Air powered orbital sanders?

[Matt Day]

I’ve only used electric ROS’s, and have someone asking me about air powered ROS’s. I’m guessing some pro shops use these? Can anyone suggest some make/models I should look at?
Thanks

[David Kumm]

Dynabrade is the main brand. Their 3/16 orbit is the one most used. 3/8 is pretty aggressive and hard to handle. The 3/32 is fine but I find the 3/16 leaves such a good finish I seldom need the fine one. You need about cfm to run them which equates to a full 5 hp ( real hp ) 80 gallon compressor. The larger the tank, the less likely you are to need a dryer. I use a dryer in humid weather to keep the sander from spitting. 3 m makes sanders almost identical. If you have the compressor, air sanders are hard to beat. Dave

[Matt Day]

Perfect David, thank you. I was going to help my friend buy a new compressor but needed to figure out what the sanders draw in terms of cfm.

[Van Huskey]

Since Dave gave what I think is a great answer I will add an aside. Mirka, in particular, is pushing their brushless electrical sanders into the markets that have been strictly pneumatic for decades. The power, longevity and form factor of brushless DC motors is starting to make a serious business case for electric. They are MUCH cheaper to run than pneumatic and I have a funny feeling pneumatic sanders days are numbered in industrial and commercial settings.

[Doug Dawson]

I’ve only used electric ROS’s, and have someone asking me about air powered ROS’s. I’m guessing some pro shops use these? Can anyone suggest some make/models I should look at?
Thanks

The problem with air-powered sanders is that they require oiling (preferably inline) and there's always an issue of residual oil spitting on the wood, which is bad mojo re finish contamination. I would never dream of using them for woodworking. This is not something you should be thinking about.

[David Kumm]

Doug, your point is well taken. I've never had oil on the wood but dry air is important to reducing the amount of oil needed. A few drops every hour or two is about all I ever need as a hobby guy. You also need a vac attachment for any sander. Buying a compressor for sanding ( and a dryer ) screws up the economics compared to a Mirka type electric so you need to have the large compressor on hand. Like any tool, you have to learn how to use it correctly. Applies both to the sander and the compressor. A slow running compressor with a large tank, good filters, and some way to capture the moisture are critical. You can't go to Home Depot and expect a great result with a compressor. Dave

[Kevin Jenness]

A good air-powered sander doesn't spit oil. They are standard in most commercial woodshops for good reasons; ergonomics, longevity and productivity. They do take a ridiculous amount of power vs electric ones and Mirka makes a very good sander, but I doubt the electronics will last as long as a minimally maintained Dynabrade at 1/3 the purchase price.

[Martin Wasner]

Since Dave gave what I think is a great answer I will add an aside. Mirka, in particular, is pushing their brushless electrical sanders into the markets that have been strictly pneumatic for decades. The power, longevity and form factor of brushless DC motors is starting to make a serious business case for electric. They are MUCH cheaper to run than pneumatic and I have a funny feeling pneumatic sanders days are numbered in industrial and commercial settings.

This.

We just bought two more Deros sanders.

My air compressor costs about $.15/min to operate. I don't know what it costs to run a Deros, but I'm pretty sure the five we have, all running at once, won't cost that. With 53cfm my compressor can really only keep up with three at a time as well.

We still use air sanders for some things. The maneuverability and balance make them hard to beat in some situations.

[Doug Dawson]

Doug, your point is well taken. I've never had oil on the wood but dry air is important to reducing the amount of oil needed. A few drops every hour or two is about all I ever need as a hobby guy. You also need a vac attachment for any sander. Buying a compressor for sanding ( and a dryer ) screws up the economics compared to a Mirka type electric so you need to have the large compressor on hand. Like any tool, you have to learn how to use it correctly. Applies both to the sander and the compressor. A slow running compressor with a large tank, good filters, and some way to capture the moisture are critical. You can't go to Home Depot and expect a great result with a compressor. Dave

You need oil _in_the_tool_. It doesn't matter how it got there upstream. I do a lot of automotive work, and I have an elaborate system for super clean/dry air, for painting, finishing, etc. But the tool needs the oil. If it doesn't get it, that tool is gonna die. Inline oilers (or the equivalent) are the way and the truth. And that's the point of contact with a sander and the wood, and there's no way around that.

[Van Huskey]

A good air-powered sander doesn't spit oil. They are standard in most commercial woodshops for good reasons; ergonomics, longevity and productivity. They do take a ridiculous amount of power vs electric ones and Mirka makes a very good sander, but I doubt the electronics will last as long as a minimally maintained Dynabrade at 1/3 the purchase price.

There is no question that for the foreseeable future the cost of electric brushless sanders will far exceed the cost of pneumatic sanders both upfront and running costs but the cost of buying, maintaining and powering the compressors and refrigerated dryers in commercial and industrial settings is where the business case goes wonky in today's world. Using compressed and dried air to spin a sander is incredibly energy inefficient. I can see industrial settings where the power is rectified in a central location and only feedback load control is built into the individual tool reducing the need for the amount of miniaturized electronics onboard the sander. In a lot of settings, you wouldn't even need speed control onboard.

[David Kumm]

The economics are not always clear. I had the compressor and shopping CL and other sources I've accumulated about a dozen sanders of various sizes, orbits, round, square, orbital, inline, etc for less than the price of one new Mirka. Some used, some NOS, and even a couple new. I'll be dust before the energy cost becomes a deal breaker. I'm not advocating but I do like my Dynabrades. Dave

[Warren Lake]

Been happy with Dynabrades as well. Four over 35 years and the last two are two different models one heavier and one maybe composite so I can fling that one around on bullnose type stuff easily. I dont run a full size air line and up my pressure so very little weight hanging off from an air line. Swivel fittings can make lots of air stuff more comfortable. As David said 5 HP 2 stage 80 gallon tank. Id consider that your minimum.

[Peter Kelly]

I’ve only used electric ROS’s, and have someone asking me about air powered ROS’s. I’m guessing some pro shops use these? Can anyone suggest some make/models I should look at?
Thanks

Either the 3m Elite Series or the Festool LEX 3 150/3. Both sell for around $250 or under.

Per above, you'll need a compressor that can deliver at least 16 CFM at 90psi to run a single sander. Not the most efficient arrangement.

[Bill Dufour]

I understand the cheap HD or Hf use about 50% more air for the same work.
B il lD

[Van Huskey]

The economics are not always clear. I had the compressor and shopping CL and other sources I've accumulated about a dozen sanders of various sizes, orbits, round, square, orbital, inline, etc for less than the price of one new Mirka. Some used, some NOS, and even a couple new. I'll be dust before the energy cost becomes a deal breaker. I'm not advocating but I do like my Dynabrades. Dave

The monetary cost/benefit analysis actually seems to become much more complex and murky for a hobbyist and why I only mentioned commercial and industrial settings. For the hobby guy a large relatively high volume compressor can be a multifuntion power source. It lets one buy high quality but much cheaper sanders, you can use a venturi vacuum system instead of a pump, you can buy a good gun instead of a 4/5 stage HVLP turbine and there are a ton of air tools that save a lot of money over electric especially if you do work other than woodworking. The energy costs can easily be outweighed by all the different things one can do with compressed air.

I really like air sanders, the feel in the hand and the control is amazing. Prior to the introduction of brushless sanders there wasn't really much of a discussion about air vs electric but the Mirka Ceros/Deros and Festool EC sanders which also bring noise and dust reduction to the mix add a lot of fuel for discussion.