# Tear-out with Incra I-Box



## Jofa (May 14, 2013)

Hey guys.

I've been using my Incra I-Box quite a bit and I like it very much. However, I'm finding that I'm getting tear-out on soft woods like pine.

I've fine-tuned the system so that my joints are aligned very well but the tear-out is an issue.

I made a supply of back plates out of 1/4" MDF but I'm finding that the tear-out is actually breaking through it. Should I possibly use 1/4" ply?


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## wapakfred (Jul 29, 2011)

You can, it will work fine. Is this on a table saw (?), maybe it's time to check the blade.


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## Jofa (May 14, 2013)

Thanks Fred.

Yes, I'm using a Freud Diablo dado set. I really hope it isn't the blade(s) as I haven't used it daily or anything. It should still be sharp. Plus, the cuts on the way into each joint and on the edges are very clean. It's just the way out.


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## ksSlim (Jun 27, 2010)

I've been using 3/8" Borg ply for a backer board.
Seemed to stop the blowout.


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## CharleyL (Mar 10, 2009)

Try some 1/4 birch ply for backer boards. Also try moving the jig much slower over the saw blade. If pushed too fast the chip removal will be too aggressive and blow through the backer. I get the best box joints by using the Freud SBOX8 blade set on my Unisaw but I also use a Freud adjustable dado blade with very good results. They are designed to provide very square 1/4 and 3/8 joints with a minimum of tear-out. Moving the jig slower should make a huge difference.

Charley


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## DocSavage45 (Aug 14, 2010)

Does tear tout occur without the Incra jig? Is this a wobble dado or the shim type. Any problems with tear out outside of this situation? Was this always a problem? That would help the problem solving.


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## Jofa (May 14, 2013)

Hey everyone. Thanks for the replies.

@ Doc: I haven't tried the dado without the jig (but I will). It's a shim type (actually, it's the Freud SBOX8)
It seems to have been an issue from the start

@ Charley and Slim: I'm going to try some different backer boards but I'll also slow down. I'm using an old Craftsman (Atlas Press) table saw from like the 40's (newer motor however) and it may not be powerful enough for the speed I'm going. I'm going to try tonight and see if I get similar results after slowing down.


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