Sleeving tube....?

[Andy001]

Search 'precision steel tube '
On that auction site.

What size you after ?

29mm OD...25 ish internal....only got 70mm stroke!

[Shed tuner]

29mm OD...25 ish internal....only got 70mm stroke!

that's tight.. go 26mm bore instead.

[hmangphilly]

I ordered one of these to experiment with https://www.amazon.co.uk/U32i-Hydrau...hydraulic+seal , it's polyurethane and has a single lip, might have to get creative with the fitting but worth a try.

Difficult to see properly on my phone but that seal described as piston rod seal .

So could be intended to be fixed on outer surface and the inner (rod) to do the moving ?

Does the inner lip have a spring for tension ?

[Shed tuner]

Difficult to see properly on my phone but that seal described as piston rod seal .

So could be intended to be fixed on outer surface and the inner (rod) to do the moving ?

Does the inner lip have a spring for tension ?

looks that way to me too... bit like an grease seal on a driveshaft...

[NickG]

Pitty its not the other way up , it looks like a u seal to me . I looked u seals , but you really need a two piece piston head to fit them , lots of lost volume in the seal.

[Artfull-Bodger]

The seal arrived today, it's a compression seal for mounting on a piston or rod, its similar to a TX seal other than the ID does not have the tapered centre, there is a lip on the bottom of the ID for location, it has a 23mm base diameter (the side shown in the photograph) it then flares out to 24.4mm at the very top and has a groove in the face 2.0mm in from the external lip 0.8mm deep , so there's enough material to size it as the lip is quite thick as it comes. reasonable flexibility, similar to the Aussie PU seals.

Looks usable but with a bit of reworking for size.

By the way I did speak to the guys who make the Aussie seals, they would be willing to make seals to any size if they receive the CAD drawings, so if anyone knows how that is accomplished a set of 23mm seals could be made to airgun spec.

[Shed tuner]

The seal arrived today, it's a compression seal for mounting on a piston or rod, its similar to a TX seal other than the ID does not have the tapered centre, there is a lip on the bottom of the ID for location, it has a 23mm base diameter (the side shown in the photograph) it then flares out to 24.4mm at the very top and has a groove in the face 2.0mm in from the external lip 0.8mm deep , so there's enough material to size it as the lip is quite thick as it comes. reasonable flexibility, similar to the Aussie PU seals.

Looks usable but with a bit of reworking for size.

intresting.. let us know / post up a pic of the reworked version

[Artfull-Bodger]

intresting.. let us know / post up a pic of the reworked version

The seal sized up nicely, just needs a clean up and ready to go.

http://i50.photobucket.com/albums/f3...pse5pzfn3n.jpg

http://http://i50.photobucket.com/al...ps3ke0agdc.jpg

[hmangphilly]

what are you going to do about fixing it on , or the tapered centre ?

new nose ?

[Artfull-Bodger]

The ID is parallel except for an inward taper right at the top, which is obviously no use but there is a retaining lip 1mm up from the bottom of the ID specifically to hold it in place, so I will be machining a seat that incorporates a groove for this to locate on when I make the piston, all it has to do is retain the seal against the cylinder drag on cocking so this should be sufficient.

My issue now is the 26mm sleeve is too tight in the compression tube even with a heated tube / chilled sleeve, so I will have to very carefully polish the tube down for a tight fit and press fit it with a little heat shrinkage to retain it.

Then I'm going to have to make a few latch rods of different lengths to play with, I have case hardening powder here so it's a matter of specifying the correct grade of steel for the job.
Don't know whether to go with a simple EN8 and do a couple of layers or something more specific like EN32, does anyone a have a recommendation on tempering colour?, right now I'm thinking straw?

[fatwelshboy]

Sealmasters in Cardiff will make custom seals, give them a drawing and specify the material and they'll make them. I posted about them a while ago but never took it any further. I also asked a top tuner about making rods and he said he uses silver tool steel, hardened so a files skates off it and then tempered to blue, he's made loads over the years with zero failures. Before I bought my lathe I showed a TX rod to a machinist to have some made and he said he'd use EN24t. I think he said to have them nitrided but I'm not 100% sure.

[Artfull-Bodger]

I'm going to start with a low carbon steel case hardened as I like the idea of a malleable core to an item under stress.

But seeing as it's going to be under tension silver steel or a higher grade is an option, I used to use En24t to make anti roll bars for my race cars, the problem with that grade is it comes pre tempered (hence the t) and any hardening process will ruin that and have to be redone so your paying for a process you don't need!

I don't bother with rotating pistons on HW's since I refined the thrust bearing installation so I'm going to make standard HW style rods, just going to have to grind a radius on one of my milling tools to prevent stress raisers in corners.

Interesting to note the Sealmasters as I live 10 miles from Cardiff, worth a chat to see how much some 23mm seals made up to HW spec for instance would cost.

[NickG]

I'm going to start with a low carbon steel case hardened as I like the idea of a malleable core to an item under stress.

But seeing as it's going to be under tension silver steel or a higher grade is an option, I used to use En24t to make anti roll bars for my race cars, the problem with that grade is it comes pre tempered (hence the t) and any hardening process will ruin that and have to be redone so your paying for a process you don't need!

I don't bother with rotating pistons on HW's since I refined the thrust bearing installation so I'm going to make standard HW style rods, just going to have to grind a radius on one of my milling tools to prevent stress raisers in corners.

Interesting to note the Sealmasters as I live 10 miles from Cardiff, worth a chat to see how much some 23mm seals made up to HW spec for instance would cost.

I have used silver steel and case hardened mild steel for rods , peace of mind with the case hardening, as hardening the silver steel can be tricky in the garage .

[Artfull-Bodger]

I have used silver steel and case hardened mild steel for rods , peace of mind with the case hardening, as hardening the silver steel can be tricky in the garage .

That's what's putting me off the high carbon steels, it's too easy to end up with a brittle material if you don't get it spot on!

What grade mild did you use?, I'm thinking En8 as it's good in tensile?

[NickG]

That's what's putting me off the high carbon steels, it's too easy to end up with a brittle material if you don't get it spot on!

What grade mild did you use?, I'm thinking En8 as it's good in tensile?

I use en3 as its easily available and dead easy to machine .