The shop I work in does mostly poplar paint grade work, but we have a job that requires hard maple. I am finding that no matter how much I sand with the Dynabrade air sander starting with 100 - 120 - 150 grit paper, I canít get out all the little swirls. This is going to be a stain grade job, so I tested a piece with the stain and the swirls jumped out at me big time. I tried the wide belt sander, but nothing seems to work, and I am still finding those swirls in all my door stiles, rails, and on my face frames. Any ideas would be greatly appreciated.
From contributor B:
I donít have a bunch of fancy gadgets like a lot of people, but I've had no problems sanding hard maple. I usually run my 3x21 belt sander over the frame/door members prior to assembly to get the jointer/planer marks out (fine grit belt), then after assembly run my PC 5" ROS over it. My eyesight isnít what it used to be, but I don't see any swirls. Maybe you're not getting a random orbit. My old Rockwell 1/2 sheet sander leaves swirls, but the random orbit doesn't.
A scraper sharpened on a belt sander is going to have built-in grit marks in the edge that will transfer to the piece. It's fine for rough scraping glue lines etc., but if you take just a few minutes to hone it right you'll find yourself sanding less and less. And once it's honed, a scraper will last a very long time with just a few touch-ups now and then.
The next likely problem is that your sanding pad is not balanced. This is also common problem, especially when the pad has been replaced with a brand other than Dynabrade. We use the 3/16" Dynabrade and have no problems with maple or any other material, so I don't believe that you need to get the 3/32" diameter sander to achieve a smooth swirl free surface.
It is important to vacuum up or blow off the dust in between grits as well, otherwise you are grinding the dust and broken grits from the previous sanding into the surface of the wood. If you've went through the above and still are having problems then most likely your sander is misbalanced and should be replaced.
Iím not sure I agree with a few things above; Dynabrade or other quality pneumatic sanders are far superior to electric sanders, especially electric sanders with brakes on them. The scraper idea is a great one, although like most hand tools, it does take some time to develop a feel for the tool and requires frequent tune ups to achieve the desired results. Then again, so does proper sanding.
In a nut shell, the article suggested first filing the cutting edges square and straight with a good mill file. Then the faces of the scraper and the cutting edges must be refined with stones or wet or dry paper to the same refinement you would apply to a fine chisel back or plane iron back.
You must use a "burr rolling device" that has a surface that is just as refined and polished as the scraper edges or else the burr you create will mirror the rough surface of the burr rolling device.
So, I heeded this advice and polished my burr rolling device on a felt wheel loaded with buffing compound. This made all the difference in the world and my scraped surfaces now shine like glass and can be stained and or finished without any further treatment.
Comment from contributor N:
I run a small door shop and we went through a very similar problem when we first started. We solved the problem by switching to Uneed sandpaper on our pneumatic sanders as well on our wide belt. We run our wide belt at 120. We then run the air sanders at 100, 120, 180 and 200.