How far is an end mill supposed to be inserted into the Collett/router? I just had a bit break and after having fun watching the sparks fly I wonder if I’m not inserting deep enough and putting pressure on the bit when it is cutting? If it was inserted further into the shop, not as much would be exposed, causing the bit to break?
I insert the bit to the top of the collet. I will go farther if the shank is long like my “V” bits.
Breaking a bit is part of the learning process. I have a pile in a drawer. For instance. Too aggressive of a cut, Dull Bit, An inclusion grown into the wood (found rocks and a nail), Knott (sometimes they cut easy other times I break a bit)
I started by buying cheap bits on Amazon. Taught me how to work with bits that break easily. Still have some that work great for what I am cutting.
Good luck
Edit:
Monitoring my cut, if I am coming to a Knot, I will slow the speed till it gets through so I can see if it cuts easily.
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General rule of thumb, you want the bit “stick-out” to be as short as possible for rigidity. Enough to reach the deepest part of your cut, and to reach the table if cutting through.
Don’t insert it all the way in the spindle. If it bottoms out, back it off just a bit. The bit will pull up a little bit as you tighten the collet.
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as short as possible to eliminate chatter I cut off end mills to shorten them all the time
I was trying to cut down on the time that it takes for the bit to get to the surface of the work by keeping the bit lower in the collet. That left a lot of bit with a lot of stress on it especially with the smaller bits like the one eighth or 1/16. I know better now. Thank you!
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It should be inserted a pinch longer than the collet as a minimum.
The collet is cut to form a sort of W shape. The inside of the router shaft is an inclined plane. As you tighten up the collet nut you are forcing the collet and bit up the inclined plane and the W pattern of the collet is being squeezed tighter and tighter to hold the bit. As others said insert at least up to the top of the collet to get the maximum holding of the collet. For long bits never press them all the way up. The reason is the top of the router shaft is rough. The second reason is as the bit is forced up the inclined plane it tightens. If the router bit does not have room to move up it might not tighten up enough.
So at least to the top of the collet but not all the way up until it stops. Anything in between would work. The further out the bit sticks out the more runout you get and the less precise it cuts. I have a couple of 4" OAL bits and I insert those long bits all the way up and then back down about 1/4". That way the very long bits do not run out of round as easily.
The Makita/C3D routers the collet and nut are separate. So when loosening the bit if it does not fall out then tap the nut lightly after loosening it and the bit will come out. Only tap and not beat on the nut and the nut should be loosened to allow the bit and collet to travel back down the inclined plane.,
The Makita/C3D routers need to be tightened with two wrenches. There is a stop button but that is only for initial tightening. So use the stop button and a single wrench to get the bit tighten enough so it does not fall out or slip down and then use two wrenches to fully tighten the bit/collet/nut.
The Dewalt 611 router the collet and nut are attached so loosening the nut will loosen the bit.
Also, no lubrication. The nut, collet, receiver and the shaft of the bit should be bone dry. Cleaning with paint thinner will remove any oily residue.
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Cutter could break for a number of reasons:
- collet not snapped into nut properly
- dirty collet or cutter shank
- excess spindle runout
- feed too high
- axial depth of cut too high
- sudden increase in tool engagement (such as tight interior corner)
- dull/worn/chipped/clogged cutter
- flex/backlash in gantry
- movement in work holding
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