safeguard yourselves please follow these instructions carefully. A wax
injector can be dangerous if not constructed and used correctly. These
instructions are given freely and must only be used by those who are competent
to undertake this work in a safe and proper manner. No responsibility
will be accepted by the designer for accidents caused during manufacture
or use of this injector.
You will require a 5 to 6 inch by 3 inch wide brass or copper
tube, silver solder a cover on both ends a thicker one or double up for
the base to retain the heat. Ideally the tube and top plate should be
1/8th inch thick with the base plate being ? inch thick approximately.
Drill a 3/4 inch hole in the top and silver solder a one inch brass internally
threaded connector over the hole and in this connector fit a brass blanking
cap with a rubber seal supplied by a plumbing store. This will serve as
a supply point for the wax pellets and also a place where air pressure
can be applied.
Drill the blanking cap to take a metal tyre valve and fit the valve into
the end cap. DO NOT BE TEMPTED TO PRESSURISE THE VESSEL AT THIS STAGE.
Next drill two holes either side of the central filler cap to take, on
one side, a pressure gauge with its connector and on the other side a
pressure relief valve with its connector. All connector can be obtained
from a plumber's supply or DIY store.
Although I made my own pressure relief valve, I would recommend buying
a professionally one for peace of mind. You will need a valve, which relieves
pressure at 30 psi. Silver solder the pressure gauge connector and the
connector for the relief valve into the top of the tank do not connect
the relief valve or the pressure gauge just yet.
Next, drill a hole in the side of the tank at the front, one inch from
the bottom to take a connector for the injector nozzle. This needs to
be silver soldered in place. If you can purchase a commercially produced
injector valve do so, but if you cannot I have included a sketch of the
type I made for my own injector. A lathe will be required to do this work.
As an update, it was found that an "O" ring works better than
a tap washer to seal the injector delivery valve and by placing the spring
outside, it allows room to fit a metal sealing cone between injector valve
and tank body giving better sealing.
To heat the wax I've used a domestic hotplate with a thermostatic control.
The thermostatic control is important to prevent overheating of the wax.
Placing the injector tank in the centre of the hotplate helps prevent
the wax solidifying in the injector nozzle.
Some way of measuring the wax temperature is required and I chose a digital
clock/thermometer for this purpose. The type I bought had a wire with
a sensor at the end, which allowed for the measurement of outdoor temperatures.
These can be bought from a car accessory shop and I paid five pounds for
mine. The range will need to measure as far as 80 degrees C. To use the
temperature sensor you must first attach it with large nylon cable ties
placed around the injector body so that the sensor is near the nozzle
and in direct contact with the outside surface of the injector tank.
To secure the injector tank during use, I obtained a plumbers flange
which fitted around the tank and then screwed it via a threaded bar securely
to a wall. You will find these are standard plumbers fittings including
the threaded bar. You should now be ready to fit and seal all components
such as end cap with tyre valve, air pressure gauge, relief valve and
To test the tank for leaks I used a tyre foot pump and pumped in air
to a pressure of 5 psi. Then using a soapy water solution, I tested all
joints for leaks and resealed as required using PTFE tape. When satisfied
release the pressure and reapply air pressure to the injector tank taking
it to 30psi (the relief valve setting)
I would recommend taking the tank to a tyre-fitting centre and asking
them to do this for you in their safety cage. Once this has been completed
and you are sure the relief valve has operated correctly you are ready
to melt some wax and use the injector.
Firstly unscrew the end filler cap with tyre valve and fill 3/4 full
with wax beads leave the top off and turn on the hotplate until the wax
starts to melt, which takes around 15 minutes. When fully melted reduce
to about half the temperature just to keep the wax molten. It will be
obvious that by leaving the filler cap off you will be able to see the
point at which the wax has melted. You will need to experiment with these
setting to get the melt and simmer temperature correct. DO NOT OVERHEAT
THE WAX. I have found that simmer temperature was about half the melt
Now you can screw the filler cap on tightly and re-seal. Using the tyre
foot pump inflate the injector tank to about 10 (ten PSI) and maintain
a wax temperature of around 65 degrees C. (sixty five degrees C) at this
point you should be ready for injecting. It may be necessary to vary temperature
and pressure under different conditions and best results will be found
If available a compressor can be used to pressurise the injector but
only when there is a pressure delivery regulator and water trap fitted.
Using a foot pump will produce about three or four waxes before having
to pump again, which is usually about two strokes.
Please follow these instruction carefully THEY ARE
FOR YOUR OWN SAFETY.
|Injector Nozzle Sketch
|Injector Nozzle Dismantled
|Plumbers Connector Used To
Make Injector Valve
|An Alternative External Spring
Arrangement for the Injector Valve