3

I'm very new to table saws, and am having trouble getting a clean cut. The blade cuts fine most of the time, but every once in a while something goes wrong and I'll get a big gouge in the wood.

Here is a picture of what I mean, done on the thinner edge of a 2x4:

gouge

I've measured the depth of the gouge, and it's 15 thou. That seems really extreme, especially considering how smooth and perfect the rest of the cut is. This kind of gouge makes fine furniture impossible.

I know the table saw is correctly aligned; that's the first thing I did when I got it. The fence is parallel to the blade, and the arbor has practically no run-out. A splitter was set-up behind the blade, and the blade I used was brand spanking new.

Here's a video of me making the cut shown earlier, so you can see my set-up and feed rate:

https://www.youtube.com/watch?v=Mr-1Yj9Ra44

Anyways, from what I can tell, the blade vibrated/wobbled a bit and that's what caused the gouge. I could probably reduce the chance of this happening by cutting in several passes, but when I tried that before I still got the occasional gouge. Any ideas on how I can fix this?

  • Your blade height looks a little low for that cut, although it's hard to tell in the video. What kind of blade are you using (diameter, TPI and tooth shape)? Also, just for completeness, what is the speed and power of your saw? – Jason C Dec 1 '15 at 4:44
  • 1
    @JasonC Blade is 10", 32 tooth, alternating bevel. A cheap "general purpose" Avanti blade. Saw is 1.5 HP, and around 3100 rpm. The blade height was set so that the bottom of the carbide tips rest on top of the wood. – Pubby Dec 1 '15 at 6:05
  • Was the 2x4 bowed or twisted slightly in any direction? – Jason C Dec 1 '15 at 13:15
  • 1
    I have the same issue at times, and the solution is to cut close and then cut final. (My setup is a bosch 4000, nice thick rip blade, fresh bearings for a minimum of runout (but not none), and good technique. This can happen in clear, straight grained wood, though it's more frequent when hitting knots.) – Aloysius Defenestrate Dec 1 '15 at 14:50
  • Also inspect the blade carefully, is there any damage? In general you should expect to have to do a bit of further machining/sanding/scraping on surfaces cut with a rip blade, I'm actually impressed your surface came out as well as it did even though the gouge is a bit conspicuous. I suspect some unintended lateral forces or wedging somewhere. Double check the straightness and trueness of your fence? – Jason C Dec 1 '15 at 14:51
9

The blade cuts fine most of the time, but every once in a while something goes wrong and I'll get a big gouge in the wood.

In my experience, this isn't really a big gouge. When you're running a board through your saw, there are a couple things that could happen:

  1. Your hand could slip and not press the wood tight on the fence, making it jump into the blade a bit

  2. The wood could relieve some internal tension, pulling itself away from the fence and into the blade.

The fence is parallel to the blade, and the arbor has practically no run-out.

"Practically no runout" is not "no runout." I suspect that a little bit of runout is at work here too, in addition to what I highlighted above. Also, if you have a cheap, thin blade, it could be wobbling during the cut.

Looking at your video, you have a more "contractor-grade" table saw. These are not truly meant for fine woodworking tasks, so some level of slop is expected.

Here's a video of me making the cut shown earlier, so you can see my set-up and feed rate:

You seem to be running the board through your saw very slowly. Unless you're cutting a very hard wood (or your blade is very dull), there's no reason to feed that slow. That pine board should be cut in about 3-5 seconds.

This kind of gouge makes fine furniture impossible.

No, it doesn't. You'll just need an additional step to clean up the gouge when it happens, such as giving it a few swipes with a smoothing plane or sanding it. A fifteen-thou gouge is no big deal.

Understand that your table saw will not make a surface that is ready for finishing. The table saw is for breaking down wood into the sizes you need and getting the dimensions correct. You will need to do the final finishing with sandpaper, scraping, planing, etc.

4

I took a long look at my table saw today and was able to find two things wrong:

  1. The splitter was too close to the fence. This was causing friction between the board and the fence, making it hard for me to push the board through. This was part of the reason why I was feeding the wood so slowly.

  2. The blade was angled very slightly towards the fence. I thought I had it set to exactly 90 degrees, but I was wrong! I've heard that having the blade on a negative angle like this makes kickback more likely, so chances are it makes gouges more likely too.

I fixed all of these things, then re-cut the 32 feet I needed. This time, I had the blade raised slightly higher, and I fed at a faster rate.

The result? No more 15 thou gouges! The wood is now very smooth and usable.

  • Thanks for coming back and posting this! I hope you've been having fun with your new saw :D – Jason C Dec 22 '15 at 18:56
3

Possible reason:
Hard to say but your hands shifted so the wood is not evenly pressured left/right throughout the cut.

Possible solution 1:
Install a feather board to press hold the wood in place right/left-wise.

Possible solution 2: Cut it half a saw blade too thick and do another cut at the exact width. Though the blade might flex then.

3

I agree with @grfrazee for saying that a table saw won't make a surface ready for finishing. I don't know if it's possible for you but in basically any professional joinery shop or similar that I've seen, ripping to size is a rough-cut operation, which is always followed by (at the very least) belt sanding, or more commonly a run to finished size through a planer/thicknesser or moulder.

Looking on ebay a thicknesser/jointer can be had for around £200 or possibly less if you go second hand, though I can't attest to how good one would be at that price.

An added bonus with a thicknesser is that you can get the finished dimensions of the timber to be very accurate, usually within about 0.05-0.1mm.

1

One important that is usually overlooked when sharpening a used blade is checking the tensioning. Any blade over 7" needs to be slightly cupped to compensate for larger blades stretching more at the perifera at working speed. This a crtaft that is nearly lost. because of the habit of replacing dull blades with new ones. Look up an old school blade sharpener in your area and get your blades tension adjusted.

http://www.carbideprocessors.com/pages/saw-blades/steel-saw-plate.html

1

Not much to add to all the other great answers but there is one thing I did not see mentioned.

When pushing the board through: Don't Stop! That is when it will most likely happen. Everything else mentioned is still relevant, but won't help if you keep stopping and starting. Even if you push it slowly while moving the other hand into place, keeping it moving ensures that it won't dig into any one spot. Careful, if the board moves of the fence it can still dig in, but you won't get that saw imprint.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.