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How to make a leather piston seal

3 days ago

Created a post 42 points @brudgers

How to make a leather piston seal

@_Microft 2 days

Replying to @brudgers 🎙

I bet I can use that to fix the seal in a bicycle pump that I cannot get a replacement seal for. Thanks for sharing!

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@iseanstevens 2 days

Replying to @brudgers 🎙

This is a great knowlecule.

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@doodlebugging 2 days

Replying to @brudgers 🎙

Thanks for this article. It reminded me of the times I fixed my old air rifle as a kid by doing nearly exactly what he described.

My kid method was to use the original seal as a pattern (Mom did a lot of sewing so I totally understood how to fit things and allow for seams, etc). I would use a leather hole punch to punch the hole for the screw and just re-use the screw. Then with a pattern made, I'd oil the seal with neetsfoot oil, sno-seal, or whatever I had handy for softening the leather. You could also just use water but it will dry out eventually. If that's what you got today, that's what you use. It just meant that I would have to disassemble the thing again to wet the seal.

Once the seal is wet and screwed to the plunger you just shove it into the chamber and reassemble things. It doesn't take long.

Leather punches can be purchased for a few dollars from Tandy Leather. There are many styles to choose from. The multi-punch wheel style is super useful around the house for punching holes in just about anything. For many of you, the time you spend sitting while you work will eventually cause you to need an extra hole in your belt. Be prepared! You'll eventually need a new belt though so here is a link to Tandy.

[Tandy Leather Hole Punches](https://tandyleather.com/collections/tools/punches-&-setters)

Another thing I discovered over the years is that leather seals were also common on hydraulics. I had an old Farmall Cub tractor with a hydraulic pump that began to leak furiously. After I tore it down I found a worn leather seal and a couple of rubber washers that were bad. I just made a new seal and a set of washers from old leather that I had bought 30 years before to do saddle and tack repair back when I had a horse. It all worked great with no leaks when I reassembled the pump and mounted it back on the tractor.

The important thing is to match the thickness and shape of the original seal as closely as possible. Then lube the seal so it forms an air or fluid tight seal and you're good to go.

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@sivex 2 days

Replying to @brudgers 🎙

Just wonderful, would never have thought to do this

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@canadian_tired 2 days

Replying to @brudgers 🎙

Sometimes old tech is best tech! Thanks for this. Although, my experience suggests that using a drill bit to put holes in leather is not the way. What you want to do is punch the holes. Easy to do...find a short length of steel tube of the right diameter and grind a sharp edge on the circumference. Or, you can buy any number of punches cheap.

Most casual, but certainly all hard-core cyclists will know the legend of the Silca frame pumps. Silca has been using leather washers forever. Read more (why leather works and why o-rings don't) here: https://blog.silca.cc/uniquely-silca-the-leather-washer

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