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Cooling pinball machine
jrock2004:
--- Quote from: MTPPC on March 28, 2013, 01:55:19 pm ---Most pinball simulators overdo the cooling. What you need to keep in mind is that the path of airflow is more important than the actual volume. "Enough" air is all that is needed. For both of my full-size simulators, I put 1 120mm fan between the coinbox and the computer and blows up toward the back of the playfield. The fanspeed is controlled by the motherboard case fan controller. The top of the backbox vents the air. My machines run cool and have never had over-heating problems. I run it for 24 hours and check it with a non-contact thermometer and its less than 15-20 degrees warmer than ambient.
The real answer is that your fan should be sufficient to replace the cubic feet of air in the cabinet every couple of minutes. If you have at least this much airflow, it can't have a delta T (change in temperaturefrom outside to inside) of more than 10 or 20 degrees.
Most go overboard because they like the LED lights of the big fans blasting out behind and under their cabinets and just don't really understand thermodynamics of a closed system.
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I think your points of overdoing cooling is what made me really want to open this thread. I will admit that cooling/airflow is not my area of experise. Thanks for all the input. Keep it coming guys and gals.
kahlid74:
--- Quote from: dandro on March 28, 2013, 01:26:43 pm ---wonder if using pegboard, like an air hockey table effect, would evenly distribute the air flow better? Never built nor seen a VPIN up close, so just generally speaking out loud here.
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Most likely it would be worse. Peg board has a lot of dead area where the air would get caught and cause a strangle on the air getting through. Essentially you'd lose CFM because of how the air would be reflecting.
--- Quote from: MTPPC on March 28, 2013, 01:55:19 pm ---Most pinball simulators overdo the cooling. What you need to keep in mind is that the path of airflow is more important than the actual volume. "Enough" air is all that is needed. For both of my full-size simulators, I put 1 120mm fan between the coinbox and the computer and blows up toward the back of the playfield. The fanspeed is controlled by the motherboard case fan controller. The top of the backbox vents the air. My machines run cool and have never had over-heating problems. I run it for 24 hours and check it with a non-contact thermometer and its less than 15-20 degrees warmer than ambient.
The real answer is that your fan should be sufficient to replace the cubic feet of air in the cabinet every couple of minutes. If you have at least this much airflow, it can't have a delta T (change in temperaturefrom outside to inside) of more than 10 or 20 degrees.
Most go overboard because they like the LED lights of the big fans blasting out behind and under their cabinets and just don't really understand thermodynamics of a closed system.
--- End quote ---
MTPPC is right about CFM and replacing the air inside the cavity every couple of minutes but recycling the air inside the cabinet will not be enough to get the hot air away from the screen.
Attached is a sketchup drawing I made quickly in case anyone else wants to elaborate. Basically air flow principles would dictate you keep the forward air as clean to 180 degrees as possible for maximum CFM. So the fan in the back would pull air in and push it over the surface. The fans in the bottom would pull air out. As the air travels over the surface and got to the front the bottom fans would pull the air back down creating an air flow. You don't want the fans in the bottom to push the air up because you would be essentially hitting a 70-90 degree turn which can cut CFM in half.
Here's the basic idea. Cool outside air pushed in from the back over the screen and sucked out the bottom. a 1/2" MDF sheet is used as a "duct" where the air can be specifically targeted:
Here's an arrow showing a small 1" gap between the top and the air duct. The monitor/TV would end where the duct begins:
Here's two more angles:
I don't remember a lot of cabs doing this type of air flow for cocktail tables, so honestly do you need it/is it overkill, sure, but getting that warm air away from the screen surface will prolong the life of that main TV/Monitor quite a bit like PL1 said.
Xiaou2:
I agree that air volume is important. However... even then, if air isnt forced over certain components or areas... they can still
get very hot, and decrease their lifespan.
The main issue is that air is very much like Fluid. It doesnt travel in a perfect linear line. If you fill a pc case with air from the bottom...
it does not guarantee that the hard drives for example, will get cool. The airflow might skip and swirl right around that area... causing hot-spots.
Look at Laptop designs. They use special enclosed channels and hoods, to keep the airflow strong and perfectly directed.
Even many of the newer pre-packaged machines, such as dells, have this same style of hooded airflow pieces.
Also, well channeled air flow will be more deficient.
Areas that are non critical, can be simply vented via some air holes, or passive vent screen. Just remember that hot air rises, so UP is the most direct root it will take.
Cool Intake air from the bottom of the machine, both passive (mesh) and forced (pathway restricted) for critical areas.
Make sure that hot-outs and cold air in's are not too close together... as sometimes that creates a warm air flood.
Air Filters can help dust trapping... but they can also reduce airflow too much. Be careful in this respect.. as its far better to have
well cooled equipment, than dealing with a little dusting.
For Pinball machines, Id also install a separate forced air system that uses small drilled holes near the buttons / hand rests.
To direct a nice breeze directly to the players hands, keeping them and the buttons free of sweat.
So again, the biggest issue here is to try to create sealed air chamber, directing the cooling effects effectively.. to
avoid hot-spots, and cooling failures, due to poor fluidic flow / poor pressure.
Best of Luck
PL1:
One reason that many people appear to go overboard on the cooling is that the Nanotech Mot-Ion board is rather sensitive to heat-related problems IIRC.
It is one of the popular encoder boards for VP builds.
Khalid74 - Great illustration in sketchup -- there are only two things I would change.
1. Reverse the airflow so that it goes up and back. Since heat rises, the fans will act with the natural flow instead of against it.
For builds that use one, this will also provide cool air for the Mot-Ion board -- which should be mounted front and center on the cab for the accelerometers to work properly.
2. Instead of using a 90 degree bend to turn the air flow and send it over the playfield, either use a curved air deflector or mount the fans close to the top so they blow straight over the playfield.
Curved -
Straight - Like this, but wider. The number of square inches at the input should be close to the number of square inches at the output.
Scott
kahlid74:
--- Quote from: PL1 on March 29, 2013, 06:19:18 pm ---One reason that many people appear to go overboard on the cooling is that the Nanotech Mot-Ion board is rather sensitive to heat-related problems IIRC.
It is one of the popular encoder boards for VP builds.
Khalid74 - Great illustration in sketchup -- there are only two things I would change.
1. Reverse the airflow so that it goes up and back. Since heat rises, the fans will act with the natural flow instead of against it.
For builds that use one, this will also provide cool air for the Mot-Ion board -- which should be mounted front and center on the cab for the accelerometers to work properly.
2. Instead of using a 90 degree bend to turn the air flow and send it over the playfield, either use a curved air deflector or mount the fans close to the top so they blow straight over the playfield.
Curved -
Straight - Like this, but wider. The number of square inches at the input should be close to the number of square inches at the output.
Scott
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10-4 man. That's what I figured originally but even curved its still a 90 degree transition which takes away CFM. I'm doing a cyclone dust removal system for my shop and they recommend no greater than 45 degrees for transitions. Mind you this scale it is probably fine but that's why I changed the airflow to be back to front.