Hardwood Floor Drum Sander Vs Belt Sander
Drum and belt sanders for hardwood floor refinishing are two different tools. For all intent and purposes you’re likely to find belt sanders at the common rental places today. Reasons being they are easier to work with not only in functioning when sanding but working on the floor itself. Another difference is common belt sanders do not require the high energy drum sanders need. Larger drum machines need 220 volt power sources, while others only 110.
The Drum Sander
The more traditional drum sander manufactured in widths of 8 to 12 inches is capable of removing more material in one pass than others on the market. Examples being floors that require heavy sanding to remove deep scratches or complete removal of older hardwood floor stains or finishes.
Or in the case of refinishing many prefinished micro beveled floors that require removing the bevel for a uniform appearance; they simply get the work done quicker, but should be left up to a professional that has knowledge of the power they exert. By way of explanation, any inexperienced person at the controls can cause serious damage requiring repairs you would rather not see.
Belt sander machines look similar to a traditional drum sander. Sanding paper is different with both tools. Belt sanders simply allow one to slip sanding belts on and off without much effort. Drum machines take longer with abrasive sheets being wrapped around one single drum (photo above) and clamped into place by way of its own locking mechanism.
What Kind Of Grit To Use?
Professionals vary in what the best sequence of sanding grits to be used. While the National Wood Flooring Association (NWFA) recommends a three step system for refinishing, not all professionals follow their guidelines. It sometimes has to do with how they were taught the trade. Just like installers, finishers do things slightly different. It’s the outcome that matters.
I’ve seen both methods. Guys that follow the NWFA way and others that only use a two grit system with absolutely no difference. The two grit system usually starts with 36 or 40 and finishes with 80 grit. Following this, both finishing methods are finally screened with a rotary machine and usually a 100 grit screen.
• Start with 36 or 40 grit
• Second pass with 60 grit
• Final drum sanding with 100 grit
How. Where To Start Sanding?
During the initial sanding with a course grit, finishers usually start off a parallel wall shown in the first picture below on the left. Consistent movements are critical. Each and every pass going parallel to the wall has to be similar. Otherwise you may face problems in getting the initial course grit scratch marks out when moving to the next grit. When sanding, one should be overlapping the previous run along the wall when going backwards on the machine.
Do I Start In The Middle?
Most recommendations say to start the sanding process where two thirds (illustration below) of the floor is done on the first pass going forward. As you can see in the second picture (left below) the finisher has started by taking off about 80% of the room going in one direction. It doesn’t matter. It’s more of what the finisher feels most comfortable with, or how he learned the trade.
Old Floors. Wax Or Shellac
If you’re dealing with floors that have been covered with carpeting, or were installed prior to the 70’s, chances are great waxes and or shellacs were used. Methods will be a little different in that the staring grit may be twenty. See my pages on wax buildup removal that also includes a video.
View The Video
The following video covers these topics:
• Differences between a belt sander and drum sander
• Recognizing what grit to start with
• Proper grit sequences
There are several big machines used for refinishing hardwood floors. First we have a belt sander that rental centers offer, but far and wide a traditional drum sander is the choice of most professionals as they tend to have more power or torque in getting much older finishes off the floor like this heavily waxed and shellacked example. Don’t get me wrong, a belt sander works fine for floors that don’t need aggressive sanding.
So how do we know what needs to be done? By analyzing. In the example shown here the finisher checks for flatness and what kind of finish may be on the floor. If there are boards higher and lower than another or an older finish present, he needs to be more aggressive with a lower sanding grit to start.
Often it doesn’t take much thought in how to start like this massive dog stained floor that was actually brought back to life. You can view that in our related videos at the end. On this job all the rough edging while also using 36 grit was completed prior to using to the drum sander.
Assuming your floor doesn’t have the mentioned issues we’ll use an example floor that was probably installed in the 70’s judging by the pegged style. Regardless of what the handyman says, 36 grit is a standard starting grit for a typical hardwood floor like this. In this first drum sanding sequence the goal is removing all the older finish to bare wood and removing scratches dings and dents
After full trowel crack filling followed with a proper drying period, the edger is used again with a finer 60 grit. This is then followed up with the drum sander a second time with 60 grit as well. The purpose here removing the deeper scratches made by the coarser 36 grit.
Important tips for drum sanding include:
• Keep a steady and consistent pace.
• Lower and raise the drum lever when in motion, not when stopped.
• Never, ever stop the machine in one spot when the drum is lowered.
The last and final sequence with the drum sander before the buffer is brought in is an 80 grit sanding paper that follows the same sanding procedure. It’s purpose is to finely tune the floor removing the previous grit sanding marks.