How To: Block Off Large Bore Pipe

[MrCrowley]

Well in this how-to, i'll show you my way of sealing off large bore pipe for a stock or something similar.

I'll be using a 2" tee as the fitting I want to seal off, it should work with any fitting.

What you need:

Sheet PVC
Fitting (that you want to seal off)
Pipe (the same diameter as the fitting)
PVC primer and glue
Hole saw
Bolt

Step 1: Making sheet PVC

1. Cut a piece of PVC pipe lengthways
2. Heat the PVC with a heat gun (or other method) until soft.
3. Lay flat and put something flat and heavy on top until cooled down.

You now have sheet PVC.

Step 2: Cutting the PVC

Grab a holesaw that is similar size to the I.D of the fitting you want to block off.

If you don't have one that is close enough, just go a bit bigger, it's easy to sand down sheet pvc.

If your holesaw has a drill bit in the middle, don't worry we can close the hole in the PVC up later.

Once your PVC disk is cut, cut another one that is similar in size to the I.D of the piece of pipe that fits into the fitting.

This piece of pipe is going to be used to join another fitting on, say if you wanted a stock on your gun etc. In my case it's a barrel support.

Step 3: Covering hole in disk made by holesaw

Well if your holesaw is like mine and drills a hole in everything it cuts, you'll need to cover the hole up.

I did this with a simple nut and bolt. Just adjust the hole in the disks to a size that fits a bolt nicely.

Step 4: Joining the disks

Thread the bolt through both disks, and apply PVC glue and primer between the two disks and hold together for 30seconds.

Tighten the bolt up and apply some silicon sealant or other sealant or epoxy around the bolt to make sure a good seal.

Step 5: Finishing

Check the disks fit in the fitting all the way down to the lip, and then apply glue and primer to the inside of the pipe (not the fitting) and the smaller disk on the larger disk should fit inside this pipe.

Once that's glued, apply glue and primer to the inside of the fitting and the outside of the pipe and on the face of larger disk that is going to seal against the lip in the fitting.

Now just push the pipe into the fitting and hold for 30seconds.

And that's that, now you just need to glue on your stock or other fitting onto the other end of the pipe.

Here are some pics...

Oh yeah i know the fittings are dirty and look like sh|t, I just threw this together for show

If you're confused, feel free to ask questions but it's pretty straight forward.

[jackssmirkingrevenge]

I would have gone for a foam or cardboard disk and epoxy poured over it but this looks like it would work pretty well for those with a PVC fetish, neat

[c19o]

Very nice How-to, would a hairdryer work to make the sheet pvc?

[MrCrowley]

Yeah I don't see why not, just don't burn it. PVC fumes are dangerous.

[jimmy101]

Nice write-up MrC.

Another easy way to flatten the PVC is to just boil it in water then press it with something flat and heavy until it cools. It might take more than one heat/cool cycle to get it flat. The advantage of boiling water is that you don't have to worry about burning the pvc.

The heat capacity of PVC is so low that you can handle it with bare hands even when it is ~212F as long as you are quick.

I wonder if there is a way to make the plug without the central hole caused by the holesaw?

If you glued an oversized piece of sheet PVC on the end of the pipe you could use a flush trimming router bit to cut the flat sheet to the exact OD of the piece of pipe.

A single piece of PVC but-glued onto the end of the pipe probably wouldn't be strong enough. MrC's design is nice in that it includes one (or more) inner pieces that significantly strenthen both the flat end cap and the glue joint between the end cap and the pipe.

Could the inner pieces be cut with a router as well?

If you took a peice of flat pvc, placed it on the end of the pipe and did a plunge cut into the center with the flush trimming bit you could cut a hole in the flat piece with the exact diameter as the ID of the pipe. From there I can't figure out how to cut a disk of PVC with the same OD as the holes ID.

[elitesniper]

hey thats really cool , also looks like it would make a mean piston

[MrCrowley]

Nice write-up MrC.

Another easy way to flatten the PVC is to just boil it in water then press it with something flat and heavy until it cools. It might take more than one heat/cool cycle to get it flat. The advantage of boiling water is that you don't have to worry about burning the pvc.

Thanks, yeah i've heard about that. With my heatgun it honestly takes about 5seconds so i've never bothered trying it out but it probably is a safer option.

I wonder if there is a way to make the plug without the central hole caused by the holesaw?

I think there is, thing is my holesaws are about 20years old, the new ones I see these days don't have the same locking in system for the drill so they may not require the drill bit.

If you glued an oversized piece of sheet PVC on the end of the pipe you could use a flush trimming router bit to cut the flat sheet to the exact OD of the piece of pipe.

Yes you could, one of the reasons for having the smaller disk is that sheet PVC is quite thin when homemade, about 3mm if that.
The smaller disk inside the pipe is glued in place, so it stops the bigger disk under pressure from flexing inwards.

A single piece of PVC but-glued onto the end of the pipe probably wouldn't be strong enough. MrC's design is nice in that it includes one (or more) inner pieces that significantly strenthen both the flat end cap and the glue joint between the end cap and the pipe.

You pretty much said what I just explained above

This design has a 3 way seal system, first the larger disk makes the important seal against the fitting's lip, if this leaks the pipe glued in the fitting should stop the leak from going anywhere, and if it decides to leak through the smaller disk, well that's glued too and has PVC cement applied on the inside edges to make sure.

Could the inner pieces be cut with a router as well?

Don't see why not, it's really trial and error. I spent half the day coming up with this and was not really happy when the day ended seeing that's all I had done, but it was worth it I guess.

If you took a peice of flat pvc, placed it on the end of the pipe and did a plunge cut into the center with the flush trimming bit you could cut a hole in the flat piece with the exact diameter as the ID of the pipe. From there I can't figure out how to cut a disk of PVC with the same OD as the holes ID.

As long as you cut a disk bigger then you need, it will only take like 5 minutes of sanding and checking to get it to fit. This stuff sands down incredibly fast from friction alone.

I was all out of sandpaper and found some old used stuff, the friction from that seemed to sand it down nice and smooth pretty quick.



I need to bore out the lip from another 2" tee I have but I can't with my holesaw because it's one like this:


So the thing holding the saw in place doesn't allow me to fit the whole thing down the tee as it's so big.

Might have to buy some new ones, which are bloody expensive.

[grumpy]

@ MrCrowley, so you are going to build the launcher from the video, can't wait to see your version of it , should be pretty nice.

[MrCrowley]

Yeah may take some time, I need to locate about 4' of 2" pipe for pretty cheap.

Also nerfs are hard to locate, I may have to resort to going into a toy store

I'm also considering CO2, I found <A HREF="http://www.trademe.co.nz/Browse/Listing ... =134236753"> This</a> for $45NZD, about $35USD and it comes with a reg.

If I had similar specs as that other gun, how many shots do you think i'd get out of one of those CO2 bottles if I charged the gun to 100psi?

Edit: CO2 tank is 390gm, about 14oz

[bigbob12345]

This is a very good idea but you could just go get a 2in plug instead.
But still this is a very good how to and a clever idea. Would be useful to people that dont have acsess to 2in plugs.

[jrrdw]

Nice thinking MrCrowley, a shouldered stop/plug. Even if you could get the drill bits out of your hole saws, it hell to get the saw started without the center. I've tryed it a bunch of times, it can be done but it's tough no matter what your cutting. I didn't know PVC became flexable so easy, nice!

[grumpy]

@ MrCrowley, you might get 20 or so shots out of that tank, it is realy hard to say, a soda stream tank would be better as it can be refilled. why not just use air?

[MrCrowley]

@Bigbob

Yeah I can't seem to find plugs in NZ for some reason


@grumpy

Because i'm limited to 115psi by my compressor and thought I may as well have a some-what portable cannon. If it's going to be too much of a hassle I may not bother, I can always add it on later.

@jrrdw

Yeah I know what you mean, it's like trying to use a holesaw to make a hole bigger, but since the drill has nothing to grip it's pretty darn hard.