Chipper blade snapped

[monkeybusiness]

I’m surprised that the operator’s manual doesn’t stipulate NOT using any lube if it is that critical.
I’m certain that not lubricating bolts before torquing isn’t covered in any NPTC or Lantra chipper training (the unofficial industry benchmarks, and in reality a level of training that is over-and-above what should be anticipated by a manufacturer of anyone operating and maintaining a chipper).

It surely can’t be assumed by a manufacturer that a chipper operator would know that torquing up bolts with lube on them might be an unsafe practice? If it makes that much difference then the manual should stipulate cleaning the threads with brake cleaner etc before mounting? 

[butters]

I’m surprised that the operator’s manual doesn’t stipulate NOT using any lube if it is that critical.
I’m certain that not lubricating bolts before torquing isn’t covered in any NPTC or Lantra chipper training (the unofficial industry benchmarks, and in reality a level of training that is over-and-above what should be anticipated by a manufacturer of anyone operating and maintaining a chipper).
It surely can’t be assumed by a manufacturer that a chipper operator would know that torquing up bolts with lube on them might be an unsafe practice? If it makes that much difference then the manual should stipulate cleaning the threads with brake cleaner etc before mounting? 

The manual says as soon as the blades come out and another set fitted new bolts must be fitted. Then on the invoice for the bolts it says fit dry. I change my blades every 50hours and every time change the bolts.

For I think they are 7-8 quid a set why wouldn’t you just change them?

[Stubby]

I still maintain that the torque is governed by what your torque wrench is set at . If the bolt is lubed then yes it will go in further a tad making it tighter but the torque needed to achieve that will be the same if it is not lubed . It just won't go in quite as far .

[Deafhead]

1 hour ago, Stubby said:

I still maintain that the torque is governed by what your torque wrench is set at . If the bolt is lubed then yes it will go in further a tad making it tighter but the torque needed to achieve that will be the same if it is not lubed . It just won't go in quite as far .

If you lubricate a fastener that had a torque setting calculated for a dry thread, then you will end up with much more tension than the designer intended. Possibly to a dangerous level. The principal behind lubricated fasteners is that they are more consistently tensioned, as in cylinder head studs etc. The torque setting being adjusted for a lubricated thread.

[Deafhead]

18 hours ago, PeteB said:

Thanks for the heads up and clarification. Tbh, I'll still use copper grease myself.....

 

Back to the OP, the bolts are in situ and still tight, 'nothing other than timber went through' but they bust and someone is quoting an inordinate amount of money for two bearings and a mornings work. What caused the failure he asked.....

That would be a job for a qualified professional I feel.

[openspaceman]

39 minutes ago, Deafhead said:

If you lubricate a fastener that had a torque setting calculated for a dry thread, then you will end up with much more tension than the designer intended. Possibly to a dangerous level. The principal behind lubricated fasteners is that they are more consistently tensioned, as in cylinder head studs etc. The torque setting being adjusted for a lubricated thread.

Back in the day IIRC conrod bolts on cars were length measured with a micrometer to establish the right amount of stretch

[Stubby]

1 hour ago, Deafhead said:

If you lubricate a fastener that had a torque setting calculated for a dry thread, then you will end up with much more tension than the designer intended. Possibly to a dangerous level. The principal behind lubricated fasteners is that they are more consistently tensioned, as in cylinder head studs etc. The torque setting being adjusted for a lubricated thread.

Exactly but the torque needed to achieve that unwanted , extra tension will be the same .

[dig-dug-dan]

I am sure timberwolf advise using copper ease when changing blades to make it easier next time you change blades?

[Mike Hill]

Have you checked that the counter sink on the blade is concentric with the bolt hole?

 

[PeteB]

We use copper slip on CS100 blade torch bolts.