a quick & easy torch (made by bending coat hanger around paper towel). This will put distance between your fingers and the bottom of the tube, in case of a blowout.

Generic safety stuff: Use adequate eye, ear, nut-sack, and various other body part protection.



To prepare for firing: Set up the mortar in a large open area where you have little risk of hitting someone. Squirt about 1-2 teaspoons of lighter fluid down the barrel of the mortar, making sure to aim for the bottom can. Spray a little extra through the hole in the bottom, to help aid in lighting, or, if using hairspray, you can spray hairspray down the mouth of the barrel for a few seconds. Drop the tennis ball down the barrel. The mortar is now loaded, and from now on no one should pass in front of it.

To fire: Wait about two minutes after pouring, to give the chamber enough time to fill up with the evaporating lighter fluid (Pouring the perfect amount of fluid, and waiting till exactly the right time to light are the two things to master when it comes to tennis ball mortars). Light the barbecue lighter or torch, and hold it close to the hole on the bottom. If all goes well you should hear a loud bang, and see the ball sail off into the distance.
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49 comments
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May 6, 2011. 5:36 PMEverett_McKinley says:
I want to use it for airsoft and I wanted to know if anyone knows how to make the tennis balls explode and shoot BBS everywhere.
Any ideas?
Apr 10, 2012. 4:59 PMpoikilotherm says:
Maybe put a small explosive in the center of the tennis ball, and fill it with BBs. Then leave the fuse to the explosive trailing out of a hole in the tennis ball, and launch it from the mortar with the fuse on the back of the tennis ball so the action of firing it lights the fuse.
Oct 1, 2011. 1:14 AMexplosivesroxdawrld says:
just wrap the BBs in aluminium foil or place a paper ball underneath it
Jul 27, 2011. 4:58 PManguil13 says:
what i did was put a hole in the tennis ball with a drill and add a fire cracker...filled it with bbs....but you need to take a knife and cut make the tennis ball a little thinner by cutting some of the stuff off it....also try other things that the fire cracker will explode easier like a ping pong ball with weights or something
Apr 19, 2008. 4:42 AMthedog458 says:
hey really good Instructable. now this is gona be a really dumb question but do u have to use the lighter fluid?(coz where I live they don't sell it) :(
Apr 5, 2010. 11:14 AMjackh94 says:
 you seem to have the internet, anything can be got on the internet, including lighter fluid
Aug 2, 2009. 10:39 PMThundertydus says:
Yes they do No matter where you live, they sell light fluid
Aug 2, 2009. 6:58 PMfreakytail says:
are u serious?? where on earth do you live???
Jun 14, 2008. 12:00 AMpyromanizak says:
spray some butane in there
Apr 14, 2011. 5:36 PMxs0skill3dx says:
na dont use butane... last time i tried with it the whole thing just caught alight... the result was a 30inch candle and a flaming tennis ball rolling down my street..not cool
Apr 16, 2009. 9:51 PMjdoucette83 says:
Gotta be careful of that stuff, it'll go without even needing the "perfect" air mixture. For my potato canon I usually use Starter Fluid because its strong as hell and if you get too much the chances of it blowing up without enough air are pretty slim. I haven't made one of these yet, but I'm going to try to make it out of PVC instead...Pringles cans seem more like a cardboard pipe bomb.
Jun 26, 2010. 4:32 PMM4industries says:
PVC potato cannon with starting fluid is a potential is pipe bomb held under your arm. Just to make a point that only hair spray is the safe propellant
Feb 4, 2011. 11:17 AMTXTCLA55 says:
why are you putting lighter fluid it that? I just use Axe, or Right Guard and that potato fly's damn far.
Feb 9, 2011. 7:52 PMM4industries says:
Same here, but we were discussing starting fluid, a VERY flammable liquid that can aerosolize by dripping down the inner surface of the spud gun.
Feb 9, 2011. 10:38 PMTXTCLA55 says:
oh I see. well based on my experience you better be using some really strong PVC; I built two spud guns in the past, both firing chambers cracked with in 15-20 uses.
May 11, 2009. 4:35 PMpian0man says:
I got a garage shop ballistics book, and it says that hairspray can work too, which makes sense. Would the whole thing just blow up?
Aug 21, 2009. 9:45 AMPikesPeak says:
Yes, you'll be amazed what hairspray and a lighter can do. Instant blowtorch.
Oct 25, 2009. 4:52 PMPastTheVoid says:
 Back-feed.
Nov 16, 2009. 1:14 AMcodz30 says:
This is an old wives tale,
Fire needs oxygen to burn, their is no oxygen inside aerosol cans or else they could spontaneously combust at anytime.
Therefore, flame has no way of getting into the can, no back-feed
Jun 26, 2010. 4:34 PMM4industries says:
There is an issue however. The flame can melt the regulator or nozzle and all the propellant can come out at once. But it won't go back in the can.
Jun 22, 2010. 9:00 AMnigel da nautilus says:
hmm everyone seems to think that. if i put a match near a deodorant can all my freinds go OMG IT WILL BLOW UP AAAAAAHHHHH. it never has although i was once near an almost empty butane canister when the gas blew back twas F*****g scary
Jan 15, 2010. 6:21 AMmacmccune says:
wow. thank you. i never thought of it that way. i have always been terrified  to hold a flame for more than a second on an aerosol can. it makes a lot of sense. thanx. :D
Apr 19, 2008. 11:20 PMthedog458 says:
lol no I live no coober pedy. but thanks any way.
Feb 7, 2010. 9:32 AMElQuirko says:
Doesn't work with hairspray - at least, not for me.
Nov 16, 2009. 6:38 PMneeds_more_to_do says:
Alternative fuel source, propane and oxygen in small balloons. It requires that you use PVC because of the smooth inside of the barrel but its far more reliable than lighter fluid albeit a bit more expensive, and if you have leftover balloons you can scare the neighbors by turning them into loud explosions!
Apr 28, 2008. 2:31 PMmitch_mason77 says:
cost me about 20$ to make, where i live pringles are like 3.00$ a bottle because right now the only way to get in and out is by plane.
Aug 29, 2009. 5:01 PM#9EJV says:
how far does this shot i wana make one
Aug 21, 2009. 9:49 AMPikesPeak says:
$3.00 a can? For good (un)healthy junk food. Bummer. Anywhere from $1.00 to $1.50 here.
Apr 28, 2008. 7:55 PMpieboy1992 says:
where do you live?
Apr 28, 2008. 8:14 PMmitch_mason77 says:
In this far off land once thought to be just a legend, but after recent studies its concluded that this place is real, has a name as well as a population of about 500 people. St Paul's River, Quebec, Canada:).
Apr 28, 2008. 9:17 PMpieboy1992 says:
hahaha, sweet
Jul 2, 2009. 5:42 PMben080196 says:
ok i finaly got it to work, but my tube cuaght on fire and i connot usa it any more the out side is ok but the inside is burnt
Aug 21, 2009. 9:44 AMPikesPeak says:
It's only obvious why. Picture 7 says Made in China.
Aug 12, 2009. 9:49 AMmrkane says:
Lol!
Jul 2, 2009. 5:08 PMben080196 says:
i did just as the instuctions say and i couldnt get it to worj except for 1 time and it went about 10 yards
Jan 2, 2008. 11:14 AMirish meatball says:
i love this thing! i almost lit my neighbors house on fire with it though.... when i shot it the ball came out on fire and landed on their roof! (thank god it rolled off)
Mar 13, 2008. 6:54 PMpaintballer111 says:
hey you can soak the ball in water and it'll still shoot
Jun 13, 2008. 11:58 PMpyromanizak says:
its better to soak it in petrol
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I'm attending NYU-Poly.