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3/8” LP carbide tooth chain breaking at the driver hole.

67L36Driver

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My friend Allen has a loop of the Stihl carbide chain on a 40 (ish) cc Echo. Broke at the driver rivet hole now three times.

Echo CS400 w/14” IIRC.

Maybe the shock load when limbing small branches??

I know, I know. This is worthless without pictures. [emoji37]
 
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Wilhelm

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I think the loop might be dull so that he utilizes the saws spikes to make the chain cut which causes increased wear.

I have a Stihl Rapid Duro 3 & Picco Duro 3 loop, one each.
The Picco still cuts great, it is not an agressive chain so shock loading should not be a concern.
My Rapid Duro 3 is out of commission due to dullness.
The Rapid will still cut when I utilize the saws spikes, but I don't want to do that in order to prevent additional wear on the drive links and tie straps.
Ways of getting my Rapid Duro 3 loop back to glory are in the works.

Once I figure out a way to sharpen these carbide tipped chains myself I am getting more of them, that is how much I like them.

I guess either dull, or unevenly sharpened if it got sharpened which actually will shock load the loop.
 

Homemade

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From carbide machinists tooling I know that carbide doesn’t like”interrupted” cut. And the carbide chain I use for fire department saws, it’s all about keeping the chain speed up. That’s why they are usually run on 70+cc sized saws. It’s not so much the power in the cut, but being able to rpms in the cut without bogging. When the chain slows down and has to bludgeon it’s way through a nail, it will chip or break off.

Tell your friend to keep the revs up and it might last longer.

And To 64driver. They do make diamond bits for rotery dremal style sharpeners.
 

Homemade

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Edit:
Sorry it was wilhelm needed the sharpening advice and 67 driver started the post.

That’s the problem with Tapatalk, you can’t see previous posts while your typing your reply.
 

XP_Slinger

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From carbide machinists tooling I know that carbide doesn’t like”interrupted” cut. And the carbide chain I use for fire department saws, it’s all about keeping the chain speed up. That’s why they are usually run on 70+cc sized saws. It’s not so much the power in the cut, but being able to rpms in the cut without bogging. When the chain slows down and has to bludgeon it’s way through a nail, it will chip or break off.

Tell your friend to keep the revs up and it might last longer.

And To 64driver. They do make diamond bits for rotery dremal style sharpeners.
Makes a lot of sense, I had never thought of this. Hard as the carbide may be, it is brittle and less likely to hold up to abuse if not sharpened properly or chattering on an under powered saw
 

Wilhelm

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From carbide machinists tooling I know that carbide doesn’t like”interrupted” cut. And the carbide chain I use for fire department saws, it’s all about keeping the chain speed up. That’s why they are usually run on 70+cc sized saws. It’s not so much the power in the cut, but being able to rpms in the cut without bogging. When the chain slows down and has to bludgeon it’s way through a nail, it will chip or break off.

Tell your friend to keep the revs up and it might last longer.

And To 64driver. They do make diamond bits for rotery dremal style sharpeners.
Solid Carbide drills love high rpm's, small diameter ones require really high rpm's in order not to shatter.

Edit:
Sorry it was wilhelm needed the sharpening advice and 67 driver started the post.

That’s the problem with Tapatalk, you can’t see previous posts while your typing your reply.
I received a mini dremel type grinder with chain sharpening attachment this week.
It is just a cheap China made eBay unit, I tried it on my regular steel .404" loop yesterday and got decent results.
I already have diamond laced burs that I will utilize in combination with the grinder to sharpen my dull carbide tipped loop.

Makes a lot of sense, I had never thought of this. Hard as the carbide may be, it is brittle and less likely to hold up to abuse if not sharpened properly or chattering on an under powered saw
Generally if Your friend is cutting only clean wood the carbide will not chip no matter how slow the loop turns.
Not even a knot should have enough density to cause shatter of the carbide insert.

The potential of chipping the carbide inserts depends on the conditions the chain is being used in and the tooth geometry itself.
From what I have seen rescue carbide tipped chains are fairly dull in design which gives them strenght against impacts with foreign objects and hard materials.
I have two Stihl Duro 3 in Picco and Rapid (Picco = 3/8" low profile, Rapid = full size 3/8") and their carbide inserts are shaped like a round ground semi chisel tooth - You do not want to hit any stones nor nails with these chains!
They perform exceptional in clean logs and endure a whole lot of abuse in skidded dirt infested logs.

Picco Duro 3
Copy of P1030205.JPG Copy of P1030204.JPG


Rapid Duro 3
Copy of P1030217.JPG Copy of P1030219.JPG

Skip to the end of this clip to see how much dirt will not matter to a Carbide tipped loop.

 
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67L36Driver

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No problem with the cutters as they remain sharp as the day it came out of the package.

It’s the rivet eye breaking out of the driver links.
 

Wilhelm

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That sounds like he is dogging the saw through the cut and causing wear & tear, 3/8" low profile doesn't take too much to break - but I could be wrong.

Maybe it is a loop out of a bad batch, kinda doubtful with Stihl though.
 

Wilhelm

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Here is a stupid thought, is he running the correct sprocket for 3/8" low profile?

A wrong or severely worn sprocket might "tear" the drive links apart.

Just a thought that popped into my mind.

Same goes for the bar tip sprocket.
 
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