Bent Chipper Blades

[Old Monkey]

I have the big ass torque wrench as well. Putting that much torque on the bolts, I notice that the plate that holds the blade down wears down a little over time. I have had my chipper for almost a year and a half and have put only a 120 hours on it but have replaced those brackets. When I look at Brett's they do not seem that worn. Makes me wonder.

Larry you're using the anti seize stuff on those bolts aren't you?

What I wonder about is that one of my knives seems to always wear down quicker than the other. I have looked at the blade spacing with the anvil and both sides seem even. I need to check it again.

 

[sotc]

darin, i lied last time you asked chipper hours. i looked today and had 444 on it.
get grade 8 flat washers for your knife bolts, they save that plate

 

[Mr. Sir]

Not my cranes. The crane guy is helping me out with this. He does the welding too. I turn wrenches, grind stuff, and break things.

 

[stehansen]

Ax-man, 5 years ago I bought a Vermeer 1250 and a couple of years after I got it, it developed this annoying tick that wasn't regular but seemed to get worse over time. We would look and the blades were all missing the bed knife by a 1/8" and I would put a pry bar on the disk to see if the bearings were loose and I couldn't feel any slop in that. Well one day the chipper started making a really bad noise all of a sudden and the bearings were out and it had wrecked up the shaft. I replaced the bearings and the shaft and you know we don't have that annoying tick anymore. If I would have just replaced the bearings when it started ticking I would have saved replacing the $500 plus shaft and I don't know how many hours of looking with a flashlight and prying with a bar and wondering what the hell is wrong with my chipper. So I know our chippers are quite different but, the next time mine is making a noise I can't figure out I think I will try changing the bearings.

 

[Mr. Sir]

Ax-man. You definitely want to track down that ticking sound. That's what ours was doing before it self-destructed.

OM. That plate wears out fairly quickly. I had recently replaced mine. On an older chipper I had, I used the Grade 8 flat washers to reduce wear. I don't know why I haven't put them in the new one yet, just never got around to it. But make sure the bolt heads don't extend above the arc of the blades.

 

[Old Monkey]

Good point.

 

[Cobleskill]

On that broken off bolt- a lot of times once you drill it out to just nicking the threads of the housing you can work the bolt out and not have to rethread. Is it a dead-end hole? That would be more difficult.

 

[Mr. Sir]

It is a dead end hole. I'm going to try the easy-out first. I just have to find a carbide bit to drill that Grade 8 steel.

 

[Cobleskill]

Try the heat then quench method. After a hole is drilled the heat works even better. Easy - outs scare the hell out of me and they never seem to work that well. Seems like they squeeze out and bind even more to me. And how do you drill out an eazy-out?

 

[Reddog]

It is a dead end hole. I'm going to try the easy-out first. I just have to find a carbide bit to drill that Grade 8 steel.

High speed Cobalt drills will work to drill GR 8 bolts. Just keep squirting WD-40 or some thing similar to lube and cool it. And try to keep your drill rpm's low and the bit sharp. The bad thing with Carbide is, if you break it you have to torch the bolt out.

If Netree is offering to have a metallurgical analysis done, take him up on it.
If you send the blade company a report showing the blade did not match their spec. They do not have much of a leg to stand on. Or at the least when you bad mouth them you have a report to back it up.

As for the quality of Steels. You can buy the same grade from multiple mills and get very differing results. But all will meet the spec, some will just not perform as well. We have to buy mill runs and spec the exact chemistry we need for our work.

 

[Al Smith]

On this broken or stuck bolt,that's a problem alright .You need a series of solid carbine bits ,sharp ones . You have to step drill it out .

In the drilling process make sure the drill is pulling chips because if it is just rubbing away at it the damned metal will just get harder from the heat . The chip actually pulls the heat of machining out with it . When you get a tad over about half the diameter out of it then use an easy out .

Once you get it out use never-seeze on the new bolt .The acidic property of the wood chips plays hell on high carbon steel .Make sure you torque the bolt to it's proper values .A loose bolt will break faster than one with proper torque .

 

[Al Smith]

--more food for thought on this .It's a good idea to chase the bolt holes with a tap and also a capitol idea to use new bolts every so often . After a period of time the bolt will fatigue from use in this type of rotational impact loading .

 

[Reddog]

On this broken or stuck bolt,that's a problem alright .You need a series of solid carbine bits ,sharp ones . You have to step drill it out .

Okay Al,
I'll bite, And what do you do after the newbie breaks the carbide bit off in the bolt?

 

[Frans]

but managed to snap a 1/2 inch Grade 8 bolt in the process. It had an old crack about halfway through, so I replaced all ten of the bolts that hold the drum assembly to the feed wheel housing with brand new. Now I have the pleasure of trying to drill out that bolt and retap the hole.

It's unclear if you were putting the bolt in, or taking out an old bolt which busted as you tried to unscrew it.

No matter what, make a darn good attempt to drive it out first with a hole punch and a hammer before drilling. Take your time drilling a little crater on one side of the broke bolt shaft end.

Good luck with that.

 

[Al Smith]

First of all ,don't use a bit with an inserted carbide,I'll bet a dollar to a doughnut these will break like a toothpick . You can not burn out carbide with a torch ,it takes an arc . If you use the step drill method you won't break the bit . It might take 4 different sizes of bit to drill out a 3/4" bolt .

About the only thing that will happen is possibley snapping off a little of the bit edge .If this happens,use a center punch to knock it all out before you try a new bit because the embedded carbine will just clean off the next bit .

It's a real pain to drill out a grade 8 bolt but you get real good at it after you've done a few .--and after a few you won't forget to use never-seeze either .

--and another thing,if you have to buy the bits and work for 2 hours drilling one out,you'll come to the realization that new bolts are actually cheap in the long run .

 

[Al Smith]

Another method .I've seen the machinery repairmen at work do this .On say a 3/4" bolt they have dummied the socket head on ,they weld a 5/8" or 1/2" into the socket and back them out that way .Works sometimes,sometimes not . The actual socket head is not nearly as hard as the rest of the bolt .

 

[Mr. Sir]

It broke as I tightened it with the impact gun. I was half a second too slow getting off the trigger. It's probably a blessing that it did break, otherwise I would not have known that it was cracked and I wouldn't have replaced all of the others. I've got carbide bits (and I've broken enough of them to know how to use them), I just have to locate them in the shed. Lots of seldom used tools got packed into various boxes the last time I moved the shop.

 

[Reddog]

No matter what, make a darn good attempt to drive it out first with a hole punch and a hammer before drilling.

Good advice before starting to drill.
The other option is take a 7/16 nut and weld thru the middle of the nut to the bolt. Don't try to penetrate to much at the edge of the nut. Build a good bead into the bolt and then up into the nut. 6011 rod works well for this. Or a wire feed running hot.
If it was larger than 3/4" welding a nut on thru the middle works real well. But on 1/2 it is 50/50.

 

[stehansen]

Good advice before starting to drill.
The other option is take a 7/16 nut and weld thru the middle of the nut to the bolt. Don't try to penetrate to much at the edge of the nut. Build a good bead into the bolt and then up into the nut. 6011 rod works well for this. Or a wire feed running hot.
If it was larger than 3/4" welding a nut on thru the middle works real well. But on 1/2 it is 50/50.

I've had much better luck with this method than with easy-outs. A wire welder works even better as you don't get all the smoke and slag that you get with a stick.

 

[Frans]

Forgot to mention that you said it is a half inch bolt which broke. Be very very careful, thats a small carbide bit you will be using to extract it with.

I wish I had Al's experience with this, orrrr maybe I should be careful what I wish for!

 

[Mr. Sir]

Un-frikkin-believable

We put everything back together today, then cut down a small live oak at the neighbor's house to make sure everything worked. The brush went through fine, but on the fourth or fifth 8" to 10" log I heard that tell-tale ticking sound again. Shut it down quickly and sure enough, ANOTHER bent blade!!! WTF is going on here!!!

 

[sotc]

quit buying that crap!

 

[Mr. Sir]

Here's a few pics. Notice the gap under the blade as well as the damage to the leading edge where it struck the anvil on the right side.

 

[Thor's Hammer]

Not good....

 

[Al Smith]

If a bolt head snaps completely off then chances are the threads are not under torque . Old trick,take a real sharp prick punch or a little drill bit ground to a sharp point and back it out .

I've done this many times at work and twice on a chipper after first drilling the head off .