Sanding Hard Maple

A cabinetmaker complains of little swirl marks, and gets advice on sanding (and card scraping) technique. July 21, 2005

Question
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 can’t 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.

Forum Responses
(Cabinetmaking Forum)
From contributor B:
I don’t 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 isn’t 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.


From contributor J:
I would suggest easing up the down pressure on the sander, and see if that helps. Too much pressure increases swirl, instead of random orbit.

From contributor T:
What is the diameter of the orbit of the sander? We use two Dynabrades in our shop, a 3/32" orbit and 3/16" orbit, and the 3/32" is for finer sanding. Hard maple is one the toughest to sand because there is minimal grain and it is very hard. I sand with my wide belt sander up to 180 grit, and then use 120, 180, and 220 with my Dynabrades and then follow that with a small amount of hand sanding.

From contributor S:
I would suggest that after you sand with 150, grab a block and wrap it with some 220 or higher, then start sanding with the grain. It’s more work, but it does work well.

From contributor K:
While the posts above are viable alternatives, there's another that solution I'm surprised no one has mentioned. A well-honed card scraper (not a cabinet scraper) will eliminate any and all sanding marks, swirling or otherwise, in just a few pushes and/or pulls. The hardness of the material is irrelevant, in fact, the harder the better.

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.


From contributor E:
The problem you have could actually be one of several things. Most likely you are applying too much pressure on the sander. Let the sander do the work. Your rougher grits will take a while to get through, but by the time you get to 220 or 320 it will go rather fast. (Don't skip grits.)

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.

I’m 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.


From the original questioner:
I checked the wide belt Timesaver (built in 1974 and is a great tool), and the paper was 80 grit. I can’t believe I neglected to check it before I started. It was set for poplar face frames. My shop only carries 80,100,120, and 150 grit Dynabrade sandpaper.

From contributor R:
Not all, but most people don’t like sanding and try to get this important task finished as soon as possible. I found that slowing down the speed of the sanding helped in eliminating the swirl marks. Sanding with the proper grit paper also helps.

From contributor F:
I have something to further add about using card scrapers. I had been sharpening and using them for about 15 years and they would remove stock, but never really leave a finish that didn't need further refinement. Then one day I took the time to read a good article on preparing them and for once I decided to really take the article seriously and heed the advice.

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.


The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

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.

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