The Holy grail?

[Dan Maynard]

I think some of the Oregon confusion is that they make two types of .325 0.050 chain - 20BPX and 95TXL.

 

The 20BPX is what they call standard kerf and similar to the type 21 and 22 which are .058 and .063

 

The 95TXL is "Speedcut" which is matched with Speedcut bars and is their "narrow kerf" system. I've not used it but Oregon seem pretty clear it cuts a narrower slot in the wood. The bars and chains have a special logo to differentiate.

 

Stihl used .063 for their bars until the Light04 which was introduced with a new narrow kerf .050 chain. Personally I think they were forced to do this because Husqvarna had previously brought out their own SP33G narrow kerf system so the 550XP was cutting faster than standard MS261.

[Trailoftears]

12 minutes ago, bmp01 said:

And what about the outside diameter ? 

 

[Trailoftears]

Blimey,its all bit of a handful.Just staring at the much larger picco super rim and trying to work out the ramifications of making it larger than the standard .325 rim.faster chain travel/or slower due to larger circumference?

[Trailoftears]

Also,the super picco kit is marketed as being better/faster cutting in softwoods-pine is specifically mentioned.But,if the teeth are identical (ish) why would it not be equally good in typical hardwoods?A sharp chain is surely a sharp chain-it does drop 7 cutters tho compared to the stock chain supplied on the ms261.

[bmp01]

6 minutes ago, Trailoftears said:

Blimey,its all bit of a handful.Just staring at the much larger picco super rim and trying to work out the ramifications of making it larger than the standard .325 rim.faster chain travel/or slower due to larger circumference?

Make the assumption engine speed is the same. Chain speed is faster by the ratio of diameters....

Then accept that in reality the engine cant necessariy provide enough torque to keep engine speed the same. But you'll have an overall gain in chain speed. 

Slight narrower kerf will help keep engine speed up.

 

[Trailoftears]

Right,I get that I think!

[bmp01]

4 minutes ago, Trailoftears said:

Also,the super picco kit is marketed as being better/faster cutting in softwoods-pine is specifically mentioned.But,if the teeth are identical (ish) why would it not be equally good in typical hardwoods?A sharp chain is surely a sharp chain-it does drop 7 cutters tho compared to the stock chain supplied on the ms261.

Hard wood is still 'harder' to cut meaning you need more engine torque to maintain engine speed. Just like you need more engine torque to run a longer bar if its cutting over full length, or conversely you can run a 25 cc saw to cut 3-4 " branches.

Its all a compromise....

 

[openspaceman]

 

1 hour ago, bmp01 said:

Sounds like we are on different wavelengths. ... ?

The teeth, left hand and right hand are separate items attached to their drive links on opposite sides of the drive link...

Yes and the teeth edge only overlap to the drive link so the cut is wider than the cutter by at least the gauge of the steel.

 

Edited November 20, 2022 by openspaceman
added lines, red shows extent of cutter edge blue shows kerf

[bmp01]

Sometimes you've just got to go and look at stuff....

[bmp01]

Take this with a pinch of salt, its not the whole answer because the teeth will be pulled every which way when cutting. For reference the steel ruler against chain are 1.07mm thick each.

 

Edited November 20, 2022 by bmp01
Clarification