Buttoning a Piston

[pelletcaster]

You do mean 12, 4 and 8 o'clock don't you?

Ah, I can see in the picture that is what you do. Typo.

Thanks,
you're right of course.
:shame:
Will edit.

[pelletcaster]

The button at 12oclock is the one that takes the most punishment on a breakbarrel, I had mine quite snug & set the power to mid 10’s when I first put them on. 500 shots later, I was up to 16ftlb as the buttons wore in. When I stripped the gun & sold off the parts, the 12oclock button was doing zero to prevent metal on metal, has it had worn flush with the surrounding piston body material. This was delrin rod btw, drilled into the piston skirt.

Yes I agree to the 12 o'clock button "punishment".
You may have had already some galling on the sys tube side thus acting to the newly installed button as a grinder sanding it down.
Or it wasn't real DELRIN but something else.
BTW - some proper lube is necessary anyway.

[Thegreg]

It is not so simple my friend. It dependson how well they were sized to the comp tube and what sort of plastic was used. In general I'd say that if you are not familiar with engineering or model engineering works then leave it alone. Some people are quite happy with metal running on metal and genrally if they are correctly lubricated then it is fine.

A.G

I'm a time served machinist/toolmaker by trade, this sort of thing doesn't faze me, don't worry! I understand the principle of them I just want to know whether they're a worthwhile improvement and if prior work to the piston is done, in general.

Yes I agree to the 12 o'clock button "punishment".
You may have had already some galling on the sys tube side thus acting to the newly installed button as a grinder sanding it down.
Or it wasn't real DELRIN but something else.
BTW - some proper lube is necessary anyway.

Thanks for going to the effort of putting all the pics up. The piston is pushed upward by the cocking arm so the 12 o'clock area will see the most wear, they always show that when you take a piston out (of a break barrel anyway as someone else has said).

Is anyone familiar with PEEK? I think it'd be my first choice for material. I've used it with great success in the past in many applications where low friction & good wear characteristics are required. It's not cheap stuff if you were to buy it but I've got quite lot that I've saved.

I might give it a whirl when I get chance. I rely on using friend's machine shops nowadays for doing bits like this, the only engineering I do now in my day job is on a screen

Cheers
Greg

[pelletcaster]

Is anyone familiar with PEEK? ...

Never heard of but googled. Looks interesting.

https://en.wikipedia.org/wiki/Polyether_ether_ketone