Absolute newbie here, getting back into modeling after too many wasted years. I’m having way too much fun buying tools and learning from you all, and have been lurking here for some time now.
I’ve been trying to decide about air/CO2/Nitrogen sources for the airbrush my wife is going to be getting me for Christmas (she doesn’t know this yet!). Since I already have a (loud) 1 HP household compressor that I use for filling tires, etc., I’ve tentatively decided that the most economical way for me to go is to buy an air tank/regulator/moisture separator combo and just wander out into the garage with the tank to refill when it runs low. My questions are: 1) Is this really a good idea, and if so 2) what size tank would be sufficient? I’m hoping that a 4 or 5 gallon tank will do for an evening’s painting, since anything larger takes up too much space IMO. Since my compressor is right at hand, even having to top it off once a night won’t be a hassle. So does anyone with experience with this setup have an opinion about tank size?
BTW, my compressor is rated at 1 HP/125psi.
Also, I’m thinking a Badger 155 would be a good choice that I wouldn’t outgrow any time soon.
My compressor has a three gallon tank and it pressurizes to 110 psi before kicking off. It will then kick back on at 70 psi unless I turn the switch off. One tank, without recharging last for about 7 minutes of solid spraying and then the pressure is below 20 psi and very unreliable.
I would guess that a 4 gallon would add to that time and a 5 gallon would nearly double it. Since you’re going to go to 125 psi, I would guess that it will give you about 10 minutes for the 4 gallon and 14 minutes for the 5 gallon. Note that these are just rough estimates and your air/paint mix and pressure will affect the time somewhat.
Check out Badger’s Garage Sale Page They have some rebuilt Thayer & Chandler Air Star V compressors for $99. By the time you buy a tank, regulator / filter, and some fittings you’ll probably have $50-$75 in it.
yeah my neighbor tried to talk me into the tank thing. He had a 10 gal tank in his garage and a monster compressor that filled it up in like 3 minutes. But after playing with it a bit, I decided on a compressor instead of the tank. it’s noisier than the tank but I never get nervous about the psi getting low on it halfway through a fuselage etc…
if you do decide on the tank, the numbers Foster told you seem small, but really arent. that’s 14 minutes of constant spraying, and unless you are building in the 1/8 range you wouldn’t do that. I would think that it would last you through almost an entire kit in 1/48 if you are careful and turn off the regulator after spraying each time.
I agree with Scott, the 155 is a really good brush. I know, I have one! [:o)]
I think a compressor might be abetter choice… some of them are really quiet and all. Still saving up for that badger 155. I might have it by December mom willing.
Hi, woodworks, and welcome to the forum family!
Not trying to be too complicated, but here’s the basic math to determine spray times:
Most full size gas bottles (the ones you see in oxyacetylene torching setups, for example) have a maximum volume of about 6 cubic feet. Making an assumption that the gas bottle for airbrush use is about half that size, then the volume should be around 3 to 3.5 cubic feet. If you multiply 3.5 cu.ft. times the pressure on your regulator (1,000 psi) and then divide by 14.7psi at sea level to adjust for standard pressure, you get 238 standard cubic feet. If your airbrush is being powered at, let’s say, 10 cfm, then your total (continuous) spray time is only going to be about 24 minutes before you’re going to need a refill.
Gip, I don’t think an airbrush uses anywhere near 10cfm. I base that on the fact that my 5-gallon compressor pressurizes to 140 psi. If I let it pressurize and then shut the motor off manually I can get about 30-45 minutes of painting before it gets too low to use.
Backing that into your forumulas, I get:
5 gallon = 0.6685 cubic feet
@ 140 psi = (0.6685 * 140) / 14.7 = 6.366 scf
6.366 scf / 30 minutes = ~0.21 cfm
Using 0.25 cfm for a 3.5 cf bottle at 1,000 psi gives about 16 hours of painting, which fits better with the reports of guys who have said they only have to fill their tanks once or twice a year.
Regardless, thanks for the forumlas. I had wondered how to convert that.
Scott,
Glad you worked it out. Not sure how I came up with 10 cfm as a number, but it does seem to be a bit much, doesn’t it? Must have been a really BIG airbrush…
Thanks for all the excellent replies. I guess no one thinks my tank scheme is such a bad idea. Though I agree, MusicCity, that compressor is awfully tempting. And it’s good to know that the Badger 155 will make a great Christmas present for me. I just hope I can hold out 'til then.[:D]
Paul Boyer uses CO2, and I use a nitrogen tank to run my airbrush. I bought the regulator, and essentially rent the tank. A welding-supply store near here supplied everything I needed, including the how-to info.
The tank lasts a looooong time, and a tank-pressure gauge helps me keep track of how much gas is left. Even as much as I build, I only go through a couple of tanks a year. I have an old Badger piston compressor on-deck just in case I ever run out mid-project, but it hasn’t happened yet.
The nitrogen tank’s silent, and I can throttle it anywhere from 1 to 1000 psi (just before the airbrush blows up, I’m guessing, but you get the idea). The hugely variable air pressure does make a lot of different effects possible.
When the tank runs down, I drop off the empty and exchange it for a full one. I did so over the weekend, and it took 10 minutes and $20.
Something to think about, and I hope this info helps.
If you are feeling really ambitious you could run an air line from your garage to your basement. Depending on your basement it could be fairly easy. (On the other hand it could be a tremendous pain in the tuckus). My basement is unfinished, so I’m considering running one before I finish it.
