Finger Joint Tearout - Router Forums
 
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post #1 of 9 (permalink) Old 12-17-2013, 11:13 AM Thread Starter
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Default Finger Joint Tearout

I experience a lot of frustration attempting to make good finger joints (box joints) on my router table. I have a shop made jig which allows me to cut good sizes and fits, but I can't get away from alot of tearout on the back side of the cut.
Any suggestions?
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post #2 of 9 (permalink) Old 12-17-2013, 11:47 AM
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Use some sort of backer board behind the work piece. That will go a long way in preventing tear out.

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post #3 of 9 (permalink) Old 12-17-2013, 02:04 PM
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What Mike said and they need to be clamped together snugly to work well.

Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.
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post #4 of 9 (permalink) Old 12-17-2013, 02:21 PM
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Hi David

You can fix that error with a new and very sharp router bit,not all router bits are the same.. some are sharp and some are very sharp...this is one of the times you want to buy the best bit you can find...the good ones are not cheap...

http://www.mlcswoodworking.com/shops...tana_bits9.htm
" High Hook and Shear angles allow cutter to slice smoothly into stock, producing clean splinter free cuts"
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Quote:
Originally Posted by jdnordstrom2 View Post
I experience a lot of frustration attempting to make good finger joints (box joints) on my router table. I have a shop made jig which allows me to cut good sizes and fits, but I can't get away from alot of tearout on the back side of the cut.
Any suggestions?



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Last edited by bobj3; 12-17-2013 at 02:28 PM.
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post #5 of 9 (permalink) Old 12-17-2013, 04:50 PM Thread Starter
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Any suggestions for router bit make or style?
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post #6 of 9 (permalink) Old 12-17-2013, 06:37 PM
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I don't have a lot of experience but I've had good success with MLCS spiral bits that are not expensive. The use of a backer board works great. You can even add a board in front, even better. Oldrusty.

Last edited by oldrusty; 12-17-2013 at 06:41 PM. Reason: Better phrasing.
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post #7 of 9 (permalink) Old 12-18-2013, 07:53 AM
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Hi David, I make box joints all the time. The only time I get tear out is with rosewood since it is so brittle. In those cases I have to put a board in front and rear of the work piece. I use Whiteside spiral bits and I am very pleased with the results. I have also noticed that the work piece may be clamped to the fence, but it may not be completely flat. Sometimes I have to use two clamps to ensure the work piece doesn't vibrate. For the backer board I like to have it supporting the work piece on both sides of where the router bit will cut plus pass the spacer pin so that I can clamp the work piece from both sides. To do that I take a scrap board and start cutting box joints until I get about 1/2 way across the board. I then stop the router and move the board from the last cut and over the spacer pin. This board will be my new back support board. I screw it to the original backer board. Since you can not replace the original board without it changing the distance between the spacer pin and the router bit. I hope I explained that well enough. Malcolm / Kentucky USA
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post #8 of 9 (permalink) Old 12-18-2013, 09:32 AM
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I also use the Whiteside spiral up cut bits and am very happy with the results.

Mike
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post #9 of 9 (permalink) Old 12-18-2013, 09:49 AM
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I find that tear out is less of a problem using a table saw with a dado blade for box joint projects, but do still use backer boards.
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