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Forum topic by GT350 posted 05-06-2018 02:26 PM 910 views 0 times favorited 9 replies Add to Favorites Watch
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GT350

371 posts in 2397 days


05-06-2018 02:26 PM

I was trying to make a 3/4” deep stopped dado in the side of a 14” long piece of cherry. I made the first pass 3/8” deep and then turned the piece around to center it and when I started the cut it pulled the piece out of my hand, broke the 1/4” spiral bit off and threw it across the shop. I was using the fence and a push stick, I think what happened was it pulled a little bit away from the fence. Any ideas how to stop this in the future?


9 replies so far

View EricTwice's profile

EricTwice

248 posts in 949 days


#1 posted 05-06-2018 03:28 PM

First thought, I would have used a heavier bit, 3/4×3/8 can put a load of stress on a bit even if you are just cleaning it up, a 1/2 in shafted bit will do a better job.

Your object is to control the cut.
push sticks are for tight places where you don’t want to or can’t put your fingers. They do not help you with control. It is a stop dado on the bottom side. (I am assuming this) Loose the push stick and hold on with both hands.
If you are unwilling to do this, you must capture as many sides of the piece as possible. block the top of the fence so the board cannot move upward and hold it to the fence with a finger board. With 4 sides held tight you may use a push stick

Be careful and have fun

-- nice recovery, They should pay extra for that mistake, Eric E.

View Rich's profile

Rich

4548 posts in 1005 days


#2 posted 05-06-2018 03:50 PM

Hard to say for sure, but it sounds like when you turned the board you created a climb cut situation where the bit pinched the board against the fence and its rotation pulled it. That also would explain the broken bit. I had the exact same thing happen to me once.

-- Knowledge is not skill. Knowledge plus ten thousand times is skill. -- Shinichi Suzuki

View Redoak49's profile

Redoak49

4036 posts in 2405 days


#3 posted 05-06-2018 04:09 PM

Spiral carbide bits especially smaller ones can be brittle. I think you took too deep of a cut and did not control it. I have some push pads and also a Gripper. I very seldom use a push stick on my router table as it is not secure enough but do use feather boards to control the work piece.

I think you were fortunate not to get hurt.

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GT350

371 posts in 2397 days


#4 posted 05-06-2018 04:41 PM

Yes I know I was very fortunate, maybe my description of a push stick was incorrect, what I had was more of a push handle where I am holding the handle and it has a lip to push the piece but there is a long piece that holds the part being cut down. I am not sure that I was taking too big of a cut because the first pass was ok but all I was doing with this pass was centering it by just cutting one side of the dado. Thinking back it was a climb cut and I did see on the part the blade marks, what broke the bit was when the bit hit the end of the dado, I can see a nick. I guess my problem now is how to prevent the climb cut so while evening it up it doesn’t pull it out of my grip. Maybe this is an incorrect cut on the router table, it did give me a reminder about safety though, I am going to finish it on the table saw and just make a though dado.

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Rich

4548 posts in 1005 days


#5 posted 05-06-2018 05:03 PM

<blockquotei>

It’s OK to do on the router table. The key is to be sure the second cut is done on the side of the dado away from the fence, and to be pushing the board into the rotation. If that’s not possible make certain it’s not a climb cut. That’ll get you every time.

-- Knowledge is not skill. Knowledge plus ten thousand times is skill. -- Shinichi Suzuki

View bondogaposis's profile

bondogaposis

5452 posts in 2767 days


#6 posted 05-06-2018 05:19 PM

The key is to be sure the second cut is done on the side of the dado away from the fence, and to be pushing the board into the rotation.

Thats it right there, Rich has it right. Another thought is that 3/8” is too big of a bite.

-- Bondo Gaposis

View GT350's profile

GT350

371 posts in 2397 days


#7 posted 05-06-2018 05:20 PM

I’m trying to figure out how to do it without a climb cut, the first one is against the fence and the entire 1/4” bit, when I turn it around to center it the side that is being trimmed is now toward the fence which makes it a climb cut. Oh and thanks for pointing that out because it hadn’t occured to me what the mistake was until you mentioned it.

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Rich

4548 posts in 1005 days


#8 posted 05-06-2018 05:38 PM


I’m trying to figure out how to do it without a climb cut, the first one is against the fence and the entire 1/4” bit, when I turn it around to center it the side that is being trimmed is now toward the fence which makes it a climb cut.

- GT350

It’s only a climb cut if you push it right to left along the fence, since the fence side of the bit is cutting towards the left. If you do the cut pushing the board from the left to the right, you’ll be pushing the wood into the rotation of the bit which, while still iffy since it’s against the fence side of the dado, is likely to give you no trouble.

-- Knowledge is not skill. Knowledge plus ten thousand times is skill. -- Shinichi Suzuki

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GT350

371 posts in 2397 days


#9 posted 05-06-2018 05:56 PM

Thanks, I think I’ll have to go out and look at it and think about it a little while.

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