Turning Sander on while touching the workpiece?

[ForumMFG]

Guys,

I found that if you use an oil to finish something you get better results to start the sander on the work piece and then turn it on instead of turning it on and then go into the work piece.  If you don't come into the work piece at just the right way while it's on, you will get swirl marks and they stand out a lot more then just on bare wood.  I'm a person who starts the machine off the workpiece but I have since changed that for wood that is finished.

 

[peter halle]

During the training class this issue came up.  There is a split of opinion there also.  Brian recommends starting it while on the workpiece.  Any scratches will be sanded out.  Also, starting it in the air and then lowering it onto the piece requires that it is placed evenly flat so as not to cause gouges.

When sanding drywall compound I start the sander while touching the surface.  Soft surfaces will gouge easily.

Peter

 

[Dave Ronyak]

Brice's comments well explain why it is important to not press down on your RO sander and why use of an adjustable vacuum machine (Festool's CT 22, for example) have a significant influence on sanding effectiveness.  I have an older Bosch 5" (125mm) RO sander which does not have a Pad Brake and Festool's ETS 125 which does.  With the Bosch, I place the sander on the workpiece, then start it.  With the Festool sander, I normally start it off the work.  If the downward pressure on the pad is too much, the pad will not rotate, and you won't get the best finish possible with an RO sander.