Ground Level Fog Effects

Fog machines are cool, but what is even more cool is fog that floats a few inches from the ground and over yard props. This is the second ground effects fog machine I've built, and am sharing what I've learned to do (and what not to do) for the ultimate fog machine ground effects.

Fog is produced by heating an alcohol and water solution and blowing it through a tip, much like a spray gun. As you know warm air generally rises and cold air descends. Because extreme heat is required to create the fog, it mixes with the air and floats around, sometimes rising. What we are going to do is cool the fog before it hits the air so it flows close to the ground.

In this Instructable we are going to explore two designs - one in which the fog blows straight through a tube suspended in ice, and a baffle design that slows the flow of higher powered machines so the ice can cool the fog. Our amazing fog cooler will only require regular ice, not dry ice.

You will need a fog machine, a few items from your local hardware supply store, an old ice cooler, and a few basic tools. Total cost including the fog machine can range from under $80 - $150. They are now selling fog machine coolers alone for $189+.

Time to Complete: You should be able to complete this project in a single day (two if you count shopping time and paint drying time)

Materials ($140, My shopping list, actual Home Depot Prices)

- Fog Machine $69.98 (1000 watt, see Step 2 on choosing your fog machine)

- Fog Machine Fluid $19.98 (Gallon size, can buy quarts)

- Old Ice Chest $6 (Goodwill)

- 2' X 5' galvanized 1/8" mesh screen, AKA "Hardware Cloth" $9.48

- 2' length of 3" black ABS pipe $7.56

- 1 Coflex 90 degree elbow (thin plastic you can mold) $5.96

- 1 3" female to female ABS 90 degree elbow $4.72

- 1 3" female to male ABS elbow $4.78

- 1 3" X 2" ABS reducer $3.70

- Only for 400 or 750 watt fog machines, 1 2" X 1 1/2" ABS flush bushing $1.10

- Handful of 4" zip ties (already had these)

- 2 really long zip ties, or 4 8" zip ties

- Shoe Goo or Amazing Goop

- OPTIONAL 5/16" weather stripping

- Flat black spray paint (I already had some)

- Cardboard box

- Sandpaper is helpful

- When you are done, two or three bags of crushed ice

Tools

- Leather gloves and eye protection (both of these are VERY important)

- Fold up table or other light work surface

- Drill

- 3 1/2" hole saw (you could use a jigsaw here, not recommended)

- wire cutters

- pliers

- Hack Saw

- Heat gun or high temp hair dryer

- Carpentry Square or metal straightedge

- Clamps - Spring clamps large enough to fit the edge of the table. Larger C clamps or wood clamps optional but helpful, I used wood clamps, see step 3

- Pair of cheap heavy duty scissors (do not use your wife's sewing scissors if you hope to see another Halloween)

- Hemostats

- Tape measure

- Box knife

- Small funnel (for filling the fog machine)

- Masking tape and packing tape

- Dremel with a cutoff wheel is a bonus

The first bit of advice: don't buy an expensive fog machine. The way a fog machine works is it has a high temperature coil wrapped around a tube through which it pumps an alcohol and water solution, similar to the solution used in modern vaping fluids. The superheated solution vaporizes at the tip of the tube producing the fog.

This combination of high temperature and fluid flow basically means this device has a limited life span. Fog machines always go eventually. The coils burn out, the pumps fail, the tip will refuse to unclog (see below on how to care for your fog machine,) something in the circuit board goes out, it doesn't matter, they are not designed to last forever.

So don't fret over smart shopping for a fog machine. Just decide which wattage you want and buy the cheapest one.

Important: do not ever, ever touch the area where the fog exits the machine after it has heated up. This is really important. When I say superheated, I mean hot enough to give you third degree burns. This also becomes important when we position the fog machine so it doesn't melt the input vent tube.

Wattage = More Fog + Higher Flow

That's the basics of what you need to know. Off-the-shelf fog machines come in three sizes and wattage: 400 watt, 700/750 watt, and 1000 watt. The higher the wattage, the more fog produced in the few minutes it runs and the harder it blows.

All fog machines run for a minute or two and have to shut off to cool. This doesn't seem to vary with the wattage, and it makes sense: the coil reaches a temperature at which it would start melting wires and starting fires. Internal circuitry detects the overheated condition and it shuts off until it can heat up again.

So which do you buy?

400 watt fog machines: These tend to produce less fog and a slower flow, which is perfect for the "straight-through" cooler design I will show you. The last ones I bought came with wireless remotes but the fog produced by a single machine wasn't sufficient for what we wanted, so we bought two and swapped them out. When one shut off we turned the other one on. They were so cheap it wasn't that big of a deal to have two. You can get a 400 watt machine for $29, $20 on sale. With a wireless remote, when the fog machine shuts off to cool, you have to check it and manually turn it back on again, even though its wireless.

700 watt fog machines: these blow a little more fog and still work well with the "straight-through" design. The ones we've had came with a wired remote (plugs into the fog machine) which was cool in itself. You turn the control on, when the fog machine gets too hot it shuts off. With the remote left in the on position, when the fog machine is ready it just starts up. This allowed us to leave it unmonitored, only having to check the fog fluid every now and then.

Both 400 watt and 700 watt machines usually have the fluid tank inside the machine which means you have to precariously turn the fog machine over to empty the tank. Not that big a deal, but much easier with most 1000 watt machines.

1000 watt fog machines: this year we decided to up our game and go with a 1000 watt, which changed the playing field a little. This thing, even the cheap one ($69.98,) is a beast! it blows a LOT of fog, but it turns out that it blows it too hard - the "straight-through" design doesn't work. It blows through so fast it doesn't have a chance to cool the fog and it floats around as if we didn't have a cooler. If you're down for the challenge, I invite you to take on the "baffle design" which slows down the flow enough to cool the fog and produce the ground effects you see in the introductory video. It really was worth the effort: we now have a slow moving plethora of fog and Halloween this year will be the ultimate creeptasticness. :-D

Most 1000 watt machines also have a tank you can just lift out and clean when you are done. This is a minor point but it makes it much easier to maintain. They probably come in wireless or wired control, the one we got is wired which I prefer anyway for the reasons stated above.

Caring for Your Fog Machine

Generally don't do anything but drain the tank and rinse it out with water when you are done with it. If it is stored for a long time and doesn't appear to be working, or doesn't produce the usual volume of fog, there is a way to clean the machine without taking it apart.

Don't rush out and buy a $14 bottle of fog cleaning solution. Fill the tank with . . . are you ready? . . . vinegar. Let it heat up and run the fog machine until you see a steady flow of air out of the tip, and revel in how much you've made the area stink like a salad.

When you are pretty sure you've cleaned the tip, put enough fog solution in it to produce fog, and run it to verify it's working as expected. If it's still slow, run some vinegar through it again.

Do not ever store the fog machine with vinegar in it. Vinegar is an acid and will eventually corrode the delivery tube. Always finish by running fog fluid through it, rinse and dry the tank, and store it that way.

Do not let the fog machine run dry or run out of fluid during operation. This will very likely damage the fog machine.

Let's get started building.

(For both straight-through and baffle designs)

Generally speaking, the larger the cooler the more the fog will cool, but you will use more ice. A smaller cooler will use less ice, but may not provide enough cooling. This Instructable was created with a 5 gallon Coleman we picked up at Goodwill for $6. Previous ones I've built were 10 gallon, and after completion of this project I am happy with using less ice and the compact size of the smaller cooler. You get to make the call, none of the other materials or tools change.

Locate the center line on the short ends of the cooler. You want the point that is halfway from the sides and halfway top to bottom. Make a mark , this is where you will create the vents in either end of the cooler.

The outside diameter of 3" ABS pipe is 3 1/2". Get out your 3 1/2" hole saw and begin drilling the hole from the outside. When you feel the hole saw punch through the outside layer, stop. You should now have a guide hole on the inside of the cooler from the center drill bit punching through.

Remove the hole saw, then finish cutting the hole from the inside of the cooler. This will avoid a messy and ragged hole.

If you don't have a 3 1/2" hole saw, you could probably get away with drilling smaller holes and cutting out the 3 1/2" hole with a jigsaw, but that will probably be a little more messy. It wont matter, we're going to seal up the opening later.

When finished, slide your 3" ABS pipe through both ends, make sure it goes in but feels pretty snug. We're now ready to fit the vents into both ends.

(For both straight-through and baffle designs)

Now we're going to cut pieces of our 3" ABS pipe to provide openings for input and output.

The output end will require a slightly longer piece on the outside than the input end. The pipe will only have to extend about 1" inside the cooler. Any longer and the baffle design will be harder to fit, and we'll waste some precious direct exposure to the ice.

Measure the thickness of your cooler wall. Then slide the female/female elbow onto one end of the ABS pipe and put a piece of masking tape on it to mark how much of the pipe goes into the elbow. Don't push it on too hard, you want to be able to take it apart in practical use.

Add the distance of the end of the pipe to the tape, the thickness of the cooler wall, and one extra inch. This is how long you will cut the input end of the ABS pipe.

Repeat the process with the soft plastic 90 degree elbow. Note that the output end will have to be a little longer than the input end to fully slide the plastic elbow on.

When done, wrap a piece of masking tape all the way around the pipe where you are going to cut, mark the distance of the cut every inch or so on the tape, and begin cutting the pipe with the hack saw. Rotate the pipe often and make sure you're not going off-track. I found it helpful to use wood clamps to hold the pipe to the table, if you're really cool you will have pipe clamps (right tool for the job and all that.) Otherwise you can just hold the pipe steady and take your time.

When done cutting you should have two pieces as in pic #4. Clean up the cuts with a little sandpaper and slide them into the openings in the cooler and verify they fit: 1" inside and both input and output pipes fit onto what's outside the cooler.

If you mess up, no worries. Cut another piece. You will have plenty of ABS pipe to make lots of mistakes. :-)

If you chose a 400 or 700 watt fog machine, don't glue in either ABS vent until the last part of step 4.

If you chose a 1000 watt fog machine, put a good bead of Amazing Goop or Shoe Goo around the pipe as in pic # 8 and position the ABS pipes in each end of the cooler with 3/4" - 1" on the inside. Once the pipes are in position, put a good bead around the inside and outside as well. You want this to be a solid bond so it doesn't move around on you when you add or remove the outside pipes. Let it set while you work on other parts.

Please note: this is where the "straight through" and "baffle design" steps diverge. If you chose a 400 or 700 watt fog machine, complete this step. If you chose a 1000 watt cooler, refer to this step in step 5, you will need to make shorter pieces of the wire mesh tube.

The concept is to create a wire mesh tube that extends from one ABS pipe to the other. When we fill the cooler with ice it will completely surround the mesh tube and cool the fog as it travels through it.

Before doing anything, put your leather gloves on. The wire mesh is worse than a cat, it will hook you and leave punctures in your hands when you least expect it. Always wear the gloves when handling the wire mesh, and be sure your tetanus shots are current for good measure.

Remove the wire holding the tube of wire mesh closed and wrap the wire mesh around the ABS pipe as a guide to how big your tube will be. Mark the point at which the edge of the wire mesh overlaps by two to three rows. Get out your heavy duty scissors and cut along this row. You can use tin snips or wire cutters here, but the wire mesh is light enough that a cheap pair of scissors will handle it.

Measure the inside dimension of the cooler, then cut off the end of the wire mesh about 1/2" shorter. Make sure you didn't error in measurement and the long side of the finished screen piece fits inside the cooler.

Wrap the cut piece of screen back around the ABS pipe and thread one of your zip ties in near the center of its length. Make sure the mesh lines up square and pull the zip tie tight. The hemostats come in real handy here to thread the zip ties through. Go along the edge every two to three inches and thread the zip ties through, pull them tight, trim off the excess of the zip ties with wire cutters, and slide the ABS pipe out of the wire tube.

Fit the wire tube inside the cooler as shown, if everything lines up, run a thick bead of Amazing Goop or Shoe Goo around one of the ABS pipes 1" from the inside end. You can see in the pic I roughed it up a little with sandpaper to increase the bond, but it's probably not required.

Slide it into position so it protrudes 3/4" - 1" inside the cooler, and make sure it seals all the way around the pipe. You can apply a bead of Amazing Goop around both the inside and outside for an extra sure seal.

It's important to glue this into the cooler well so it doesn't move on you when you attach the input elbows. It also serves to seal the joint it so it doesn't leak water when the ice melts.

From the inside of the cooler, slide one end of the wire tube onto this piece, then from the outside of the cooler, apply the Amazing Goop to the other pipe piece and slide it into the cooler and wire tube. You should now have the completed wire tube installed as in pic #7. Let the glue set and move on to the next step.

It's probably not necessary for the straight-through design but you can optionally use large zip ties around the pipe ends as shown in pic #8. If your zip ties aren't long enough, put two of them together.

Note: This step is only for higher powered 1000 watt fog machines. if you are using a 400 or 700 watt design, you may skip to step 7.

The baffle design consists of a cage with two boxes and four wire mesh tubes at angles connecting the boxes. This forces the air to slow down and wind around in between the ice, giving it a chance to cool. In this step we create the end boxes and vent tubes connecting to the ABS pipe inside the cooler. You will need two of these.

Measure the width of the inside of your cooler. Our goal is to create two square wire boxes 2 inches thick and at least two inches narrower than the width of the box, leaving at least a 1" space on each side of the boxes so the ice can go down the sides of the wire box. In my case that was a box 7" X 7" X 2".

You should be wearing the leather gloves throughout most of this step. I can't stress this enough, working with wire screen is nasty and handling it without gloves will use up all your band-aids.

Skip ahead to pic #3 and look at the overall pattern. Your goal is a single piece of screen with a "flap" that will fold up over one side and down the other, with three flaps to close up the ends. The size will depend on the size of your cooler.

In my case, for a 7" X 7" X 2" box, it was a screen cut to 18" X 11" with 2" X 2" pieces cut out of one end and 2" X 9" pieces cut out of the other. Measure off your pattern and use masking tape to mark where you are going to make the cuts.

Clamp the screen to the table to facilitate cutting. Once cut, roll the screen over the leftover piece of 3" ABS pipe in the opposite direction of how it is curled to flatten it out a little bit. (pic #1) You should only have to roll it a couple times.

Once cut to shape, use the carpenter's square or straightedge clamped to the edge of the table to fold the flaps at 90 degree angles. Start with the short sides, then fold the square side over first, finishing with the last side so you can slide the square out of the last side of the box.

Your box may be out of square at this point, give it a little tweak, bump and push to square it up. Hold it flat against the table as you thread a few zip ties in each side to close up the box and keep it more or less squared up. It doesn't have to be perfect.

At this point it's a pretty good idea to go around all the sides and bend all the wire ends that are sticking out toward the inside of the box so they don't snag someone's hand should they be fiddling around inside the finished cooler, possibly to retrieve something dropped in or get the last piece of ice out after use. It's a tedious task, but you should. You can even fold some of the longer ones around the opposing end wire to help hold the sides together.

You should now have two boxes as in pic #7. Find something to use as spacers in the bottom of the cooler. (pic #8) This is so when you put ice in it, the ice can fill up under the box, exposing the fog to the ice from all sides.

Position the boxes against the ABS pipes inside the cooler and put a piece of tape to mark the top of the vent. Extract the boxes and lay them flat on the table. Using the leftover ABS pipe as a guide, use masking tape to mark the circle you are going to cut in one side of each box (#10.)

Warning: using a Dremel in the next step is recommended ONLY if you are very familiar with how fragile cutoff wheels are, and have eye protection. Cutoff wheels are awesome and save a lot of time, but they shatter very easily. I went through 6 cutoff wheels during this build. If you have any doubts at all, use wire cutters or tin snips, you will not be able to "reach" the cuts with scissors. It will be much slower going but far more safe.

Using the tool of choice, cut around the inside of your tape marks to create a 3 1/2" circle in one side of each box. It doesn't have to be perfect, but take care it isn't too big.

Now return to step 4 in this Instructable to create two short tubes 4" - 5" long for each end of the baffle. Once created, it's a pretty good idea to cut or grind off any wires sticking out of the short wire tubes, it will make handling them much easier. (Pic # 11)

Do not attach the tubes to the boxes yet. Slide the wire tubes onto the ABS pipe inside the cooler, then position the holes in the boxes over the tubes. There should be enough wires sticking out of the screen to get them to stick together loosely. (Pic #12) The goal is to position them where they will fit so you can take the measurements to build the baffle in step 6.

Note: This step is only for higher powered 1000 watt fog machines. if you are using a 400 or 700 watt design, you may skip to step 7.

With the boxes and wire tubes loosely in place inside the cooler, measure the diagonal distance between the boxes as shown in pic #1. The goal is to create four wire tubes that span this distance. We want to create the tubes much longer than we need so we can trim them out later.

Find something cylindrical to use as a "template" to create the tubes. You want something 1 1/2" - 2" in diameter, half the diameter of the ABS pipe. The goal is to slow the high powered fog flow through these tubes. A scrap of PVC pipe or something would be perfect, anything cylindrical of that size. In my case, it was a very tall shot glass (that I've never used, honest. :-) )

Using the same method to create the larger tubes in step 4, cut four pieces of screen and create four tubes (pic #2 and #3.) Lay one of the tubes over the top of the boxes as in pic #4, and place some masking tape over the tube to approximate where we are going to trim the tubes on an angle. When trimming, cut these larger than you need them so we can fine tune the cuts later.

Set the rough cut tubes aside and measure the distance from the outside edges of the box. We are going to create a jig for the boxes and tubes so we can assemble the whole thing and keep it square. A jig in this context is not an Irish folk dance, but a device used to hold pieces in place for assembly. Skip ahead to pic # 6 to see what I mean.

The jig is nothing more than a box made of cardboard the exact width of our boxes and the length of which extends from one wire tube to the other inside the cooler. Using the carpenter square and a box knife, cut the pattern shown in pic #5 and tape it up using packaging tape.

When making the jig, make it shorter than the height of the boxes so you can access the tubes to put the zip ties on, see pic #9.

Slide the two boxes inside each end of the jig with the 3 1/2" holes facing outward. Double check your measurements and make sure the length of the box is just slightly less (1" or so) than the distance between the two wire tubes inside the cooler. You want it slightly less so when we're done it will be easier to mount the entire baffle inside the cooler.

One by one, lay each of the rough-cut tubes diagonally across the boxes in the jig and fine-tune the diagonal cuts as in pic #6. They should fit between the boxes from corner to corner as shown.

Once they are all trimmed to fit, remove the boxes from the jig and turn the boxes with the large 3 1/2" hole facing down. Loosely set the tubes on the boxes as in pic #7. Use masking tape to mark where you are going to cut the holes in each corner. This should produce a roughly 2" X 2 1/2" oval hole in each corner. Frequently check that your angles are correct by setting the tubes on the box as shown in pic #8.

Warning: using a Dremel in this step is recommended ONLY if you are very familiar with how fragile cutoff wheels are, and have eye protection. If you have any doubts at all, use wire cutters or tin snips, you will not be able to "reach" the cuts with scissors. It will be much slower going but far more safe.

With all 8 holes cut in the boxes, slide the wire boxes back inside the jig and position one of the tubes diagonally. You can fiddle with getting it inside the holes but it is not necessary, the goal is to just line up each end of the tube with the respective holes. Fasten it with two zip ties on each end as in pic #9. Once again, the hemostats are extremely helpful here. Remove the assembly from the jig, turn it over, and attach two more zip ties on the underside of the tubes as in pic #10 and trim off the zip ties.

Slide the baffle back into the jig with the assembled tube on the bottom of the box, and repeat the process for the second tube as in pic #11. Rotate the baffle 90 degrees in the jig and repeat the process for the third side, then 180 degrees for the last side as in pic #12. You should now have the completed baffle as in pics #13 and #14.

Now attach the 6" wire tubes to the outside of the boxes with zip ties. You want this joint to be fairly solid, so use as many zip ties as you feel is required.

Note: for the following step you could just "guesstimate" how much of a support you need and put the bottom spacers on before setting the baffle into the cooler.

Set the completed assembly into the cooler by sliding one of the wire tubes onto one of the ABS pipes, then gently "compress" the entire assembly so you have room to slide the other end on. Jiggle it up and down a little, see how it feels, then measure the distance between the bottom of the cooler and the bottoms of the boxes as in pic #16.

Remove the baffle assembly and use some of the scraps left over from the build to create two V-shaped bottom supports. You want to do this so it doesn't get squashed down from pouring ice in the finished assembly. Attach these to the bottom side of each box, pics #17 and #18.

Set the assembly back in the box, slide the wire tubes onto the ABS pipes, and fasten them with large zip ties. If the assembly is too short, you may have to stretch it a bit and hold it in place with a small 1/4" screw and washer as I did.

We're done inside the cooler! Now let's fit the input and output pipe assemblies.

(For both straight-through and baffle designs)

Lay out the ABS elbows as shown in pic #1: the 2" bushing, the 3" x 2" reducer, and the male/female 90 degree elbow. Assemble them as in pic #2, but don't glue anything together, it is not necessary.

Determine if the 2" flush bushing is the correct fit or if you need more reduction. You should be able to slide the hole over the tip of the fog machine nozzle with it not being too large as in pic #3 (although it will never actually touch the head.) For smaller 400 or 700 watt machines, you may need to add the 2" X 1 1/2" bushing. The reason you want to get this as close as possible is so when the fog machine blows into this hole, it doesn't back-flow the fog out of the pipe and waste the effects.

Attach the female/female 90 degree elbow to the vent on the cooler. Set the fog machine on top of the cooler and hold the pipe assembly so the input hole is level with the fog machine nozzle as in pic #5 (you can just slide the pipe onto the nozzle for this part.) Measure the distance between the bottom and top elbows.

As you did in cutting the cooler vents, slide an end into each elbow and mark how much it slides in with masking tape. Add the distance between the pipes and the two inset measurements to determine length of the pipe you will need to create the vertical section.

Cut the pipe to this length, clean up your cuts with a little sandpaper, assemble the pieces as in pic #9, and confirm the input pipe end lines up with the fog machine nozzle as in pic #10.

Note this position carefully: the nozzle is right up next to the input pipe but not touching it, with the center of the fog machine nozzle pointed perfectly into the input hole. This is the position it should be in when operating the fog machine.

If the pipe doesn't align with the nozzle as shown, or at some point the pipes settle and shift out of this position, cut another piece of ABS pipe. If at some point you get a different fog machine with a different height as it sits on top of the cooler, just cut another piece of ABS pipe to align it perfectly. This is also why you don't want to glue any of these pieces together.

(For both straight-through and baffle designs)

There are a few options you can do for the output pipe but for the purpose of this Instructable we are going to modify a 90 degree elbow for direct output as shown in the opening video. I will also show you the solution we are going to use, a long output pipe with a "wye" to split the flow of the fog in two directions.

Option 1: direct down flow pipe: Fit the 90 degree plastic elbow to the leftover scrap of ABS pipe, put on your leather gloves (the plastic will get pretty hot,) and get out the heat gun or high temp hair dryer. Heat up the plastic, being careful not to melt holes in it, and begin shaping it so it's squashed a little bit and pointed outward slightly. If you leave it in the 90 degree shape, it will billow around the cooler, you want to shape it so it blows away from the cooler as it does in the video.

As you heat up the plastic, shape it slowly with the gloves and hold it in position until it cools and stays in that shape. You will also have to heat the inside of the elbow to get it to cooperate. When complete it should be no more than an inch above the bottom of the cooler and pointing slightly away from it.

Option 2: longer pipe output and split pipe design: This describes the actual final output we decided to use, a longer pipe extending from the output vent with a "wye" to split the fog in two directions. This adds a 10' length of Coflex drain pipe and a Coflex Wye to the project, approximately $15.

I was surprised I couldn't find an actual "Y" shaped wye pipe. The only one available is the Y joiner you see in pics # 5 and #6. As you might guess, it is likely to flow more fog out if the straight side than the "Y", which is exactly what happened. Easy fix, as below!

The female end of the pipe only fits loosely on the output vent, so begin with wrapping a bit of the 5/16" weatherstripping around the output vent as in pic # 7. This allows the Coflex to fit snug on the vent (pic #8,) and stops any fog leakage.

You can choose any configuration you want, but I began by cutting a 36" section of the pipe for the output (pic #9) and measured the length of the remainder which I cut in half. The coflex is easily cut with a box knife.

I then assembled the pipes into the wye for a test run. It takes a little wiggling and jiggling, but you can hear when they snap into place. (pic #10.)

I fired up the fog machine through the cooler without ice just to test the output flow (which is why the fog is floating.) As expected, video 1 shows the straight pipe blowing more fog than the side pipe, and additionally we have a little leakage at the wye. We'll fix both of these.

Pics #12 and #13 show the inside of the wye and what I used to fix it. Just like we control the flow of air in the cooler with the baffle design, we are going to restrict the flow of air on the straight side of the pipe.

The top part of a half gallon milk jug was perfect for this. I cut the threads off leaving about a 1-12/" - 2" hole and trimmed off the bottom to about an inch past the "shoulder." Be sure to cut it thin enough to go past the spot where the pipe slides into the output side of the wye.

In pics #14 and #15, you can see I put a bead of Amazing Goop on the inside of the pipe where my constrictor will go and a line of weatherstripping around the pipe ends to stop any leakage. Pic #16 shows both the constrictor position on the right and the weatherstripping seal on the left, from inside the pipe.

In video #2 you can see the constrictor works almost perfectly - we now have an even flow of fog from both pipes.

The final step in pic #17 is to get out the heat gun and using two boards, slightly squash down the ends of the pipes to help the cooled fog disperse horizontally.

(For both straight-through and baffle designs)

Use the 5/16" weather stripping tape to seal the lid of the cooler all the way around. You may not need to do this step, so you might want to see if the cooler lid leaks on the test run. If it does, apply the weather stripping.

Lay down some drop cloth plastic or newspaper and spray the entire cooler with flat black paint.

(For both straight-through and baffle designs)

We're done, let's test it!

Always use a funnel to put fluid into the fog machine tank or to our it back out into the fog fluild container. You don't need to completely fill it for the test run.

Half fill the cooler with regular ice and shake it around a bit to ensure the ice is fully in contact with all areas of the screen mesh (pics #3 and #4.) Top it off and completely fill the cooler with ice. (pic #5.) If you can get crushed ice or snow, all the better! You want as much contact with the screen as possible.

Put the lid on the cooler and set the fog machine on the cooler with the nozzle pointed directly at the input opening, but not touching it, see pic #6.

Turn on the machine and let it warm up. If your fog machine has a wired remote, the red light will come on the remote when it is ready (pics #7 and #8.) With wireless remotes or no-remote fog machines, there will be a "ready" indicator light on the fog machine itself.

Turn it on and let that bad boy fog!

Try the following if something doesn't seem right with your fogger.

No Fog/Nothing Happening

-- Fog Machine Not Heating: DO NOT TOUCH THE NOZZLE FOR ANY REASON! This can give you third degree burns. The first thing to check is look for on switches, it is not always as obvious as it may seem. You turn it on and it has to heat up before it will produce heat or fog.

If you're sure it's on and it's been on for at least two minutes, hold your hand over the machine, you should feel heat coming off it. If it's not heating up, check electrical connections or if it's old, the coil or circuitry may be bad.

-- Fog Machine Heating, no flow out of the nozzle: This may indicate a bad pump. If it's under warranty, get it fixed, if not and you're good at electronics, time to disassemble and investigate (not recommended.)

-- Fog Machine Heating, Flow Out of the Nozzle, No Fog: You did put fluid in it didn't you? Okay, had to ask.

The first thing to check is to make sure the tube going into the tank is completely inserted and all the way to the bottom of the tank as shown in picture #1. With a 1000 watt machine, you can see the filter as in the picture; with fog machines that have the tank inside the machine, slide the tube in and then up and down, you should be able to hear the filter tapping on the bottom of the tank.

If you still have no fog, see Step 1, "Choosing Your Fog Machine," for information on cleaning the nozzle. Be sure you let it completely cool before cleaning the nozzle!

Fog Floating and Not Staying Low

-- Air currents or breezes: not a lot we can do about that.

-- Ambient Air Temperature Too Low: The concept of ground fog requires that the temperature of the fog is lower than the ambient temperature; heat arises, cold descends. If you are in an environment where the air around you is colder than the fog vapor, it very well may mix with the air and not stay to ground. Not a lot we can do about this one. Dry ice may work but that makes for a rather expensive fog machine run.

-- Air moving through fog cooler too fast and not having a chance to cool: you shouldn't have this problem with 400 or 700 watt designs, if you do and don't want to take on the baffle design, try plugging up the output vent just enough to slow down the flow with something like a piece of styrofoam (not covered in this Instructable)

I'll add more as comments are added on this Instructable.