Can random orbital sander be used for keeping sharp edges/corners?

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Forum topic by CrankAddict posted 10-22-2019 04:07 PM 370 views 0 times favorited 6 replies Add to Favorites Watch
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61 posts in 345 days

10-22-2019 04:07 PM


I’m finishing a picture frame that is 2” deep and 1” wide (no bevels). I need to do some sanding to remove slight flaws, ensure flush joints, and remove some glue residue on the ends but I’m concerned about rolling the edges and corners. Is it better (i.e. safer for a newbie like me) to use sandpaper on a flat block? If so, I wasn’t sure how to go about sanding the face corners in that case because in a single section I’d be going with grain on part and across grain on another part. What do you guys suggest?

6 replies so far

View Phil32's profile


699 posts in 446 days

#1 posted 10-22-2019 04:13 PM

With any sanding you use progressively finer grit until you’ve removed the scratches. So even though you will go cross-grain on part of the miter, you will have a smooth surface. Don’t be too aggressive!

-- Phil Allin - There are mountain climbers and people who talk about climbing mountains. The climbers have "selfies" at the summit!

View Dustin's profile


702 posts in 1283 days

#2 posted 10-22-2019 04:19 PM

I think I’d probably try to use my card scraper for the glue, then switch to sandpaper and block if I felt like the scraper weren’t sufficient. I definitely don’t trust myself to use my ROS without rounding those nice crisp corners.

-- "Ladies, if your husband says he'll get to it, he'll get to it. No need to remind him about it every 6 months."

View wildwoodbybrianjohns's profile


464 posts in 90 days

#3 posted 10-22-2019 04:35 PM

I always round over any sharp edges, sometimes just slightly, sometimes alot.

Not suggesting you should, but I think many woodworkers would agree that doing so gives a more professional look overall. This, of course, is for edges that the hand may contact. If it is something that hangs on a wall, for example, then maybe I wouldnt do so.

-- Wildwood by Brian Johns: It is wiser to find out, than to suppose (S. Clemens)

View Phil32's profile


699 posts in 446 days

#4 posted 10-22-2019 04:36 PM

If there is some slight misalignment of the miter, you might start with a block plane, taking very very thin shavings – then sanding with a flat block (no padding) behind the sandpaper,

-- Phil Allin - There are mountain climbers and people who talk about climbing mountains. The climbers have "selfies" at the summit!

View Bill_Steele's profile


597 posts in 2275 days

#5 posted 10-22-2019 06:41 PM

I think a sharp block plane or a hard block with sandpaper are good choices in this situation.

A block plane will make a very clean cut and will enable you to level one side of a miter joint that is a little proud. The flat block with sandpaper will enable you to do the same thing but may take longer.

With either approach, you will need to be careful around the joint line—because that is the place where you can easily sand or plane across the grain. If you do that don’t worry, just work through the grits as Phil32 identified and you will reduce or eliminate the cross-grain scratches.

I often use hard block with sandpaper. I buy different grits of sandpaper in rolls (~3” wide) with pressure-sensitive adhesive (PSA) on the back and make sanding blocks from MDF scraps. I mark the grit on the back of the block. You can cut the blocks into whatever shape will help you sand a tricky profile.

You could also use contact cement to glue normal sandpaper to blocks OR wrap it and staple it—lot’s of options here. A cork block also works well and has a little bit more give than a hard block.

For your miters you could angle the block and sand right up to the miter joint w/o crossing over. You may even be able to come up with a block shape that rides along the edge of the frame, has a miter on it, and will only allow you to sand to the joint line.

A ROS would be a good choice if it wasn’t so easy to round over the edge. I recently bought a hard sanding pad for my Festool sander and I noticed that this does reduce (not eliminate) edge round over.

I also agree with Brian that the edge needs a slight break. If you leave it sharp it may be easier to damage and any damage may be more obvious next to a sharp edge. You could break the edge with a block plane or sandpaper. I have a 1/8” roundover bit that I like to use.

Good luck.

View CrankAddict's profile


61 posts in 345 days

#6 posted 10-22-2019 07:00 PM

Thanks everyone, lots of great advice in here! I think I’ll try my hand at sandpaper on a square block. Don’t really have a quality plane nor a vise yet (yeah, I know). I do have a card scraper set so I may give that a whirl, but I just get a little scared of card scraping all the way up to a edge and “breaking off” the edge or something. Sandpaper on a flat block seems like it wouldn’t have that risk.

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