Sealing a hop-up

[Stealthbomber]

I keep reading about people using plumbers tape to "seal" thier hop-up to the barrel of a gun and it's gotten to the point where I have to say something about it or I'm going to end up putting my foot through my monitor.

 

Right, before we go any further, here's the real scoop:- PLUMBERS TAPE IS NOT A SEALANT.

It's proper name is PTFE tape. That's PolyTetraFlouroEthylene tape, to you. None of the compounds it's made from are a sealant. In fact, as the smarter members of the class will know, it's a lubricant.

PTFE tape works when you wrap it around a joint that will be compressed, such as in a tapered thread. You wrap it around the fitting and, because it's a lubricant, it allows the thread to be tightened fully. At the same time (and this is the clever bit) the tape can break up and plug any gaps in the joint as the joint is tightened. For such a simple thing, it's pretty smart.

 

It will NOT seal your hop-up though.

 

At best, what it'll do is pack the join between the hop-up sleeve and the barrel and then, when you rebuild the hop-up, it'll cause the hop-up to press on the sleeve and make a better join.

However, there's also a good chance that forcing the hop-up back together will twist the sleeve out of shape so the nozzle won't seal with it any more.

If you do it right then you'll get an improved seal. If you get it wrong you'll be wasting your time or, worse, you'll break the hop-up or damage the sleeve.

 

So, here's the smart way to seal your hop-up, if you must. I should say, at this point, that unless your hop-up sleeve is really loose on the barrel then this probably isn't worth doing but god kills a kitten every time somebody wraps PTFE tape around an airsoft gun barrel so I am doing this to save the kittens.

 

You need a tube of silicon tile sealer from a DIY store. A tube costs about £5 and will contain enough silicon to seal a squillion hop-ups.

You need a fibre-tipped pen to mark where the hop-up sleeve ends on the barrel.

You need a couple of sheets of kitchen roll to wipe your fingers on. Really, the silicon stuff gets everywhere. Wipe your fingers. A lot.

 

 

Remove the barrel and sleeve from the hop-up and draw around the end of the sleeve so you can see where to apply the silicon.

 

 

Apply a small blob of silicon a couple of mm behind the line you drew.

 

 

Smear it neatly right around the barrel. Wipe your fingers afterwards or you'll end up with dabs of silicon everywhere.

 

Obviously, the trick here is to create a seal forward of the area where the bucking presses down on the sleeve. Make sure none of the silicone gets near the back end of the barrel. Keep it in a nice neat area just rearward of the line you marked on the barrel.

 

 

Slide the sleeve back onto the barrel.

 

 

Run your finger carefully around the edge of the sleeve to remove any surplus silicon. Wipe your fingers afterwards or you'll end up with dabs of silicon everywhere.

 

WAIT FOR THE SILICON TO CURE

It's normally pretty quick. It'll take something like half an hour to cure. During this time I'd suggest you leave the barrel hanging over the edge of a desk or something so the sleeve isn't leaning on anything and possibly causing a flat spot.

 

 

Once the silicon is dry, bung it all back together and enjoy that warm fuzzy feeling you can only get from knowing you're doing things better than everybody else. Unless they're also doing it the same way, of course.

 

Silicon makes an incredibly good seal. I've seen 12" valves, weighing hundreds of kgs, remain stuck in place after all the bolts were removed cos they'd been installed with silicon on the gaskets!

However, once the seal begins to break it peels away pretty easily.

If you dismantle your gun for maintenance the sleeve should stay stuck to the barrel.

When you need to replace the sleeve a few seconds scraping at the edge of the sleeve with a fingernail should see it come loose and then the silicon will peel off like a big booger.

 

Crucially, of course, if people stop mis-using PTFE tape to seal hop-ups then no more kittens need die.

 

 

THINK OF THE KITTENS!

[DarkLite]

This is a good point though.

[Tom Andrews]

Na.......I still prefer killing kittens...........

[morcant]

I also thought this, as when I wrapped PTFE tape around my G-spec barrel the hop was always a bit tight to put back together.

 

A few weeks back I bought a tube of silicone gasket (Dow cornings) to try the same.

 

Just been to lazy to do it yet!

 

[bjorn]

Basically you can still use the PTFE tape cause it does not smell that bad and it still works - if you do it properly. Still,if you want the BEST out of your gun, then yes, you pretty much have to silicon gasket it.

 

 

Thanks a lot for the pics , specially the kitty.

 

 

Cheers,

 

Bjorn

[The Captain]

Thanks for that very detailed guide. I'll favourite this thread for when my hop up fails me (which, realistically is all too likely to happen).

[ruzzz]

I agree silicone sealant is better , but make sure it IS silicone....you can get all sorts of acrylic sealants which arnt as good.

 

I was told it is used on high performace engines rather than gaskets beacause of its properties and heat resistance.

 

BUT PTFE tape is a seal for threads

 

http://en.wikipedia.org/wiki/Thread_seal_tape

 

[Stealthbomber]

BUT PTFE tape is a seal for threads

 

http://en.wikipedia.org/wiki/Thread_seal_tape

Erm, yes.

 

Read the description in the link you posted.

It works by squashing into gaps as the fitting is tightened.

You can also get stuff called Self-Amalgamating tape, usually used for sealing electrical cables. SA Tape IS a proper sealant. You wrap it around a cable and it melts and bonds into a sticky blob.

PTFE tape just doesn't do anything after you wrap it around a pipe it just sits there and it'll fall off again if you wave the pipe around. It has no actual sealing properties of its own.

 

That's why trying to use PTFE tape to seal an airsoft gun hop-up is just a bit silly. For all the good it does, you might as well wrap string around the sleeve. It'll work just as well.

[Tom Andrews]

You can also get liquid PTFE which dries in a similar fashion to Locktite.

 

The only very minor problem I can see with using the £5 silicone sealant is the fact that the moment you open the tube, air gets in and the whole tube eventually goes solid.

 

Halfords and car accessory shops sell small tubes for slightly less money - £3.00, but the chances are you wouldn't be able to finish a complete tube anyway.

 

Silicone (RTV) rubber is also useful for potting MOSFET circuits, adding 'shock absorbers' to the inside of butts to support batteries, and for retaining items like flashiders that always work lose even when you locktite the locking screw.

[Stealthbomber]

You can also get liquid PTFE which dries in a similar fashion to Locktite.

Nope.

 

Liquid PTFE works just like PTFE tape. It's got rather large particles in it and they get squashed into gaps as the fitting is tightened.

As a matter of fact, it never dries.

 

The only very minor problem I can see with using the £5 silicone sealant is the fact that the moment you open the tube, air gets in and the whole tube eventually goes solid.

Nope.

 

The sealant in the nozzle hardens and creates a seal to stop air getting into the stuff underneath.

Every time you need to use it you just need to unscrew the nozzle, poke out the plug of dried sealant and off you go again.

 

[Swerve]

What does god do to your hop up if you use PTFE tape on kittens?

 

just covering the angles here

[Stealthbomber]

What does god do to your hop up if you use PTFE tape on kittens?

 

just covering the angles here

That will be the subject of my next experiment.

[MDK_Marshal]

To use a bit of the old 4chon lingo (and risking banzoring... )

 

Epic Thread!

 

Seriously. Good sound advice, and a healthy dollop of humour with a side of sarcasm and wit. Excelent. I propose there is a new rule enforced on arnies that there must be one such topic made a week (if not more regularly), on punishment of... Eh.... I dunno, something bad

 

Also, to cover one more angle; What would happen to my PTFE tape if I used kittens to seal up my hop unit?

 

I don't want it melting or anything... It'd probably leave a stain...

[Stealthbomber]

Also, to cover one more angle; What would happen to my PTFE tape if I used kittens to seal up my hop unit?

Well, the kitten would do just as good a job as the PTFE tape so you'd be fine there.

Then you could sell the thread tape to a plumber.

 

I guess that'd be what you call a win-win situation.

[MDK_Marshal]

sweeeeeet...

 

*finds some kittens*

[transist]

What if I used my hop-up to seal my PTFE tape's kitten?

[gunfighters]

lol.

**prepares to kill a kitten**

"For all the good it does, you might as well wrap string around the sleeve. It'll work just as well."

very true!!!! it creates a "better" seal by compression, however the tape is thin enuf that you can but it back in the hop unit, witch is why is came in to use by people trying to do something quick and easy on a crappy gun

 

Nice tip stealth

[DarkLite]

What if I use hop-up kittens to seal my sealant's PTFE tape? Will that increase my FPS?

[transist]

What if I increase my FPS to seal my hop-up's kitten tape?

[wolfstein5]

What if I keep wearing out a joke that was pretty poor to begin with? Will I get banned?

 

Nice job dispelling myths Stealth.

[DarkLite]

Another place that silicone sealant can be used is to seal the cylinder head to the cylinder - just don't get any INSIDE the cylinder.

 

It's also rather good as a space filler to reduce noise.

[bjorn]

Another place that silicone sealant can be used is to seal the cylinder head to the cylinder - just don't get any INSIDE the cylinder.

 

It's also rather good as a space filler to reduce noise.

 

 

I also knew about the cylinder head. Have not tried it myself though. I presume that you have to clean the contact areas out of any oil correct?

 

And after applying the silicon you have to put the cylinder head with the cylinder into the gearbox, otherwise when installing them later on you may risk of separating them?

 

 

Bjorn

[Stealthbomber]

What if I keep wearing out a joke that was pretty poor to begin with? Will I get banned?

No.

 

They never ban you twice.

 

Apparently.

[Tom Andrews]

Nope.

 

Liquid PTFE works just like PTFE tape. It's got rather large particles in it and they get squashed into gaps as the fitting is tightened.

As a matter of fact, it never dries.

 

Actually the PTFE liquid I have, is described as anerobic ie hardens in the lack of air. As I've never needed to undo one the joints yet, it could still be liquid.........

 

Nope.

 

The sealant in the nozzle hardens and creates a seal to stop air getting into the stuff underneath.

Every time you need to use it you just need to unscrew the nozzle, poke out the plug of dried sealant and off you go again.

 

 

From experience of silicone rubbers and sealants going back some 30 years, I can assure you once you have opened that tube it will harden gradually thoughout the tube. Of course if you use the stuff on a regular basis then only the cone in the dispensing end goes hard before you use it. I have a tube on the bench now - black Hammerite gasket silicone seal which I used to seal a windscreen. The entire tube is solid. In fairness its only a 1/20th of the volume of a large tradesman sized silicone sealant from Wickes, but it was a lot cheaper.

[Docv400]

Another place that silicone sealant can be used is to seal the cylinder head to the cylinder...

Not neccessary, that's what the oring's for.

 

AS I understood it, the plumbers tape trick is only any good on guns with a tight fitting hop unit that completely encloses the hop rubber.

The only gun I've used it on is my friends UTG M324 spring sniper.

I chrono'd it before and after and it gained 90fps.

If you pull the plumbers tape tight as you wind it and break it off by stretching it until it breaks it will stay in place pretty well.

Self amalgamating tape is a bit too thick really.

On AEGs I use the silicone sealant method or superglue, just put a drop on the edge of the rubber when it's assembled on the barrel and feed it round the whole circumference with a pin/needle and wipe off any excess with a tissue.

Nail varnish (colour/shade of your choosing) works well also.