Getting serious about lo-pro

[Rob D]

Who uses 404 for milling ?

.404 is my main chain for milling.

Personally I have found it to be the fastest over a number of cuts in that it seems to retain the best stay sharp quality. And I find I mill quick with it.

I know the leading edge (or corner) is the critical thing with a chainsaw chain and this will be the same size low pro or not...... but I just find that .404 chain keeps cutting better for longer.

I may not be right this is just my own experience

 

[BobL]

Just have to say a great thread and I'd like to stick my neck out a little and add my pennys worth -
SNIP
So in relation to the above does switching over to a low pro system really warrant the effort anyway? As the first post says there seems to be no clear consensus on using low pro chain - that says a lot in itself!

I'm not sure how others (intend to) use LP but my experience so far on my 50 cc Plastic Fantastic Homelite 340 with a 20" bar is that it is faster than regular 3/8 to break up short logs that are smaller than 16" in diameter. I then resaw these on my 19" conventional bandsaw. Because the LP has shown a lot of promise I have bought a 25" .050 bar and will use it with a 441 to be able to tackle logs up to 21". At this stage I don't intend using it on anything bigger because the wood I cut is too hard and the bigger powerheads will almost certainly over stretch the LP chainb.

One reason why 404 has the potential to cut faster than 3/8 is that it has a bigger chip carrying capacity - but it also cuts a comparatively bigger kerf so the overall gain is not always as great as might be imagined. This gain is more visible in softer wood using big saws where cutting is limited by the chip carrying capacity of the chain.

In wood above about 1900 lb Janka hardness, milling is usually wood hardness limited so making a narrower chip is advantageous. A 3/8 chain makes a narrower chip than a 404, but then there are more cutters in the kerf. One way to reduce the number of cutters in the kerf is to use skip chain but the way full comp chain (of any size) cuts, is not the way most people think. Only about every 3rd or 4th cutter is cutting a serious chip, so it's already acting a like skip chain to begin with. The normal cutting action results in all chain porpoising up and down off the bar with only every cutter on top of the wave cutting significant wood and this is why semi-skip or full skip makes little difference compared to regular chain, if anything skip chains go blunter quicker because there are fewer cutters. To see a significant benefit in load reduction on a saw using skip, one needs to go to 3 or 5 skip chain.

One reason why operators prefer 404 over 3/8 is because they do not realize that because 3/8 cuts a smaller kerf it can operate with a higher cutting angle which creates deeper chips. Whereas, raising the cutting angle on a 404 chain to the same extent can just bog the saw. The 404 has other advantages eg if the chain strikes something large, the cutters are likely to stay on the chain compared to the 3/8. In terms of going blunt I agree 404 tends to stay sharp a little longer. The main thing for me is will a chain make it through a slab without having to drag it out of the kerf to resharpen it. As long as it gets to the end of the cut whether its 404 or 3/8 it's going to have to be touched up anyway. Up to about 12' long in big (36") hard wood (36 sqft of cut) the 3/8 chain is OK. Above this area I would consider going to 404.

 

[Rob D]

Thanks Bob. That's definately given me some food for thought!

 

[mtngun]

Trigger-Time posted some excellent info on picco chain a while back. I thought we had determined that Stihl Picco was somehow different than Oregon/Carlton lo-pro, but then I went back and re-read those old threads and ...... it's as clear as mud.

In any event, I have no plans to run picco/logosol chain because of the price, nor do I have any picco chain on hand to examine and compare.

However, I would like to know if picco sprockets are suitable for Oregon/Carlton lo-pro.

Since Picco is the same pitch as lo-spro, and since the picco drive sprocket diameter is a little larger than a 3/8 drive sprocket, I suspect the Picco drive sprockets would work perfect with lo-pro -- unless there is big difference in the shape of the drive links.

Here is some of Trigger-Time's info on picco sprockets from this thread.

Picco 7T.....1.433 dia = 4.502 circumference..........+0.167
Reg. 3/8 7T 1.380 dia = 4.335 circumference

Picco 8T......1.664 dia = 5.260 circumference........+0.183
Reg. 3/8 8T..1.606 dia = 5.077 circumference

 

[huskyhank]

snipped....

Since Picco is the same pitch as lo-spro, and since the picco drive sprocket diameter is a little larger than a 3/8 drive sprocket, I suspect the Picco drive sprockets would work perfectly with lo-pro -- unless there is big difference in the shape of the drive links.

If you know the pitch to be the same this will work. It would sure be nice to compare the drive link shapes. I wonder if you can get an engineering drawing for the chains? Or do you know someone with a machine shop who has high end metrology equipment?

 

[Mad Professor]

If you look at the conversion charts from the chain manufacturers:

stihl 63 PM (picco) = carlton NC1 = oregon 91VS (low-pro) = windsor 50R

It would be nice if someone manufactured the CORRECT rim (e.g. NOT regular 3/8) sprocket to fit the bigger saws.

You can adapt a small style 036 rim type drum to run on the bigger stihls but it will have a little wimpy bearing, this will allow you to run a stihl picco rim.

 

[mtngun]

stihl 63 PM (picco) = carlton NC1 = oregon 91VS (low-pro) = windsor 50R

You are probably right about picco being Stihl's equivalent to lo-pro. I owe you an apology for not listening to you sooner. But, this has been a confusing subject, and few of us have all the components available to examine and compare.

 

[Brmorgan]

Who uses 404 for milling ?

.404 is my main chain for milling.

Personally I have found it to be the fastest over a number of cuts in that it seems to retain the best stay sharp quality. And I find I mill quick with it.

I know the leading edge (or corner) is the critical thing with a chainsaw chain and this will be the same size low pro or not...... but I just find that .404 chain keeps cutting better for longer.

I may not be right this is just my own experience

I have a 33" .404 milling chain for my 090, but that's just because the .404 is the only bar I have for it! I don't have to worry about bogging that saw no matter how I file it, either! I'd love to get a 9 or 10 pin 3/8" sprocket to really make that thing sing though. Just not enough RPMs to warrant using it over the 395 in that size of wood.

Mtngun and BobL:

I just picked up a brand-new 25" .050 bar for that 066 I just finished rebuilding. Admittedly, the LP chain does ride quite high on the nose sprocket teeth on this one since they're brand new. On the old bar I've been using it sat down nice and tight on the nose. In any event, I used it all day yesterday with a brand-new Oregon 91VS chain filed at 25° in 12-18" W.R. Cedar, and yes it did stretch a bit on the first couple cuts, but it cut beautifully smooth and without incident. I forgot the camera though so I can't give a shot of the smoothness of the cut - but I bet a 1/32" pass on the planer would have taken any saw marks out, it was that good. And FAST! Not sure I feel the need to buy actual low-pro milling chain anymore, really. Anyhow I'm heading outside to work on that stuff a little bit right now - another beautiful sunny day here. I'll take some pics.

 

[Kicker_92]

One reason why operators prefer 404 over 3/8 is because they do not realize that because 3/8 cuts a smaller kerf it can operate with a higher cutting angle which creates deeper chips.

What is the limit for cutting angles? I'm using 8° for softwood with 3/8" semi-skip right now. Is there a point where the cutter becomes less efficient? (10°, 12°, 20°?)

 

[BobL]

What is the limit for cutting angles? I'm using 8° for softwood with 3/8" semi-skip right now. Is there a point where the cutter becomes less efficient? (10°, 12°, 20°?)

Assuming the chain is already cutting, the cutting efficiency (size of chip) keeps increasing with cutting angle (CA) utilthe powerhead finally bogs. I could suggest you just try gently increasing the CA but before you do perhaps you would like to see what the raker depths are for different CAs.

For those that are unsure - this is what I mean by cutting angle.

This table shows the raker depths for various cutting angles (CA) in red, at various gullet widths in blue.

A "normal" CA, eg for a chain fresh out of the box chain is 6º, so this means using the green line at different gullet widths.

Rather than mucking about with measuring gullets and depths I find it easier to use a digital angle finder (DAF) and file the raker and measure the angle direct with the DAF. For those that still confused, check out the FOP sticky in the CS forum. Towards the end of that thread (post #68) I posted a movie about how I do this. Please note I don't do this every time I touch up the rakers. I touch up the cutters (2-3 strokes) after about every 32 sqft of milling, whereas I free hand the rakers (~2 strokes) after every 3-4 touch ups. I reset the rakers like this off the mill after every 2-3 full days of milling when I swap out the chain and flip the bar.

Note after the cutter is about 1/4 worn an FOP only creates a 4.6º CA which is on the wimpy side of CA's especially for bigger saws.

As a guide I can cut up to about 50" wide very hard wood with my 880 using a CA of 6º on a 3/8 chain. Currently the raker depths on some of my chains are around 0.045" and look quite squished but I have never made such lovely fat chips as this with used chain. If I was going to cut bigger wood than than this, in my harder woods I have several options, using 3 or 5 skip, or reducing the CA, or using a bigger powerhead.

Skip chain, softer wood and smaller cutters should permit use of a higher CA without bogging the saw. Although I haven't tried it I don't think there is much advantage in going to a higher CA for skip chain unless it is something like 3 or 5 skip chain. Regular skip may have other advantages especially in softwoods like more room for sawdust and less cutters to sharpen but these are less of an advantage in harder woods.

With an 090 a 9º CA would not be out of the question for shorter bars in softer wood

On a 30 HP Lucas slabber even using 404 chain, a 10º CA is possible.

At some point or other the chain will eventually run out of raker, if so you should be using 404 or harvester chain.

BTW Old timers didn't worry about any of this. If their chains weren't cutting they would keep filing their rakers until they made chips again. The FOP is a distinct improvement on the fixed gauge supplied by most CS and chain manufacturers who probably think this is too technical for weekend warriors to work out. I don't blame them - it probably reduces the number of kickback incidents that would result from making mistakes in raker adjustment and increases new chain sales.

What's this got to do with lopro? Well, in theory the smaller LP cutter should permit a higher cutting angle (provided the saw can pull the chain and the chain can cope with the strain). I'm planning on using a 25" bar on a 441. I'll start with 6º but 7 or even 8º might not be out of the question, even with the 441. On a 660 an 8º CA may just wreck the chain?

 

[Mad Professor]

You are probably right about picco being Stihl's equivalent to lo-pro. I owe you an apology for not listening to you sooner. But, this has been a confusing subject, and few of us have all the components available to examine and compare.

I've been running the 63 PMX (the milling stuff only available via logosol) on my 066 and M5 mill since 1998.

Most of the stuff is for grade, cherry heartwood, so I like the narrow kerf/less waste/sawdust.

I've only snapped one chain (24") so far, when a vibration set up and I kept on cutting, instead of backing out (MY fault). Nothing lost except the chain.......which needed a repair.

The less expensive equivalents might be a good buy, but you loose a bunch of tooth grinding them back to a milling angle, and a bunch of time grinding.

The other pisser is the $40 picco spur sprocket for the 066. The adapt to a small/early 036 that will take a picco rim is tempting, but if you trash the diminutive bearing you might trash your $$$$ crankshaft.

The other option is 0.325, for which there are rims to fit the medium/big saws. I've not tried this but others report good results.

I hope to skid some logs and will post some (milling) pics soon.....got to do something while the sap is boiling!!!

 

[Philbert]

This table shows the raker depths for various cutting angles (CA) in red, at various gullet widths in blue.

Thanks again BobL!

Do you have some simpler rules of thumb that can be generalized, based on your experimentation? Specifically, I would like to know your recommendations for cutting angles for:
- cross-cutting hardwood;
- cross-cutting softwood;
- ripping hardwood;
- ripping softwood;
- etc.

I realize from your post above that it will vary with the powerhead and chain, but it would be nice if it could be summarized, e.g. '6º for general cross-cutting, Xº for ripping, Yº for . . . ' recognizing that some adjustments will always need to be made from these starting points to optimize a cutting situation.

Philbert

 

[BobL]

Thanks again BobL!

Do you have some simpler rules of thumb that can be generalized, based on your experimentation? Specifically, I would like to know your recommendations for cutting angles for:
- cross-cutting hardwood;
- cross-cutting softwood;
- ripping hardwood;
- ripping softwood;
- etc.

I realize from your post above that it will vary with the powerhead and chain, but it would be nice if it could be summarized, e.g. '6º for general cross-cutting, Xº for ripping, Yº for . . . ' recognizing that some adjustments will always need to be made from these starting points to optimize a cutting situation.

Philbert

Sorry but there are too many variables and even personal saw operator pressure preferences. Some operators like to hoik on their saws while others like to feather them etc - this will be very sensitive around the "chain grabbing point".

Some other variables that have to be included are;
Bar/chain length or more importantly wood cut width, wood hardness, wood cleanliness, chain gauge, skip, cutter size and cutter profile, as soon as you mess with any of these that will affect the optimum CA.

I only occasionally cross cut so I have not been able to devote any time to experimenting with optimising this sort of cutting.
I only have access to hard or harder or incredibly hard wood so I can't comment on softwood either.

About the only variation I can comment on is that using a 7º CA on a 3/8 full comp chain on an 880 (with a muffler mod) doesn't grab in my hardwood up to about 40" in hard wood. Above that it gets grabby and I have to hold back the saw so 6 to 6.5º is about optimum. 7º might be OK with Skip under the same conditions

The starting point for any saw is the factory recommended bar and chain and raker depth setting.
This is normally ~6º for most saws/chains.
Then vary the CA gently upwards until the saw bogs and back it off from there.

 

[Brmorgan]

Bob, I assume when you say "cutting angle" it's equivalent to what I would more commonly call the "hook angle"? If so I probably run about 10° on most of my chains, firewood, milling, or whatever. I've never measured though. I usually find the first pass a little bit grabby after freshly sharpening that way, but it seems to cut faster with less load on the saw if you control the cut. Of course I'm not dealing with wood nearly as hard or wide as you usually do though.

Here's a pic of the new Oregon 91VS on the brand-new Stihl bar I've been using the last couple days:

As I noted, it rides a bit high on the sprocket. However since the whole idea of a sprocket tip is to keep the chain from riding on the bar nose in the first place, I don't really see it as much of an issue. I checked and even a new standard 3/8" chain sits a little high too. The hook angle on this chain is a little on the low side still; even my 5/32" files seem a bit big for it because they're already starting to bite into the tie straps and it's only been filed 4 times, and even then only touchups. This Oregon stuff sure has small cutters to start out with. Here it is beside some WP/Carlton LP ripping chain:

The Oregon is on top. As you can see the Carlton has much more cutter life, and costs less to boot. But the Oregon cuts just as quick and leaves just as smooth of a surface.

 

[Brmorgan]

Made a quick video today of three passes with the Oregon LP chain on an 8-pin rim on the rebuilt 066 in 11" Pine:

http://www.youtube.com/watch?v=zZt4nFXKzsg


Here's what the milled surface looked like on today's cuts:

And here's what the Carlton produced last night on the same bar & sprocket:

To me the final result is indistinguishable and the cut speeds are pretty close too.


Here's what I ended up milling in total today:

I got 21 boards between 7-12" wide from the four Pine logs I cut. I also milled the remainder of an old spalted Birch piece I've had for a couple years which just thawed out of the snowbank, and a Juniper log as well.

The Birch looks really nice, but is pretty soft in areas. It might take a lot of CA glue to make it workable. They're 1-1/2" thick and bookmatched quite well though, so I'm going to do my best to save them.

 

[BobL]

Bob, I assume when you say "cutting angle" it's equivalent to what I would more commonly call the "hook angle"? If so I probably run about 10° on most of my chains, firewood, milling, or whatever. I've never measured though. I usually find the first pass a little bit grabby after freshly sharpening that way, but it seems to cut faster with less load on the saw if you control the cut. Of course I'm not dealing with wood nearly as hard or wide as you usually do though.

CA is different from hook. CA is the angle between 1) the raker, 2) the cutter top plate, and 3) the wood.
Like this.

CA has been discussed in grimy detail in the CS forum sticky.
http://www.arboristsite.com/showthread.php?t=114624

In summary I end up describing that one can forget about worrying about what raker depth to use because ideal raker depth changes with cutter/gullet length, and just concentrate on maintaining a fixed cutting angle for a given cutting setup.

Its probably has less of an impact on cutting softwoods, but I have never see such consistently fat chips from well used before in the hardwoods I cut. Everyone that has had trouble with getting nice chips from old chains is really impressed that they can get back "new chain cutting action" by using (aspects of) this approach.

As I have already said, old timers did it by just continually filing their rakers till they got chips. The FOP approach is a rough approximation and a tad on the wimpy side. This just quantifies the process enabling (particularly) newbies to have a bit more control over what they are doing

 

[Brmorgan]

Ah yes, of course I remember now. I've never bothered to measure that either! I'm by no means an old-timer but that's more of the approach I take. I also keep an eye on the rakers - if they're getting really polished down smooth from being pushed into the wood, I knock a couple strokes off of them again.

 

[Kicker_92]

What's this got to do with lopro? Well, in theory the smaller LP cutter should permit a higher cutting angle (provided the saw can pull the chain and the chain can cope with the strain). I'm planning on using a 25" bar on a 441. I'll start with 6º but 7 or even 8º might not be out of the question, even with the 441. On a 660 an 8º CA may just wreck the chain?

Another option that increasing the cutting angle is to gear up the saw. I've got some loops of 3/8" lo-pro to go on the 85cc, and the 7-pin sprocket might be a tad on the slow side. For a 20" wide cut, it should be able to pull that smaller chanin with an 8-pin, or maybe even a 9-pin if I can find one.

 

[Brmorgan]

My 066 does really well on an 8-pin in up to 20" of wood (as in the video I posted on the last page if you missed it). I haven't tried longer though because that's the most clearance I can get from the 25" bar once it's mounted up on the mill. I wouldn't dare a 9-pin really; maybe you could get away with it up to 10" or so. But who knows. For the price of them I'm not about to try it on a whim. I find the 8-pin somewhat easy to bog out if the chain is freshly sharpened a bit aggressively anyway unless I make sure to take extra care to control the cut.

 

[BobL]

Another option that increasing the cutting angle is to gear up the saw. I've got some loops of 3/8" lo-pro to go on the 85cc, and the 7-pin sprocket might be a tad on the slow side. For a 20" wide cut, it should be able to pull that smaller chanin with an 8-pin, or maybe even a 9-pin if I can find one.

Another possible way of putting this to good use when doing long days in the field is to start out with aggressive rakers and run a 7 pin sprocket. Then after touching up the cutters 3-4 times swap to an 8 pin sprocket.

This saves the hassle of doing the rakers in the field.