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Thread: Adequate air compressor size for pneumatic tools

  1. #1
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    Adequate air compressor size for pneumatic tools

    As I prepare to outfit a new shop for myself and consider my compressed air needs I am wondering if I should go big enough to run some pneumatic tools. Most RO palm sanders require 14scfm from a compressor but that is one big air tank needed for that. Has anyone run a sander off of a smaller than recommended air compressor and had any ill effects other than it running more often? I don't plan to do that much sanding so this would an infrequent event and the rest of the time the compressor would have much smaller requirements from me.

  2. #2
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    Most air sanders eat a lot of air very quickly. If you don't already own one you may want to consider one of the better electrics instead….Festool and Mirka make some really nice sanders. If you do own one already then try for as large a pump as you can afford. Otherwise the compressor will be running continuously while your sanding.

    good luck,
    JeffD

  3. #3
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    You can get away with a little less than 14 scfm, but not much. You're going to need a big compressor to run an air sander, period.

    I used to run my Dynabrade on a 13.5 CFM Kobalt compressor, and the Kobalt worked adequately (but noisily) for me in my home woodshop for nearly a decade before dying last month. I just bought a Quincy QT-5, because I choose to keep the Dynabrade going rather than go the Festool/Mirka route. The Quincy is a big investment, but I consider it a "lifetime" compressor to go with my "lifetime" Dynabrade.

    Here's my suggestion:

    If you are talking about a tool for occasional use (an hour or two per week), and if price matters, and if portability is an issue, then the Festool or Mirka should be a tool that will get the job done, be enjoyable to use, and last a reasonable number of years. (My Mirka had serious QC issues, but I'm in the minority.)

    If you do more sanding than that, and if you don't need to sand off-site, then seriously consider a strong compressor with a Dynabrade. Here's why I make that suggestion:

    1) The up-front cost of buying an adequate compressor and a Dynabrade will run you over $1k (more like $2k if you go a good compressor route). You can get a very nice Festool/Mirka for $500. So the up front cost is much cheaper with the Festool/Mirka. If you are not going to be doing enough sanding that maintenance/replacement costs are an issue, then Festool/Mirka are a very good buy.

    2) If you are going to put a lot of hours on your sanders, then Dynabrades become a no-brainer because of the maintenance/replacement costs. Each time the Festool/Mirka wear out, you'll be throwing them away and buying another, for another $500. The Dynabrades last longer (they have no motors that fail), and even when the Dynabrade wears out, you spend $75 on a rebuild kit and you essentially have a new tool again. Or you can splurge and get a brand new Dynabrade for less than $200.

    3) Dynabrades also make a lot of sense if you need to do wet-sanding. Wet-sanding is bad for electric sanders. Pneumatic sanders handle wet sanding the same as normal sanding.

    4) Dynabrades also make a lot of sense if you need a good compressor anyway. I run compressed air lines throughout my shop for several tools. My multi-router uses pneumatic hold-downs. My wide belt sander has a pneumatic oscillating mechanism in it. I use my compressed air to spray finishes when hauling out the Graco HVLP system is not convenient. (Plus, it's super convenient for filling up tires.) A nice compressor is a very valuable tool in a good workshop. If you're going to invest in a good compressor anyway, it's not much more money to invest in one that can run your pneumatic tools. At that point, Dynabrades become a no-brainer, IMHO.

    5) Don't let anyone fool you into thinking that electric sanders are as smooth as Dynabrades. They can leave just as smooth a finish, but I'm talking about smoothness in terms of vibration and operator fatigue. To me, holding a Festool sander is nicer than a lot of other sanders, but they're much heavier and bulkier than a Dynabrade. Mirka solves that problem with the CEROS, and the CEROS is nice, but it has a bit more vibration than the Dynabrade. After a while, that little bit extra vibration gets tiring. They are all nice sanders, but Dynabrades are really a treat when you are sanding for hours at a time.

    6) The cost of running a compressor is much higher than the cost of running an electric motor. So your shop electricity cost will be higher for a Dynabrade. But if you are using the tools a lot, the cost delta for the electricity pales in comparison to the maintenance/replacement cost when your sanders wear out.

    Good luck whichever direction you go.

  4. #4
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    Pneumatic tools like sanders eat air like no tomorrow...you need a hefty compressor with a very large air tank to service them. The SCFM specificed isn't a "suggestion"...it's a requirement for the tool to operate correctly.

    You can buy some pretty darn nice electrically powered sanders for a lower budget than the big-butt compressor is going to cost you to use pneumatic sanders! And that includes Festool. (my choice) And the air sanders that also support good dust collection add to the bill, too.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  5. #5
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    Very informative answers, thanks to you all. I believe I owe it to myself to look into the Festool/Mirca idea.

  6. #6
    I would second everything Kelby said. I work in a shop with six Dynabrade sanders in daily use powered by 7.5 and 5 hp Ingersoll Rand compressors running in tandem. We are still running a sander that was well used when I started 14 years ago. The larger compressor is 6 years old and the 5hp is just old- 25 years or more. More upfront cost, less ongoing cost than electric tools. One of our suppliers loaned us a Mirka CEROS sander a few weeks ago, and it is comparable to the Dynabrades, quieter but slightly more vibration. I am sure it will not have the life of the air sanders. It would be a great choice for site work.

    For setting up a new shop, investing in a good quality (IR, Quincy or similar) low rpm 5hp compressor and dryer will pay off in the long run. Change the compressor oil and air filter every six months and put a couple drops of oil in the tools daily. If you go with a lower output compressor, get a large tank (80 gallons or more) and accept that the lower hp motor will be running longer to replenish it when sanding or spraying finishes. You may find with industrial pumps that the manufacturer uses the same pump at different rpms with various hp motors, so the cost difference is between a 3 and 5 hp motor. If you find yourself in the middle of a long sanding session and having to stop while the pressure rebuilds, you will wish you had paid the upfront cost for a unit that would pump at your use rate.

  7. #7
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    Running a sander on a small compreeor:

    BRRRrrrrrr... stop and weight... BRRRrrrrrr... stop and weight... BRRRrrrrrr... stop and weight...

    No damage... no problems... just slow and annoying.

    I have a medium sized compressor in my shop. I went with a medium sized compressor so I could run air tools and still have a compressor that was somewhat portable... Big mistake. I should have gotten a huge shop compressor to pair with my small portable compressor I ended up buying anyway because the medium sized compressor is too big to move around much.

    I have a random orbit air sander and never use it. I use one of my electric Porter cable random orbit sanders instead... works much better!

    Good Air tools: impact wrench, die grinder, miniature belt sander, scaler, BLOWER, Nailers (brad, pin, framing, stapeler, etc. They run great on a small compressor), paint/finish sprayers.

    Most other air tools are best off being electric in my opinion.

    The one air tool I wish I had enough cfm for is a sand/media blaster... but that requires a really big compressor!

  8. #8
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    William

    I kind of started down the same path as you are contemplating a few years back. In the end I ended up corded sanders. It takes a boatload of air to run a sander properly, which meant a big compressor and upgrading all of the electric to my garage/shop. Too much$$$$.
    I've scaled my needs back to having a compressor capable of doing some spray painting, and running an impact wrench. About 8-11 scfm for me would be good.
    "The first thing you need to know, will likely be the last thing you learn." (Unknown)

  9. #9
    I've never seen the sense of having air sanders. I have a big compressor that could handle them but I prefer electric sanders and haven't plugged in an air sander in many years, I just don't see the point to it. My compressor handles sprayers and nailers perfectly well, but to each their own, I guess.

  10. #10
    For an amateur shop, a smaller compressor may be the best choice. For daily use sanding and spraying finishes a low rpm compressor that puts out 15 cfm or so will prove to be a good investment. Most shops in business to turn a profit (not all) go in this direction.

  11. #11
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    After some consideration and appreciating the input here, I have decided to go with an electric RO sander and a much smaller compressor. I am looking in the 20 to 40gal $500-600 range. Leaning towards vertical but horizontal is certainly an option. Any favorites out there?

  12. #12
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    Quote Originally Posted by William Mark Dulken View Post
    After some consideration and appreciating the input here, I have decided to go with an electric RO sander and a much smaller compressor. I am looking in the 20 to 40gal $500-600 range. Leaning towards vertical but horizontal is certainly an option. Any favorites out there?
    In your stated budget, the IR Garage Mate would be a very nice compressor to consider. For just a little more, you could go with a 60 gallon unit, too.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  13. #13
    Quote Originally Posted by Kelby Van Patten View Post
    I used to run my Dynabrade on a 13.5 CFM Kobalt compressor, and the Kobalt worked adequately (but noisily) for me in my home woodshop for nearly a decade before dying last month.
    Probably the same compressor I had for a while. It's the only thing that didn't survive the trip from California to New England. I thought it was a great compressor. What was it? $600, or something like that? They don't make anything with those kinds of specs anymore, as far as I know.

  14. #14
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    http://www.aircompressorsdirect.com/...or/p12330.html
    $800 shipped.

    I've heard the 3HP 60 gallon Puma is decent too. Should be a little less expensive.

  15. #15
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    I just can't see the value in using a 3-5 horsepower compressor running 100% to do what a 3 amp electric sander can do. That being said, if my 1 hp 35 year old Craftsman ever dies I would get a 60 gallon vertical tank model that has at least 125 psi and 3 hp. Home duty would be fine with me as long as it had a CI compressor. My biggest need is busting loose lug nuts that some idiot put on with a big impact gun and my compressor cycling 80-100 psi doesn't do it.
    NOW you tell me...

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