near miss

camgeeves · 16th March 2010, 07:29 PM

about a week ago a chipper knife snapped off while the machine was running.
the blades had only had a few hours work and were pretty careful about what goes through. just wanted to find out why it happened?
also bolts are changed regularly.
noone was injured and the blade ended up being in the chute.. but i was feeding branches in at the time and felt a bit lucky.
the blade cracked the housing in two places.

Eric Frei · 16th March 2010, 09:15 PM

Any pictures of the damage, knife etc?

stjawa · 16th March 2010, 09:21 PM

camgeeves can you give us a bit more information.

Any damage to the anvil?

Type of material you where putting through?

Do you use a torque wrench to do up blade bolts?

What was the brand and model of chipper you where using?

Did the blade break through a bolt hole or did a piece snap off from the cutting edge?

Was it a one piece break or multiple pieces?

Any thing else you can add.

Thanks Steve.

newguy18 · 17th March 2010, 02:18 AM

Metal fatigue?damaged bolt threads?blade not tight enough?if you only changed one blade and not the other[s]it could have been thrown off balance.

Morbark - RSA · 17th March 2010, 07:54 AM

I was a metallurgist in a previous life - there is so much in todays knives and so many companies making them as cheap as they can with shoddy materials and processes that its dangerous to get them from an unknown/unrecognised source. If your getting them from any of the larger manufacturer (Vermeer, Bandit, Morbark, Rayco) then it should be of good quality.

There can be a huge difference in the price of knives, but again you get what you pay for!

camgeeves · 17th March 2010, 05:04 PM

sorry no pictures, probably should have a camera at work though for interesting stuff.
the chipper is an auschip? i think. 9 inch
no damage to the anvil, the blade snapped through a bolt hole in one piece , makes me think the bolts were too tight, we have since bought a torque wrentch and seems these bolts dont need to be as tight as we thought.
at the time we were feeding it Grevillia robusta limbs only 2 or 3 intches diameter

stjawa · 17th March 2010, 07:27 PM

Looks like you may have found out yourself why the blade snapped.

You wouldn't be the first person to think that the tighter the better,always use a torque wrench to tighten chipper blade bolts.

Also take special note what our learned friends Morbark RSA and newguy18 these factors could also have contributed to the break .

Good to see there was no injuries .

You never stop learning,good luck in the future.

16th March 2010, 07:29 PM	#1
camgeeves I'm new here so be nice Join Date: Feb 2010 Location: Tasmania Posts: 3	near miss about a week ago a chipper knife snapped off while the machine was running. the blades had only had a few hours work and were pretty careful about what goes through. just wanted to find out why it happened? also bolts are changed regularly. noone was injured and the blade ended up being in the chute.. but i was feeding branches in at the time and felt a bit lucky. the blade cracked the housing in two places.

16th March 2010, 09:15 PM	#2
Eric Frei Admin - Owner Palm & Tree Services in Brisbane Join Date: Jan 2007 Location: Brisbane Posts: 12,986	Re: near miss Any pictures of the damage, knife etc? __________________ Protect your rights to work - Join Australian Tree Association My businesses:- Qualified Brisbane Tree Lopping \| Stump Grinding Brisbane \| Brisbane - Gold Coast Consulting Arborist

16th March 2010, 09:21 PM	#3
stjawa Sappling Join Date: Nov 2009 Location: Vic, Australia Posts: 39	Re: near miss camgeeves can you give us a bit more information. Any damage to the anvil? Type of material you where putting through? Do you use a torque wrench to do up blade bolts? What was the brand and model of chipper you where using? Did the blade break through a bolt hole or did a piece snap off from the cutting edge? Was it a one piece break or multiple pieces? Any thing else you can add. Thanks Steve.

17th March 2010, 02:18 AM	#4
newguy18 Part of the Furniture Join Date: Jun 2007 Location: orlando,fl Posts: 4,948	Re: near miss Metal fatigue?damaged bolt threads?blade not tight enough?if you only changed one blade and not the other[s]it could have been thrown off balance. __________________ Have your say join us today. old schooler

17th March 2010, 07:54 AM	#5
Morbark - RSA Semi-mature vigorous tree Join Date: Jul 2009 Location: Ballarat Posts: 51	Re: near miss I was a metallurgist in a previous life - there is so much in todays knives and so many companies making them as cheap as they can with shoddy materials and processes that its dangerous to get them from an unknown/unrecognised source. If your getting them from any of the larger manufacturer (Vermeer, Bandit, Morbark, Rayco) then it should be of good quality. There can be a huge difference in the price of knives, but again you get what you pay for!

17th March 2010, 05:04 PM	#6
camgeeves I'm new here so be nice Join Date: Feb 2010 Location: Tasmania Posts: 3	Re: near miss sorry no pictures, probably should have a camera at work though for interesting stuff. the chipper is an auschip? i think. 9 inch no damage to the anvil, the blade snapped through a bolt hole in one piece , makes me think the bolts were too tight, we have since bought a torque wrentch and seems these bolts dont need to be as tight as we thought. at the time we were feeding it Grevillia robusta limbs only 2 or 3 intches diameter

17th March 2010, 07:27 PM	#7
stjawa Sappling Join Date: Nov 2009 Location: Vic, Australia Posts: 39	Re: near miss Looks like you may have found out yourself why the blade snapped. You wouldn't be the first person to think that the tighter the better,always use a torque wrench to tighten chipper blade bolts. Also take special note what our learned friends Morbark RSA and newguy18 these factors could also have contributed to the break . Good to see there was no injuries . You never stop learning,good luck in the future.

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