need help for school project and first combustion gun.

[crazyivan]

hi guys i am new here...i am 16 and i am making a mini cannon that fires small wooden balls(made myself) for my school project....i hope to achieve the most "cannon-like" gun thus i have chosen to use combustion instead of pneumatic....my english isnt very good hope u guys dont mind.

i have made a very rough diagram about the dimensions..i will be using a sparker and bolts as electrodes..i want to ask if it is possible to thread bolts into pvc?

with my setup will it be possible to propel a wooden ball about the weight of a marble over 50meters? what fuel do you guys suggest? i read starting fluid is good..i kinda like it too as its widely availible in my country. if not i will stick to aerosols. can you guys also help me look at the dimensions of my cannon and see if it would work in theory?

also to seal the barrel to the chamber i would have to use reducer bushings and what kind of glue?

[MrCrowley]

Your English is better then half the members on here who speak it as their first language

Now the cannon...I would say a 300mm long 80mm diameter chamber with a 20mm barrel 800mm long should work. Since this is only a combustion using DWV(reducer) should be fine but you can use a bushing which does that samething but reduces the size immediatly instead of a gentle slope like a reducer if you get what I mean.

Since your using metric I doubt you will find sch40 ratings. What country do you live in? Every country uses a different rating system.

Buy the 20mm barrel first before you make the wooden projectiles as the I.D of 20mm PVC isn't exactly 20mm.

[crazyivan]

thanks i live in singapore....i think i will go down the the plumbing shop tonight and take a look at the pipes and ratings and ask a bunch load of questions...and i think i will use the reducer u mentioned instead of a bushing...

but about the dimensions u mentioned 300mm long 80mm diameter...thats too big! i can only go smaller but not bigger length wise as theres a restriction to the size.

[MrCrowley]

Other way round You want the bushing not reducer 8)

Ok if size limit it 10cm long make the chamber 10cm diameter if you can.

[Mudbubble]

O.O I live in Singapore too!

I'm not sure we're allowed to make a spudgun here,but heck i'm going for it!
I'm currently on my first big project

[Mr.Russ]

this might sound stupid, but you could always get a block of wood and sculpt it (using a lathe) to look like an old cannon... use a copper barrel that will slide into the middle of it... i think that would look quite good

[Mudbubble]

That is really mini!
So small that in fact you don't need proper pvc stuff to make!

Here's one of my mini gun using a pen and fruittree bottle