Chipper blade snapped

[tonytree]

Working on Friday all going ahead of schedule until the chipper blade broke. All bolts where to the correct torque, sharp and are genuine blades.

 

Has this happened to anyone else just trying to work out why it happened. Nothing was put through it apart from an ash log when it happened 

[Stubby]

Incorrect heat treatment perhaps ?

[Khriss]

Yup.. Way too hard  ?  K

[monkeybusiness]

Definitely fitted with clean mounting faces?

[tonytree]

Yeah always clean them

[aspenarb]

Just now, tonytree said:

Yeah always clean them

 

Have my guys been working for you on the side ?

 

Bob

[Stubby]

4 minutes ago, tonytree said:

Yeah always clean them

Take the broken bits to a tool room and get them tested on a Rockwell hardness tester . Check that result against the spec . Looking at the fracture I would say that was at least 62 Rockwell C .

Edited June 14, 2020 by Stubby

[Mick Dempsey]

Stuff happens, it’s a pretty violent process.

 

No damage to the anvils?

[Khriss]

Yup. Steel needs to be tough enuff to keep an edge -  but too hard an its too brittle to put up with the hammering - hence yr near miss.  K

[PeteB]

Sure nothing bad went through to start it off? Was the infeed speed too high and the blade was being asked to par off too much in one bite? 

I 'ring' blades before fitting them, my old arboreater used a few blades and we learnt after a similar failure to check before fitting. A dull ring and that set was put aside!