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Box joint tear out

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Forum topic by otis501 posted 1217 days ago 1859 views 0 times favorited 11 replies Add to Favorites Watch
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otis501

21 posts in 1244 days


1217 days ago

I get tear out on the back side of my box joint on the table saw even when I have a backer board.
I have a Freud dado blade and cutting ½ in oak.
What am I doing wrong or is this typical.


11 replies so far

View tenontim's profile

tenontim

2131 posts in 2340 days


#1 posted 1217 days ago

I scribe the top of the cut, like laying out dovetails.

View TheDane's profile

TheDane

3647 posts in 2259 days


#2 posted 1217 days ago

Do you clamp the backer board and the workpiece to the jig?

—Gerry

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

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Gerry

253 posts in 1836 days


#3 posted 1217 days ago

+1 With the Dane! For sure, the backer board should solve the issue. Scribing the board is a good idea too!

-- -Gerry, Hereford, AZ ” A really good woodworker knows how the hide his / her mistakes.”

View juniorjock's profile

juniorjock

1930 posts in 2361 days


#4 posted 1217 days ago

I’ve used clear tape on the back of boards and had pretty good cuts. This may be dangerous and I just don’t know it….. (but I’m sure someone will tell me if it is). One thing for sure…. never but tape on a piece that is going to be a cut-off. Unless you want a piece of wood hitting you between the eyes….
- JJ

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Jim Finn

1637 posts in 1518 days


#5 posted 1217 days ago

Do you think the backer board has to be as hard as the board that the box joint is being cut into?

-- In God We Trust

View gfadvm's profile

gfadvm

10533 posts in 1286 days


#6 posted 1217 days ago

You must keep your workpiece tight against the backer board or youll get tear out.I usually use eighth inch ply for a backer board.I use the Freud box joint blades and have no tearout in half inch oak.If your blades are dull or dirty this might be your problem.Hope this helps.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

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TopamaxSurvivor

14584 posts in 2272 days


#7 posted 1217 days ago

Does the Freud box joint blades cut 1/4 slots?

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View TheDane's profile

TheDane

3647 posts in 2259 days


#8 posted 1216 days ago

Topa—If he has the same set I have, the Freud cuts both 1/4” and 3/8” slots.

—Gerry

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

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TopamaxSurvivor

14584 posts in 2272 days


#9 posted 1216 days ago

Thx Gerry, I remember that set now ;-)

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View wb8nbs's profile

wb8nbs

137 posts in 1288 days


#10 posted 1216 days ago

I have good luck using 1/4 inch masonite as backer (cheap). I wet the shiny side with water and a little detergent, let that soak in a couple minutes so it’s not so slippery. Have the Freud 8 inch stack dado set and because of the design of my box joint jig, I can hard clamp the the work and backer together.

http://www.flickr.com/photos/27392624@N00/sets/72157622846581829/

-- The only difference between men and boys is the price of their toys.

View otis501's profile

otis501

21 posts in 1244 days


#11 posted 1216 days ago

Thanks guys, I use a 3/4 in backer board screwed to a board monted onto my miter gage to cut 1/4 slot. I tried the scribe and that made a big difference but still a little tear out, I will try the scribe and add 1/4 inch masonite to the backer board and give them both a try.

Thanks to all Otis

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