Great 1/2'' piston design

[Sticky_Tape]

I have a great 1/2'' piston design to show you guys.
I have already made one of these for my 5mm and I didn't have to make any services on it yet.
The top of the piston is counter sinked with holes drilled in the cone of the sink for the hot glue to hold onto. The o-ring is casted right into the piston so you don't need to make a grove. Tell me what you think.

[MaxuS the 2nd]

I just bolt rubber sealing faces to mine and that works almost too well also.

[psycix]

Ah so the hot glue is the sealing face?
Could work. Make sure it is 100% flat.
You could add more then one o-ring, just because.

[Sticky_Tape]

This is for small bores like 6mm
Try finding bolts for that.

[Sticky_Tape]

I already made one works really well I just quickly torch the hot glue to make it flat.

[jimmy101]

This is for small bores like 6mm
Try finding bolts for that.

McMaster part #91290A120
Metric Class 12.9 Socket Head Cap Screw Alloy Stl, M3 Thread,
3mm Shank
5.5mm D Head
2.5mm Hex Drive
16mm Long

[Sticky_Tape]

Oh so you can get a bolt that size but would it be good enough to hold on a sealling face? I don't think so. I would preffer the hot glue tipped one because it is alot easier to build and probably better.

[ALIHISGREAT]

yeah, i agree the hot glue tipped piston design is probably better for smaller bores because i wouldn;t want to thread the hole, i just use self tapping screws.

[mark.f]

I think most people with bores that size just glue on the sealing faces, but I'm not 100% sure. I know everything 1/2" bore and up you should bolt the face on.

Good idea though. I don't see how you would cast the O-ring in place and have it be a tight enough fit to seal correctly. Also, wouldn't you need two to prevent wobble? Also, I guess you could put some teflon tape under the ring when the piston is dried to build up the O.D.

[Sticky_Tape]

The width of the piston is 1/2''. The o-ring isn't suppost to seal olny make the fit tight. when you cast a piston in epoxy you need to lube the wall of the mold to make the pistong come out. This makes the o.d. of the piston to be about .2mm smaller than guns chamber. Putting a oring in the cast gets rid of the lube on the wall of the mold in that spot making the o.d. of the pistong just right but not sealling.