haenel xxxxx piston seal

[ambrose]

evening,this is my first ever post so hello to everyone.
im trying to get my neices haenel xxxx back in working order but cant for the life of me find a new leather piston seal to replace the one that fell to peices.any help would be most welcome.
thanks in advance.lee

[Phil Russell]

Hi Lee
Leather seals are not too difficult to make ... I found the most difficult part was getting the leather. I now use bits from belts and my wife's (old) handbags.
There is a thread on here that gives instructions. Here is a version:
Adapted from an article that appears on the Airgun BBS by Rob M

Material: off-cuts of sole leather from a cobbler's shop or hide from a bag maker, leather cycle saddles, leather belts, handbags. Car boot sales are good sources.


The ways that leather washers are affixed to the piston vary from manufacturer to manufacturer. Some are held on by bolts, hex bolts or machine screws, others are riveted on.

To make the washer, measure the diameter of the old washer (or the piston) then add twice the height of the washer to the diameter. Cut out a disc this size (approximately) from your leather This can be done by:
1. Use a holesaw designed to cut holes in wood. Clamp the leather between two sheets of ply or hardboard and cut the disc. This is easy to do and gives you a centre hole from the start.
2. Cut the disc out with a sharp knife or fretsaw or similar. Find the centre of the leather disc, and drill a small hole there.

To size the disc, with a nut and washers, fasten the leather disc to a bolt that you can hold in the chuck of an electric drill. Now you can use the drill as a lathe, and use some clean files and wet and dry abrasive paper to round the disc off perfectly and also make the leather thinner if necessary. It has to be "Wet and Dry" type abrasive, as sandpaper or glasspaper will shed bits of abrasive that might end up embedded in the leather, this doesn't happen with "wet and dry". If using a drill or lathe wear eye protection. Depending on how much reshaping you need to do, a dust mask might also be necessary. You can shape leather like this easily by hand if you don't have power tools, but it will take a little longer.

If the leather has a shiny side, remove the shine with Wet and Dry, as it is sometimes a paint-like finish applied to the leather and could have adverse effects on the efficiency of the finished washer. Some say that the shiny side should go on the outside of the washer where it contacts the cylinder wall, but washers made of raw unshiny leather soon develop a shine after a few dozen shots anyway.

Most leather washers are actually a pair of washers; a large rear washer that is formed into a cup shape, then a smaller front washer that fits inside the cup to minimise lost volume, so you will probably end up making two discs, one smaller than the other. Sometimes the ‘inner washer’ is a countersunk steel or brass one.

Fit the washer(s) to the piston, then fasten a jubilee clip loosely around the washer to shape it into the necessary 'cup' shape. I spray the washer liberally with a little aerosol of stuff I got from a cobbler's shop called 'Leather Stretcher', which actually just softens leather enabling it to be formed into shape more easily. Tighten the clip gradually over a period of a few hours to get the correct shape. It's worth taking your time. This stuff really helps, and makes the job much, much easier. Tighten up the jubilee clip until the washer fits easily into the cylinder. Spray it, retighten the jubilee clip until you are happy with the fit and shape, then leave it to dry and set overnight or for a day or two if you can. If necessary, any bits of leather that you feel need removing can be carefully trimmed off now with a sharp knife.

Don't worry if, at the moment, it does not look anything like the old washer: The last step in the procedure will shape it precisely to fit the piston and the cylinder. At this point, the washer might appear much thicker than the original, and have a large gap between the back of the washer and the piston, especially around the outside, but don't worry. The important thing now is that the piston can be refitted into the cylinder without the leather washer getting damaged on threads, cocking slots, etc.

Before refitting it, let some "Bisley Gun Lubricant", or "SM50" soak into it for a few hours, or overnight, this is a silicone oil that will not cause the leather to disintegrate over time, plus it contains molybdenum which will lubricate the leather in use. Let the Bisley Gun Lubricant soak well in, but before refitting it, you might need to dab it with a clean cloth or tissue if there is much silicone lube on the outside of the leather. Silicone lube is good for the leather, but no good where metals will be in contact with each other, so you don't want it dripping off the washer into the cylinder or smearing the cylinder wall, for instance.

Obviously, if you are going to put GN paste or moly grease on the piston, do that now. When you have finished reassembling the gun, let the gun stand for a few days with the piston at the end of the cylinder under spring pressure (as if it has been fired), so that the spring pressure can slowly form the washer to fit the cylinder perfectly. Avoid the temptation to fire it straight away! This last step shouldn't be rushed, as allowing the leather to gradually conform exactly to the shape of the cylinder, rather than slamming it suddenly into shape by firing the gun straight away, will increase its life and help to stop it disintegrating when it gets old.

If you do all this, and haven't made the washer too big or too small, you should have an efficient and long-lasting piston head washer... It may take a short while to bed in, but it shouldn't require any more lubricant for thousands of shots now. If you should ever want to relube it I recommend taking it out of the gun to do it, rather than putting silicone oil down the transfer port which could end up damaging the piston and the cylinder.

Cheers, Phil

[john de Beck]

well done! some products mentione are not in USA, but process is clear! thanks