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I'm working on an old house with 2x8 T&G subfloor planks. All of the structure is sound and has been reinforced but there are areas where the edges of subfloor planks are not level.

This has previously been under carpet, which hides the edges better... but I intend to put an underlayment over it and put down hardwood. To do this, I either need an elaborate setup of ramps or I need to sand/grind the extra material away.

In some places there is as much as 1/4" of a lip.

How effective are the wood-grinding discs for angle grinders? Would that be an effective way to handle this task?

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up vote 6 down vote accepted

An angle grinder can use several "disks" that are very efficient for removing wood. You can buy what is essentially a chainsaw wrapped around a disk. Great for carving and able to throw chips around like mad, but I would NEVER bring it anywhere near a possible hit with a nail.

There are also textured carbide wheels you can put in a grinder. Also able to grind wood rapidly, and perhaps safer if it hits a nail head. Finally, you can buy a disk that is essentially layers of overlapping very coarse sandpaper. This will be less aggressive yet and the paper will wear down with use.

The other problem with using an angle grinder is it won't leave you with a flat surface easily. A grinder is a very local tool. And you want a reasonably flat surface. So if you did choose to use an angle grinder, you might still want to come back to it with a belt or disk sander to get it flat.

Of course, it is also true that other tools may not like nails either. A router for example is a BAD idea here, as that rapidly spinning carbide bit may well meet an untimely end as soon as it hits a nail. And there WILL be nails in a subfloor. If this is a sufficiently old house, they may even be great big, clunky square headed nails.

A problem with anything you use that will remove a lot of wood is the dust it creates. So make sure you use dust protection for the well being of your lungs.

Overall, my choice would be a belt or disk or drum sander designed for floor use. They are fast and efficient, and will give you a flat floor. And they will grind off any nails they hit, although nails may wear down the belts a bit more than just wood.

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+1, totally agree – shirlock homes Jul 27 '12 at 11:24
I marked this as the answer because it reflect the reality after my testing with various grits in the belt-sander, orbital sander and grinder. – Matthew Jul 31 '12 at 22:00
Re. the "layers of overlapping very coarse sandpaper" angle grinder disks: I have used them on wood, and they work well for shaping (not so much for planing). But they have a tendency to overheat / burn that wood if the disk is starting to wear down a bit. I think with very coarse variants of these disks and / or a speed-adjustable angle grinder at slower speeds, this problem can be overcome. – tanius Dec 8 '15 at 21:19

I really think a belt sander would do a nicer job than an angle grinder. You could use a small handheld model with 40 or 60 grit belts, or rent a larger one used to refinish hardwood floors if you need to do larger areas.

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Where two planks of 2x8 butt together, one has a lip 1/4" above the other. I have a belt-sander too, but I thought the grinder attachments would be more aggressive... It is not because of the fasteners, either... all boards in the house have been re-screwed to the joists. – Matthew Jul 27 '12 at 5:15
Shirlock is right. Using a grinder sounds good but grinders have thin edges and will take you ages. Using a belt sander is great because you will eventually get the perfect level. Yu could look into hand held router with a levelling attachment from a hire place-faster and less dust. – ppumkin Jul 27 '12 at 9:50
@ppumkin - I think you misunderstand what the asker is saying. There are some VERY effective tools for removing wood that are made for an angle grinder, NOT just the standard thin disks for grinding/cutting metal one often sees. – user558 Jul 27 '12 at 10:11
Possibly- that is why I opted into commenting. As I have little experience with that wood fixing area. I have seen some various equipment before but I always try and stay away from grinders. I hate them :) – ppumkin Jul 27 '12 at 10:15
I just don't like grinders. They are hard to handle and keep flat on the work, have a tendency to run, etc. Another good tool would be a power planner. I have a nice Mikita that planes about 2 inches wide. Just be careful of hardware with a planner, it will ruin the knives if you hit a screw. I still think a belt sander may be a good choice. – shirlock homes Jul 27 '12 at 11:08

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