Makita makes a point of advertising that the 9403 has the lowest decibel level in its class. It is supposed to operate at a mere 85 decibels. This is an unusual feature, but a welcome one. It makes the 9403 much more usable inside or on a jobsite in an office building.
The 9903 comes in at 13 pounds. Like its powerful motor, the 9403’s weight places it in the heavy-duty category of belt sanders. That 13 pounds comes in handy for sanding a hardwood floor or grinding away at angle iron for hours on end. Of course, the heavy weight means it’s best to keep the 9403 in the horizontal position.
Makita has really designed the 9403 for heavy duty use. In addition to the powerful motor and bulky design, specially engineered seals are used throughout the motor compartment to abate dust infiltration. Fine dust particles, which are constantly produced by belt sanders, can sneak into an electric motor, clog the bristles, and render the entire thing a paperweight. The heavy-duty seals on the 9403 mean the sander can suffer heavy use on job after job without ever slowing down.
The use of ceramic platens on which the belt is attached are replaceable, and it is an interesting design feature. Many sanders use stainless steel in an effort to reduce wear on the platen and extend tool life. Ceramic does not heat up as quickly as those metals, meaning the platen retains its shape longer and doesn’t transfer wear to the belt. While the ceramic may crack eventually, where the stainless steel wouldn’t, simply replace the platen and move on.
The Makita 9403 has the basic, boxy design like most belt sanders. A pistol grip handle is located on the anterior of the tool with a trigger operation switch. This pistol grip handle has a familiar operation mechanism (squeeze the trigger) and makes for a comfortable place to rest your hand. The slanted angle means the user can transfer a little bodyweight onto the tool, both for applying pressure to the workpiece and reducing user fatigue.
The 9403 has another handle on the front end of the belt sander for the other hand. The 9403 is a little lacking here, though. While many sanders have a bulky, padded handle on the front, the 9403 basically has a small knob. It’s not really enough room to rest one’s hand. Better off placing the hand on top of the motor.
The 9403 has Makita’s most powerful belt sander motor. At a whopping eleven amps, the 9403 is just about as big as it gets for belt sander motors. Eleven amps translate into 1,640 square feet per minute. This tool can chew through hardwood like child’s play. In fact, a belt sander with this kind of power is best reserved for wood and metal surfaces only. This is not the belt sander for drywall work or sanding small furniture parts or carvings.
The 9403’s variable speed control allows the user to throttle down the power generated by the electric motor. While the amount of material sanded off in one pass can be partially controlled by the pressure applied by the user, a variable speed control means no gouging when starting sanding. It also makes the tool more usable for softer surfaces like pine, balsa, or plaster. (Still, there are belt sanders in the five or six amp range that are better for those materials.) Simply turn the variable speed knob back and forth to make the most of the 9403’s powerful electric motor.
The 9403 goes all out in every design feature, sanding belt included. The 4”x24” belt is absolutely huge, removing 0.75 square feet of material at a time. When you’re facing down a pile of fence planks or three thousand square feet of oak flooring, every extra inch on the sanding belt counts. Noticing a pattern? The 9403 is heavy-duty and big.
The 9403 has an exposed nose, meaning it can be used for flush sanding. Run it right up against baseboards to sand every last inch on a wood floor. The nose is not really exposed enough to use for contour sanding, though.
The 9403 has an auto-track system rather than a manual belt centering system. These automatic systems can sometimes be unreliable. However, Makita has spared no expense to deliver reliability with the 9403, so the auto-track system is better than most. Make sure to check the belt regularly and the auto-track system will not disappoint. With the extreme power and weight of the 9403, it’s especially important to check that belt to prevent accidental gouging.
Makita includes a 80 grit sanding belt with all 9903 purchases.
Belt sanders, like all removal tools, constantly produce large amounts of sawdust and other fine airborne particles. Both for keeping a clean worksite, reducing potential health hazards, and ensuring proper tool performance, it’s important to reduce the amount of particulate being thrown around in the air. Sawdust is, of course, a pain to sweep up. Worse, fine dust can get into the motor housing and eventually wear it down. Worse still, that same fine material can be accidentally inhaled and create respiratory problems over time. Wear a dust mask and make use of the 9403’s built-in dust collection system.
A tiny exhaust fan directs sawdust being created underneath the sander up through a port into a cloth collection bag attached to the top rear of the sander. Cloth has its drawbacks for dust collection since some finer particles will escape through the cloth. Again, wear a dust mask. Don’t worry about the 9403’s motor since it has those specially designed seals.
For convenience, the dust collection bag on the 9403 can be rotated 360 degrees. This feature makes it easy to keep it out of the way in tight spaces.
Makita may not be known for producing heavy-duty, pro grade tools…yet. If they keep churning out beasts like the 9403 belt sander, that reputation will change. This tool represents the most powerful, biggest, most feature-packed class on the belt sander market. It’s a great choice for any carpenter or contractor.