Chipper blade snapped

[tonytree]

4 hours ago, GA Groundcare said:

Lubricated threads and dry threads torqued to the same setting will give a different tightness. But not to the effect of snapping blades. If that’s correct they should 100% have a decal saying only torque dry, that commonly chosen method of lubricating threads shouldn’t carry a risk of killing someone / damaging the machine. 

 

That must of been what I was getting confused with torque and tightness.As you say though I don’t think the tightness would be that great it would cause a blade to snap. 
 

3 hours ago, treeclimber26 said:

Hi Mick,

ive just had the same with my Forst st6p. I greased the bolts and as standard practice for blade replacement we did it. In the manual on blade change section says nothing at all not to grease. My machine is wrecked and probably going to be over £8k in damages . They now tell me it’s not covered in warranty. The bolts snapped but blade fine

Yours isn’t a blue one by any chance as he mentioned it when on the phone as he asked if mine was the blue one. 

[Ty Korrigan]

2 hours ago, butters said:

It does state in the manual to change the bolts, nuts and washers on every blade change. Probably down to the fact they are torqued to 300nm. But for 7quid a set it’s worth it in my opinion.

£7...? Can anyone confirm the price of GM blade bolts? Or a supplier of the same?

 Stuart

[GA Groundcare]

8 hours ago, Ty Korrigan said:

£7...? Can anyone confirm the price of GM blade bolts? Or a supplier of the same?

 Stuart

The M16 bolts are £2 something, nuts are 60p and nordlock washers about £1. Genuine new blades are £39.50. 
 

As the blade sits in its own pocket in a GM the bolt doesn’t really take any of the load. If it’s a machine we look after half the time we just replace the washers & locknuts so the nylock is fresh. If it’s a used machine / Part ex that we have never seen before we’ll always stick new bolts on. 
 

 

 

Edited July 5, 2020 by GA Groundcare

[treeclimber26]

10 hours ago, butters said:

It does state in the manual to change the bolts, nuts and washers on every blade change. Probably down to the fact they are torqued to 300nm. But for 7quid a set it’s worth it in my opinion.

We have changed them every time. This machine only on 152 hrs. 

[GA Groundcare]

Being a GreenMech dealer, if this was a GreenMech and you had used genuine blades, bolts and a torque wrench (even using an uncalibrated torque wrench is a massive step to show you’re carrying the job out correctly) 

I would be opening a warranty job card and shovelling it through as warranty unless evidence was found during the repair of improper fitment or use. 
 

I don’t mean this reply as a “you should of bought a GreenMech”  

 

Professionally detail to the supplier what you’ve done prior to the fail and the fail itself. If it’s falling on death ears look to get an independent engineers report? 

[monkeybusiness]

17 hours ago, tonytree said:

Thanks I’ll have to try that. 
 

update on the chipper and I’ve never heard of this and was wondering if anyone else has.
 

Apparently the blade snap was caused by me using copper grease on the bolts as it increases the torque by 40% or something along these lines. 
 

Unless I’ve understood him wrong I can’t see how copper grease would effect the torque.

 

now I’ve always been told to use copper grease when changing chipper blades as it stop the bolt from seizing. 
 

anyway it needs a new flywheel bearing due to the impact. 

I wonder if they would have told you that you need to lubricate the bolts to achieve the correct tightness had you told them you assembled dry?...

[Deafhead]

The instruction when assembling engines etc. was to lightly oil threads before applying the torque to the fastener, this to prevent seizure and a false reading.

[aspenarb]

Copperslip is not a lubricant, it's an anti seize compound.

 

Bob

[treeclimber26]

On 04/07/2020 at 23:25, tonytree said:

That must of been what I was getting confused with torque and tightness.As you say though I don’t think the tightness would be that great it would cause a blade to snap. 
 

Yours isn’t a blue one by any chance as he mentioned it when on the phone as he asked if mine was the blue one. 

Yes that’s the one

[Mick Dempsey]

On 04/07/2020 at 21:20, treeclimber26 said:

Hi Mick,

ive just had the same with my Forst st6p. I greased the bolts and as standard practice for blade replacement we did it. In the manual on blade change section says nothing at all not to grease. My machine is wrecked and probably going to be over £8k in damages . They now tell me it’s not covered in warranty. The bolts snapped but blade fine

If you go on Facebook and search ‘Forst issues and faults’ there’s a group (of which I’m a member) that log and discuss this sort of thing.

Photos are useful.