Steel vs. chipper knives

nuthin_special

nuthin_special

Location
Thunder Bay, Ontario
So, this is what you get for lending a chipper to a friend on a sunday.

He managed to insert a large piece of steel in with some brush and destroyed both knives and sent a piece through the bottom of the housing.

Here's the question: The 3 holes that the bolts go into to hold the knives are slightly stretched. When the bolts are screwed in there's a little bit of play. But there's also a little bit of play on the other set where the holed aren't stretched. Is the drum pooched or is this not an issue.

I need to use the machine tomorrow of course and would like to chip with some peace of mind.

Does anyone have any experience with this?

It's a 2005 Vermeer bc1400xl.


I've attached a photo.

vince
 

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Get a price for welding and re-drilling/tapping the holes. The least he/she could do is pay for the repair. Bottom line is, it wasn't like that before as far as you know. People should pay for their mistakes, as painful as it is.

-Tom
 
With damage to the bolt holes I wouldn't operate the chipper until it was repaired to the satisfaction of your Vermeer dealer. I shudder thinking about free flying chipper knives at full RPM.

Loaning out chippers and stump cutters rarely works in favor of the owner, unfortunately.

Is the borrower going to pay for the repairs?
 
There's no vermeer dealer anywhere close to us Unless you call close an 8 hour drive. I'm always on my own with repairs.

The issue isn't how the repair will get done or who's going to pay for it. I need to know if a knife will come flying out of the thing or not.

v
 
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I need to know if a knife will come flying out of the thing or not.

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I wish I had the answer. The only way you're going to answer that question is to try the experiment. Personally, I wouldn't take the chance until the chipper is repaired properly by someone familiar with chipper drums. The consequences are too severe if the bolts fail to hold the knives properly.

I've had similar, but more severe, damage to a BC1800 caused by the winch hook going through the machine. In my case the entire drum had to be replaced, but fortunately insurance covered most of the cost.

In the event that you do take the risk and run the machine, at least run some large test pieces through, away from people and property, and then recheck the knives and bolts. But without repairing it, I would be forever worried when operating it.

Good luck.
 
[ QUOTE ]
[ QUOTE ]
I need to know if a knife will come flying out of the thing or not.

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I wish I had the answer. The only way you're going to answer that question is to try the experiment. Personally, I wouldn't take the chance until the chipper is repaired properly by someone familiar with chipper drums. The consequences are too severe if the bolts fail to hold the knives properly.


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X2
 
I would NOT run the chipper with the bolt holes deformed.
Also remember that the disc is balanced so that it is spinning "smoothly" once the inertia is achieved.

I would worry that once the stress between the knives and the piece of wood along with the anvil could cause the disc to crack..

Postpone the job and have a professional look at the machine even if it is 8 hrs away.

good luck either way..
 
Knives and bolts shouldn't have any "play". Clearance between the knives and the anvil/bed knife is usually quite narrow (although I'm not familiar with this particular chipper). The risk is that everything checks out during knife installation and then when chipping at full RPM a knife moves/shifts enough for the knife to impact the anvil/bed knife during full RPM rotation. Grenade would ensue. Carbide metal chunks anywhere/everywhere. Not worth the risk for me. Even if no one was hurt, it could do even more damage to the chipper than if you were to just repair it properly now. Let us know how things work out so we can all learn a lesson.
 
I don't have much experience working on chippers but I have been around sawmills quite a bit and large, heavy speeding chunks of steel are to be respected. I hate to say this less than your gonna hate doing it, break it down and fix it- if it isn't right. You will be doing yourself a favor in the long run, even if it still chips there may be slight additional vibrations/distortions that could cause some bearing or spindle, etc. to prematurely wear out. Plus if you work on it you could gain additional experience into the inner workings of your tool.
 
I definitely recommend NOT using that chipper until you get it back from Vermeer.
We had an incident with that exact model this past winter.
After a knife change (with out a torque wrench) the chipper threw a blade followed by the second blade. It made one of the strangest sounds I ever heard a chipper make (almost hypnotic). Jesse saw the sparks flying from the shoot and another guy shut the machine down. We found bolt and knife shrapnel in the chip box and under the chipper. It blew a hole threw the bottom of the chipper and caused many dents in the shoot. Luckily no one was hurt or killed.
When the knives are installed properly there should be no play. If the bolts are torqued too much they can crack under use. If they're not torqued enough the can come loose while in use. The bolts actually sheered off.
We also lucked out that the drum did not need to be replaced. It cost over $2,000 to fix it.
So as much as you need to work tomorrow, it's not worth risking any lives for. Rent a machine or reschedule the job.
Sorry this happened. Hopefully your friend can help out with the repair, if not you learned an unfortunate lesson.
I don't recommend renting equipment unless they are also renting you to operate it.
 
Gulp.

I was hoping that some of you would respond with: "that's nothing! Chip away and don't be concerned!"

You're all echoing my concerns, i just don't want to jump the gun and replace parts, pay for down time etc. This is going to cost me lots.

To clarify: there is no play in the knives when torqued down, just the bolts if they're threaded in by hand without a knife. You can see the hole stretch in the picture even though it's only slight. We chipped a little bit last night, including one big log and re checked the knives. They were fine albeit dinged some more by a couple pieces of residual shrapnel. They really should make these things with a trap door under the drum to extricate shrapnel and dropped bolts or sockets.

I'll get in touch with Vermeer today and make a plan and i'll keep you posted.

The guy i lent it to runs a landscaping company, lots of trucks, skid steers and steel in general. I figured it was in good hands. He's the only person that i've ever lent a chipper to without an operator. Lesson learned, always the hard way with me.

v
 
It might be possible to drill out the threads and insert a large threaded insert. This isn't an uncommon repair in industrial maintenance.

LockTite also makes a 'thread reformer' product that I've used. A tap is used to chase the deformed threads. A bolt is covered with a mold release fluid. then the bolt and deformed threads are covered with the LT product. When the product dries the bolt is unscrewed and you're left with repaired threads.

this isn't a 'no skill' repair but it doesn't require an aerospace engineer either. A good millwright shop or LockTite vendor should be able to help you.
 
Update: I took the machine to a local machine shop. A reputable machine shop with smart people who work there. They said the play in the holes didn't look to be of major concern. AS long at grade 8 bolts are used, the knife mounting surfaces are perfectly flat and the bolts are torqued to spec, there should be no problem. The vermeer mechanic that i spoke to agreed.
They could have welded over the holes and drilled new ones (10 hours shop time anyway) but that would be an unnecessary cost.

So, i feel better about using the machine.

Tom, vermeer drums have a block insert with threads that comes out and is replaced if the threads are damaged. We've done that a couple of times due to sheared off bolts when torquing. We replaced the torque wrench with one that actually worked to solve that problem.

Thanks for all the advice. Treebuzz is a super great tool for us arborists. Especially those of us whithout a clue.

v
 
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