How to Avoid Tear-Out? - Question of the Week

October 6, 2008 by loglad
Filed under: Question of the Week, Techniques 

This week’s question comes from Don who writes: “Just discovered the Wood Whisperer and your site and videos are great. Besides we’re neighbors. I have a small shop in Las Vegas and we make Adirondack furniture from Western Red Cedar. My question is this. I round over all parts on a router table using a 3/8’s round over bit. I get a lot of tear out during this process. I read the grain but when you flip over the part to do the other side you are going against the grain. I always use a good sharp bit and I have played with feed rates. It seems no matter what I try I still get a lot of tear out. I have ruined a lot of wood. Others have suggested using a ¼ inch bit but it doesn’t give me the profile I want. Any advice would be appreciated.”

And this was my response: “Hey Don. Glad you found us! Welcome. So what brand bit are you using? Obviously, using a top quality bit is the first step to great results. The second would be to take lighter passes. Don’t bring the bit all the way up. It will take a little longer, but try taking 3-4 passes, raising the bit a little each time. Obviously that’s not an efficient solution, but its much better than losing a whole chair arm because of tear out. Also, you could relieve the sharp corners with a rasp before routing which can sometimes relive tear out. But honestly, the incremental passes is probably your best bet. Whenever I am dealing with a tear out prone wood, that’s exactly what I do. Hope that helps.”

In a follow up e-mail Don writes: “Marc, I tried your suggestion about taking lighter passes and IT WORKED. I take 3 passes and after about 30 or 40 pieces I only lost 4 due to tear-out Thanks so much. You saved me tons of wood not to mention money. Thanks again!”

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Comments

6 Comments on How to Avoid Tear-Out? - Question of the Week

  1. Paul-Marcel ST-ONGE on Mon, 6th Oct 2008 12:17 pm

    2. Depending on how fast the router passes are, you might switch to a round-over plane. They are pretty cheap at Lee-Valley. I doubt you could give 4 passes as quickly as the router method, but you could instead take almost the entire cut for a single pass with the router then give a last pass with the round-over plane for cleanup.

    Another less Galoot option would be to pick up a used shaper. While I haven’t used one, one big advantage of a shaper vs a router is that they can spin either direction.

  2. Leon on Mon, 6th Oct 2008 2:03 pm

    3. If you use a rolling rubber hold down clamp you can feed the wood from left to right and therefore avoid tear out. I have used this method succesfully in the past, but I never tried for 40+ pieces only for a ocasional piece. This method demands a lot from the operator, because the wood want to run away from you so you need some king of brake suystem. I happen to have rubber clamps that only rotate in one direccion, but I am sure that there are other brake systems that you could use.
    Another thing that I use some times is to wax the wood before the cut. I use either wax bars or soap bars for that

  3. Leon on Mon, 6th Oct 2008 3:54 pm

    4. Oh, I just remember, You can also reduce your router’s RPMs

  4. Vic on Mon, 6th Oct 2008 6:24 pm

    5. Here he comes to save the DAAAAY!!! It’s Mighty Marc!
    Marc’s suggestion is right on (obviously). Freud has started making 3 blade versions of some of their bits. I have a two inch flush trimmer that works great!! I disagree with Leon’s suggestion of slowing the RPM on the router. That would tend to make the tear out worse unless you really slowed the feed rate. Slowing the feed rate itself may be an option. You’d have to experiment to find the point at which the bit starts burning the wood. As with most things, sometimes the best solution is to take your time and do things right, which in this case, is taking multiple passes.

  5. Russ on Tue, 7th Oct 2008 10:57 am

    6. Some say that climb cutting is another way to avoid tearout when routing against the grain. I’ve never been comfortable with that myself except for the smallest of cuts because the bit tends to grab the workpiece and send it flying. Not fun. It’s also harder to make sure the workpiece stays in contact with the fence or bearing or whatever you’re using as a guide. However, it’s an option that works if you can safely manage the difficulties. YMMV.

    – Russ

  6. Mario on Tue, 7th Oct 2008 12:27 pm

    7. Hi Don, I do a lot of work with red cedar and aromatic cedar and know where you are. Climb cutting on cedar´s uneven grain will tear it useless. Set your table featherboard, hold your work carefully and do a down climb cut with your router. A single pass 3/8 roundover should not be a problem once you get the feeling for routing this way.

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