Original Diana 35 - elastomer piston seal ? Better?

[Jimny4x4]

Polyurethane elastomer seals are by far the best. Having "memory" resilience they can take a pounding and keep their shape. I make my own on a lathe and seen old rifles improve after fitting replacements. Having a thin lip parachute design gives the best results. Most manufacturers today use polyurethane.

Baz

Benelli B76 - Where do you buy the raw material ? Am interested .

[Benelli B76]

Benelli B76 - Where do you buy the raw material ? Am interested .

There are various diameter rods advertised on the evil bay. Just search polyurethane rod. Be careful some companies charge a lot more than others. May be best just to google it and find the original suppliers.

Baz

[jonnyone]

There are various diameter rods advertised on the evil bay. Just search polyurethane rod. Be careful some companies charge a lot more than others. May be best just to google it and find the original suppliers.

Baz

Is that the same as OEM seal materials or better Baz?
Do you think its possible to machine a seal to fit on Diana piston heads or would that have to be injection moulded due to the dovetail shape of the retaining stud? Or would it be better to dispense with that fitting arrangement and do a different design?
I'm
very interested in this aspect of air rifle improvement but I have neither.the knowledge, skill, or.equipment to pursue this myself
Dave

[Benelli B76]

Is that the same as OEM seal materials or better Baz?
Do you think its possible to machine a seal to fit on Diana piston heads or would that have to be injection moulded due to the dovetail shape of the retaining stud? Or would it be better to dispense with that fitting arrangement and do a different design?
I'm
very interested in this aspect of air rifle improvement but I have neither.the knowledge, skill, or.equipment to pursue this myself
Dave

Dave, the PU rod I buy works as good as factory supplied and is available in similar hardness as measured with a Durometer at 90 to 95 Shore A scale. I have made seals for the Original 6 M pistols with the dovetail taper fitting just by setting up cutting tools as required on my little Emco Compact 5 lathe. Making PU replacement seals for leather ones in old classic air rifles like the Bonehill Brittania and others sometimes gives up to a 100 fps increase in power. Obviously you have to get a good fit, neither too tight or too lose. Having a thin undercut lip on the edge of the seal helps it seal in the chamber bore under compression.

Baz

[jonnyone]

Dave, the PU rod I buy works as good as factory supplied and is available in similar hardness as measured with a Durometer at 90 to 95 Shore A scale. I have made seals for the Original 6 M pistols with the dovetail taper fitting just by setting up cutting tools as required on my little Emco Compact 5 lathe. Making PU replacement seals for leather ones in old classic air rifles like the Bonehill Brittania and others sometimes gives up to a 100 fps increase in power. Obviously you have to get a good fit, neither too tight or too lose. Having a thin undercut lip on the edge of the seal helps it seal in the chamber bore under compression.

Baz

You lost me with the hardness scale. But I certainly understood the benefits you mention there.
That sound like a real benefit to some of these classic guns. Increasing the efficiency and then reducing spring input to drop cocking effort, wear n tear and improving the shot cycle. Sounds like a win win to me.
I would be guessing that you make these seals bespoke to each gun or can you make them based around known manufacturers dimensions and tolerances?
I'd like to try one on my .177 50T01 in the future should you be.interested in a small project? For a sum of course! Only thing is on the T01 is that the existing leather head is riveted on and would need to be turned off and drilled/ tapped. Nothing to a man of your capability but a non starter for a wood butcher
Good stuff mate.
Dave