Alaska Mill Chain Safety

[Daninvan]

I'm interested to find out if anyone has had a chain break on them while milling full out with an Alaska mill. Did the chain whip around in the cut and hit you? Or how did it behave?

I'm interested to know if this is something that I should be worried about, and perhaps change the way I mill, or where I stand when I mill?

FYI I generally stand behind and push, which leaves me open to pretty much being sliced quite badly if the chain whips me. It seems that standing to the "outside" of the powerhead would be safer, but then it's hard to push the mill. It seems that standing in front of the log, protected by the uncut section, and pulling, would be the safest place to stand short of a Mallof winch arrangement?

What do people think? (Other than I need to wear my chaps when I cut!)

(And I apologize if this has been discussed a million times already!)

 

[smithie55]

Hey there Dan,
Have you had a chain break?
I have milled several thousand board feet with my Alaskan mill, and I have never had a chain break. I also make my own loops, and have never had a chain break ever, either milling or falling or bucking.
If it were in the cut and it broke there is enough resistance from the wood and saw dust that it would decelarate pretty fast.
I would'nt worry about.
Happy milling
By the way what you milling there on the beach? do you have any problem with the sand dulling the cutters?

 

[Daninvan]

Thanks Smithie, I was wondering if the friction, sawdust, and wedges in the cut would be enough to prevent the chain from whipping around with much force. Perhaps sometimes that would be the case, but I would not want to be at the helm on one of the other times!

I have never had a chain break while milling (or ever for that matter), I'm interested to hear what others have experienced and how the chain behaved.

The pic is an older one of me milling Port Orford cedar. I've since learned to take the bark off first when milling at the beach. Just one pocket of sand trapped in the bark is enough to dull the chain!

Dan

 

[Brmorgan]

I've never broken a chain, and I've hit nails with even the low-profile on a big 066. Also hit a 3/8" lag bolt with the 090 once without incident. Though a few folks here have had a few breaks, so I'm not sure if it's more of an hours issue or a maintenance issue that accounts for the difference. I think if you have the nose guard on the mill and clutch cover on the saw in place, it would be pretty tricky for you to get whipped by a broken chain. If it breaks on the nose end, there's no way it's going to be able to whip you since it'll just jam against the uncut wood ahead of the bar. And if it breaks at the saw end, there should be plenty of structure in the way to prevent any sort of major incident. I've never felt the need to wear chaps etc. while milling, but obviously good gloves and face (at least eye) protection are a must just in case.

 

[ran3465]

Yeah i dont think it is possible for the chain to hit you if the bar in is the cut, never broke one though. Id be more worried about someone seeing you in those sweat pants

 

[BobL]

Though a few folks here have had a few breaks, so I'm not sure if it's more of an hours issue or a maintenance issue that accounts for the difference.

I Agree. If milling chains are likely to break, the tough conditions encountered during the milling of Aussie timber are probably a good place to see what happens.

Anyway, have a look at this break discussed in grimy detail on an Aussie Milling Forum.

This guy was continually breaking his newish chain, on a new sprocket.

A) Newish chain

B) New sprocket

C) But just take a look at his bar?

My explanation was for this break was;
1) New chain placed on an undressed bar.

2) The chain is not in full contact with the bar so chain is riding or slipping on and off those little lips on the bar rails (See Picture B above).

3) The lips are not dead square notches but slightly wedge shaped like in this picture.

This also explains the groove along the bottom edge of the cutter and the mangled backs of the drive links (see picture A).

4) constant pressure on the chain pushes the chain down into the wedge jamming the chain down into the bar, loading up the rivets and stretching the chain. If it doesn't jam, the undressed bar can tilt the cutter over getting it to take too wide a side bite - chain could load up and break here.

5) The effect of the chain stretch is shown up by the mangled areas between the sprocket slots (see red outlined areas in Picture B) and teh corresponding mashed backs of the drive links

6) Eventually stretch is so great it allows a drive links to jump a drive sprocket slot which tears the drive link away from the cutter.

I think if you have the nose guard on the mill and clutch cover on the saw in place, it would be pretty tricky for you to get whipped by a broken chain.

Yep - agree.

If it breaks on the nose end, there's no way it's going to be able to whip you since it'll just jam against the uncut wood ahead of the bar. And if it breaks at the saw end, there should be plenty of structure in the way to prevent any sort of major incident. I've never felt the need to wear chaps etc. while milling, but obviously good gloves and face (at least eye) protection are a must just in case.

The most likely place for the chain to break when milling is the same as a CS in regular use, either on the sprocket or somewhere between the sprocket and the cutters in contact with the wood. If the chain breaks somewhere in the cut, the "whip around" can only be as long as the distance between the sprocket and the log. But if the operator stands facing the top of the CS, the operator has the entire saw between them and the chain. This is also a good reason to push and not pull a mill. A chain catcher is also not necessary on conventional mill because the bar clamp will act as an chain catcher. Also the inboard verticals will act as a chain catcher to some extent.

The risk of an operator being hit by a chain breaking on the back of the bar while standing in the regular milling position is very very low because the sprocket is pushing the chain away from the operator. It usually just ends up just folding itself up inside the kerf.

Even though the risk is very low I still wear chaps while milling. It's mainly a habit from regular saw use - every time I use a saw I put my chaps on, that way I don't forget in between slabs or logs when I go to use a CS in a regular way.

Recently I did a sort of a basic risk assessment for milling and I will post that in the milling sticky.

 

[BobL]

I'm interested to find out if anyone has had a chain break on them while milling full out with an Alaska mill. Did the chain whip around in the cut and hit you? Or how did it behave?

I'm interested to know if this is something that I should be worried about, and perhaps change the way I mill, or where I stand when I mill?

I'd be more worried about giving myself a bad back than what the chain might do

Compare your stance with these.

This log is on a very slight slope and even though this is very hard wood but there is no pushing, just a light forward pressure with my left knee/thigh on the wrap handle. To mill this way a mill needs a handles located in slightly different places but it's not rocket science.

 

[SilverBox]

I've never snaped one milling. But I've broke several dropping trees and bucking, the chain catcher always caught the chain.


Once when trying out a new saw the previous owner had reveresed the chain catcher so that it was not blocking the chain, the chain came off while brushing and swung around and whacked me in the leg. I was like WTF!! Then while I was putting the chain back on I looked it all over, because I've never been hit in the leg hard by a chain coming off before, the chain catcher always stopped the chain and if it hit my leg it was hardly even noticable. Thats when I notice the chain catcher had been reveresed and I immediately fixed the problem. The next time that chain came off, it did not hit me in the leg.

I was wearing Levi's with thermals on underneath. The chain did not go thru the Levi's. It hit me about as hard as if someone were to whip a chain at your leg holding it in their hand.

Anyways, in conclusion, I'm not worried at all about snapping a chain milling, the chain catcher will catch it.

 

[Kicker_92]

I've broken one in the cut and it really didn't go anywhere. Chaps won't help much, other than the extra padding. The broken chain will never grab enough of the kevlar fibers to jam up the saw. The only dangerous position I see would be if your using a helper handle. The chain could whip out the front and catch that persons hand.

My chain broke from a bad splice, the links that were riveted were bent and would have stressed back and forth until it failed. Like Silverbox said, feels like someone whiped you with it, no cuts in chaps.

 

[irishcountry]

I have the same phobia but I think buried in a cut it would take the steam out of a chain pretty quick. I have throw a chain off the saw cutting firewood and that came close to wrapping around my leg I had my chaps on so no worries but makes you think it is a powerful/dangerous tool to be respected at all times!!!!

 

[Daninvan]

Interesting comments, thanks everyone! I'm learning quite a bit from the discussion.

If the chain breaks somewhere in the cut, the "whip around" can only be as long as the distance between the sprocket and the log.

Ahh, I understand better now. So if the chain breaks at the far end of the cut on a fully buried 36" bar, you would have up to 36" (roughly) of chain that would potentially be 'whipped'.

With that in mind, I am not sure what role the nose guard would play in preventing the chain from whipping then? It would seem that if the chain was to whip it would do so in the direction away from the nose guard rather than towards it?

Also not sure how the bar clamp would help prevent a whip. It is not in the same plane as the chain so it doesn't seem to me that it would get involved.

I can see the benefit of a chain catcher here though. I had to go look on Wikipedia to see what a chain catcher is. I don't think my 25+ year old Husky 2100's have one of those on them!

Also the inboard verticals will act as a chain catcher to some extent.

Well I couldn't find on Wikipedia what the 'inboard verticals' are on a chainsaw mill, so I will have to ask here: What are these?!

But if the operator stands facing the top of the CS, the operator has the entire saw between them and the chain. This is also a good reason to push and not pull a mill.

By top do you mean the trailing edge? I agree that the saw is between the operator and any potential break in the chain in this case. But if you pull, then you have the entire uncut portion of the log between the operator and the potential break. That doesn't seem unsafe to me? I think if one was to stand right in front of the leading edge of the powerhead that would be the most unsafe place.

Id be more worried about someone seeing you in those sweat pants

Yeah, I got rid of them. The dust stuck to them like a fat kid on a candy. Now I use plastic rain pants, the sawdust never sticks! Since I mill mostly in cooler weather they are not too hot either. Still, I think I will invest in a pair of chaps to wear underneath them.

In any case it sounds like a chain break while milling is a rare event if the gear is properly maintained, so I am not going to lose any sleep over it.

Dan

 

[Brmorgan]

Ahh, I understand better now. So if the chain breaks at the far end of the cut on a fully buried 36" bar, you would have up to 36" (roughly) of chain that would potentially be 'whipped'.

With that in mind, I am not sure what role the nose guard would play in preventing the chain from whipping then? It would seem that if the chain was to whip it would do so in the direction away from the nose guard rather than towards it?

If it broke at the far end in the cut, the entire chain is probably just going to stop dead almost instantaneously. The chain on the leading edge will just bite into the wood, and since after breaking the chain won't be tight on the drive sprocket anymore, there will be nothing to keep pulling it through the wood. The chain on the trailing edge of the bar is the only stuff that even COULD really move much, though I doubt it would because sprockets aren't much good at pushing chain, just pulling. All of that notwithstanding, and assuming a worst-case scenario, the nose guard is so close to the tip of the bar (less than 1" normally) that any chain that tries to whip around the nose will likely just pile up and catch on it.

Also not sure how the bar clamp would help prevent a whip. It is not in the same plane as the chain so it doesn't seem to me that it would get involved.

Well I couldn't find on Wikipedia what the 'inboard verticals' are on a chainsaw mill, so I will have to ask here: What are these?!

I believe that would be referring to the upright depth adjustment posts, but I'm not sure. Neither these nor the clamps are directly in the bar/chain's cutting plane, you're right, BUT keep in mind that chain has a significant amount of lateral flex, so won't necessarily stay in a perfectly horizontal plane once the drivers are out of the bar groove, especially if the chain's broken.

I think probably the worst case scenario would be a breakage RIGHT where the chain exits the wood on the leading edge of the cut, right in front of the powerhead. If it broke right there, the sprocket could still whip that small (maybe 10-12" long) section of chain around the drive sprocket and towards the operator's legs. But that's assuming you don't have a clutch/sprocket guard (original or custom) installed.

 

[BobL]

Dan, your alaskan uses what I call a "naked bar" design. It has a major advantage of being able to chain the chain without removing the saw from but has no bar clamps to act as chain catchers. I will be modifying my small mill along these lines soon but I have a couple of mods to add that will act as chain catchers.

When a chain breaks the most common thing I have heard that happens is it pops off the drive sprocket and flops off the bar - ie no big deal.

In teh very unlikely event of a the chain breaks on the operator side of the bar the remaining chain on the pull side of the sprocket may be whipped around the nose like this.

A conventional bar clamp at the nose will catch the chain before it can form a long whip

On the operator side of saw the only think that matters is the amount of chain between the log and sprocket. Here, if enough chain exits the log, the bar clamp may also act as a catcher.

As far as the milling uprights go I was referring to the GB mill design that bolts the saw to the mill via the uprights like this.

There are no inboard bar clamps on these designs and the chances of them acting as a catcher only apply if a lot of chain exits the log.

In all cases if the mill is pushed the bulk of the saw is between the operator and any whipping chain, so the chance of contact are small.

A significant risk at least to another person on your setup is your naked bar nose. I'd rate that as a significantly greater risk than chains breaking.

 

[Daninvan]

Bob,

Great info, thank you!

I think some projects over the holidays will be a nose guard, a pair of chaps, and putting some wheels and handles on.

Dan

 

[BobL]

Bob,

Great info, thank you!

I think some projects over the holidays will be a nose guard, a pair of chaps, and putting some wheels and handles on.

Dan

Sounds like a good plan

 

[billstuewe]

I have milled about 12000bf with an 066 with picco chain and have had about 4 breaks. Every one instantly stopped and just layed there. I had a major problem getting one out of the cut--it bound the bar into the cut and I could not slide the saw back and could not pull the chain out. It took about 15 minutes of fussing with it but finally got it out. Nothing wipped anywhere on any of them.

 

[Stihl-in-Ky]

I have broken 2 chains with nothing hapening the chain just laid there but it shure stopped cutting in a hurry.

 

[Daninvan]

Ha! Well I had a chain break the other day. Luckily no injuries to report.

It was a Granberg ripping chain on a 36" bar powered by a Husky 2100.

I had invited some friends to join me for a milling session. One of the guys was using the mill in a fairly wide birch log. I had noticed his technique was quite rough but let him go at it since he had a smaller mill of his own and seemed to know what he was talking about.

So the chain broke on him, I did not see it but he said it just slid out of the log away from him and landed on the ground. Sounded very undramatic.

I have not had a chance to examine the chain closely since the event. I did notice that when I tried a new chain on the bar, the chain seemed to be bound in the bar's groove. I tried a second (third?) chain and it was the same, so obviously there is a problem with the bar. Cause or effect? Not sure yet.

We'd had a problem with that powerhead earlier too, trying to run the 60" bar, so we demoted it back to the 36" mill, and I let the other guys do the reassembly and chain tightening. In hindsight I should have done it myself, or at the least better checked their work. I did not do so because I was working on an oak crotch piece with another guy using the 60" bar.

Luckily no one was hurt. I need to do some analysis to see if I can understand what caused it to happen.

Dan

 

[Daninvan]

Well I had a chance to look at this more closely today but was not able to glean anything more. Other than the broken link the chain is not obviously damaged in any other way. I think I have a couple spare links so should be good to go again once I dig them up.

The bar is definitely pinched though. I cleaned the bar up, greased the tip, fitted a new chain in it, and it was so tight I could not move it by hand at all. I fired it up and the motor could not even spin it on the bar! This is the same thing I noted with two different chains right after it happened.

It's odd though, I ran a couple links through it by hand on both sides and there was not anywhere that it was obviously tight.

I am guessing that somehow the bar was damaged, causing it to squeeze the chain, causing the chain to break.

Anyways, I guess I'll take the bar in and get it repaired. Luckily I still have one bar that's good to go, going to do a walnut tree at a friend of a friend's place on the weekend.

Cheers,

Dan

 

[mtngun]

Thanks for the pic.

You said Granberg Milling chain. Would that be lo-pro or "regular" 3/8 ?