HW35 Fettling

[Shed tuner]

I'd never thought about it before, but the 35 is actually a great candidate for an o-ringed piston

- Small port (has to be due to length)
- large 30mm cylinder bore
- not too heavy a piston

By reducing friction and bounce, it gets the most out of the shortish stroke, with the somewhat compromised long port...

[NickG]

I'd never thought about it before, but the 35 is actually a great candidate for an o-ringed piston

- Small port (has to be due to length)
- large 30mm cylinder bore
- not too heavy a piston

By reducing friction and bounce, it gets the most out of the shortish stroke, with the somewhat compromised long port...

Long port would keep the cycle soft as well 👍

[Shed tuner]

Long port would keep the cycle soft as well 👍

true..... I might have to copy your tune

[NickG]

true..... I might have to copy your tune

Not really a tune , just a piston head I made up for tony

[Shed tuner]

Not really a tune , just a piston head I made up for tony

Mate, all we ever do is just make something up

[TonyL]

I'd never thought about it before, but the 35 is actually a great candidate for an o-ringed piston

- Small port (has to be due to length)
- large 30mm cylinder bore
- not too heavy a piston

By reducing friction and bounce, it gets the most out of the shortish stroke, with the somewhat compromised long port...

Fully agree, Jon. And, y'know, the very loose fit of the (new) HW parachute seal was a blessing in disguise, really, as the rifle was demanding a bespoke fitting piston seal. And what a result! It performs and shoots beautifully.

I have another older '35 that I sealed myself a few years ago just by forcing some JB Weld Perma Lock thread lock into the void. But I was struggling to do the vacuum thing. So, at a future point, Nick's going to do that one for me too (thank you, Nick). That cylinder has the larger diameter port and I was thinking about maybe reverting to leather for that classic old-school charm. But this 'O' ring set-up impresses so much that that one might go the same way too. I wonder if the 'O' ring set-up will work with the larger port (it's a .177), or whether the TP will be better sleeved?

[TonyL]

Not really a tune , just a piston head I made up for tony

To you it might "just" be a piston head that you made, Neil. But there's no substitute for skill and the experience you've banked over the years. Especially with your unswerving commitment to piston rings (of various designs) and engineering the groove depths / crush so that they're just right. You're a wizard!

[Shed tuner]

I wonder if the 'O' ring set-up will work with the larger port (it's a .177), or whether the TP will be better sleeved?

Just sleave it

[T 20]

Just sleave it

He could try long stroking to 71mm to increase the scr before sleaving, Jon.

Something I don't think I tried on mine.

But having said that, I did sleave mine down to 3mm after the stroke increase.

[TonyL]

That one currently houses the later, longer stroke piston which I got from you on our exchange deal, Mick.

I've never sleeved a TP down. If going down the 'O' ring route (and it's looking increasingly tempting after witnessing this one) I'll see if Nick is happy to do it along with the sealing and 'O' ring conversion.

[deejayuu]

And here's a picture of said piston sporting its lovely new head.

Thank you, Craig, for posting. :-

Lovely job. Can you say dimensions please? i.e. Body length, rod protrusion, and is the seal groove in the original piston material/head or added item?
Can't see the join.

[NickG]

That one currently houses the later, longer stroke piston which I got from you on our exchange deal, Mick.

I've never sleeved a TP down. If going down the 'O' ring route (and it's looking increasingly tempting after witnessing this one) I'll see if Nick is happy to do it along with the sealing and 'O' ring conversion.

No worries Tony.

[TonyL]

Thank you, Nick.

[TonyL]

Lovely job. Can you say dimensions please? i.e. Body length, rod protrusion, and is the seal groove in the original piston material/head or added item?
Can't see the join.

Sorry, I didn't take any measurements. However, it is a standard, old-style (leather seal) piston with the seal and holder removed. I'm guessing Nick's 'O' ring piston head screws onto existing thread?

[NickG]

Sorry, I didn't take any measurements. However, it is a standard, old-style (leather seal) piston with the seal and holder removed. I'm guessing Nick's 'O' ring piston head screws onto existing thread?

I made it the same depth as your old seal and carrier. Didn't measure the stroke.