325 ripping chain

[mtngun]

Search is not working well these days so I'll have to start a new thread for this subject, even though I'd prefer to tie it in to a couple of previous threads that discussed 325 cutting speed and kerf width.

Conventional wisdom here is that 325 is the fastest chain for 120cc saws, for up to 4' bar length, anyway.

So I ordered a reel of Carlton 325 x 0.063 semi-chisel. When I took it out of the box, my first thought was "that's just as wide as 3/8 milling chain." Hmmmmm :msp_ohmy:

How to measure kerf width precisely ?

I clamped a loop between two machinist's parallels, like this.

Side view.

Then used calipers to measure the gap between the parallels. Results:

30 RC -- 0.270" new 3/8 chisel
33 RP -- 0.266" used 3/8 ripping
325 x 0.063 -- 0.267" new Carlton semi-chisel
325 x 0.050 -- 0.260" new Laser ripping
30LP -- 0.221" much worn lo-pro ripping

This method of kerf measurement suggests that lo-pro is 17% narrower than 3/8, which roughly agrees with various cutting speed tests that I have performed.

But 325 kerf would appear to be identical to 3/8. :msp_sad:

Plus, 325 is limited to a 9 pin rim. A large spline 8 pin rim is not available for 325. I suspect my 084 would not care for a 9 pin 325, judging by how it struggled with an 8 pin 3/8.

Perhaps there is some advantage to 325 having a few more cutters in the wood than 3/8. Aggie once posted speed data showing that 325 was faster. If I remember correctly, Rail-o-matic favored 325, as well.

But, I'm skeptical. I feel like I wasted my money. I may just sell my reel of 325 and not even bother testing it.

 

[BobL]

Good bit of research Mtngun but width of chain may not necessarily translate into kerf width. with cutters closer together the wave length of the cutting action will probably change (ie shorter for the 325) so the degree of sideways cutting may be smaller.

I still reckon it's worth a couple of trials,

 

[hamish]

Dan, the gauge will be directly proporptional to the final kerf, as BobL mentioned the side to side movement will vary with the different distance between the cutters. 3/8" x .050 is almost spot on with respect to measurements as .325" x .050, yet the kerf is completely different once in the wood .003 seems like nothing but in use the difference is much greater.

I should have sent you some Oregon 95R, its much closer to the 3/8" lo-pro as its an NK style ripping chain.

Laser and Granberg style I dislike for extra effort required when sharpening, and the difference in the final product is negligible.

 

[AndrewMoizer]

Since we were discussing 3/8" low pro in my CSM topic I've been pondering the chain situation, likely letting the "best be the enemy of the good" but anyway!

Struck me the other day that even if 3/8" low pro and .325 cut the same it seems to me that the "logistics" of .325 might be easier. As long as I'm reading Baileys' right, you can get .325 sprockets and tips that would work straight off the shelf, and can get chain in either .050 or .063, so it makes bar choice easier. For instance a 36" .050 bar for my 1100 would be special order, but there's lots of .063 options. Looks like I could get .050 bars off the shelf up to 32". I'm not sure of the relative choices of off the shelf ripping chain, but if you're grinding your own I don't think that matters.

There must be more to it than that, but I'm pretty sure I've read examples of people having real good success with .325 chain with larger saws.

So I guess this is a vote for "more tests please".

cheers,
Andrew

 

[mtngun]

Struck me the other day that even if 3/8" low pro and .325 cut the same it seems to me that the "logistics" of .325 might be easier.

True on the logistics of .325, but the kerf is nowhere near as skinny as lo-pro. At least, not regular 325. Not sure about the narrow kerf 325, or if that is available for 0.063.

I put my reel of 325 on the 'bay. It didn't seem worth pursuing.

 

[srcarr52]

True on the logistics of .325, but the kerf is nowhere near as skinny as lo-pro. At least, not regular 325. Not sure about the narrow kerf 325, or if that is available for 0.063.

I put my reel of 325 on the 'bay. It didn't seem worth pursuing.

.325 NK is only available in 0.050". It may make it easier to do a 32" or less setup easier without having to make your own sprockets and modify the bar tips. You can get longer bars in 0.050" but they are hard to find.

BTW. I'm going to try my 3/8 LoPro setup in a large stick of Walnut soon. I'm going to try a modified Marlof grind, 5 deg top plate instead of 0 but I'll keep with the lots of hook angle theory.

 

[AndrewMoizer]

Measured my .325 NK

Today I finally got around to measuring my new Oregon 95VP .325 narrow kerf chain in the name of science if nothing else . I used much the same method as mtngun except I don't have a set of parallels so I used some cold rolled squares. It's a bit hard to know how tight to crank in the vice as the chain does seem to squeeze in some. With fairly light pressure things seemed to average out around .240. I used the same setup measuring a (what looked like lightly used) loop of 3/8 Low Pro that I had and it was definitely narrower, perhaps by 20 thou or so. Again it's hard to get an apple to apples comparison with knowing how hard to clamp things.

So the long and the short is that they're roughly the same. I'm thinking of getting a 28" .050 bar to fit my 1100. That's all I'd ever need for cross cutting and I expect for 95% of my milling too.

(As an aside, I'm moving closer to trying out the rig with the .404 .063 chain. Cut a few cedar spars left over from the ice storm to practice on today. Forecast is for 35°C and humid tomorrow here so I don't think I'm going to be too motivated to do much that involves any lifting outside tomorrow)

cheers,
Andrew