Sizing Compressor for Small Projects

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PostPosted: Fri Sep 18, 2020 9:47 pm
Okay, so I'm not working on an auto body. I build and fly large rockets and want to start painting my own, not using a rattle can. Searching for help in picking the right size compressor for projects that are smaller than cars.

Most of the rockets I'll be painting will be between 3-inches in diameter and 8-inches in diameter. Anywhere from 2 feet tall, to over 10 feet tall. Curent project is 4 inches in diameter, 3.5 ft. tall and approximately 700 square inches to cover.

I've purchased an Iwata Airgunsa HVLP gun with 1.3mm tip and several of Createx AutoBorne and Auto-Air paints. Need to figure out how much of an air compressor I will need to paint my projects. Won't be doing any of the bigger projects, just yet, but do need one for the current project that won't break the bank.

Also, what accessories should I make sure to get in order to have a reasonably decent looking paint job? ("Decent" is defined as following the 3 ft. rule: If it looks good at 3 foot, it's good enough.)

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PostPosted: Mon Sep 21, 2020 8:33 am
Your tools determine the air requirements of your compressor.

Check the CFM (volume of air) needed for each of your tools. Make certain the compressor you buy exceeds the CFM output by at least 10%.

Tank size won't be as critical with small projects but is critical for larger ones as it keeps the compressor from having to run constantly to keep up.

Water separator and filtration system for your air supply are critical and you can do a search for information on running air lines, etc.

A booth with air filtration, painter's suit, gloves, tack rags, etc for dust control.
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PostPosted: Mon Sep 21, 2020 9:35 pm
So, then at 340 Nl/minute, it's just a hair over 12 CFM @ 29 PSI. That's one hefty compressor for a DIY/Hobbyist. I'm not finding anything that capable for less than $600 in my area.

:shocked:



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PostPosted: Tue Sep 22, 2020 7:56 am
holy crap!!! ive been wondering if id ever see an HPR rocket addict coming on here asking about painting!
having painted rockets from 2-6" diameter, ive found that since the gun is running for maybe 2-3 minutes per coat, theres room. i sprayed a loc mini magg and THOY nightwawk with a cheap home depot gun and pancake compressor and had great results. i wouldnt try using that on,say, a madcow DX3 lr wildman ultimate darkstar,though.
you could probably get good results with something in the 20 gallon size. gonna take practice to get the fan pattern smaller and fluid control set for painting round body tubes- spaying with my gun set up like i would for painting large surfaces=lots wasted in overspray.
this is also where multi color paint schemes can come in
another thing:
this is where a touchup gun comes in handy. they can have smaller fan patterns and hold less paint. i believe lower cfm,too.
as im sure youve read on TRF and FB groups, prepwork is vital to final results. dark colors make the spirals in paper body tubes stand out big time! one plus ya have is that getting away from spray bombs and to auto finishes, the primers now offer higher build so less coats if you go that way and want to fill spirals. 2 coats of highbuild fills a LOT more than what spray bombs do.youd need a larger tip gun, which this is where the harbor freight purple paint eater comes in nice! they have a 1.9 tip one real cheap and it gets the job done.

get a good quality respirator.

you might be able to find a local jobber with mismatched paints you can purchase at a reasonable cost to practice with,too. a friend should have a rocket to practice on. :happy:

one thing ive learned when it comes to spraying rockets:
i like to have a few lined up at one time for at least primer. it goes quick and i get tired of gun cleaning.

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PostPosted: Tue Sep 22, 2020 2:12 pm
TechnoToad wrote:So, then at 340 Nl/minute, it's just a hair over 12 CFM @ 29 PSI. That's one hefty compressor for a DIY/Hobbyist. I'm not finding anything that capable for less than $600 in my area.

:shocked:


That is the reaction of most when finding out the proper way to size the compressor needed.

There are guns that take less CFM to operate so you might check out specs on some guns and then see how much the compressors are that will handle them.

Keep in mind that the gun manufacturer gives those specs (12 CFM at 29 PSI) because that is the amount of air it takes for that gun to properly atomize the paint so that it sprays correctly.

A twenty gallon tank holds 2.6 cubic feet of air. Under say 100 psi of pressure that increases to approximately to about 19 cubic feet. So if your gun requires 12 (cubic feet per minute) that tank isn't going to let you spray more than 1 minute without having to wait for the compressor to recharge the tank.
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PostPosted: Fri Sep 25, 2020 11:03 am
tomsteve wrote:holy crap!!! ive been wondering if id ever see an HPR rocket addict coming on here asking about painting!

I been playing with Rockets forever. basically anything that flys
Dennis B.
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PostPosted: Fri Sep 25, 2020 5:32 pm
Doright wrote:
tomsteve wrote:holy crap!!! ive been wondering if id ever see an HPR rocket addict coming on here asking about painting!

I been playing with Rockets forever. basically anything that flys


here,too, with the rockets. got a wee bit addicted to em back in the 90s when i learned there was more than estes motors. hadda vendor about a hour drive from me. i was there every friday night talkin rockets and spending a "couple" dollars.
ive backed off since then. sold just about my entire fleet and supplies in the .ate 2000's. been building back up the last few years but not going bonkers. been keeping it low and mid power.
although i do have an L1 rocket ready to go.
been havin fun,though clustering and staging bp motors. still pop up some on mid power aerotechs,though.



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PostPosted: Tue Oct 06, 2020 9:29 am
tomsteve wrote:
Doright wrote:
tomsteve wrote:holy crap!!! ive been wondering if id ever see an HPR rocket addict coming on here asking about painting!

I been playing with Rockets forever. basically anything that flys


here,too, with the rockets. got a wee bit addicted to em back in the 90s when i learned there was more than estes motors. hadda vendor about a hour drive from me. i was there every friday night talkin rockets and spending a "couple" dollars.
ive backed off since then. sold just about my entire fleet and supplies in the .ate 2000's. been building back up the last few years but not going bonkers. been keeping it low and mid power.
although i do have an L1 rocket ready to go.
been havin fun,though clustering and staging bp motors. still pop up some on mid power aerotechs,though.


I never got into club rocketry although I wanted to get certified to level 2 maybe 3 after seeing the big boys play on You tube. But with my commute and so many projects going the shop & cars its hard throw more money in another direction and get things done,
I have a RC plane on the shelf I still haven't finished and I have everything to finish it!
The older I get the more I am looking at a Real airplane as well went and looked at a Beech Bonanza project recently took everything in me too walk away from it! I keep telling myself finish and sell what you got now....Then maybe? I really want one!

Tripoli has a local Launch coming up on the 16th I may go too? maybe fly one or two that I still have on the shelf both will take a D or E engines with a Little fiddling nothing special though just little boy toys but they can still be a challenge to recover!
Both have made several flights each, on D power I would really like to see my Big one fly with an E or F motor! that would be cool to see, it was very under powered with a D but fun to fly.

http://www.tripolivegas.com/OktoberFest.html

I also like
http://www.skarclub.org/skar-youtube/ and follow their stuff.
Dennis B.
A&P Mechanic, FCC General radio Telephone Operator
Line Maintenance A&P Mechanic and MOC Tech specialist.

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PostPosted: Thu Nov 16, 2023 9:40 pm
Sorry about the delay in response. Been busy painting rockets!

Tried a pancake compressor from Horrid Fright. I kept having to stop after about 1/3 of a coat, wait for it to build back up pressure, then shoot another 1/3 of a coat. This was on a 4" diameter fiberglass Der Red Max.

Friend of mine's dad passed away and she asked if I wanted to buy his old 20 gallon compressor. It's an old Sears model, that her dad had replaced the original motor with a Northern Tool 2HP motor. I can shoot a fairly large sized rocket without stopping until that coat is done. It builds back pressure fine while I'm waiting for the current coat to dry enough to shoot the next. Cost $100. Runs my air sander/buffer with no problems, as well.

For those who are commenting on flying rockets, I've been flying rockets for over 50 years. Got certified with TRA back in the early 90s, went all the way to L3 in 2000, then let my membership lapse until the last few years. Currently in the process of going through the cert process all over again. Up to L2, plotting and planning my L3.

:happy:

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PostPosted: Fri Nov 17, 2023 8:59 am
Painting any kind of tube can be tricky. You need to choose your gun carefully because tube will waste vast amounts of paint in overspray or result in runs if you narrow down too much.

The HVLP version of the AZ3 has a fan width of around 11" in 1.3mm which I'd think is a little big for what you're painting. The RP version is a little better at 9.5" but has a huge advantage in air consumption at 7cfm vs 12cfm for the HVLP and transfer efficiency is also much better.

However, if I was painting these I'd go for a smaller gun. My current favourite for jobs like this is the Iwata AZ4 (link here). Fan is only 160mm with 1.2mm tip but air usage is down to 3.7cfm. So no need for a new compressor at all. You could go a bit bigger if you really wanted to, something like the ANI R160 (link here) which, with a 1.2mm tip only uses 4.2cfm. Also a nice midi gun and very good value. I have two and use them often.
Chris
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