Broken chain, common occurrence ?

[bmp01]

45 minutes ago, openspaceman said:

I think I agree but need to clarify your naming convention. The preset is a tie strap with the rivets already set in it, the loop is closed and a second tie strap is then place over the rivets and the rivet is spun. If the rivet is first forced hard then the new tie strap is fixed securely to the rivet, with the rivet now fully expended into the tie strap hole  and the increased friction between the rivet shoulder and tie strap adds strength, it also reduces any play.

 

I wonder if there is play then the one of the tie straps can flex. This flexing could fatigue and snap the tie strap in the middle,  the extra stress then straining the weakest part of the remaining tie strap at the rivet??

Spot on - exactly that....

Plus there has to be clearance between the rivet and the tie strap in order to assemble but its a good thing if there is no clearance once the rivet if finish formed.

No wonder joining links are the weak point.

 

 

[Macpherson]

On 24/06/2022 at 18:59, bmp01 said:

Newbie to milling question about chain life really. Would you expect to get the full tooth life out of a chain used for milling or is it typical to bin the chain after say a 1/2 or 2/3rds tooth wear ? Let's assume no chain damage through its life, just wear.

Reason for qu - I've busted an Oregon 75DPX chain where the chain has been used for milling the majority of its life. To be honest it doesn't owe me anything, for the cost of the chain I've milled a good deal of oak. But well ye know the chain teeth still look very servicable and the links still feel pretty tight.

Power head is a tuned up Husky 395XP, chain is  Oregon 3/8 regular, chamfer cutters, ground to 15 degrees. Chain did see some metal a while back but very minor just dulled the teeth and quickly fixed with routine file sharpening. Failure was through the preset joining link which always makes me suspicious. I'll see if I can find a picture.... 

 

Thanks for any input. 

 

All I can say is that as the joining link was [ and usually always is ] the weakest link in any chain, that would fit exactly with motorcycle chains where this has long since been the story, so if that is all that's happened just re-join the chain with a new link and use it for the rest of it's life, I'd bet the joining link was aftermarket or badly fitted👍

[Wonky]

I  have only 2 problems with chains while milling  the 2nd chain broke after hitting nails after nails. I'd lost about 8 or 10 cutters on this 25” chain before it finally let go..🤔 so I can’t blame the chain.

 

the 1st time I was lucky to spot while sharpening it and before it let go. yes this Oregon 18” chain  was on the joining link, so Its the fault of the person/company that spun the loop up.

[bmp01]

11 hours ago, Macpherson said:

 

All I can say is that as the joining link was [ and usually always is ] the weakest link in any chain, that would fit exactly with motorcycle chains where this has long since been the story, so if that is all that's happened just re-join the chain with a new link and use it for the rest of it's life, I'd bet the joining link was aftermarket or badly fitted👍

That is the plan, new joining links are here. Now I need to know how best way to DIY fit new link, not convinced the spinner is best way anymore...

2 hours ago, Wonky said:

I  have only 2 problems with chains while milling  the 2nd chain broke after hitting nails after nails. I'd lost about 8 or 10 cutters on this 25” chain before it finally let go..🤔 so I can’t blame the chain.

 

the 1st time I was lucky to spot while sharpening it and before it let go. yes this Oregon 18” chain  was on the joining link, so Its the fault of the person/company that spun the loop up.

 

 

Looks like that's cracked through the preset (looks just like the 'spinned' finish of a new preset).

[Macpherson]

20 minutes ago, bmp01 said:

That is the plan, new joining links are here. Now I need to know how best way to DIY fit new link, not convinced the spinner is best way anymore...

 

Used to be when you bought a motorcycle chain you got a removable spring link and a riveted permanent link the latter being the stronger and more reliable, although it was also known as a soft link in order that it could be home rivetted without special tools which to me made it super prone to be wrongly fitted very often causing this link to be tight and fail prematurely.

 

So from an accuracy of assembly point of view spinning the rivet on a saw chain would seem a much better way of doing it... but as I said before I wonder if the joining link for saw chain could be either after market and a weak point or just assembled by someone who was heavy handed.... or maybe both.

 

I'd imagine that if you take care with your new joining link [ as I'm sure you will ] all will be fine, cheers.

[bmp01]

19 minutes ago, Macpherson said:

 but as I said before I wonder if the joining link for saw chain could be either after market and a weak point or just assembled by someone who was heavy handed.... or maybe both.

Not really the time to punt for an ebay special is it....

Oregon rolls of chain come with presets and tie links,  40 off pairs per roll so I'm told, NewSawChains sell their surplus. Other route is to buy a bag of Oregon presets and a bag of Oregon tie links by their part nos from likes of L & S Engineers but by then you're well past the price of a new chain. The guys in the States are better supported in this respect.

 

In my case the failed link appears the same as the NewSawChains supplied link which I'm told is Oregon....but.... there is a marked absence of the word I Oregon stamped on the preset or the tie link.

 

Wonky's picture above (second one with one half broken) looks the same too. 

[gobbypunk]

I have only broke 1 chain in 10yrs of chainsaw milling and that was in the biggest hardist Oak ever .

[Rob D]

I think you need to rule out some of the other more straight forward reasons before thinking too much about the chain or joining rivet that is at fault. Prob something else caused this to fail.

 

The joining link is likely one of the weakest areas on the chain - but just because it breaks does not mean it's been incorrectly spun up - more likely it's that it's the first thing to break due to other stresses being put on the chain ie. it's the first point of failure.

 

If you look carefully at this chain that has broken there is too much peening on the drive links to be regular wear - you need to check the drive rim or sprocket as first thing - and second the condition of the bar is 2nd thing - has it been de burred and carefully checked for any chips or damage inside the rails? These are what generally cause a chain to break IMO.

 

That's not to say you can pin down exactly why the chain has failed - often multiple factors. But prob best to rule the obvious out before looking at the less obvious.

 

 

 

 

 

 

 

 

[openspaceman]

19 hours ago, bmp01 said:

That is the plan, new joining links are here. Now I need to know how best way to DIY fit new link, not convinced the spinner is best way anymore...

It probably still is the easiest and less prone to mistakes. Oil the spinner anvil well and really wind the take up handle hard.

 

I would do repairs in the field before I had the sense to carry spare chains and buy the chain making kit for home. A hammer and punch and anvil with a selection of slots to remove the broken tie strap and then a flat piece of steel to rest the preset on and an initial heavy blow on the rivet followed by shaping with a ball pein hammer. Keeping everything level to not bent the preset or ti estrap is essential.

 

I suppose a sett with a hole say 0.5mm too short to put over the  rivet would initially compress the rivet better, the shoulder then ensuring the tie strap is firmly against the preset rivet shoulder, before finishing with a domed one.

[bmp01]

On 26/06/2022 at 20:12, Rob D said:

I think you need to rule out some of the other more straight forward reasons before thinking too much about the chain or joining rivet that is at fault. Prob something else caused this to fail.

 

The joining link is likely one of the weakest areas on the chain - but just because it breaks does not mean it's been incorrectly spun up - more likely it's that it's the first thing to break due to other stresses being put on the chain ie. it's the first point of failure.

 

If you look carefully at this chain that has broken there is too much peening on the drive links to be regular wear - you need to check the drive rim or sprocket as first thing - and second the condition of the bar is 2nd thing - has it been de burred and carefully checked for any chips or damage inside the rails? These are what generally cause a chain to break IMO.

 

That's not to say you can pin down exactly why the chain has failed - often multiple factors. But prob best to rule the obvious out before looking at the less obvious.

Thanks Rob and sorry for show response. 

I'll look into those points tomorrow, 'peening' on drive link is an interesting one.... its the non-loaded side of the drive link ? Wonder if that is same across the whole chain or local to the failure, there is other damage that surely came from the links bashing into each other as all came to a abrupt halt. I'll check.

New clutch and rim (Oregon brand) were fitted at the same time this chain was fitted. Bar was dressed at the same time. Bar is used Sugihara, it was on the saw when I bought saw secondhand (previous chain was well used at that point).....nose sprocket has a question mark over it, likely to be worn, I'll check. 

 

 

Edited June 28, 2022 by bmp01