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Homemade small wax injector
(acc.to many asks of customers)

Kudelya workshop

Small wax injector assembly

Regarding to description of wax injector shown below I receive some reclamations. The customers complain that it is difficult to build and the temperature control processor is too expensive.
 So if you really want – I have it.
 Having met all the expectations of you, my dear customers, please find the economic wax injector with the easiest control system of temperature. Easiest doesn`t mean worst. As for precision of measurements and keeping the temperature – it is not worser than positional controller OVEN described before. This wax injector is worser than described before, but in one option only – regarding to temperature curve during initial warming.
 Certainly, volume of tank is not large – it is 430cm3, but it has its advantages. Using this device you can quickly heat wax and put wax on some parts, e.g. on small jewelry items.

Let`s start with tank.
First of all I would like to show you the detailed drawings of tank. I did not kept the assembly drawing, but I in any case you will not need it.

Drawing detailing 1           Drawing detailing 2

The core part of device is heat wax tank itself (part #6). It is rather difficult to make it from cooper (which would be an ideal case) because it is hardly to turn it due to its high viscosity. That`s why I used bronze.
Wax tank with cover, assembled. Places for soldering are shown with arrows. In first you put the core bar in appropriate holes in order to keep its coaxiality. It can be just any wooden bar. Then you should clamp everything and make soldering. It is better to use silver solder. Pure silver is an ideal variant, but you can use silver-based solders. It is most preferable due to its better heat conductivity.
 Please keep attention on two ring grooves above throat aimed for better sealing In part 4 (square-shaped heat-conducter) you will make a pit, with dimensions acc.to part 9 (injector`s housing). Please don`t forget about thread in heat conductor on the side of tank. You should not put a solder on it. This thread is useful for further turning on the cooper pipe.

Capacity for wax from the bottom             Capacity for wax top

The attentive reader of this work certainly will get sight of the fact that after soldering the tank with its cover became not able to be dismantled. It is correct, but I don`t plan to dismantle it. Than you make the removable heater. It is to make on cooper foil which you should wind up around of wax tank.
Heater with wax tank, assembled. Cooper foil has to be fixed on the edges by two windings of thick cooper wire, soldered on its whole longitude to foil by common solder. This wire has two functions: It fixes both the foil and nichrome

Heater with wax tank 1           Heater with wax tank 2

Heater with wax tank in injector`s housing, assembled After fixing the cover to housing, you can start to assembly the injector and put a heater. After mounting of heater, please put ceramics on ends of nichrome and throw it outside through holes on housing. Than you should fix the cooper pipe to tank
Heater with wax tank and nichrome-fixing coating You can make coating acc.to above mentioned approach I used for injector, but usage of liquid glass is also possible. On the picture you can see how to fix the end of winded nichrome.
Please notice that assembled heater should free slide in tank but without any large gap.
 You put special insulating tape with mica added on foil, in order to insulate the foil. Than you evenly wind up the measured and prepared piece of nichrome. Ends of winded nichrome are to be fixed by screws M3 which are fixed on the rings of the above mentioned cooper wire. Please insulate nichrome from screws by using the mentioned special tape, or: any ceramics.
 About nichrome. Surely, now when Internet sources are available everywhere it became easy to calculate the characteristics of nichrome. You can use the link: http://www.metotech.ru/art_nagrev_1.htm
In the past, calculations were determined by available materials only, not by real necessity.
For example, I had nichrome 0,23mm. Having capacity of 140 Wt and diameter of 0,23mm, I calculated:
- Resistance 356 Ohm;
- Current 0,62 A;
- Taking resistance of my nichrome 28 Ohm/meter, length of wire would be: 356/28= 12,7 m.
 Than I had to distribute it on heater`s surface. Now I should explain why I use the removable heater. The reason is: it is not possible to put the pipe inside of housing. You should put the tank in housing (without heater) and put pipe in hole. Than you should fix cover to housing.

Wax tank in the housing      Wax tank with a heater in the housing

Injector parts   Tubes for thermometers

It is not mandatory to put rubber sealing ring on injector`s rod. But you have to achieve the sliding position of the rod with injector`s body. Than you need to seal (by using of paste) the cone assembled with housing. Pipe and its parts should be made from cooper with further soldering. You have to fix the pipe to tank by using of screws, coated with silicon organic glue solution (Vixint) , but it is possible to use by silver solder also.
Tank`s cover has ring grooves, corresponding to furrows on tank`s throat. Grooves are filled with silicon sealant.

Mount nichrome                     Tank insulation                             Thermal insulation of the injector

On pict.14 there is cover fixed on the injector, the cover is made of fitting`s housing. The space between cover and housing is filled with the same thermo insulation material, slightly wetted by liquid glass. Please be careful while putting thermo insulation in housing, in order not to destroy the nichrome. Please put an upper cover.
Tank`s cover assembled with manometer (0-2 kg/cm2) and fitting for connection of compressed air. There you can see thermometer, inserted in cooper pipe.

Tank cover                 Cover the tank with pressure gauge and thermometer

Control unit

Certainly, it is not control unit but the enhancer of low-amperage connected to thermometer. But we call it control unit - acc.to our tradition to call such way everything which is more complicated than simple piece of steel.
 General electric scheme. It is production scheme, issued specially for these thermometers. I added here one button for self-check of device. This button is connected to terminals – thermometer`s contacts. It is made – in order to be assured in thermometer`s efficiency without ned to wait until mercury will come to thermometer`s contacts.

Circuitry injector

On front panel there are located: input of 220V, lamps of position switched off (red) and switched on (green); also thermometer`s connection socket and self-checking button of this scheme. Compressed air has impact on surface of melted wax and put it in cooper pipe. Cooper pipe goes from injector to bottom. The pipe is cutted by angle near to the tank`s bottom , in order it is not stopped up by bottom. The pipe will be sectional (connected by silicon pipe section), in order to be able to insert pipe and to cleaning of injector.

Installation of the control unit              The control unit

For those who is not acquainted with such a useful thing like a mercury electro contact thermometer , I showed its manlual. You can read it if you have time. Otherwise it can become a rarity like amplifier lamps.
 But it is available to buy on web sites for laboratory equipment. Hereby some advises from my side: please don`t make waving motions with your arms, don`t sing, don`t dance close to this device. Otherwise it can be easy destroyed. After having such bad experience – I made a special hole for fixing of injector`s bottom by clamp.
 And something more. Please put a little bit glycerol or silicon oil in cooper pipe – for better heat contact. If you don`t have it - talc is also acceptable.
Besides, about air. The device is suitable to work with any compressor with capacity up to 2 kg/cm2, with minimal consumption. You can use the one dismantled from fridge, described here.

Addition 1.
 I`d like to add something – about tank`s inner parts.

Insides wax tank

Device in operation is similar to equipment for production of soda water. Compressed air has impact on surface of melted wax and put it in cooper pipe. Cooper pipe goes from injector to bottom. The pipe is cutted by angle near to the tank`s bottom , in order it is not stopped up by bottom. The pipe will be sectional (connected by silicon pipe section), in order to be able to insert pipe and to cleaning of injector.

Small wax injector, assembled.
 Temperature sensor here is electro-contact thermometer with mercury. This thermometer has to be inserted in cooper pipe which goes along bronze tank with wax. There are connection and heat exchange contact between thermometer and cooper pipe. Level of requested temperature will be installed due to the special switcher, located in upper part of thermometer. After getting the certain temperature, impulse goes to the control box (white box).
 This control box will switch the heating on / off. This device was created recent decades ago. The initial point of design of this wax injector was statement in book (author is Mr.Brepol) that wax should be injected during having certain pressure and temperature. I did not see anything like this at that time, there was no internet, I had to invent it by myself.
 I didn`t came to the idea to use the horizontal injection like it is commonly in all modern devices now. But, due to the fact I used good materials and assembly of high quality, I got the device with very good characteristics.
Pipe for thermometer. Places for soldering are shown with arrows.
Thermo insulation material. Asbestos cord. Please don`t use it. Now we have more safety materials available. I mean Rockwool etc.
The nichrome ends are needed to be put outside by using of ceramics and fixed to the terminals. Terminal box is made of ceramic insert of glow lamp`s cartridge. Than you should put a cover.
Parts of injector. You should align the spring, in order it freely can compress on housing`s hole. Please put a rubber sealing gasket.