Stumped? Everything You Need to Know about Stump Removal Attachments

Loftness Stump Ax

There are many types of stump removal tools and procedures. Some are suitable for property owners but not contractors, like those walk-behinds offered by DR Power Equipment. Two other examples include chemical treatments and burning. Both take more time than a contractor is willing to allot, and both have safety and environmental considerations making them generally unsuitable for commercial use. Some stumps require brute force. Stump pullers use simple mechanical devices to remove stumps, but their capacity is limited. A stump grapple attached to a host machine, typically an excavator, pulls the stump out like a tooth extraction. There are hand tools, but a worker with an adze and a reciprocating saw is going to take a long time to remove a stump of more than 4 to 6 in. in diameter — if it can be done at all. This brings us to the two most common stump removal attachments — the wheel saw and the screw type.

Wheel Saw: Low Cost, but Slow and Messy

ASV Stump Grinder

Wheel saws are what come to mind first for most folks when thinking of a stump cutter. They’re popular for several reasons, not the least of which is their low cost. A simple wheel-type stump cutter may be as little as $5,000. They’re simple to set up and operate. Larger styles are often mounted on a dedicated trailer, but smaller ones can be easily mounted to a skid steer or compact track loader using a universal skid steer mount or Common Industry Interface (CII) mount. Hydraulic demand tends to be high, but there are models compatible with standard-flow hydraulics. Flow dictates wheel speed, and generally higher is better. Maintenance costs are low and consist mostly of periodic replacement of cutting teeth.

Drawbacks? Two, mainly. First, they’re slow. Stump removal entails multiple side-to-side passes, each one taking mere inches off the stump. The least expensive models require the operator to use counter-rotation steering of the host machine to accomplish this side-to-side motion, which makes the process even slower and adds the cost of tire or track wear to the net profit calculation. Some wheel-type stump cutters have a sweep feature built into the attachment. This speeds up the process, but it’s still not fast. Sweep right, inch forward, sweep left, inch forward. Repeat the process, lowering the stump cutter a few inches after each complete series of sweeps. A big stump can take an entire afternoon, depending on the depth of the cut. And you don’t want to stop too soon, especially if the stump is located in a finished area. Shallow soil will dry and turf will brown quickly during dry spells, calling attention to the stump that remains just below the surface.

Second, wheel-type saws fling debris widely. This can present a safety hazard — see sidebar at the bottom — but really adds time to the cleanup process. Is cleanup required? In a finished lawn, yes. In a pasture or other unimproved site, no, but why remove stumps from such sites in the first place? Most stump removal will entail cleanup and a fastidious customer may insist no chips remain. Steps can be taken to limit the area over which chips are dispersed, but that only helps a little with cleanup.

Loftness offers two models of its Stump Ax wheel-type stump removal tool — 24- and 31-in. diameters. Both have direct-drive hydraulic motors. “These are pretty simple attachments with few variations, so there aren’t a lot of options available or required for spec’ing a Stump Ax to the customer’s needs,” says Tryg Waterhouse, director of sales. He says the one key spec is to match the hydraulic needs of the Stump Ax to the hydraulic output of the host machine — see sidebar — and the Loftness website gives clear guidance for this. Each pass is good for about 2.5 in. of depth with the 24-in. model and up to 4 in. for the 31-in. Stump Ax, says Clint Major, product specialist with Loftness.

Hydraulic Horsepower

Attachment manufacturers list the hydraulic flow and pressure requirements for their products, typically in gallons per minute (gpm) and pounds per square inch (psi). Most equipment manufacturers list the same specs for the machines, including skid steer and compact track loader makers. But there is a move in the industry to list hydraulic horsepower, which some consider a better indicator of performance. The formula for hydraulic horsepower is simple: It is flow times pressure divided by 1,714, or (gpm x psi) ÷ 1,714 = hp. (We acknowledge that the parentheses are unnecessary because of the order of mathematical functions, but we include them for clarity for those unfamiliar with PEMDAS, which prescribes the order of those operations as parentheses, exponents, multiplication, division, addition, subtraction.) Because stump cutters are heavily dependent on flow, knowing only hydraulic horsepower is not enough. It is conceivable — although unlikely — that a host machine could have sufficient hydraulic horsepower but insufficient flow for a particular stump cutter. Be sure to check the flow requirements of the stump cutter and flow specs of the host machine when pairing one with the other.

Screw Type: Fast and Tidy but Expensive

John Deere SS30 stump shredder

The other main type of mounted stump cutter is the screw type. These cut quickly, and a single pass can clear the stump to the width of the cutter to a depth of several inches or more. Whether they are quicker than a wheel-type cutter depends on the specifics of the particular job. Repositioning the cutter removes stumps larger than the diameter of the tool. The chips mostly pile up around the tool, much as dirt would when using an auger, which expedites cleanup. There’s also a set-it-and-forget-it benefit of a one-time positioning of the tool. In very large stumps the tool may need to be repositioned, but in many cases a single pass is sufficient.

The downside is cost. Screw-type stump cutters can easily run $20,000 or more, although that additional cost is quickly offset with reduced cutting and cleanup time for contractors for whom stump removal is a frequent part of their business.

John Deere offers one stump removal tool, the SS30 High-Torque Stump Shredder. It is a low-speed, high-torque screw-type tool that is 28 in. wide. As with a wheel-type cutter, hydraulic flow controls cutting speed. The SS30 is designed for slow speed operation; 20 gpm provides 7.0 rpm of the cutter head and 45 gpm is still just 16.5 rpm. A single pass will remove stumps 8- to 28-in. in diameter. Repositioning the tool for additional passes removes larger stumps. A hardened pilot cone draws the cutter into the stump so that the blades can do their job. The blades are made of 0.75-in. thick AR500 steel. With a Brinell hardness rating of around 500 HBW, AR500 provides excellent resistance to damage from soil, stones and other non-wood materials. The blades are not replaceable but can be sharpened. Operating weight is around 1,400 lbs, “and no counterweight is needed during operation, although as in any application, counterweight can increase stability,” says Doug Laufenberg, sales marketing manager for compact construction equipment and attachments, John Deere.

A test was scheduled by Loftness for their prototype screw-type stump cutter for the week after our interview. It may be that the attachment is nearly ready for production or the test may lead to additional rounds of development and testing. “That’s just the way product development goes,” says Major. “You want to make sure the product meets reliability and performance standards before offering it to the customer, and that takes time.”

Richard Ries is a freelance writer for Compact Equipment.

Safety Factors

Regardless of type, stump cutters turn big, bulky stumps into little chunks of wood. Wheel-type cutters fling these chunks some distance. Screw-type cutters tend to mound the chunks near the tool, but it is possible they will throw a chunk and that chunk will likely be larger and heavier than those produced by a wheel-type cutter. Regardless of cutter type, steps must be taken to increase safety. Here are three fundamental considerations. 1) Do not allow people near the worksite. This includes other personnel and spectators from the public. 2) Protect the operator with a break-resistant door and eye protection; doors can be added to canopy-style machines for this purpose. 3) Consider fencing or barricades of closed material to confine chips to the workspace, especially when using wheel-type cutters. This will also make cleanup easier.