router tear out

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Forum topic by paulwl posted 02-02-2015 02:51 PM 889 views 0 times favorited 6 replies Add to Favorites Watch
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3 posts in 1206 days

02-02-2015 02:51 PM

Topic tags/keywords: question

New to the lumberjocks. I hope that someone can help me with my box joints. I keep having tear out when using my router for the box joint. I can get the jig to work on my table saw. The only thing about it is that it tacks a long time. I can’t use a dado with my table saw. I am new to woodworking, I can do some work on my house without help.

6 replies so far

View RogerM's profile


792 posts in 2395 days

#1 posted 02-02-2015 03:17 PM

First, Welcome to Lumberjacks. I was able to stay in a cottage in Chester Nova Scotia up in your country last September. Nice country!!!!

As you are finding out, table saws are better for making box joints than routers. The best method for reducing tear out on a router table is to us a scrap backer board. This helps but will probably not eliminate the tear out. Another way to deal with the tear out is to accept it as it comes off the router table , glue your box up then after the glue sets up trim the faces on the box with a table saw or band saw. This eliminates the tear out but reduces the thickness of the sides of the box.

Also, you may want to consider doing a different type of joint for your purpose such as a keyed miter joint, or drawer lock joint.

-- Roger M, Aiken, SC

View goochs's profile


56 posts in 1225 days

#2 posted 02-02-2015 03:25 PM

FYI I use a backer board BUT also on the router make smaller height cuts and work my way up to the depth I need. This is fairly simple for me for I use a Incra LS system so I can make exact repeats.

View Bill White's profile

Bill White

4929 posts in 3956 days

#3 posted 02-02-2015 04:16 PM

I must ask if your bit is sharp. Don’t take full cuts. Sneak up on the depth, and as has been said, use a backer.
I have also seen some routers that “chatter” due to less than accurate construction. Kinda like the collet is not true to the arbor in the router.


View JesseTutt's profile


854 posts in 2106 days

#4 posted 02-02-2015 04:33 PM

Are you using carbide bits or HSS (high speed steel) router bits?

Half inch shank or quarter inch shank?

-- Jesse, Saint Louis, Missouri

View HornedWoodwork's profile


222 posts in 1210 days

#5 posted 02-02-2015 04:42 PM

The backer board will help and so will sneaking up on the final cut. Is your tearout above the cut or on the side of the side of the tooth? if it is above the cut, use a knife to score the cut line first before you go to the router. If it is on the side you might consider how sharp your bit is, and sharpen it if you find the need. Also try supporting the whole area with masking tape (watch for changes in tolerance here, it should not have an affect if you keep tape on the face only, not the edges.)

Is your router variable speed? depending on the size of the bit you may want to INCREASE the speed. Blowout is caused by pressure applied to the woodfibers before the blade can reach the fiber to cut it, the solution is to move the piece slower and the bit faster.

-- Talent, brilliance, and humility are my virtues.

View knotscott's profile


8008 posts in 3371 days

#6 posted 02-02-2015 05:20 PM

Try a backer board and better router bit.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

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