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Article B04

The basic STJ Cylinder- Making your own

An "STJ" refers to a combination-style (penis and balls) pump, made from what is called a "sun tea jar". It's a housewares item, sold at Walmarts, hardware stores and grocery stores all over the country. As glass products go, it's made heavier than most. The jar is used to make iced tea, by filling it with water and tea bags, then letting it sit in the sun for a few hours. It's usually not available in the winter, but found readily in the spring and summer.. iced tea season. Thousands of these jars have been made into inexpensive pump cylinders. Pumptoys gives you two alternatives in making an STJ. One is a "Conversion Kit" that takes all the work out of it, and costs a little more. But this article covers doing it from scratch- so here's how it's done!

Materials list:

Total cost of parts of our STJ- $8.77!  Here's the parts picture:

Parts picture

We need to modify the valve that came with the jar to accept the tubing. This is accomplished by bonding the female connector to the valve outlet. The connector is threaded; the valve outlet is not- but it's a tight fit.

First, you need to remove the valve and inspect the jar carefully- it is glass, and may have flaws.

  1. Remove the valve from the jar by unscrewing the plastic nut inside, then pulling outward.
  2. Remove the rubber gasket from the valve opening by pushing the side of the gasket toward and then through the hole.
  3. Examine the rim of the valve hole and the top rim of the jar. You are looking for small cracks, which might become big ones under pressure.

If any such flaws are found, or if the top rim has sharp edges- replace the jar.

Here's the valve out of the jar body:

Valve removed

Next, we'll modify the valve.

(1) Using sandpaper or an emery board, roughen the exterior surface of the valve on the outlet end.
(2) Mix a small amount of the epoxy stick putty. No more than a small marble in size is needed; mix thoroughly.
(3) Rub a coating firmly around the roughened area of the valve, working it down to a layer about 1/16" thick.
(4) Rub a coating inside the threaded fitting end, filling the threads- but not leaving excess. If you squeeze epoxy into the valve opening, it will interfere with valve function.
(5) Insert the valve into the fitting. Turning will allow the threads to grip the fitting.
(6) Wipe away any excess epoxy around the outside of the fitting.
(7) Set this aside and allow it to harden fully.

Note: There is a curved extension on the valve, a finger grip. In some valves, this grip bevels down the side of the outlet more than others, and may need to be trimmed back by filing in order for the straight connector to fit well.

The assembly should look like this:

Valve & fitting

After the valve assembly epoxy has hardened, we can add the tubing.

(1) Remove the small nut from the fitting, and look for the small compression ring inside.
(2) Push the support insert into the end of the vinyl tube.
(3) Slide the nut over the end of the tubing, starting on the smooth side of the nut.
(4) Slide the compression ring over the tubing until about 1/4" of tube sticks out of the ring.
(5) Insert the tube into the connector fitting. Slide the nut down and tighten, making about one turn with a wrench after it becomes finger tight.

The valve unit will now look like this:

Assembly with tube

Now, we can assemble the STJ.
(1) Install the rubber gasket, by folding it in to start and then pushing into place.
(2) Insert the valve stem through the gasket and tighten the nut on the inside, a good "finger tight" will do.

Here's the valve installed on the jar:

Assembled STJ

The STJ is now ready to pump- almost. If you were to use the jar as it is (and many try) you would find it quite uncomfortable. The rim is made to seal to a lid, and we need to do something that will make it comfortable and help it seal to the body surface. Over the years since this started, STJ pumpers have used a wide variety of materials to make a sealing edge for the jar.

Here are some of the methods I've seen:

NONE of these are very satisfactory- and all of them depend heavily on the hand skills of the person doing the job. The seal is a critical part of pumping, probably the most important. If it leaks, you will become tired of the hassle. If it's uncomfortable, you won't spend much time doing it, and time is what makes it work. As a result of this one issue, the STJ has always been cheap but not very satisfactory.

To solve this problem, PumpToys designed a seal to be produced by an industrial process called injection molding. For the first time, a professional solution was created. We eliminated the seal problems, improved the pump's effectiveness and made the STJ comfortable and enjoyable to use. the copyrighted seal configuration. The only seal method that makes the STJ work well is The PumpToys Precision Seal, now a copyrighted design.

Here's the PumpToys Precision Seal in place on an STJ:

Seal in place

Once you have a seal- the pump is ready to work, and you are set up for a total of under $40, or about 1/3 of what a two-stage cylinder without a seal would cost. Oral vac is all you need to get started. Simply apply suction to the tube while holding the valve in button in, which keeps it open. Release the valve and it seals, holding the vacuum. You are almost ready to go!    JUST ONE MORE IMPORTANT CONSIDERATION!

WHILE WE HAVE NEVER KNOWN OF AN STJ THAT HAS BROKEN IN USE- REMEMBER THAT A THIS IS A GLASS JAR. BREAKAGE CAN OCCUR, AND INJURIES COULD RESULT IF THAT HAPPENS. WE DO NOT RECOMMEND YOU PUMP WITH A GLASS CYLINDER, BECAUSE WE CAN'T TAKE THAT LIABILITY. BUT IF YOU DO, PLEASE- USE THE APPROPRIATE CAUTION.

PumpToys makes a pump of STJ size in acrylics. Take a look at The Acrylic STJ.

FOOTNOTES:
(a) Many types of glue or cement would work to join the fitting to the valve. Just be sure that it will bond to both plastics and metal, and that it's waterproof.
(b) Clear tubing is advisable, so that you can be sure the tube interior is clean. This is especially important if you use oral suction.
(c) Shaving or shortening of the pubic hair is usually required to keep a reliable seal.
(d) Lubricants around the seal area make pumping more comfortable and the seal more reliable. be sure and use a lube that is compatible with your cylinder and seal materials. Lubes that contain petroleum or mineral oils or bases will damage both acrylic products and PumpToys's seal material! Water based lubricants, like KY Jelly, will break down if you are pumping with water in the cylinder. PumpToys recommends Glyde, a lubricant specifically made for pumping that is excellent for this purpose; it will not hurt cylinders or seals and will not break down when wet.

Got a question we didn't answer? Check the library for more assistance, or- ask The Bagman!

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