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.
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.
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 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.
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.
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.
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.
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.
For those who is not acquainted with such a useful thing like a mercury
electro contact thermometer , I showed its
You can read it if you have time. Otherwise it can become a rarity like
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.
I`d like to add something – about tank`s inner parts.
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.