If you plan to sand any curved surfaces you should look for an orbital sander. Random orbital sanders can be used for both flat surfaces and finishing work, and are just as easy to handle as orbital sanders as they do feature a similar design. For overhead sanding jobs, use a drywall or long reach drywall sander.
This “random” motion results in a smoother finish, without the swirl pattern that can come from standard orbital sanders that only move in a circular motion. Random orbital sanders are extremely efficient for large projects.
If you had to purchase just one sander, a random orbital sander is probably the way to go. It's versatile, it does a great job, and can do most anything a sheet sander can do. However, most serious woodworkers will likely want to have both tools in their sanding arsenal given the relative merits of each machine.
For general DIYers, a good place to start is with a basic random-orbit sander—a square 1/4-sheet sander or round model. If you do a lot of furniture work, adding a detail random-orbit sander with a pointed, contoured head might be a good second tool to own.
In comparison to palm sanders, orbital sanders can remove material more quickly. Compared to palm sanders, orbital sanders will also remove more material. Although both sanders are regarded as being mild, the orbital sander in this comparison is more potent and will still remove more material than palm sanders.
5" models: Lean, light, effective
No wonder few models have handles for two-hand use. Sanding speed: As a rule, these models just can't match the fast stock-removal rate of 6" sanders. So expect to spend 30–50 percent more time using a 5" machine versus a 6" model for the same job.
The 240W 1/3 sheet sander (3.5 x 7.2 inches) offers no-load speeds up to 8,000 RPM. On the smaller side, the 200W 1/4 sheet sander (3.9 x 4.3 inches) reaches no-load speeds up to 12,000 RPM. Both sanders feature variable speed control which allows you to choose the right sanding speed for your projects.
A 1/2 Sheet Sander is usually a fairly large and heavy machine which is ideal for larger surface areas, while a compact 1/4 Sheet Sander is usually gripped in the palm of the hand and will fit into much tighter spaces.
We recommend you purchase a random-orbit sander as your first power sander. Random-orbit sanders can handle nearly any DIY task. Sure, they won't smooth gnarly wood as quickly as a belt sander or sand details like an oscillating multitool, but they can do just about anything when paired with the right sandpaper grit.
Random orbital sanders do the best job of finish-sanding wood. It's hard to know what type of sander to buy for your projects. We'll take the confusion out of buying a sander for finishing kitchen cabinets and explain why a random orbital sander is the best choice.
Besides operating at no less than 90 PSI of air pressure, random orbital sanders should run with a minimum speed of 10,000 RPM. If you run the sander at a slower speed than this, swirl marks MAY also appear. But if you drop below 90 PSI at any time during your orbital sanding process, you WILL get swirl marks.
Firstly, a final hand sand before finishing will always give a better finish than ending with a power sander as, no matter how fine a grit you use, there will always be scratch marks left by the power tool. You can also fine tune spots that may need extra care, which could be too small for a power sander.
Generally speaking, the higher the wattage the more powerful the sander but belt speed / orbits per minute (OPM) is also an important consideration when buying a sander. If you're working outside, consider a cordless sander.
Random orbital sanders are designed to be used and moved slowly. So, what's the ideal speed? About ten to twelve seconds per linear foot, about an inch per second. This feels incredibly slow and tedious, but that's what it takes to let the random oscillations do what they're designed to do.
A hand sander or sanding block is needed for lower and middle drywall areas. Use a pole sander with an attached extension handle for higher wall areas and ceilings. Hand sanders and pole sanders use sanding screens fitted with sandpaper.
Your best bet is probably an orbital sander. You could hand sand your cabinet, but it will take a lot of elbow grease. You may even want to use both. An orbital sander can make quick work of the bulk of the cabinet door, but a sanding block or sanding sponge can help you cover any grooves or tight spots by hand.
Random orbital sanders have two major things in common with rotary sanders: (1) they use a circular pad, and (2) disk moves in rapid circles. But the 'random' part of the name tells you the major thing that sets it apart: random orbital sanders vibrate.
2.5mm: For fine finishing, ideal for between coats to provide a premium finish. 5mm: For aggressive stock removal and fast sanding of fillers, primers and old paints.
Most random orbital sanders used by DIYers take 5-inch discs, which is the best size for fine sanding without creating any swirl marks or scratches. However, you'll also find sanders that use 6-inch discs.
Disk sanders range in size from small, hobby machines with 4"-dia. disks to industrial, 36"-dia. giants. For the home shop, 12"dia. is a pretty common size.