Faulty blade bolts...

[john87]

Hi All,

 

More than a bit concerned...

 

I have a timberwolf 13/75 chipper.. I bought it used. It was owned by a millionaire that bought it when removing a few trees on his land. Once he did that it was never used again and needless to say is like brand new..

 

Now, i was preparing to use it for the first time. I decided that i would give it a service first and as part of that i thought i would fit the spare [new] blade that came with it. So, the machine was on its original blade..

 

Timberwolf tell you to use a torque wrench for doing up the bolts and so i went out this morning and paid £85 for a decent one from Halfords..

I was fitting the new blade, and, as i did up the second bolt i felt it break..

 

It was nowhere near the 22ft/lbs they tell you to use and i nearly had a heart attack as i thought the thread must have stripped.. Turns out the bolt broke at the base of the socket in the head..

 

From looking at what is left, it appears that there was a fatigue fracture underway from a bit of very slight corrosion on the side of the bolt..

 

Anyone else had any problems like this..??

 

I will try to take some photos now..

 

john..

[AHPP]

Do Timberwolf not tell you to use new bolts too? Torque specs for stuff that you really don’t want to come off accidentally are often such that the bolt will stretch and become a use once item.

[AngrySquirrel]

32 minutes ago, john87 said:

Hi All,

 

More than a bit concerned...

 

I have a timberwolf 13/75 chipper.. I bought it used. It was owned by a millionaire that bought it when removing a few trees on his land. Once he did that it was never used again and needless to say is like brand new..

 

Now, i was preparing to use it for the first time. I decided that i would give it a service first and as part of that i thought i would fit the spare [new] blade that came with it. So, the machine was on its original blade..

 

Timberwolf tell you to use a torque wrench for doing up the bolts and so i went out this morning and paid £85 for a decent one from Halfords..

I was fitting the new blade, and, as i did up the second bolt i felt it break..

 

It was nowhere near the 22ft/lbs they tell you to use and i nearly had a heart attack as i thought the thread must have stripped.. Turns out the bolt broke at the base of the socket in the head..

 

From looking at what is left, it appears that there was a fatigue fracture underway from a bit of very slight corrosion on the side of the bolt..

 

Anyone else had any problems like this..??

 

I will try to take some photos now..

 

john..

Hi did you "Set" check the torque wrench before using? esp from new.on low torque but not just on free/unwound torque somethings up then tighten few more times and redo so mechanism is "clicking" out as needs to or torque setting esp at lower rate can be way out.

What wrench you get from HalFrauds for £80??? There Pro range is Britool .Facom who own Britool.

 

Are they Shear bolts? designed to fail if jammed so blade comes away rather than destroy unit? there are also ones that are stretch bolts so torqued up but need to be replaced for new ones next time?

Use them a lot in Auto trade esp on Cylinder head bolts!

[AngrySquirrel]

9 minutes ago, AHPP said:

Do Timberwolf not tell you to use new bolts too? Torque specs for stuff that you really don’t want to come off accidentally are often such that the bolt will stretch and become a use once item.

Just typing similar thing in as you posted!

[john87]

2 minutes ago, AngrySquirrel said:

Hi did you "Set" check the torque wrench before using? esp from new.on low torque but not just on free/unwound torque somethings up then tighten few more times and redo so mechanism is "clicking" out as needs to or torque setting esp at lower rate can be way out.

What wrench you get from HalFrauds for £80??? There Pro range is Britool .Facom who own Britool.

 

Are they Shear bolts? designed to fail if jammed so blade comes away rather than destroy unit? there are also ones that are stretch bolts so torqued up but need to be replaced for new ones next time?

Use them a lot in Auto trade esp on Cylinder head bolts!

No, just got the torque wrench out of box and used it. Was only calibrated about two months ago so should be ok..

 

Torque wrench was a halfords one. I got it as i read some tests a while back, and halfords ones came out the best. Britool were just about the worst..

 

I actually have a britool torque wrench tester and when i tested the other halfords one i have, it was very accurate.. I will have to dig it out and test the new one too..

 

No, timberwolf say nothing about new bolts.. I expect they will once i have finished emailing them though!!..

 

john..

[openspaceman]

Could it have been that the "fatigue" crack you point out was because the machine had been used with the bolt under tightened and had flexed too much?

[htb]

How blunt were the old blades?

[john87]

24 minutes ago, openspaceman said:

Could it have been that the "fatigue" crack you point out was because the machine had been used with the bolt under tightened and had flexed too much?

I would not think so as they were the original factory fitted bolts.. No idea really.. I had tightened one, and that was ok, it was the second one that broke so i did not try the other.. They were all tight when i undid them though..

 

Just testing the torque wrench with this thing a minute..

 

john..

[john87]

14 minutes ago, htb said:

How blunt were the old blades?

Not sure how to quantify it.. Sharp, but the edge was not too good. I will take a photo and post it..

 

john..

[Moose McAlpine]

So... a bolt broke. Replace it with a new bolt.

 

These things happen, not really a big deal. Could just be a manufacturing defect in the bolt.