VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics


Go Back   VAF Forums > Main > RV General Discussion/News
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #11  
Old 07-23-2018, 03:28 PM
DRMA DRMA is offline
 
Join Date: Jan 2016
Location: Sugar Land, TX
Posts: 327
Default

Jeremy,

I did a quite a bit of research and thinking before selecting a compressor for my RV-10 build. Like most things in life and building there are trade offs and so no single right answer.

When it comes to compressor size there are 2 key measures of size. The first is the compressor (air pump) output, measured in standard cubic feet per minute (cfm) at working pressure. Typically 90 psi pressure is used for rating air compressors for our use. If you have a compressor with an output that is equal or a bit higher than the air volume used by your tool, your air tank can be very small without impacting your work.

The second key measure however is tank size. The tank stores the air and allows the compressor to cycle on and off rather than run continuously. Since most tools we use only draw air for short periods of time (from a few seconds for a rivet puller or squeezer to a few minutes for an air drill), a large tank can provide the air at higher volume than the compressor can produce for a period of time, allowing a smaller compressor to support your work. But when you require a high volume of air for an extended time period as required for a spray paint gun, the stored air in the tank will run out before you have completed the task, requiring you to stop and wait for the compressor to catch up by refilling the tank.

So you are looking for a balance between compressor size and tank size. But compressor price increases with larger capacity, and the power required increases driving a change to higher voltages and amps, and then to 3 phase power in industrial size compressors. And as tanks get larger, weight goes up, portability goes down, and price goes up. Higher operating/storage pressure is another factor that can help storage volumes but also drives up cost, weight, power, etc.

Another factor worth considering is noise. Belt driven, lower speed, oil lubricated compressors tend to be less noisy and longer life than direct drive non-lubricated compressors, but these also cost more. So unless you can place the compressor in a different location or sound attenuating enclosure, noise (measured in dB where a higher dB is a louder machine, and every 3 dB increase doubles the noise level) is also a selection consideration.

So what is the electrical capacity in your shop, how much space do you have for the compressor, how much noise can you accept, how much money do you want to spend, do you want to be able to move the compressor without a crane or pallet jack, do you want to do high volume painting, etc. are a few of the considerations.

For my shop, after weighing all these considerations including reliability, longevity, availability (what compressors are available for purchase), etc, I ended up buying a Quincy 26 gallon, 7.4 SCFM at 90 psi, portable electric vertical compressor. This was the highest capacity I found that would run on a 120 VAC, 20 amp circuit, had wheels and so could be moved without tools, could be re-wired for 220 VAC in the future if I wanted to do so, was oil lubed, belt drive and so relatively quiet, assembled in the USA with a good reputation for reliability and reasonable quality.

I bought mine from Lowes https://www.lowes.com/pd/Quincy-Comp...essor/50073349 as they were in stock and lower price when I bought mine a couple of years ago.

I have been very happy so far with my selected compressor. I have been able to do some painting, including primer and painted the interior of the cabin. I plan to have the exterior professionally painted, so don’t need a larger compressor and paint booth. I only moved it around my shop a couple of times, preferring to leave it in one place next to a power plug and using a long hose instead. I was pleasantly surprised to find that it worked well on a 120 VAC, 20 amp circuit that also has some lights on it, so I didn’t need to run a separate circuit or convert it to 220 Volts. So for my purposes, I would give it a full 5 star rating.

Sorry for the long dissertation, but I find that a lot of people don’t fully understand the air compressor sizing and compressed air physics that impact the selection and satisfaction, and often just look at the air tank capacity. Hope something in this post is helpful.
__________________
Dave Macdonald

RV-10 Fuselage Moved to Airport Sept 15th for Finishing.
2019 VAF Dues Paid
Reply With Quote
  #12  
Old 07-23-2018, 03:34 PM
wirejock's Avatar
wirejock wirejock is offline
 
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 3,348
Default 20 gallon

I too haved an oldl Crafstman 20 gallon 240v. It served me well for a long time. I drain it often.
I primed with it. No problem but sessions were kept short enough so it didn't get too hot.
A large 5 HP, 60 gallon, 240, single phase would be nice.
__________________
Larry Larson
Estes Park, CO
http://wirejockrv7a.blogspot.com
wirejock at yahoo dot com
Donated 12/27/2018. Plus a little extra.
RV-7A #73391, N511RV reserved (2,000+ hours)
HS SB, empennage, tanks, wings, fuse, working finishing kit
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
Reply With Quote
  #13  
Old 07-23-2018, 03:43 PM
flyabq's Avatar
flyabq flyabq is offline
 
Join Date: Jul 2018
Location: BELLA VISTA
Posts: 48
Default Thank you

Quote:
Originally Posted by DRMA View Post
Jeremy,

I did a quite a bit of research and thinking before selecting a compressor for my RV-10 build. Like most things in life and building there are trade offs and so no single right answer.

When it comes to compressor size there are 2 key measures of size. The first is the compressor (air pump) output, measured in standard cubic feet per minute (cfm) at working pressure. Typically 90 psi pressure is used for rating air compressors for our use. If you have a compressor with an output that is equal or a bit higher than the air volume used by your tool, your air tank can be very small without impacting your work.

The second key measure however is tank size. The tank stores the air and allows the compressor to cycle on and off rather than run continuously. Since most tools we use only draw air for short periods of time (from a few seconds for a rivet puller or squeezer to a few minutes for an air drill), a large tank can provide the air at higher volume than the compressor can produce for a period of time, allowing a smaller compressor to support your work. But when you require a high volume of air for an extended time period as required for a spray paint gun, the stored air in the tank will run out before you have completed the task, requiring you to stop and wait for the compressor to catch up by refilling the tank.

So you are looking for a balance between compressor size and tank size. But compressor price increases with larger capacity, and the power required increases driving a change to higher voltages and amps, and then to 3 phase power in industrial size compressors. And as tanks get larger, weight goes up, portability goes down, and price goes up. Higher operating/storage pressure is another factor that can help storage volumes but also drives up cost, weight, power, etc.

Another factor worth considering is noise. Belt driven, lower speed, oil lubricated compressors tend to be less noisy and longer life than direct drive non-lubricated compressors, but these also cost more. So unless you can place the compressor in a different location or sound attenuating enclosure, noise (measured in dB where a higher dB is a louder machine, and every 3 dB increase doubles the noise level) is also a selection consideration.

So what is the electrical capacity in your shop, how much space do you have for the compressor, how much noise can you accept, how much money do you want to spend, do you want to be able to move the compressor without a crane or pallet jack, do you want to do high volume painting, etc. are a few of the considerations.

For my shop, after weighing all these considerations including reliability, longevity, availability (what compressors are available for purchase), etc, I ended up buying a Quincy 26 gallon, 7.4 SCFM at 90 psi, portable electric vertical compressor. This was the highest capacity I found that would run on a 120 VAC, 20 amp circuit, had wheels and so could be moved without tools, could be re-wired for 220 VAC in the future if I wanted to do so, was oil lubed, belt drive and so relatively quiet, assembled in the USA with a good reputation for reliability and reasonable quality.

I bought mine from Lowes https://www.lowes.com/pd/Quincy-Comp...essor/50073349 as they were in stock and lower price when I bought mine a couple of years ago.

I have been very happy so far with my selected compressor. I have been able to do some painting, including primer and painted the interior of the cabin. I plan to have the exterior professionally painted, so donít need a larger compressor and paint booth. I only moved it around my shop a couple of times, preferring to leave it in one place next to a power plug and using a long hose instead. I was pleasantly surprised to find that it worked well on a 120 VAC, 20 amp circuit that also has some lights on it, so I didnít need to run a separate circuit or convert it to 220 Volts. So for my purposes, I would give it a full 5 star rating.

Sorry for the long dissertation, but I find that a lot of people donít fully understand the air compressor sizing and compressed air physics that impact the selection and satisfaction, and often just look at the air tank capacity. Hope something in this post is helpful.

Thank you for your input. I am looking along the lines that you are talking about. I appreciate you taking the time to respond.
Reply With Quote
  #14  
Old 07-23-2018, 05:41 PM
Jake14 Jake14 is offline
 
Join Date: May 2014
Location: Seattle
Posts: 236
Default

The HF compressor I started with was incredibly noisy, I had to wear hearing protection whenever it was running. I wound up with a California air tools 6gal model which advertised 60db. Don't know about the 60 db, but it's about as loud as a washing machine. You can have a normal conversation standing next to it. no problem with capacity, but I used an air brush with Stewart Systems eko prime to prime the surfaces..takes a bit longer, but not much, no cleanup, no toxic fumes, no paint booth....just toss the airbrush into some water 'till next time.

https://www.homedepot.com/p/Californ...10SE/205602927
__________________
RV-14A #140158 flying
Reply With Quote
  #15  
Old 07-24-2018, 12:41 PM
dave4754's Avatar
dave4754 dave4754 is offline
 
Join Date: Oct 2009
Location: Edson, Alberta, Canada
Posts: 469
Default Budget = Auction for me

I purchased a 60 Gallon 5 hp at auction for 200 Cdn. Surprise it worked? Got lucky i guess but they are out there.

For any amount of painting, air sanding, air drill work the smaller ones just dont cut it.

I did build most of my 7 with a small 20 gallon and it will do but you have to wait for it after heavy use of air drill or die grinder which you use alot.

I agree with the other responder, wait till the bills for the rest of the airplane come in.... this will seem like peanuts!

Dave
__________________
Dave Cobb
[color="Red"]=VAF=2019 Donation - and a bit extra for great work![/COLOR="blue"]
Empennage RV 7 - Tipper
Wings complete

Dynon installed and running
Fuse closer to completion, Canopy complete
AME reviewed and repaired O-320-Lyc installed
Reply With Quote
  #16  
Old 07-24-2018, 02:19 PM
Draker's Avatar
Draker Draker is offline
 
Join Date: Jun 2016
Location: Livermore, CA
Posts: 279
Default

Don't forget about sound output! I originally got a 20 gallon Home Depot special, which worked, but was so loud in my small garage I felt like I'd get hearing loss if I forgot my ear plugs. About when I started my wing kit, I replaced that with a 10 gallon California Air Tools compressor, which ended up being much quieter. No hearing protection needed, in fact, sometimes I forget to leave it on, it tops up in the middle of the night, and nobody in the house hears it! The 10 gallon tank is small but sufficient. Honestly I think anything over 20 gallons or so would be overkill for RV building. I currently have a 5 gallon external tank in the system to add a little extra capacity, but even the 10 gal on its own is enough.
Reply With Quote
  #17  
Old 07-24-2018, 02:50 PM
odens_14 odens_14 is offline
 
Join Date: Jun 2007
Location: Alexandria, MN
Posts: 230
Default

Quote:
Originally Posted by Draker View Post
Don't forget about sound output! ...
But also don't forget about air volume as well: Be aware the California Air Tools is much quieter because it's much less powerful. I've never used it but I'd have to imagine it cant keep up with an air drill or die grinder used with any frequency with only 2.2 CFM; adding tanks would run less but would take a long time to recharge. Maybe some users of the california air tools could chime in if they use an air powered drill or die grinder, do you frequently have to wait for the compressor to catch up?

Per their stats:

California Air Tools 3.10 CFM / 40 PSI and 2.20 CFM / 90 PSI
Harbor Freight 5.8 CFM @ 40 PSI, 4.7 CFM @ 90 PSI

some commonly used tools with high air demands in CFM:
Die Grinder 1/4" 4 - 6
Drill, Reversible or Straight-Line 3 - 6
__________________
Chris Odens
Alexandria, MN
RV-7 N914N
FLYING!!! as of 7/22/10
Build Log
Reply With Quote
  #18  
Old 07-24-2018, 06:56 PM
Draker's Avatar
Draker Draker is offline
 
Join Date: Jun 2016
Location: Livermore, CA
Posts: 279
Default

Chris,

The California Air Tools compressor I have is model # 10020C, with the following specifications:

6.40 CFM @ 40 PSI
5.30 CFM @ 90 PSI

I just finished up my wings and so far, I have found its performance satisfactory for drilling and squeezing rivets, and adequate for my die grinder and HVLP spray gun. It cycles pretty frequently while spraying primer and cannot keep up with sustained spraying, so I work in short bursts. Otherwise I'm happy with the setup.
Reply With Quote
  #19  
Old 07-24-2018, 10:41 PM
jcarne's Avatar
jcarne jcarne is online now
 
Join Date: Jul 2016
Location: Worland, Wyoming
Posts: 945
Default

I too went with the 26 gal harbor freight special. I have had it for about a year now maybe a little more and have already had to replace the reeds in it. Now don't get me wrong, this compressor will most definitely do the job but it is freaking loud and runs a lot. I sincerely regret quite often not spending the extra money and buying a 60 gal unit. Before I build my next plane (which will be a -10) I will definitely purchase a 60 gal model. I even have this one book marked.
__________________
Jereme Carne
PPL
RV-7A Emp. done
Wings mostly done
Fuselage almost done
Finish kit arrived
Exempt but gladly paying!
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 06:42 PM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.