The Offcial Machinist Thread: Revised 01/04/2014

[Crna Legija]

If you know how to make key way groves on a lathe you use that technique to do it.

[youtube][/youtube]

[cannon monkey]

dont know how to do that just yet i will post up wat monkey knows how to do i can make small parts i have 1018 steel for the time being

[sagthegreat]

i need a piston machined for my barrel sealing tee, (1/2 in tee).
How much will it cost me. thanks

[MrCrowley]

Should cost about twice the going rate for a piece of string.


What are the piston dimensions? Do you want o-ring grooves? What do you want the piston to be made from? Where abouts do you live?

[sagthegreat]

I live in Sterling Virginia, my dimensions can vary, just need it to fit in a t, no o-ring grooves, but i need a working sealing face for a barrel sealing tee

[velocity3x]

One solid gold, 1/2" x 12" piston coming right up! That'll be 5 grand

Better add another 10k for shipping and handling!

[cannon monkey]

i have some hdpe rod left over if you like i can try make machine it for you to size send me a pm i wont charge much shipping+ like 3-5 dollars depending on what i have


i can make it out of
hdpe
or steel
or anything u have in mind

[jackssmirkingrevenge]

had a go at making a bullet mould, haven't tried it out but pretty happy with it

[Gippeto]

Might be the lighting, but I can't tell for sure if that's brass or aluminum...aluminum would be the better.

Will have to add some venting...small grooves running from the mold cavity to the edge...to allow the air to get out. Divot at the fill to act as a funnel will help too.

Will suggest you add some taper to the section that forms the inside of the skirt as well....a couple degrees is plenty (iirc I used 5). Will make removal a HECK of a lot easier.

Mold will need to be HOT to fill the skirt nicely.

[jackssmirkingrevenge]

Might be the lighting, but I can't tell for sure if that's brass or aluminum...aluminum would be the better.

Brass. Should work though, right?

Will have to add some venting...small grooves running from the mold cavity to the edge...to allow the air to get out.

Quick MS Paint scribble of where you would do it?

Divot at the fill to act as a funnel will help too.

Added it after I took the pictures

Will suggest you add some taper to the section that forms the inside of the skirt as well....a couple degrees is plenty (iirc I used 5). Will make removal a HECK of a lot easier.

I was thinking about that, will do.

Mold will need to be HOT to fill the skirt nicely.

That will be jake's problem, but given his sharpness workshop he shouldn't find that an issue

[Gippeto]

Brass will work...but mold release will be important...hot lead WILL bond to hot brass surprisingly well... if given an opportunity. Smoking the mold with a sulphur match might work...this is how the old cast iron molds were prepped. There are also commercially available release compounds that might work.

Vents should be spaced about every 3mm of the projectile height. Don't need to be deep, .005"-.010" has proven adequate. Make them on both sides of the cavity.


I suspect Jake CAN indeed get it hot enough.

[jackssmirkingrevenge]

Don't need to be deep, .005"-.010" has proven adequate. Make them on both sides of the cavity.

So basically... scratches?

[jakethebeast]

Hehe, i can melt it
But that's not the idea of it, i need proper projectiles for my bullpup

[Gippeto]

So basically... scratches?

Yup...a quick "lick" with a triangular pin file does the trick.

[jackssmirkingrevenge]

That seems to have turned out pretty well

It seems to have some stability issues though, maybe the wall thickness of the cavity is too much.