# .375 vs .404 pitch question ?



## Arky217 (Apr 19, 2009)

I have the Logosol M7 mill setup. I've broken 2 of the low profile special Stihl chains that Logosol sells for this mill. I am now using a regular Stihl low profile chain that my local Stihl/Hardware store sells. The top angle is 35 rather than 10 like the Logosol chain, but it seems to cut just as fast, though the finish is slightly rougher.
The chains are being used on a 20" bar driven by a 395XP.
The biggest difference seems to be the kerf; about 1/4" for the Logosol chain and about 5/16" for the hardware store chain. This caused me to adjust the mill scales slightly and allow 3/8" for the kerf (finest mill adjustment is in 1/8" increments).

If I continue to break these .050 gauge chains, I may go to a stronger chain ( really need a slightly longer bar sometimes anyway). I am considering either a .375 pitch, .063 gauge chain or a .404 pitch, .063 gauge chain. Of course the .063 gauge adds a lot of strength over .050 gauge, and though I haven't had a .404 pitch, I assume that it is somewhat stronger than .375 pitch due to more 'meat' around the drive link rivet hole.
What I don't want to do, however is exceed a 3/8" kerf.
So the question: Is the kerf from a .404 pitch chain greater than the kerf of a .375 pitch chain, everything else being equal, and do either one exceed 3/8" when used in milling ?

Thanks,
Arky


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## BobL (Apr 19, 2009)

Arky217 said:


> I have the Logosol M7 mill setup. I've broken 2 of the low profile special Stihl chains that Logosol sells for this mill. I am now using a regular Stihl low profile chain that my local Stihl/Hardware store sells. The top angle is 35 rather than 10 like the Logosol chain, but it seems to cut just as fast, though the finish is slightly rougher.
> The chains are being used on a 20" bar driven by a 395XP.



If you are breaking LP chains on this setup then something is definitely not right. 
If you would like a chain break diagnosis post a close up picture of the 
- chain breaks
- a side on view of the tie straps 
- a side on view of 2 consecutive cutters 
- the top of the sprocket



> If I continue to break these .050 gauge chains, I may go to a stronger chain ( really need a slightly longer bar sometimes anyway). I am considering either a .375 pitch, .063 gauge chain or a .404 pitch, .063 gauge chain. Of course the .063 gauge adds a lot of strength over .050 gauge, and though I haven't had a .404 pitch, I assume that it is somewhat stronger than .375 pitch due to more 'meat' around the drive link rivet hole.
> What I don't want to do, however is exceed a 3/8" kerf.
> So the question: Is the kerf from a .404 pitch chain greater than the kerf of a .375 pitch chain, everything else being equal, and do either one exceed 3/8" when used in milling ?


The 404 kerf is significantly larger than the 3/8.

How hard are you pushing the 395? The 395 should be able to cut with very little pushing on a 20" bar How often do you sharpen? If your chain sharpening technique is not up to scratch and you push too hard these chains will break.


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## BlueRider (Apr 19, 2009)

you didn't mention what size sprocket you are running. if you swap out to a larger sprocket it will increase the chain speed and lower the torque and your saw has plenty of torque for a 20" bar no mater what size sprocket. By decreasing the torque, even if it is only a little it may keep you from breaking chains. as a bonus it should also increase your milling speed.

and don't forget that if you do switch to .404 it will increase the chain speed and drop the torque if you use a sprocket with the same noumber of pins.


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## MR4WD (Apr 20, 2009)

BlueRider said:


> and don't forget that if you do switch to .404 it will increase the chain speed and drop the torque if you use a sprocket with the same noumber of pins.



The cutter on 404 are farther apart, balancing chainspeed with "cutters in the cut", but 404 does cut a wider kerf.

As stated, I might try an run an 8 pin with 3/8" on a 20" bar, for milling.

I have found that the top plate angle at 30 degrees will cut a wider kerf than at 10-15 degrees since the cutters try and dive sideways into the wood.

I might suggest that your chains aren't that sharp as even processing wood AND milling with it starting from new chains to unuseable I haven't busted anything in 3/8...


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## Brmorgan (Apr 21, 2009)

I agree, something doesn't sound right. Perhaps the LP chains are being run on an old, almost-worn-out sprocket? If that's the case, the sprocket will stretch and wear the chain far too much right off the bat and could cause breakage. 3/8 LP on a <24" bar & 8 pin sprocket is a great combination for a 90cc-class saw & I've had no such problems with mine.

I'm with Bob - throw some pics at us and then we'll know more definitely what's going on.


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