In this issue, I’m taking a close look at a few miscellaneous air tools for the home shop. Air compressors can power much more than nailers; there is a wide selection of other tools that can be powered by a compressor. I will be taking a close look at hoses, air sanders, and paint sprayers. These valuable tools can transform your compressor from an occasionally used tool to one that you rely on daily. While air sanders require a big compressor to power, the sprayers I tested in this article will work with a few of the compressors I tested in our Aug/Sept 2015 issue. Be sure to check your compressor’s CFM rating, no matter what tool you’re powering with your compressor.
While hoses are not exactly tools, they are a critical part of owning an air compressor. The air has to get from your compressor’s tank to the inlet on your tools. Four types of hose are widely available in the market today: PVC, polyurethane, hybrid polymer and recoil.
PVC hoses are generally the least expensive type. The hard shiny outside is easy to clean. PVC hoses do the job, but the downside is that they are the least flexible of all the hoses available, especially in cold temperatures. Many manufacturers offer this style of hose, complete with air coupler, in both 25′ and 50′ lengths.
Polyurethane hoses are a step up from PVC. Polyurethane hoses are not only strong and puncture resistant, but they are very light, weighing as little as half of the same-sized PVC hose. Polyurethane hoses are also non-marking, so you can drag the hose over a floor or around trim without worrying about marking everything up. Polyurethane hoses also stay more flexible at colder temperatures, and are very flexible in warm temperatures. One downside to polyurethane hoses is that they tend to have a mind of their own. Polyurethane hoses have some “memory”, and they tend to have a natural curl, recalling the days and months spent coiled up before use. Because of the curl of the hose, it doesn’t always lay flat across the shop floor, and that can be a bit of a trip hazard.
Hybrid Polymer hoses are newer in the market place, but several manufacturers in Canada, like King Canada, Crisp-Air, and Bostitch, offer these hoses to consumers. The hybrid polymer hose blends PVC with rubber to provide a hose that is very soft and flexible, kink resistant and strong. Hybrid hoses cannot be used in as cold of a climate as polyurethane hoses can be (typically -30C as compared to -40C), but for indoor users, or non-extreme winter conditions, they are ideal. The flexibility means they will not kink or bunch up on the floor like other hoses, and they do not have a “memory” so if they’re left coiled for a long time, they will not try to hold that coil shape. One disadvantage is that hybrid hoses are heavier than PVC and rubber hoses.
Recoil hoses are purposefully made in a spiral shape and will self-coil. Recoil hoses are designed to be easy to put away and store as they wind themselves up when you let go of them. Recoil hoses can be made from several different types of material, the most common being PVC, nylon, and polyurethane. While the price point of the PVC and nylon hoses might be very attractive, these hoses don’t typically function well. The plastics they are made from are too stiff to allow the hose to move and stretch as needed to function well. Over-stretching these hoses, especially in cold weather, can cause them to crack. If you are going to buy a recoil hose, be sure to buy a high-quality polyurethane version, which is strong and flexible. Play with the hose in the store as much as you can before you buy it to see how soft and flexible it is. Generally, the more flexible it is, the better the hose will perform.
I was able to test drive several Mirka air sanders for this article. I tested Mirka’s MR-6SGV, MR-38SGV, and PROS 650CV. I was impressed by the sanders. Not only did they run smoothly with very little vibration, but I was also surprised how well the self-powered vacuum worked. I didn’t really expect much from the vacuum portion of the tool. Most sanders with a dust bag don’t collect half of the dust you generate, but these vacuum systems picked up most of the dust generated by the sander. Mirka’s sanders also use a fine mesh abrasive, as opposed to sheets of sandpaper. The mesh allows the vacuum to pick up dust through the many holes in the backing pad, and prevents the sandpaper from clogging. I was surprised during my testing how long a piece of the mesh abrasive lasted compared to conventional sandpaper. During my testing, I sanded some fairly fresh epoxy to see just how well the mesh performed. I was able to sand about 2 sq. ft. with just one piece of abrasive. The same job with my electric random orbit and sandpaper required six pieces of sandpaper.
Mirka’s 6″ round random orbit machines do an excellent job finishing broad flat surfaces. They also have 5″ round random orbit sanders available. The MR-38SGV is a rectangular random orbit sander, 77 × 193 mm, or roughly 3″ × 8″. This sander is useful for reaching into corners. Both types use Mirka’s Abranet (mesh abrasive), which is available in a wide range of grits.
Festool has a number of air sanders available, but for this article I took a look at the new LEX77. This model is very compact, with a 77 mm diameter pad. The small size is ideal for spot sanding, and for touch-ups during finish coats, not to mention smaller projects. However, out of the box, the sander cannot be run on its own. Festool uses a special connection on the sander to connect it to a unified air/vacuum hose, which is designed to connect to their dust extraction system. Alternatively, users can purchase a special adapter which allows the sander to be connected directly to a standard air line.
The Campbell Hausfeld sander spins at a high RPM (18,000) and is designed to get the job done quickly. The machine comes with several different sized back up pads, to which you apply sandpaper discs. The Campbell Hausfeld sander simply spins; it does not have a random orbit, and because of this it is very aggressive. However, it is more suited to rough stock removal than finishing work. This type of sander is designed more for quick levelling of fillers and rapid stock removal than finish sanding.
The Mastercraft sander I tested also has a self-powered vacuum similar to the Mirka sander I tested. The Mastercraft sander comes equipped with a 5″ × 8-hole Velcro pad that is quite common amongst most electric random orbit sanders. It also comes with a 5″ no-hole PSA backing pad that can be installed as an option on the machine. The advantage of the stock Velcro pad is that you can find sandpaper in a 5″ × 8-hole configuration at just about any hardware store, and use dust collection on the machine. The self-generated vacuum did not work nearly as well as the Mirka. While the vacuum hose was more flexible, it was also smaller in diameter and shorter, placing the vacuum bag closer to the sander, which was less ideal to work around. (The hose on the Mirka was long enough that I could place the bag under the bench, out of the way.) While the collection bag on the Mirka sander had a substantial amount of dust in it by the end of my testing, the Mastercraft had collected almost no dust at all. The sander functioned well, but be prepared to supply a vacuum if you want to minimize dust.
I was pleasantly surprised with the Mastercraft sprayer (58-9312-8) I tested. This is a compressor driven HVLP gun. This gun is designed to run from a conventional air compressor rather than a special turbine. While these types of compressor driven HVLP guns used to take large amounts of air (CFM) to run, newer compressor driven HVLP guns use much less air. The Mastercraft gun uses 5.1 CFM of air, which is within the capacity of some smaller compressors. (There are guns on the market that use as little as 3.5 CFM.) I was able to spray water-based lacquer with the gun right out of the box. The gravity feed cup makes the gun a little top heavy when full, but it is still quite manageable. The gun did an excellent job atomizing the lacquer and making a nice smooth even coat, actually better than the name brand HVLP/turbine system I have been using for a few years. The small needle in the gun is ideal for thinner materials like lacquer, but thicker finishes will require thinning.
The Campbell Hausfeld gun I tested was a similar design to the Mastercraft gun. The finish on the gun is not quite as nice, and I did notice that the air cap configuration was different than the Mastercraft. The Campbell Hausfeld has fewer holes in the air cap, and I was concerned that the atomization would not be as good. However, after some test runs, the gun seemed to work fine, so this is not an issue. The gun did require some tinkering to get the right setting for the lacquer I used, but after I had it set, it sprayed just as good as the Mastercraft. It seemed like the paint volume setting was a bit more sensitive than the Mastercraft. It seemed to go from zero to full blast very quickly.
The third gun that I tested was a very basic unit, which operates on a siphon principle, spraying right out of a mason jar. The adjustments on the gun are very simple. There is a valve on the top of the siphon tube to open and close it gradually, and an on/off trigger. The gun sputtered a bit when I tried to spray with the siphon tube open only very slightly, but opening the tube up a bit gave a steady flow. To my surprise, I was actually able to spray some lacquer with the gun. The finish had some runs in it because the minimum nozzle opening required to get a steady stream with no spurts allowed too much finish through to get an even coat. I think this gun would be better suited to non-topcoat jobs like spraying stain or adhesive.