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For the builders who use air compressors in your own shop might you help recommend a few models or sizes for my small one room shop?

I have dug into the archive and found a lot of useful info, though the sizes (cfm), power (HP), etc. are a bit baffling for one who has yet to use this tool.

I have been taking a look at Nagyszalanczy's 'Setting Up Shop' book and he recommends getting a compressor rated by scfm (not just cfm). Is this rating needed only for the larger compressors and other larger woodworking shops?

From every point of view it is recommended to buy a bigger/more powerful compressor than what your current needs may be. Below are a few of my limitations/needs:

Current needs:
1.) Small one room shop; not a lot of room for a big 5HP/60gal model.
2.) Vacuum jigs for radius dishes/bracing; bridge clamps; work holder.
3.) ROS

Future needs:
1.)HVLP system
2.)?

Thanks!

SCFM is just CFM at a particular pressure (usually stated at 90 psi). This allows you to compare apples to apples. There are several factors that go into this. It is not just a matter of looking at the maximum air consumption of your air tools. The size of the tank also is a factor. A larger tank allow you to use a smaller compressor than needed since you are probably not running anything continuously.

I have a 33 year old Speedaire 2 hp compressor that is completely adequate for spraying finishes and smaller pneumatic tools. The tank is 20 gallons which really compensates for the small motor.

You do have to be careful when selecting an HVLP conversion gun, because most are air hogs. But I did find a couple of smaller guns that were within the capacity of my compressor.

Best way to look at this is to know the air consumption of each tool you intend to run off the compressor as well as the combination consumption of muli-toos used simultaneously like a venture vacuum generator running a vacuum clamp while running a sander and other such situations. Now add 15-20% to your minimum requirements.

MichaelP and Barry, thanks for your replies so far.

Here's a link to a used compressor in my area. At 5HP/20 gal tank could this be one to grow into? This brand is new to me. Does anyone have any opinions on ProAir?

http://stlouis.craigslist.org/tls/833676835.html

Thanks also for the reply Todd, our replies must've crossed en route...

Getting into using a compressor I would rather take the plunge and get the 5HP/60gal, but simply do not have the room in my current digs.

I don't anticipate getting any HVLP equipment for the next 12+months until after moving out of my current loft space. Todd, what do you think of the linked compressor for vacuum, pneumatic tooling, etc? Thanks.

Horsepower games are widely played in the compressor market. Go by what volume can be delivered at a specified pressure. As with any machine, it's a good idea to figure out the maximum you can see yourself needing, and then get something bigger and more powerful than that. Also, do not get an oilless, diaphragm type compressor.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

I agree with the first part of what Howard has said but an oil-less isn't to bad depending on the duty cycle one will require from the compressor. They can be a nice option if one wants a quieter compressor. Now if you were going to be using it full time or even part time (like 2-4 hours a day) then I would agree with Howard and say don't get an oil-less, but for a home use where you will be spraying a handful of guitars a year, the odd molding job etc... than an oil-less will work just fine and last a good long time.

From the sounds of it Andrew, you will be moving shop in about 12 months so what's the pressing need right now for a compressor? Could you wait till you move to your larger shop space and get the compressor you want and one that will fit your space well?

The rule of thumb again like Howard and the others have said is figure out what your air capacity needs are per tool and get something a bit bigger. No one has ever complained that their compressor was to big.

Also on the note of using the compressor for vacuum clamping. I would suggest getting a vacuum pump instead as using your compressor for it will tie it up and you won't be able to use it for other things. Also the vacuum pump is smaller, quieter and more efficient at creating the vacuum.

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Rod and Howard thanks for your thoughtful replies...

Currently I am moving my shop from one bedroom to the larger bedroom of a 2bd loft space. Fortunately this is a live/work space where all tenants in my building are able to use these lofts as work spaces. The room I am moving out of is quite small and limiting as each task requires set up and tear down before moving on to the next step. The room my shop is now in is about 224s/f and almost twice as large as the previous.

Looking into a compressor would enable me to ditch the go bar deck which I had double-stacked in a corner. Not a lot of space but ditching it and putting the dust collector in it's spot gives a bit more wiggle room.

I anticipate staying in this space for at least a year from November (when next year's lease ends). Perhaps, as you suggest Rod, going the more efficient route with a vacuum pump may be a better way to get started?

I can't comment on what you should get, vacuum pump or compressor, but I've always liked that upright compressors don't take up a lot of space. Probably less than that rolling one you linked to on Craigslist. But they cost a lot:

http://www.northerntool.com/webapp/wcs/ ... 143+771258

That is cheap compared to most comparable ones. Don't know if you have a northern tools nearby. We happen to have one 50 minutes drive from my home. But I'm sure there are comparable deals near you.

Good luck,
Todd

Oh yeah, if you don't mind going really nice, this one's price includes shipping, which is probably over $100 given what it weighs:
http://www.northerntool.com/webapp/wcs/ ... 284_158284

A ROS uses a LOT of air, if you ditch that requirement you can get by with a lot less. If you want to use a ROS then you either need a 40-60 gallon tank and a lot of downtime or a real 5HP compressor (ie: comparable to a 5HP DevAir rather than a Porter Cable).

Venturi vacuum setups are great and pull vacuum faster and ever so slightly harder than a vacuum pump, but they eat up a lot of air as well (around 1/3 what a ROS does).

I'd say save your nickels and get a good brand like a DevAir if you're committed to using high-flow air tools or get a good electric sander and a vacuum pump and use a much cheaper compressor just for spraying and the occasional small air tool. If you want to spray finish then you should have an air dryer with a compressor, and that can cost as much as the compressor itself unless you're using a dryer with expendables.

(Note that I can only recommend the DevAirs personally as that's what I've seen working best at a professional capacity in my own shop and others, though I'm sure there are other brands on par with them. I'm definitely of the 'cry once' philosophy on tools, so that's the grain of salt with any of my advice)

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Bob,

I've seen ROS that say they require 8-9 cfm and some pistol grip styles that require over 20. Since I've never considered buying one, I haven't looked into the differences. Are the ones that require the much higher flow significantly better? I'm quite happy with my little DeWalt ROS, so I'm only asking out of curiosity.

Thanks,
Todd

I have a Sears 5 hp "oiless" compressor and I would never buy another one. I can't wait for this one to die. It is fine for the air output, but has got to be the loudest, most annoying sound made by any machine. It is literally ear-splitting and the noise is amplified in my garage. I was warned about this feature of oiless comps, but unfortunately, didn't heed the advice.

While we're at it, anyone have experience with a lower RPM compressor. I remember hearing an old Devilbis compressor that ran at maybe 600 RPM. It was quiet and the pup, pup, pup sound was almost musical. The owner bought it used and figured the lower RPM made it run cooler.

As far as recommendations, you could probably get by with a 2 hp if you're not planning on working all day long with an air tool. I survived for several years with an old 1 hp in a 3 man shop. Stay away from oil-less. The noise isn't worth it. Stick with Industrial Name Brand stuff. Buying used is a crap shoot and could be dangerous if the tank is getting weak.

I agree with Glen. My Craftsman oilless would probably run all day, but who would want it to? It is in a sound-suppressed closet, and it's awful with the door closed. I may not wait for it to die, but rather switch out the pump for a belt-driven conventional.

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Dan
http://www.acme-archtops.com

???????? Am I missing something??? I guess you mean using a venture vacuum system ran off a compressor and bracing and other vacuum fixtures would eliminate the need for a go-bar deck.

Personally I would try to find a way to keep a go-bar deck. Compressors fail hoses and seal break and leak but a go-deck will work with out power and air. I am not knocking using vacuum to glue in braces as I intend to go that way soon but I would never dream of not having a go-bar deck. it is too useful of a tool.

I have a Grizzly which I like a lot. I did change the relief valves (that let air out of the tanks) with much better ones. Wished I'd gotten a larger one so I could run air sanders etc., but I do use it for spray finishing.

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Rich Smith
Issaquah, WA

Here's a good read on Air Compressors for Newbies.

http://www.practicalmachinist.com/vb/showthread.php?t=110655

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- Louis Freilicher

Oh No! Not another learning experience!

I think it's a matter of torque and RPM at the sander, more torque and RPM means more air. I have a Mirka 12K RPM sander (3.5", which is perfect for getting into places) which has plenty of both but really eats up air. The sander is off limits when other air tools are running as a shortage of pressure could be costly with my other air tools.

_________________
Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services