April 19, 2022

Why does my drum sander leave roller marks?

Roller marks are a result of failure in the drum sander. These include incorrect sandpaper alignment, uneven wheels, incorrect drum pressure, imbalanced drums, loose V-Belts, failed bearings, or poor subfloor construction.

Roller marks can come from using too fine a grit with a big machine. Drum sanders are great at initial cutting passes, but aggressive sanding with the highest grits can lead to complications. A drum sander can leave swirl marks due to poor quality sandpaper, improper technique, or an inability to clear the dust from the surface.

Once the roller marks appear, there are solutions to fix the problem to be discussed later in this review.

Serious mature carpenter putting wooden plank in drum sander for woodworking

Possible reasons a drum sander leaves roller marks

  • The reason that a sander will side-cut, is an incorrect sander set up to cut flat. That leaves lines on the floor on one side of the cut path. It’s a good idea to take some time to level the machine at the start of your job.
  • Too much drum pressure on the wood can also cause this problem. The softer the wood being sanded, the less pressure you need from the drum on the wood. However, it happens with hardwoods like oak, maple, and pecan but checking the drum pressure, and adjusting pressure eliminates this cause of vertical sanding lines on the floor.
  • Speed of sanding affects the performance of your machine. Moving too slowly while sanding will leave lines on both sides of the sanding path. Make adjustments to your sanding speed.
  • There are times when the new drum’s edges are not bevelled. Beveling the edges involves little sandpaper and rounding off the edges.
  • Sometimes the rubber delamination on the edge of the drum, and centrifugal force causes the rubber to move away from the centre, causing vertical lines on the floor. If that happens, replace the drum.
  • Sanding over nails or staples dulls the mineral on the sandpaper, which leaves a line of less sanded streaks in the cut path. If the fastener has cut through the abrasive and gouged the drum, replace the drum because the abrasive will not be supported where there is missing rubber.
  • If the paper tracking is not consistent, the paper might be moving back and forth on the top roller. That leaves vertical lines. Adjust the paper tracking, centre the sandpaper on the drum, and check the quality of the sandpaper to take care of a few of the troubleshooting. If this does not work, try replacing the top roller.
  • Wheel problems also cause vertical lines. Drum sanders with steel wheels cause vertical lines when the wheels are worn. Sometimes the steel wheels on the sander become so worn that there is no crown left. That leaves edge marks, especially on softer species of wood. Bent truck brackets, where the machine is cutting flat but where one wheel is at a severe angle, will leave lines. Check to make sure the wheels are in tip-top shape. Replace the wheels. Lubricate the wheels for maintenance (Jettools) .
  • Debris on the top roller and drum will cause the sandpaper to bulge, leaving the vertical lines on the floor. Keeping your machine clean will solve this.
  • When sanding the floor, if the operator does not follow the same path on the forward and back passes, does not use the proper overlap on the cut pattern, or pushes on the feathering handle, there can be lines left on the floor. Sometimes it will leave broken or skipped lines.

How to remove chatter marks from hardwood floors

Hard plate

Amongst the solutions you can use to remove chatter marks from hardwood floors is hardplate. It involves taking an aluminum felt-backed block known as a hard plate and attaching it to a floor buffer. You can then attach a Velcro Abrasive disc or bolt on a paper disc.

The purpose of the rigid plate is to spread the sanding out in a larger surface area. It does not allow the abrasive to follow the chatter pattern. That makes it an effective method for cutting through the peaks and valleys of chatter to get the floor flat again. The hard plate has a felt pad attached (Norton abrasives.com).

Multi-disc sander 

Using a multi-disc sander is another method that removes roller marks. It looks like the Lagler Trio. 

Change grit

You can try taking off less on each pass or change the grit to 120. However, using your random orbital sander after the drum sander can be the best option. Sand the whole item to the desired smoothness. If the doors are already assembled, you cannot avoid cross-grain sanding using a drum sander. 

It will be a challenge removing those scratches with a random orbit sander, even if you start with 80grit. If you had started with 120G or 180G in the drum sander, you would also have cross-grain scratches, but it would have been easier to eliminate with your ROS. 

Perform maintenance tasks, troubleshooting, and repairs to your drum sander to eliminate the vertical lines.

Chatter marks wood

Chatter marks describe a rippling pattern of half-circle marks that appear on hardwood floors due to improper sanding. Although these marks are hard to detect during the sanding process, they become more visible after applying stains.

How to get rid of sanding marks

  1. After final sanding, add some mineral spirits or denatured alcohol. It makes the remaining sanding scratches much easier to see.
  2. Inspect your sanding job between each grit.
  3. Apply enough coats of finish.

How to fix swirl marks in wood

  1. Sand the wood in the direction of the grain. It has to be parallel with the grain in a small oval-shaped area around the scratch.
  2. Sand in 1-inch movements forward and back, over the crack with minimum pressure.
  3. Check your progress as the stain begins to disappear. Lean your head down so that light reflects off the surface of the wood. If you can still see a scratch, continue sanding over the crack until the scratch disappears.
  4. Sand the area around the place where you sanded. Blend the edges of the bare wood into the surrounding stained to avoid sharp distinction from where you sanded. Keep looking at an oval-shaped sanding spot when you are finished, with bare wood tapering to stained wood.
  5. Apply stain to the sanded area with a soft cloth and wipe it off. Check to see if you have removed the scratch. Sand again and apply more stain if not satisfied.

Hard plate sander

After sending the edger, finish off with a rotary sander using a hard plate system. The hard plate has a felt pad attached. The hard plate spreads the sanding out in a larger surface area and will not allow the abrasive to follow the chatter pattern.

Sanding marks on the hardwood floor

Vacuum or sweep up the dust accumulated from sanding. Reload the sander with 180-grit sandpaper and sand the floor again to remove the remaining swirl marks. The 120-grit paper will remove most of the swirl marks, but finer-grit sandpaper will remove deeper marks.

David D. Hughes
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