Smoke generators.

Today I would like to share my experiences regarding the smoke generator machines. Here I will write all my experiments, what I discovered myself, what I researched on internet and the issues I found in the path.

Like most of us, I started with the stock Heng Long generator that came with my Panzer III. That was one of the features I liked the most in the model. I was greatly surprised and I absolutely loved it, but I am afraid that happiness did not last long. After a short while the smoke generator stopped producing smoke.

The stock Heng Long smoke generator.

I started scratching my head. I thought I just ran out of smoke oil so I put some more in the machine with no results. The pump was working but still no smoke coming out from the exhausts… I kept adding oil until I flooded it, still with the same results, so then I noticed it was time to open the tank and to try to see if I could find what was going wrong.

I took the machine apart, and from outside, the machine looked good, so I had to open the chamber’s lid to see how it looked inside, and then is when I saw it: The heating element was broken. That heating element was a very thin Nichrome wire, that after less than the expected use, failed. So then I started asking to my old friend Mr. Google what to do, and I found there were several ways.

The first and logical path was to buy a replacement machine… but that was not going to be a cost effective solution and I discarded it. I want something that lasts long.

The second path I found was to use some elements from electronic cigarettes… It looked quite complicated and I put that option in stand by.

The third one was to buy a smoke machine from the world of RC 1:10 scale cars and crawlers. But those machines were bulky and over expensive, so I discarded that path immediately.

Then I saw some people were buying diverse versions of the TARR Smoke generators. I found mixed reviews of that stuff, but most of the people said those machines produce way less than expected smoke (or none at all!), and also were a bit pricey, but I noticed those machines worked with a fan instead of a pump! I thought it was very interesting and I took good note of it.

TARR smoke generator.

Some other people were using Nichrome wire from their wives Hairdryers (Dear wife, I promise I did not strip your Hairdryer!, when I opened it, it was already broken!, you were going to throw in the bin anyway!) Pfew! So, yes, I experimented with the hairdryer nichrome wire. I tried quite a lot of different sizes, from the thicker wires to the thinner ones with diverse results. Also I experimented with different lengths… It was quite complicated, too much length and it wont be hot enough for burning the oil. Too short length and the machine will burn. And as you can imagine, it is quite complicated to find out if the smoke machine is working or if it is burning itself. Also you have the high risk of shorting your Li-Po battery, opening the gates of doom and mayhem! So when experimenting, take the battery and electronics away from the model. Yes, been there, done that. Always learning the hard way. Sigh…

I kept investigating and I saw some people were using ceramic resistors as heating elements with good results. I tried it with fairly decent results. Resistors seemed to work long enough, but after a while (long while) I ended burning them too, so that brought me back to the starting point. After some more hours of researching I found some other guys were using wirewound resistors. Those resistors are real old technology. The very few  you can find on evilbay look like they come from old soviet cold war military equipment surpluses. As you can imagine those resistors are not easy to find, but a friend of mine, Gary, found a great source of themm here. The recommended specsare 10 Ohm 1 Watt. Thanks Gary, for the specs and the source provided.

So definitely those resistors seem to be the way to go. Great, we have half of the path walked. Now I wanted to get rid of that annoying pumping noise. That noise was produced by the pump that puffs the smoke away from the box. Do you remember those TARR smokers? Well, so did I. I bought some 25mm fans from diverse china websites. I noted there were two kinds of fans, those who run with 5v and those who run with 12v. When using 2S Li-Po batteries, you are running 8,4 volts. So if you are using the 5V fan you have to fit a resistor or the fan will run too fast and it will end burning itself. When using a 12V fan you might lack a bit of blow, but I tested it and it works quite well. The only drawback when using a fan is the loss of the nice pulse effect, but it seems you cannot have everything. That’s life I guess…

As a wick, if it is still OK, you can use the stock Heng Long rope. If it is burnt, or if you are scratchbuilding your own unit, I suggest you to use some kevlar wire. It sucks the oil and it won’t burn easily.

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Burning element.

Now, there is only one thing left: What to use as burning element? As I have seen and experimented myself, you have several options.

-Original Heng Long oil. Which is expensive, the bottles are small and you have to add super expensive shipping charges on top.
-“Super smoke” scents. Which are also pricey and shipping to Europe kills the deal. Anyway, I have not tested them, but you have scents of almost everything you can dream of. From charcoal to diesel, going through bacon, hot chocolate and more. Sounds promishing! I confess I’d like to try one, but the damn shipping is too much.
-Mixture of glycerine with water. I tried it, and I noted the water evaporates rather quickly, so it is quite complicated to have the perfect mix inside your smoke generator. I had the best results with something near of 60% glycerine, 40% water, but as mentioned, it is very hard to keep that balance because the water evaporates itself and the glycerine remails forever. Also, when working, this mixture clogs the exhaust pipes. There is too much vapour and condensation.
-Used motor oil. I have seen some dumb guys doing it. Please, don’t do it! It is very toxic, and cancer is always round the corner! I have read more crazy experiments including paints, brake fluid, aircraft fluids and stupid things like that. Not sure if they were trolling, but better to stay away from that toxic stuff.
-Baby oil. Yes, no kidding, straight from the bottle. I got loads of smoke with just plain baby oil, but be sure of using baby oils made of Paraffin. My lovely wife bought one bottle with lavender scent for me. It was cool at the beginning but that lavender smell ended annoying me to hell, so next bottle was plain odorless baby oil. Half a litter will cost you a couple of Euros, and it will last for you and all of your colleagues life, and you will have plenty spare for the following generations. It is a win-win situation. Anyway, and just in case, I recommend you to use your smoke machine in open air. Or at least open the windows. The fumes are rather thick and I guess it wont be too healthy to keep smelling it.

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As a last tip, some people put some oil in their brand new tanks, and then notice that the machine is not puffing any smoke. People tend to add more, and same or worse results. Then some more and still nothing… In most of those cases the smoke generator is not working because the oil chamber has been flooded. Only a couple or three drops of oil are needed, if you put too much, it just wont work. If you already flooded the chamber, try to remove all the oil from it.

Here are some examples of my early smoke machines. I’m using cheap electronics in those videos, I did not want to risk the expensive stuff. Glad I did it, because I had some very big problems at the beginning.