SpudFiles

So, i finally got around to make my first machined aluminium piston.
Made it at school while everyone else was finishing off their Wind vanes. (Of course i finished mine first... )

While in class i had nothing to do. Other than helping out some of my class mates, when i realized the school had a supply of 30mm aluminium rods.
I asked my teacher if i could make some stuff from the left over rods.....
since i finished my assignment, and with the answer being yes.

I went over and picked the 30mm rod to machine my piston.
It took about 50mins to machine and tap the piston to the ideal measurements. ( had no dimensions at all )

With a surprise, i had a piston tolerance of something like 0.3-0.4mm.
Which will be replaced by the o-rings of course.

Anyway, here is the new piston.




My old piston

My new aluminium piston

Nice to be able to take advantage of the resources to hand looks a bit heavy though, I would say around 50 grams - you'd better have a good bumper... is this for a barrel sealer or chamber sealer? In the former case you could have made it much shorter.

With two o rings spaced like that, I thought you were going to make a QDV.. For a normal piston, only one o ring on the back is needed to seal the pilot area when the piston is extended. Nice piston.

I recommend trying to drill out part of the piston and replacing it with something less dense. That and editing the original post title to fix the infamous spelling error we all see too often on this forum.

is this for a barrel sealer or chamber sealer? In the former case you could have made it much shorter.

It's for a barrel sealer, just a replacement for the current cannon on this topic.

only one o ring on the back is needed to seal the pilot area when the piston is extended. Nice piston.

Yes i am aware of that, Though the two o-ring holes are just there to replace the tolerance. Also i'm not really looking for a 100% seal, the o-rings i currently have are a almost perfect seal, which in return the gun will seal at low pressures without me pumping like crazy before it seals.

I recommend trying to drill out part of the piston

i have considered this but i feel no need to do this, as the piston doesn't really weigh much compared to the polyester resin piston.
If i notice a loss of performance, i may drill it out.
ahhhh......... the spelling error.

Thanks for the comments

bro can you hook me up, keen as to get a metal one, the one you gave me gets stuck coz it slams too hard when i release it

Bring me the piston housing at school, and i'll try make you one by Monday.
Do you want o-rings?, also what diameter is you're sealing port?
cause i have to drill and tap a hole for a possibly M5 bolt for you're one, may differ depending on you're sealing port diameter....

you owe me bro.

yea ill bring the housing, just wanna make it light weight, i have a spring behind mine, ill tell you tomorrow.
Sealing port is 15mm in diameter so any bolt that is smaller than that M5 will do if the bolt head is a bit bigger than 5mm because the rubber has a hole of 5mm I think.
Ill buy you a pie aye.

Dude that is a really good piston in my opinion. I cant wait to see some of your next few cannons if this is what you are making now as a beginner! Excellent work my friend!!

daniel0663 wrote:

i have considered this but i feel no need to do this, as the piston doesn't really weigh much compared to the polyester resin piston.
If i notice a loss of performance, i may drill it out.
Thanks for the comments

Edit Correction. One site had the density way low. Other sites show the density at about 1.5. Updated below. Various resins have various densities.

Polyester resin specific gravity 1.5 g/cm^3
Aluminum specific gravity 2.55
This makes a metal piston of the exact same shape about 1.5X heavier than the original.

Tech;
it is x.x g/cm^3.

Got to get cubic in there! Or was that cubit?

I saw cubit and thought of the linear measurement used for a biblical boat that was a zoo. Tried to keep the thread clean of religion..

I do stand corrected on g/cm^3.. My error. Good catch.

1.5X heavier than the original.

.... yeah, due to the previous one with the screw+heavy sealing face and the o-rings. It must of added some weight, which lead me to say that the weight was quite similar compared with the bare ali piston.
no accurate weight measurements was recorded, just the "ehhh.. thats about right?"

daniel0663 wrote:no accurate weight measurements was recorded, just the "ehhh.. thats about right?"

....that would be a measurement pulled outa yer...dark place?