Broken router cutter

[bobtskutter]

Why did I break this router cutter?
It's 1/4" diameter 73mm long (3" long").
I was cutting 6mm deep into plywood and moving the router pretty fast, using the OF1400.
The chips were actual chips, not dust, so the cutter wasn't burning. It was vibrating.
When it broke the cutter was hot and there appear to be "burn" marks on the length that was jammed in the collet where the collet clamped on to the bit.
The collet wasn't tight into the router after the bit had broken - this surprised me because it was definitely tight with I put the cutter into the router!!

I think I was being far too aggressive with the cutter (I was rushing) and was cutting too deep and moving too fast. The vibration from the machine should probably have given me a clue.
Am I right in my thought process?? Being too aggressive?



Bob

 

[Cheese]

I think your supposition is correct...this has happened to me on 2 separate occasions when I was machining aluminum 8020 profiles. When I finished the bit was so loose that it actually fell out of the router and landed on the patio which surprised me because I know I tightened the collet when I started.

In my case, I think moving too aggressively (and possibly also not using the correct router bit speed) in aluminum can start a small harmonic vibration that increases in intensity and that will loosen the collet and or break the router bit...both have happened to me. The router bit that broke was a Whiteside O-flute bit that was designed to machine aluminum.

 

[Michael Kellough]

I think your supposition is correct...this has happened to me on 2 separate occasions when I was machining aluminum 8020 profiles. When I finished the bit was so loose that it actually fell out of the router and landed on the patio which surprised me because I know I tightened the collet when I started.

In my case, I think moving too aggressively (and possibly also not using the correct router bit speed) in aluminum can start a small harmonic vibration that increases in intensity and that will loosen the collet and or break the router bit...both have happened to me. The router bit that broke was a Whiteside O-flute bit that was designed to machine aluminum.

It’s happened to me on the drill press while milling aluminum.

 

[bobtskutter]

Thank you both.
Regards
Bob

 

[Packard]

The advantage of carbide is that is is very, very hard. The disadvantage is that it is very, very hard and very brittle.

 

[Steve1]

Fatigue failure.
I think you were putting too much of a side load on the bit.
Cutting less deep and/or moving slower would put less load on the bit.