Uploaded August 2026 | Updated September 2026, 1 hour ago
Random orbital sanders solved one important annoyance. Sanding almost always needed to be done with the grain. Any other way and you’re cutting valleys across your stock, which looks terrible when you’re done.
An ROS gets around this by making countless overlapping swirl marks. By working through the grits, you create the illusion of a clear surface. But every once in a while, a stray swirl can survive, and you usually discover it after adding finish.
You can do everything right with your sanding progression and still have this problem. But why? One big reason is something you may have never thought about.
If you pull off a disc to move to the next grit and set it on your bench, particles can collect on the back. These things are debris magnets.
Any contamination trapped behind the disc can create a raised spot, making a few grits stick out farther than the rest. I tested this by setting a disc on my benchtop, putting it back on the ROS, and sanding for only a short time.
Then I checked the surface under the microscope, and here’s the proof. A single pigtail emerged.
If I hadn’t caught that and continued moving through the higher grits, that deeper mark could have survived the progression and popped out when the finish went on.
The solution is to make sure your discs are clean on both the front and back before using them.
This is only one cause. There are three more ways pigtails can show up, and I cover them in my latest Make Things Simplified video.
Like step by step projects? Check out the second channel! → @makethingswithrob
Become a patron! → patreon.com/makethings ←
Huge thank you to my patrons that keep this thing going!
*MAKER TEAM*
Michelle B
Keith Current
Rich Lightfoot
Tutor the Barbarian
Aubrey G.
Nukebert
Sam W.
Aaron Knows DIY
G. Salazar
David B.
Marc B.
Richard B.
Ben. K
Bill Patterson
D. Lundman
Make Things
#MakeThings #mtbitesize
Random orbital sanders solved one important annoyance. Sanding almost always needed to be done with the grain. Any other way and you’re cutting valleys across your stock, which looks terrible when you’re done.
An ROS gets around this by making countless overlapping swirl marks. By working through the grits, you create the illusion of a clear surface. But every once in a while, a stray swirl can survive, and you usually discover it after adding finish.
You can do everything right with your sanding progression and still have this problem. But why? One big reason is something you may have never thought about.
If you pull off a disc to move to the next grit and set it on your bench, particles can collect on the back. These things are debris magnets.
Any contamination trapped behind the disc can create a raised spot, making a few grits stick out farther than the rest. I tested this by setting a disc on my benchtop, putting it back on the ROS, and sanding for only a short time.
Then I checked the surface under the microscope, and here’s the proof. A single pigtail emerged.
If I hadn’t caught that and continued moving through the higher grits, that deeper mark could have survived the progression and popped out when the finish went on.
The solution is to make sure your discs are clean on both the front and back before using them.
This is only one cause. There are three more ways pigtails can show up, and I cover them in my latest Make Things Simplified video.
Like step by step projects? Check out the second channel! → @makethingswithrob
Become a patron! → patreon.com/makethings ←
Huge thank you to my patrons that keep this thing going!
*MAKER TEAM*
Michelle B
Keith Current
Rich Lightfoot
Tutor the Barbarian
Aubrey G.
Nukebert
Sam W.
Aaron Knows DIY
G. Salazar
David B.
Marc B.
Richard B.
Ben. K
Bill Patterson
D. Lundman
Make Things
#MakeThings #mtbitesize
